*G01-1-01
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Status of the International Terrestrial Reference Frame: ITRF2014 andfuture developments* Zuheir Altamimi , Paul Rebischung , Laurent Metivier , Xavier Collilieux , Kristel Chanard
IGN France
We review the progress and continuous improvements being made since more than 30 years in thedetermination and development of the International Terrestrial Reference Frame (ITRF). We evaluate theprecision and accuracy of the main geodetic and geophysical products of the latest ITRF release, namely
the ITRF2014, using some key performance indicators. These indicators include the evaluation of theperformance of the annual and semi-annual signals and Post-Seismic Deformation (PSD) models: the twomain innovations introduced in the ITRF2014 elaboration. We address some scientific questions of space
geodesy contribution, via ITRF2014 results, to understanding geophysical processes that affect the Earthsystem, such as earthquake displacement, tectonic motion, glacial isostatic adjustment, geocenter motion
and loading effects. We evaluate in particular the performance of estimating periodic signals versus
applying a non-tidal atmospheric loading model, as well as the extrapolation of the PSD models beyond the
ITRF2014 time-span for sites that are subjects to major earthquakes. A particular emphasis will be devoted
to the level of agreement between techniques in terms of frame physical parameters (origin and scale),
Earth Orientation Parameters, and consistency with terrestrial local ties at co-location sites. Mainconclusions will be drawn to guide and improve our analysis and combination strategy for future ITRF
developments.

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*G01-1-02
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Analysis of the seasonal parameters estimated in the ITRF2014 processing* Xavier Collilieux , Zuheir Altamimi , Paul Rebischung , Laurent Metivier , Kristel Chanard
IGN France
Annual and semi-annual periodic coordinate variations have been estimated simultaneously with positionsand velocities of geodetic sites in the first step of the ITRF2014 processing. Four datasets are available
corresponding to the four geodetic techniques, namely Global Navigation Satellite Systems, Very Long
Baseline Interferometry, Satellite Laser Ranging and Doppler Orbitography and Radiopositioning
Integrated by Satellites. At sites where stations of several techniques are operating, the seasonalparameters are worth comparing. Indeed, within a co-location site, nearby instruments are supposed tomeasure the same physical ground motion. As a consequence, any discrepancy between techniques could
be interpreted as technique-specific errors if annual and semi-annual ground motions are computed overthe same period. Thus, the aim of this paper is to evaluate the level of agreement of seasonal parameters
estimated by different techniques at co-location sites.

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*G01-1-03
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

JTRF2014: A Time Series Representation of the ITRF
* Richard Gross , Claudio Abbondanza , T. Mike Chin , Mike Heflin , Jay Parker , Xiaoping Wu
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA
The Jet Propulsion Laboratory (JPL) is pursuing an approach to determining ITRF-like terrestrial reference
frames based upon the use of a Kalman filter/smoother. Kalman filters are commonly used to estimate theparameters of some system when a stochastic model of the system is available and when the data containnoise. For the purpose of determining a terrestrial reference frame, the system consists of the positions andvelocities of geodetic observing stations and associated EOPs along with their full covariance matrices. The
data consist of time series of observed VLBI, SLR, GNSS, and DORIS station positions and EOPs along withthe data measurement covariance matrices. In addition, measurements from ground surveys of thepositions of reference marks of co-located stations are used as constraints to tie the technique-specificmeasurements to each other. JPL's Kalman filter and smoother for reference frame determination(KALREF) combines these measurements to determine ITRF-like reference frames subject to constraints
imposed on the allowed evolution of the station positions. KALREF includes options to model the station
motion as linear, linear and annual, or linear, annual, and semiannual. Through the use of stochastic
models for the process noise, the station positions can be constrained to follow these models of the station
motion (by setting the process noise to zero), to recover the observed station positions (by setting theprocess noise to a large value), or to follow a smoothed path (by setting the process noise to someintermediate value). The time series approach to determining terrestrial reference frames that is being
pursued at JPL will be described along with its use to determine JTRF2014, JPL's realization of a terrestrialreference frame using the ITRF2014 input data sets.

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*G01-1-04
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

DGFI-TUM analysis and scale investigations of the latest terrestrialreference frame realizations
Mathis Blossfeld , * Detlef Angermann , Manuela Seitz
DGFI-TUM, Munich, Germany
Solutions for the most recent realizations of the International Terrestrial Reference System (ITRS) werecomputed by the three ITRS Combination Centers (CCs) of the International Earth Rotation and Reference
System Service (IERS), namely the IGN in Paris (France), the JPL in Pasadena (US) and the DGFI-TUM in
Munich (Germany). Thereby, the solutions of IGN and DGFI-TUM comprise conventional parameters of the
ITRS (station coordinates and velocities) at a reference epoch as defined in the IERS Conventions 2010
(Petit et al., 2010). The two solutions are based on identical input data, but differences in the ITRS
realization strategies lead to systematic differences between them.
The most important differences are the combination of normal equations systems versus the combinationof solutions, the application of non-tidal loading models versus the estimjation of annual and semi-amnnual
signals and the different handling of local ties.
Within all ITRS realizations, the scale is realized as a weighted mean scale between SLR (satellite laser
ranging) and VLBI (very long baseline interferometry). If the combined scale is compared to the scalerealized by both techniques itself, the IGN solutions shows significant differences between SLR and VLBI
whereas the DGFI-TUM solution shows a better agreement.
In order to investigate the question whether there is a systematic scale difference between the twosolutions or not, the combined solutions of IGN and DGFI-TUM as well as the single-technique solutions ofboth institutions are analyzed and compared. In addition, the impact of the used local ties on the scalerealization is investigated. Moreover, the realization of the origin and the orientation of the two ITRS
realizations is compared.

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*G01-1-05
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

IGS14/igs14.atx: Implications for IGS productsPaul Rebischung 1) , Ralf Schmid 2) , * Xavier Collilieux 1) , Zuheir Altamimi 1)
IGN France 1) , Technical University of Munich, Germany 2)
On January 29, 2017, the International GNSS Service (IGS) adopted a new reference frame (IGS14), basedon the latest release of the International Terrestrial Reference Frame (ITRF2014), as the basis for its
products. An updated set of satellite and ground antenna calibrations (igs14.atx) became effective at thesame time. IGS14 and igs14.atx replace the previous IGS08/igs08.atx framework in use since April 17,
2011 and in the second IGS reprocessing campaign (repro2).
The update from IGS08/igs08.atx to IGS14/igs14.atx covers three different aspects, each with different
expected impacts on the IGS products. First, the update of the reference frame itself is expected to improve
the precision of the alignment of the IGS products to the ITRF, since IGS14 includes more availablereference frame stations with more precise and up-to-date coordinates than IGS08.
Secondly, compared to igs08.atx, igs14.atx includes robot calibrations for 17 additional ground antenna
types and 19 updated type-mean robot calibrations. These calibration updates are expected to increase
coordinate accuracy for stations equipped with these antennas and may also lead to improved
repeatabilities of their position time series.
Finally, the radial components of all GPS and GLONASS satellite phase center offsets (z-PCOs) were
updated from igs08.atx to igs14.atx. The satellite z-PCOs were changed by about -6 cm on average,changing the scale of the IGS daily solutions by about +0.5 ppb and bringing it closer to the ITRF scale.
The update of the z-PCOs of recently launched satellites, from preliminary block-specific values to satellitespecific estimates, is additionally expected to reduce large-scale systematic errors in IGS station positions
and in particular to stabilize the scale of the IGS daily solutions.
This presentation will first review the elaboration of IGS14 and igs14.atx. The different impacts of theswitch on IGS products will then be quantified and discussed.

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*G01-1-06
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

The status of DORIS in light of ITRF2014* Frank Lemoine 1) , Laurent Soudarin 2) , Guilhem Moreaux 2) , Hugues Capdeville 2) , Jean-Michel Lemoine, Pascale Ferrage 3) , Jerome Saunier 4) , Denise Dettmering 5) , Marek Ziebart 6) , Pascal WIllis 4) 7) ,Patrick Michael 1)
NASA Goddard Space Flight Center, Greenbelt, Maryland, U.S.A. 1) , Collecte Localisation Satellite,
Ramonville Saint Agne, FRANCE 2) , Centre National D'Etudes Spatiales, Toulouse, FRANCE 3) , Institut
National de l'information Geographique et forestiere, Saint-Mande, FRANCE 4) , DGFI, Technical Universityof Munich, Munich , GERMANY 5) , University College London, London, UNITED KINGDOM 6) , Institut dePhysique du Globe de Paris, UMR 7154, Gravimetrie et Geodesie Spatiale, Universite Paris Diderot, Paris,
FRANCE 7)
3)

The Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) is one of the four
techniques of Space Geodesy that contributes to the International Terrestrial Reference Frame. It consistsof a network of 55-60 beacons distributed nearly homogeneously around the Earth's surface, as well as asatellite segment including up to six receiving satellites in Low Earth Orbit. Recently the DORIS community
reprocessed more than 22 years of data in order to develop the DORIS technique contribution to the
ITRF2014 realization of the International Terrestrial Reference Frame (ITRF). Six analysis centers
implemented a series of improvements in both measurement and force modeling in order to develop theircontributions. The IDS Combination Center prepared the technique contribution which revealed thatrecent data since the launch of Jason-2 have an intrinsic positioning uncertainty 9, 7, 8 mm respectively in
the North, East and Up components, and yield a standard deviation in the polar motion differences with
IERS C04 of 245 (Px) and 235 (Py) microseconds.
We discuss in this paper the continuing improvements in the DORIS technique since the completion of
ITRF2014. These include the efforts to process a rawer form of the DORIS observable in the RINEX format,
the development of a routine combination of DORIS coordinates for application to precise orbit
determination DPOD2014, and a preliminary assessment of the contributions of Sentinel-3A and Jason-3 tothe DORIS weekly solutions. We also review the performance of the “C" generation of Starec beacons,
whose phase centers are defined to +/- 1 mm, and whose development and deployment was initiated inlight of the work done by the IDS for ITRF2014.

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*G01-2-01
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Progress towards the third realisation of the International Celestial
Reference Frame* Patrick Charlot
Laboratoire d'Astrophysique de Bordeaux, Pessac, France
The presentation will review the progress towards the generation of the third realization of theInternational Celestial Reference Frame. The work for ICRF3 is carried out by a Working Group of the IAU
with the aim of completing ICRF3 by 2018 for adoption at the IAU General Assembly in Vienna. ICRF3 will
be based on state-of-the-art astronomical and geophysical modeling and will benefit from the wealth of
VLBI data acquired since ICRF2 was built in 2009 (an additional 60% of data). Areas of work include
selecting the datasets, defining the analysis configuration, identifying the stable sources, identifying the
ICRF2 to ICRF3 transfer sources, and selecting defining sources for ICRF3. The latter takes advantage ofthe many VLBI images available to derive source structure indices which provide a mean to assess theastrometric quality of the sources. Specific attention will be paid to the treatment of Galactic aberration
which affects VLBI data at a significant level due to the > 30 yr time-baseline. Besides the standard S/Xband observations (2.3/8.4 GHz), data at K band (24 GHz) and X/Ka band (8.4/32 GHz) are being
considered, while the recent Gaia Data Release (DR1) provides a unique check against optical positions.
Finally, an additional stage which combines rigorously individual solutions into a consolidated VLBI
catalog is also investigated.

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*G01-2-02
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Testing of special relativity with geodetic VLBI
* Oleg Titov 1) , Hana Krasna 2)
Geoscience Australia, Canberra, Australia 1) , TU Wien, Vienna, Austria 2)
The geodetic Very Long Baseline Interferometry (VLBI) measures the group delay observable in thebarycentric reference frame. As the Earth is orbiting around the Solar System Barycentre with the velocity
V of 30 km/s,the VLBI turns to be a handy tool to detect the subtle effects of the special relativity theory
with a magnitude of (V/c)^2. The theoretical correction for the second order terms reaches up to 300 ps,
and it is implemented in the geodetic VLBI group delay model. The total contribution of the second orderterms splits to two effects - the contraction of the Earth scale in the plane perpendicular to the orbital
velocity vector direction, and the displacement of the radio source apparent position. We are using theRobertson-Mansouri-Sexl (RMS) formalism to probe the Lorentz invariance. We analyse the geodetic VLBI
data with two independent software packages (OCCAM and VieVS) and show that the parameters of theRMS model can be estimated with a high accuracy.

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*G01-2-03
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Correlated atmosphere noise in VLBI analysis* Hana Krasna 1) , John Gipson 2)
TU Wien, Vienna, Austria 1) , NVI, Inc., Greenbelt, USA 2)
The standard assumption in the routine VLBI analysis is that the observations are station and time
independent which manifests itself in a diagonal observation covariance matrix. But this simplification
causes a mis-characterisation of the measured group delays leading to incorrect estimation of parameters
and too optimistic formal errors. In the first step we compare the estimated baseline length scatter from
CONTinuous VLBI campaigns using two ways of reweighting obsevations, i.e. adding baseline dependentand elevation dependent noise. In the second step we introduce correlations into the observation
covariance matrix focusing on mis-modeling of the atmosphere and taking into acount correlations between
observations at a common time. We demonstate that this reduces the baseline length scatter, indicatingthat the results are more consistent day-to-day. We also show that introducing the correlations improves theagreement between VLBI and GPS measured polar motion.

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*G01-2-04
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Ray-traced delays and global reference frames with geodetic VLBIDavid Mayer , Hana Krasna , Daniel Landskron , * Johannes Boehm
Technische Universitaet Wien, Vienna, Austria
Geodetic Very Long Baseline Interferometry (VLBI) observations have been carried out since 1979 with a
total number of more than 10 million group delays as of 2017. We use operational and re-analysis data of
the European Centre for Medium-range Weather Forecasts (ECMWF) with a temporal resolution of six
hours and a spatial resolution of one degree to determine ray-traced delays for every single VLBI
observation as well as to determine horizontal tropospheric north and east gradients for all sites every six
hours. We then use those tropospheric delays in the analysis of all VLBI observations to estimate terrestrial
and celestial reference frames and to compare the results against those from standard analysis setups. In
particular, we assess the influence of refined tropospheric models on the declination of source coordinates,on station heights, and on baseline length repeatabilities.

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*G01-2-05
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Space tie satellites for millimetre geodesy – a VLBI perspective* Lucia Plank 1) , Jamie McCallum 1) , Andreas Hellerschmied 2) , Johannes Boehm 2) , Jing Sun 3)
University of Tasmania, Hobart, Australia 1) , Technische Universitaet Wien, Vienna, Austria 2) , Beijing
Aerospace Control Center, Beijing, China 3)
Space tie satellites are of major interest in the geodetic community, bearing the potential of a major step
forward in realising the terrestrial reference frame (TRF). Combining all four space geodetic techniques ona single satellite platform, this novel concept will improve the accuracy and stability of the TRF, inparticular concerning the Geocentre, the scale and the connection to the inertial celestial frame. Withsophisticated satellite missions being proposed and prototype missions already in space, thorough researchis clearly trailing behind and highly necessary. This concerns predominantly the very long baseline
interferometry (VLBI) part, since VLBI observations of low Earth orbiting satellites are absolutely novel.
In this contribution we report on a series of test observations which were performed using radio telescopesin Australia. Following essential developments in the observing setup and process chain, our main result isa six-hour time series of VLBI satellite observations using a set of GNSS satellites. Further we report onobservations of the Chinese APOD satellite, which is equipped with a dedicated VLBI transmitter, using theAustralian AuScope VLBI array. Having developed a complete process chain from the observations toinitial geodetic results, we report on issues we have encountered and problems that still need to be solved.
Hereby the focus is on optimal compatibility of existing VLBI station hardware and future space tie
missions.
The first time series of VLBI satellite observations represents a breakthrough in this novel technique, now
enabling further developments and bringing the first realisation of VLBI space ties within reach.

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*G01-3-01
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Robust realization of a no-net rotation reference frame on a deforming
tectonic plate* Geoffrey Blewitt , Corne Kreemer , William C. Hammond
Nevada Geodetic Laboratory, Nevada Bureau of Mines & Geology, University of Nevada, Reno, USA
We present a robust method of fixing a reference frame to a moving and deforming plate, using the example
of North America. Scientific applications motivate that we fix the frame with a scale consistent with the SI
system, an origin that coincides with the Earth system's center of mass, and with axes attached to therotating interior of the plate. To realize this no-net rotation condition, a typical approach is to select a
subset of “core stations" that have small residual velocities. Stations in the far field of plate boundaries
and glacial isostatic adjustment can be selected to satisfy these criteria. However, such regions of the
Earth's crust may appear to be rigid (e.g., ~0.3 mm/yr residuals for core stations in our NA12 frame), but
the entire region can move relative to plate motion. Such common-mode motion biases plate rotation
estimation, with implications on scientific interpretation. Our scheme presented here (1) starts with robust
estimation of station velocities using our MIDAS algorithm, (2) then uses median spatial filtering to remove
outlier stations that do not reflect the regional trend, and (3) performs simultaneous estimation of strainrate tensor and rotation components for any chosen point within the plate using our new algorithm, MELD(“median estimate of local deformation"). MELD uses velocities from all possible triangles of stations
enclosing each point within 2 or 3 nearest neighbors of the Delaunay Triangulation. From the parameter
estimates of all local triangles, the median value for each strain rate and rotation component is then taken.
From this analysis, we then take an area-weighted sum of rotations over all points to estimate plate rotation,
which is then subtracted to define a no-net rotation, plate-fixed reference frame. This procedure estimates
the rotation pole robustly, and the residual velocities prove to be significantly different than in frames
realized using subsets of stations that appear to be internally rigid.

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*G01-3-02
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Three Dimensional Strain-Rate Field from Geodetic Measurements on the
Surface
Arturo Villiger 1) 3) , * Alain Geiger 1) , Fabian Neyer 1) , Elmar Brockmann 2)
ETH, Zurich, Switzerland 1) , Topographic Office of Switzerland, Bern, Switzerland 2) , University of Bern,
Bern, Switzerland 3)
Geodetic measurements for strain determination are in many cases carried out at the Earth's surface, thus
topologically remaining in a 2D manifold. Even though changes in the third component are determined e.g.
by levelling it will hardly be possible to determine the real 3D strain. Our method circumvents this problem
by introducing a crustal model. Even simple models help and deliver quite realistic results as shown in thispaper. In the case of Switzerland, however, this remains very demanding because of the very small yearly
movements generating equivalently small yearly crustal distortions at a maximum of 25 nstrain per year.
The available time series of GNSS and levelling measurements acquired and treated by the Swiss office of
topography, are sufficiently long to reveal deformations in Switzerland. They make it possible to determine
a coherent kinematic deformation field of Switzerland by geodetic means.
Further development of the ‚Adaptive Least-Square Collocation (ALSC)‘, which was devised at ETH, andthe implementation of a physical crustal model made it possible to directly calculate a three dimensionalstrain tensor field out of the available measurements e.g. GPS and levelling. The geodetically determinedstrain-tensors are verified versus focal mechanisms obtained from seismological data. The mechanism of a
recently induced earthquake mechanism in the region of St. Gallen close to a geothermal test site is inagreement with the strain tensors determined by GPS-data. The described method can also be applied tomore local events, e.g. the analysis of subsidence or landslides. It will allow to gain more insight into
subsurface processes from geodetic measurements.
The paper presents the method and shows results of geodetic determination of strain field in the complex
tectonic setting of the Swiss Alps.
Project partly funded by the Swiss Nat. Sci. Foundation and the Competence Center Environment andSustainability of ETH Domain (CCES), and swisstopo.

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*G01-3-03
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Spatially correlated ground deformation models in reference frame
estimation* T. Mike Chin , Claudio Abbondanza , Richard Gross , Mike Heflin , Jay Parker , Benedikt Soja , XiaoPing
Wu
Jet Propulsion Lab, California Institute of Technology, Pasadena, California
A terrestrial reference frame (TRF) is estimated from space-geodetic station-position data sets that are
several decades long. The primary model upon which the data are combined has been the linear motion
due mostly to plate tectonics and post-glacial rebound. In recent TRF realizations such as ITRF2014 and
JTRF2014, models of local motions are introduced to improve the estimation accuracy. These additionalmodels include post-seismic displacements as well as annual, semi-annual, and random grounddeformations due to atmospheric loading and ground water storage loading. Although such motions areoften regionally correlated, the models of these ground deformations are formulated to be strictly local inspace at present. In this presentation, we present our approach to include spatial correlation in the context
of the stochastic motion model of geodetic station positions used in the JTRF2014 realization. In particular,
we focus on the use of time-varying gravity data from the GRACE mission to globally determine spatial
correlations in seasonal ground deformation. We will incorporate the data-driven correlations in thestochastic model and then examine effects of the spatial correlations on the TRF estimates. We note that
the GRACE data do not directly enter in the TRF (station position) estimates; instead, the spatial
correlations estimated from GRACE data will be used as parameters of the stochastic model used in TRF
estimation.

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*G01-3-04
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Differential station coordinates changes (velocities) versus coordinate
differences (epoch solutions) for realising the time dependence in ITRF
* Hermann Drewes
Technical University Munich, Munich, Germany
The International Terrestrial Reference Frame (ITRF) and its continental densifications (e.g. EUREF,
SIRGAS) provide differential coordinate changes (linear coordinate derivatives, i.e. constant velocities) forinterpolating or extrapolating the reference station coordinates to an arbitrary epoch, e.g. for satellite
tracking or precise terrestrial positioning. These station velocities are also applied for geographicalinterpolation of the movements of intermediate points, e.g. used in engineering, surveying, precise
navigation, and geodynamic studies. If the velocities are not constant, e.g. due to effects caused by seismic
events or environmental non-linear surface deformations, the interpolation or extrapolation between
epochs has to be done piecewise for all contemplable periods and effects, and the geographicalinterpolation has to follow the same procedure which may be very complicated in unstable regions. The
present paper describes an option to use frequent (e.g. monthly) epoch reference coordinates instead ofvelocities, and to use them for practical applications (e.g. geographical interpolation of time-dependent
coordinates of other points of the Earth surface). The advantage is that the reference stations' epoch
coordinates include all occurred changes between the epochs, i.e. linear and non-linear station movements,
and discontinuities caused by seismic events or changes of the reference frame. The method is tested in
global, continental and national networks and yields good results.

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*G01-3-05
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Kalman filter terrestrial reference frame solutions based on time-variable
process noise* Benedikt Soja 1) , Richard Gross 1) , Claudio Abbondanza 1) , Toshio Chin 1) , Michael Heflin 1) , XiaopingWu 1) , Kyriakos Balidakis 2) , Tobias Nilsson 3) , Susanne Glaser 2) , Maria Karbon 2) , Robert Heinkelmann 3), Harald Schuh 2) 3)
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States of America 1) ,Technische Universität Berlin, Berlin, Germany 2) , GFZ German Research Centre for Geosciences,
Potsdam, Germany 3)
In recent years, Kalman filtering has emerged as a suitable technique to determine terrestrial reference
frames (TRFs), a prime example being the JTRF2014 solution by the IERS ITRS Combination Center at JPL.
The time series approach allows variations of stations coordinates that are neither reduced byobservational corrections nor considered in the functional model to be taken into account. These variations
are primarily due to non-tidal geophysical loading effects that are not included in the IERS conventions(i.e., non-tidal atmospheric pressure, ocean, and continental water storage loading). It is standard practicethat the process noise models applied in Kalman filter TRF solutions are derived from time series of theaforementioned geophysical loading effects and account for station dependent differences. So far, it has
been assumed that the parameters of these process noise models are constant over time. However, due tothe presence of seasonal variations and episodic events such as ENSO, this assumption does not truly
reflect reality. In this study, we derive a station coordinate process noise model allowing for such temporalvariations. Time series of daily non-tidal loading deformations between 1985 and the end of 2015 provided
by GFZ Potsdam are used to calculate monthly process noise parameters for every single station. As a test
case, this process noise model is applied in the computation of a TRF based on very long baseline
interferometry (VLBI) data from over 4000 VLBI sessions during the same time frame. The resulting VLBITRF is compared to a solution based on a constant process noise model, but otherwise on identical input
data and Kalman filter setup. In particular, it is investigated which VLBI stations profit the most from aspatiotemporal process noise model and how frame defining parameters, such as the scale, are affected.

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*G01-3-06
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Variant and Invariant Properties of Coordinate Transformation* Gilad Even-Tzur
Technion - Israel Institute of Technology, Haifa, Israel
An invariant coordinate transformation is a transformation where the quadratic form of the weighted
residuals is preserved regardless of the coordinate system in which the transformation parameters arecalculated. This implies that the quality of the transformation is invariant with respect to the coordinate
system.
An invariant coordinate transformation allows converting the transformation parameters that were
calculated in one coordinate system to another coordinate system correctly, without the need to calculate
the parameters again in the new coordinate system. It allows for a proper transformation of the same point
in different coordinate systems.
This paper discusses the invariance property of coordinate transformation and shows the complexity ofgeodetic coordinate transformations, where some are invariant and others are variant. In variant
transformations, the transformation parameters and the quality of the transformation depend on thecoordinate system and its definition, an important situation to be aware of.
We discovered that the most common transformation in geodesy, surveying and related professions, the 7parameters transformation, is invariant. However, with the widespread use of GNSS measurements,
transformations with more than 7 parameters become more common and some of them are variant. The
most general affine transformation with 12 parameters is invariant, but all transformations with a number ofparameters greater than 7 and less than 12 are variant. Thus, the transformation is variant with respect tothe coordinate system.

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*G01-4-01
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

E-GRASP/Eratosthenes: a satellite mission for improving the Terrestrial
Reference Frame* Markus Rothacher 1) , Richard Biancale 2) , E-GRASP Science Team 3)
ETH Zurich, Zurich, Switzerland 1) , CNES, Toulouse, France 2) , International 3)
The accuracy and stability of a Terrestrial Reference Frame (TRF) that are required to detect the smallest
variations (e.g. sea level rise) in the Earth system components have been identified by GGOS and thescientific community to be 1 mm for positions and 0.1 mm/yr for velocities. These GGOS requirements arefar from being met today, mainly due to deficiencies in the realization of the TRF originating from (1) the
difficulty to accurately measure the local ties between the reference points (intersection of axes of large
instruments, phase centers of antennas) and (2) the fact that each space geodetic technique suffers from its
own systematic effects.
In order to fundamentally improve this situation, the E-GRASP/Eratosthenes satellite mission has been
proposed to ESA as response to the 2017 Earth Explorer-9 (EE9) call. E-GRASP will provide a highly
accurate co-location of all four space geodetic techniques (GNSS and DORIS receivers, laser retroreflectors, and a VLBI transmitter) in space, on the same satellite platform, with particular attention paid to
the time and space metrology on board. Orbiting the Earth in a highly eccentric orbit for visibility reasons,
E-GRASP will be fully complementary to co-location on the ground and will connect all the ground stations
with its co-located instruments.
Many different simulations have been performed already, both, for selecting the best orbital scenario
according to many geometrical, technical and physical criteria and for assessing the impact on the TRF,
which is crucial to achieve the GGOS requirements.
The presentation will focus on the mission science, the instrumentation and scenario as well as thesimulation results available today.

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*G01-4-02
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Lunar Laser Ranging as tie between terrestrial and space reference systems
Franz Hofmann , * Juergen Mueller
Leibniz Universitaet Hannover, Hannover, Germany
Lunar Laser Ranging (LLR) data has been used since 1969 to determine various physical parameters of the
Earth-Moon system. LLR also acts as the connecting technique between the reference systems fixed on
Earth, Moon and in space. The estimated reflector coordinates in combination with the lunar ephemeris
represent the selenocentric reference frame and its orientation with respect to the barycentric reference
frame. LLR can contribute to the terrestrial reference frame, e.g., with the estimation of station coordinatesand velocities and long-periodic nutation coefficients with periods between 0.5 and 18.6 years. The
estimated accuracy of the nutation coefficients is about 0.1 milliarcsecond. The estimated accuracy of thecoordinates and velocities of the stations on Earth is in the order of 1 cm and 1 mm/yr which is up to now
one order of magnitude larger than the GGOS goals for the terrestrial reference frame. The deployment of
new single-corner-cube reflectors on the Moon and the recent success in infrared ranging to the Moon at
the French station in Grasse can help to get more accurate LLR data per year. Based on the LLR dataset up
to the end of 2016 we show the recent results for the estimated reflector and station coordinates, station
velocities and nutation coefficients. With simulated future data we illustrate possible improvements forthese parameters within the next years up to 2030.

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*G01-4-03
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Double-Differences Over Time for Space Geodesy Techniques with GNSS
Satellites and Lunar Laser Reflectors* Drazen Svehla , Markus Rothacher
ETH Zurich, Switzerland
We have already demonstrated that the main advantage of common-view double-differencing of SLR
measurements to GNSS is in the reduction of systematic effects, leading to differential SLR with sub-mm or
mm-accuracy. Here we extend the common-view SLR approach and make double-differences over time byconsidering the different observation times for all SLR measurements between all SLR stations. SLR range
biases and small biases between SLR sessions are removed. The scale of the reference frame is preserved
after double-differencing, potentially providing access to the utmost accuracy of SLR in the global GNSS
solutions. This SLR approach allows accurate estimation of local ties between SLR and GNSS, since relative
coordinates between stations can be estimated independently by GNSS and SLR, thus requiring only one
local tie to be estimated between ILRS and IGS ground networks. We have already demonstrated that the
double-difference SLR approach with GNSS orbits from IGS offers a bias-free estimation of relative
coordinates between ILRS stations with mm-accuracy separated by up to some 5000 km.
The same approach could also be applied between Lunar laser ranging (LLR) and SLR to GNSS satellites.
We form double-difference LLR between two Lunar retroreflectors and two LLR stations to show the noiseof the LLR of about 5-7 mm standard deviation. We managed to process LLR as one-way measurements in a
geocentric frame similar to the processing of SLR to GNSS satellites and make use of the latest Lunar
DE430 ephemerides and libration models. We present the estimation of the Lunar orbit and EOPs
(including UT1 or UT0). This offers an interesting application of SLR and LLR in the global GNSS solutions,giving, in addition to scale, a potential access to UT1 or UT0 in the global GNSS solutions.
In the last part, we discuss a possible use of double-differences over time for the estimation of GNSS biases
and resolution of integer ambiguities, as well as a possible extension to VLBI.

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*G01-4-04
IAG Symposium / IAG01. Reference Frames / G01. Reference framesMulti-Year Analysis of GNSS Local Ties at Fundamental Sites* Ivan Dario Herrera Pinzon , Markus Rothacher
Swiss Federal Institute of Technology in Zurich (ETHZ), Zurich, Switzerland
With increasing requirements on accuracy and stability for the realisation of the International Terrestrial
Reference System (ITRS), the comprehensive analysis of technique-specific systematic biases in local
measurements becomes crucial for the improvement of ties among space geodetic techniques. The qualityof the ITRS realisation, the International Terrestrial Reference Frame (ITRF), relies on the adequacy of theties of individual space geodetic techniques at fundamental sites. To this end, intra-technique co-location,
where two or more co-located instruments of the same technique are available, constitutes an essential stepfor analysing individual biases on short baselines. Although Global Navigation Satellite Systems (GNSS) are
one of the major contributors to the realisation of the ITRF, discontinuities in time series associated withhardware and software changes pose a major threat for their proper utilisation. Co-located GNSS at
fundamental sites provide the opportunity of improving the accuracy of estimated positions by examining
data breaks, local biases, deformations, time-dependent variations and the comparison of GNSS baselines
with existing local tie measurements. Typically equipped with an array of several GNSS receivers collecting
data continuously for several years, their proximity grants similar tropospheric delays, identical ionosphericconditions, same loading effects and nearly identical station motion.
With the use of precise GNSS orbits, an ambiguity fixing strategy and an appropriate parameterisation, thiscontribution presents a global multi-year analysis of a subset of IGS fundamental sites for delivering
homogeneous coordinate time series and phase residuals, based on L1, L2 and the ionosphere-free linear
combination with and without troposphere estimation, to quantify hardware and software changes, antenna
patterns, environmental effects, local deformations and other time-dependent variations of the local
baselines.

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*G01-4-05
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Non-linear Geocenter Motion from Multi-Technique Geocentric Station
Coordinate Time Series in a Terrestrial Reference Frame on Dynamic Earthand GRACE Gravity Data
* Xiaoping Wu 1) , Juergen Kusche 2) , Felix Landerer 1)
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA 1) , Institute ofGeodesy and Geoinformation, University of Bonn, Bonn, Germany 2)
Spherical harmonic expansions of Earth's surface mass variations start from three degree-1 terms. These
induce geocenter motion between the center-of-mass of the total Earth system (CM) and the center-offigure of the solid Earth surface (CF), as well as a degree-1 surface deformation field. However, GRACE's Kband ranging data system is not sensitive to these variation modes. For complete spectral coverage androbust assessment of geographic mass budget using GRACE data, very accurate knowledge of geocentermotion is required but difficult to obtain.
To address the ever-changing nature of the solid Earth surface, recently, an experimental Kalman filter andtime series terrestrial reference frame (KALREF) has been realized by a collaborative effort of JPL and IGN
to determine nearly instantaneous geocentric station coordinates of all 4 space geodetic techniques.
Through local tie measurements and co-motion constraints, satellite laser ranging (SLR)'s CM sensitivity istransferred to other technique networks, and SLR's many data gaps are bridged by co-located dense GPS
data. For geocenter motion determination, we use a new unified approach by combining KALREF
geocentric displacements of a larger and better-distributed 82-site network with GRACE gravity data. Bothtranslational and deformational signatures will be exploited for retrieval of the degree-1 surface mass
variation coefficients. Higher degree terms are estimated simultaneously using GRACE gravity data, whichfurther improves CF knowledge and reduces aliasing effects. Such a data combination also uses fullcovariance matrices of all data types to facilitate a reliable variance component estimation. The
combination of the 82-station KALREF coordinate time series with GRACE improved the precisions of nonlinear geocenter motion components by factors of 2 to 3 compared with those obtained from the
combination of SLR and GRACE.

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*G01-5-01
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

The Geocentric Datum of Australia 2020
* John Dawson , Michael Moore , Guorong Hu , Craig Harrison , Nicholas Brown
Geoscience Australia
In 2017 the Australian federal, state and territory governments implemented a new datum for the spatial
community. Named the Geocentric Datum of Australia 2020 (GDA2020), the datum will supersede theexisting datum, the Geocentric Datum of Australia 1994 (GDA94). GDA2020 is a densification ofInternational Terrestrial Reference Frame (ITRF) 2014 in Australia and is based on over 20 years ofcontinuous GPS observations together with almost 2 million terrestrial geodetic and campaign style GPS
observations. Implementation of GDA2020 is the initial phase of a longer-term government program totransition Australia to an ITRF based georeferencing system and to encourage the widespread applicationof time-varying coordinates. This presentation will overview the technical aspects of implementation ofAustralia's new datum including the development of an Australian plate model, the approach adopted forthe national geodetic adjustment and the GNSS analysis strategy.

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*G01-5-02
IAG Symposium / IAG01. Reference Frames / G01. Reference framesContinuing and Emerging Roles of National GNSS CORS as Geodetic
Infrastructure: Case study of GEONET in Japan* Hiromichi Tsuji , Yuki Hatanaka , Yohei Hiyama , Satoshi Kawamoto , Tomoaki Furuya , Basara Miyahara ,Toshihiro Yahagi , Tatsuya I. Yamashita , Hiroshi Munekane
Geospatial Information Authority of JapanGEONET, the national GNSS Continuously Operating Reference Stations (CORS) network of Japan, hasbeen operational since 1996, celebrating the 20th year anniversary. Here we review the past 20 year
operation of GEONET, and discuss continuing and emerging roles as Geodetic infrastructure.
Currently GEONET consists of 1,318 stations covering whole Japan with about 20 km spacing, tracking
signals from GPS, QZSS, GLONASS and Galileo with 1 Hz sampling. Observation data and products areopen to the public to support surveying and mapping. Private companies provide network-based realtime
kinematic positioning services using data from GEONET, now widely used for ICT constructions andprecision farming. Crustal deformations are monitored by time series of baseline vectors, revealing secular,coseismic, and postseismic deformations as well as slow slip events. The realtime analysis system for rapid
deformation monitoring (REGARD) is now in operation, aiming to assist Tsunami warning. Thus GEONET
has become the social infrastructure for surveying, mapping, positioning, disaster mitigation and Earthscience.
Because of large and complex nature of crustal deformation around Japan, maintenance of the nationalreference frame needs extreme cares. So far, GEONET identified nearly 100 crustal deformations
associated with large earthquakes. The 2011 Tohoku earthquake (M 9.0) is the largest one, recording 5.3
meter horizontal displacement, and still causing post seismic deformation. We need GEONET to generatesemi-dynamic correction parameters that account for accumulated crustal deformations after the revisionof the Japanese Geodetic Datum in 2011.
Although relative positioning that forms a baseline to delete common positioning errors is the old andreliable method for GNSS surveys, Precise Point Positioning (PPP) and PPP-AR (Ambiguity Resolution) that
do not form baselines are emerging. We show the new role of national CORS is to provide sufficient local
data for quicker fix of PPP.

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*G01-5-03
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Japan-1sec1cm accuracy -Geodetic Network Adjustment* Hiroyuki Hasegawa
GeoNet, Inc., Osaka, Japan
Having learned from Kobe Earthquake (1995) and East Japan Earthquake (2011), future solutions areproposed on satellite surveying, satellite image photogrammetry. Parameter Estimation Gnss Assisted
SUrveying System (PEGASUS for short) realizes 1 sec 1 cm accuracy geodetic network adjustment forearthquake monitoring. Now in Japan Basic Act for National Resilience Contributing to Preventing and
Mitigating Disasters for Developing Resilience in the Lives of the Citizenry (Act No. 95 of December 11,2013) has started, and for application of land administration systems, like Cadastre2014, Land
Administration Domain Model Standard and Social Tenure Domain Model, we prepare for reconstructionplans, using 4D Image Map Archive Designed Aerial Survey (IMADAS for short) technology and German
AAA Land Information System.
Kumamoto and Tottori earthquakes in Japan in 2016 motivated nationwide geodetic network adjustments,
1 sec 1 cm accuracy approach, for earthquake monitoring in 3D displacement in the world geodetic datum.
We tested feasibility of such 1 second GNSS geodetic network adjustment to forecast the earthquake
deformation of monitoring points. For reconstruction process after earthquakes to determine parcel points
in real time 3D mapping of reconstruction projects, with 1cm accuracy on the ground, we could combine
high resolution 3D satellite stereo models and precise drone photogrammetry.
Now we add 1 sec 1cm accuracy geodetic networking for Southeast Asian counties, such as Cambodia,
Myanmar and Bangladesh, for land administration and cadastral projects in real time mode (FKP) and inseismic monitoring mode (GEONAP) for UN-GGRF initiative.

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*G01-5-04
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Restoring the New Zealand Geodetic Datum after the 2016 Kaikoura
Earthquake* Chris Crook 1) , Nic Donnelly 1) , Ian Hamling 2)
Land Information New Zealand, Wellington, New Zealand 1) , GNS Science, Lower Hutt, New Zealand 2)
The 14 November 2016 magnitude 7.8 Kaikoura Earthquake and ensuing earthquake sequence resulted inwidespread damage in the North Canterbury and Marlborough regions of the South Island of New Zealand.
The earthquakes generated horizontal displacements of several metres and vertical displacements
approaching 10 metres.
The deformation caused by these earthquakes needs to be incorporated in the New Zealand Geodetic
Datum.
The datum includes a deformation model which accounts for both ongoing secular deformation andepisodic earthquake related deformation. This enables a spatial reference system in which the coordinatesof fixed ground marks are substantially constant over time despite the secular tectonic movement of themarks, thereby allowing the geospatial community to confidently combine and use spatial datasets fromdifferent epochs.
A challenge following earthquakes is to incorporate the resultant deformation into this datum in a timely
way. Until this is done the datum does not provide a consistent spatial reference frame. Spatial data
generated after the earthquake is likely to be out of terms with pre-earthquake data. Surveys conducted
relative to local control marks may obtain significantly different coordinates depending on which marks areused.
The datum is updated using GNSS and InSAR data to derive models of the deformation caused by theearthquake sequence. Although the deformation model update is based on geophysical models ofsubsurface fault ruptures, the focus in building the model is to accurately reflect the surface deformation
rather than accurately modelling the faulting.
The implementation of the model also needs to account for the needs and expectations of the geospatial
community it serves. This may lead to different implementation methods in the near-field, where there issignificant local relative movement, and in the intermediate and far field deformation, where the local
deformation is predominantly translation.

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*G01-5-05
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

SHRF16: A Stable Houston Reference Frame for Faulting and Subsidence
Study in the Houston Metropolitan Area, Texas, U.S. A.
* Guoquan Wang , Timothy Kearns , Hanlin Liu , Eleanor Dietz , Vasilios Tsibanos
University of Houston, Houston, U.S.A.
The greater Houston is one of the fastest-growing metropolitan areas in the United States. More than 150
historically active faults have been identified in the greater Houston area. Accumulated subsidence of over
4 meters during the past century has been observed in a large area of southeast Houston. Subsidence andfaulting have caused moderate to severe damage to hundreds of residential, commercial, and industrial
structures year by year in the Houston area. GPS technology had been employed in subsidence monitoringin the Houston area since the late 1980s. A dense GPS network with over 180 stations has been
established in the Houston metropolitan area through a joint effort by the government, academic, andindustry communities. One major consideration in determining the magnitude and velocity of grounddisplacement over time using GPS, particularly for horizontal ground deformations, is the selection ofreference frames. GPS initially provides positioning with respect to a global reference frame. All sites are
moving with respect to a global reference frame and site velocities are dominated by secular tectonic platedrifts. A local reference frame is needed to precisely interpret site specific ground deformations over timeand space. In this study, we established a Stable Houston Reference Frame using public-available long-term(over 10 years) GPS observations as of 2016. Ten CORS adjacent to the Houston metropolitan area wereused as common points (reference stations) to align SHRF16 with IGS08 at epoch 2012.0. The realizationof SHRF16 is defined in terms of a Helmert transformation from the global reference frame IGS08. The
main results from this study are the 14 parameters for reference frame transformation from IGS08 to
SHRF16 and current subsidence contour map (2005 to 2016) in the Houston metropolitan area. SHRF16
will be incrementally improved and be synchronized with the update of IGS reference frame.

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*G01-5-06
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Station calibration of the SWEPOS GNSS Network* Martin Lidberg 1) , Per Jarlemark 2) , Jan Johansson 2) 3) , Kent Ohlsson 1) , Lotti Jivall 1)
Lantmateriet, Sweden 1) , RISE - Research Institutes of Sweden 2) , CHALMERS UNIVERSITY OF
TECHNOLOGY 3)
While the performance of positioning services are improved to the benefit of the users, with uncertainties
from densified Network-RTK networks for construction work approaching the sub-centimeter level also inthe vertical, the error sources related to the permanent reference stations (CORS) may soon be limiting
factors for further improvement of performance.
Station dependent effects are thus important and limiting factors in high accuracy GNSS positioning.
Electrical coupling between the antenna and its near-field environment changes the characteristics of theantenna from what has been determined in e.g. absolute robot or chamber calibration.
Since the first initial tests back in 2008, Lantmateriet together with Chalmers technical University and SP
Technical research Institute of Sweden has carried out station calibration, in-situ calibration, of its networkof permanent reference stations, SWEPOS. The station calibration intends to determine the electricalcenter of the GNSS antenna, as well as the PCV (phase center variations) when the antenna is installed at a
SWEPOS station. One purpose of the calibration is to examine the site-dependent effects on the height
determination in SWEREF 99 (the national reference frame). Another purpose is to establish PCV as acomplement to absolute calibrations of the antenna-radome pair.
We will present booth the methodology for observation procedure in the field and the method for the
analysis, together with results of the station-dependent effects on heights as well as PCV from the analysis.
Some strength and weakness of our method for GNSS station calibration are discussed at the end.

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*G01-6-01
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Foundation CORS: Underpinning a New Positioning Framework* Daniel Roman , Kevin Choi
U.S. National Geodetic Survey, Silver Spring, USA
The Continuously Operating Reference Station (CORS) Network at the U.S. National Geodetic Survey(NGS) has provided improved coordinate determination to the National Spatial Reference System for 20
years. The CORS will become an integral part of the definition, realization and access starting 2022 when
the NGS puts in place a new reference frame. The CORS Network consists of nearly 2,000 stations that areprimarily owned and operated by other agencies and groups that provide their data to NGS for evaluation,archiving and use in position determination software such as the Online Positioning User Service (OPUS).
The intent of the 2022 datum is that it be closely aligned with the most recent realization of theInternational Terrestrial Reference Frame in order provide consistency in the realization of positions ineither the new US reference frame or in the ITRF. Pursuant to that, the NGS will be focusing on ownershipor at least increased oversight of a sufficient number of stations to ensure that the ITRF is adequately tied
to the new national datum. Priority is given to collocating with other techniques (e.g., VLBI) to enhance thelinkage between the IGS solution and those of the other techniques when developing a future ITRF.
Additional consideration will be to have a sufficient spatial coverage to ensure a sufficient spatial
distribution to satisfy the national integrity of the NSRS. The intent is that these sites serve as the link to the
ITRF and then serve to underpin any national reprocessing and stacking of regular CORS sites. In turn,derived positions from the CORS will lead to improved access to the NSRS for all geodetic applications.

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*G01-6-02
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

ITRF2014/IGS14 European Regional Densification Using the EPN Long
Term Daily SINEX product* Ambrus Kenyeres 1) , Tomasz Liwosz 2) , Juliette Legrand 3) , Christof Voelksen 4) , Andrzej Araszkiewicz 5) ,Jan Dousa 6) , Daniel Ineichen 7) , Elmar Brockman 7) , Marcellino Valdes 8)
BFKH FTFF Satellite Geodetic Observatory, Budapest, Hungary 1) , Politechnika Warszawska, Warsaw,
Poland 2) , Royal Observatory of Belgium, Brussels, Belgium 3) , KEG BAdW, Munich, Germany 4) , MUT,
Warsaw, Poland 5) , GOP, Pecny, Czech Republic 6) , SWISSTOPO, Wabern, Switzerland 7) , IGN, Madrid,
Spain 8)The successive realizations of the International Terrestrial Reference System are based on the analysis ofspace geodetic data series stemming from GNSS, SLR, VLBI and DORIS. Beyond the modeling refinements
the realizations (called ITRFyy, where yy denotes the end date of data involved in the solution) includes
growing data sets, therefore a gradual quality improvement of the consecutive solutions is expected.
On regional scale the geodetic reference frame realizations are maintained by densification of the global
ITRS realizations using continental scale CORS networks. Such networks are operational in Europe (EPN),
North-America (NAREF), South-America (SIRGAS), Africa (AFREF), Asia-Pacific (APREF).
In contrary to the present EPN practice, where weekly SINEX solutions are used, the European
densification of IGS14 is being prepared based on the cumulative solution of the daily SINEX productseries stemming from the EPN REPRO2 activity and the routine EPN data processing being done at 17
Analysis Centres.
As the cumulative solution is updated at each 15 weeks the agreement between the initial global frame
solution and its regional densification series may vary in time as a consequence of new data added, due tochanges in network geometry or in intermediate changes in modeling parameters.
In this paper the regional ITRFyy densification methodology is described and the European
ITRF2014/IGS14 densification solution is introduced with special emphasis on testing the agreement levelof the former IGb08 densification series and the IGS14 solution.

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*G01-6-03
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Near real time modelling of coseismic and post-seismic deformation for
NetworkRTK applications* Paul Denys , Chris Pearson
Otago University, Dunedin, New Zealand
Deformation patterns that result from large earthquakes manifest as instantaneous coseismic and timedependent post-seismic motion. For example, the deformation caused by the November 2016 Kaikoura Mw
7.8 resulted in coseismic displacements up to several metres while continuing post-seismic displacements
have amounted to 20-30 cm after 3 months. Such events deform the geodetic infrastructure, which for the2016 Kaikoura event, can be detected over 600 km from the epicenter.
Surveying applications, such as Network RTK, require precise relative and current epoch coordinates thatare typically based on an International Terrestrial Reference Frame (.e.g. ITRF2008, ITRF2014). Although
the latest ITRF realisation (ITRF2014) incorporates post-seismic decay for selected ITRF sites, commercial
software that generates time-dependant coordinates assumes linear motion and cannot (currently) deal
with non-linear motion. Abrupt changes in position i.e. coseismic displacement; are relatively easy to deal
with – a new updated coordinate is computed. However, transient and non-linear motion such as thatcaused by post-seismic relaxation and slow slip events are more difficult to model and therefore predict.
Correcting the positions of NetworkRTK sites requires the development of low latency models of both thecoseismic and post-seismic deformation. Traditionally dislocation models of earthquakes are available
months or years after an earthquake but advances in instrumentation and processing algorithms meansthat models are available in near real time. As shown by the 2016 Kaikoura event, the post-seismic motion
is evolving over time and therefore up to date positioning data is required to model the transient motion
accurately. Although early models may not necessarily have the accuracies of the final models, it should bepossible to make regular updates as additional data becomes available.

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*G01-6-04
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

New Zealand Vertical Datum 2016, an improved gravimetric reference frame* Matt Amos , Rachelle Winefield
Land Information New Zealand
In June 2016 the New Zealand Vertical Datum 2016 (NZVD2016) was released. This quasigeoid based
datum replaced the NZVD2009 and halved the nominal datum error from 6 cm to 3 cm.
The geoid underpinning NZVD2016 was improved through the acquisition of a nationally consistentairborne gravity dataset, re-analysis of the existing terrestrial database, and inclusion of of more recent
satellite gravity data. The impact of each of these datasets is assessed and quantified before incorporationin the reference surface.
NZVD2016 also differs from NZVD2009 in the way that relationships to the 13 historical local vertical
datums are managed. To ensure that the national datum is easily usable, NZVD2016 provides relationshipsurfaces to each local datum to facilitate the migration of data into the new reference frame. The
computation and error characteristics of these surfaces are discussed, along with an analysis of the datum's
performance in recent large earthquakes in New Zealand.

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*G01-6-05
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

The leveling net adjustment with a correction for altitude variations obtained
from GNSS-based control stations data
* Tatsuya Yamashita 1) , Takashi Toyofuku 1) , Kensuke Kokado 2) , Satoru Nemoto 1) , Hiroyuki Tanaka 1) , Yu
Morishita 1)
Geospatial Information Authority of Japan, Tsukuba, Japan 1) , Land Economy and Construction andEngineering Industry Bureau, Tokyo, Japan 2)
Geospatial Information Authority of Japan (GSI) has been maintaining longitude, latitude, and altitude ofcontrol points. As for the altitude reference system, we conduct leveling surveys all over Japan, thestatistical calculation (net adjustment), and revise the altitude. However, the policy of administrative
efficiency leads to a decrease in leveling survey distance. Thus, it takes more time to conduct surveys, andseems likely that gaps between calculated altitude and the current situation get larger because of crustal
movement.
Since the 1990s, GSI has been developing GNSS Earth Observation Network System (GEONET). GEONET
has two advantages: (1) observation stations exist uniformly, and (2) we can conduct a real-timeobservation. Focusing on these points, we investigated the potential to reduce the gaps of altitude byutilizing GEONET to correct altitude variations.
We conduct a new method for net adjustment as follows: (1) we apply curve fitting to GEONET time-series
data to obtain altitude variations between the observation days for surveys and the reference day. (2) We
apply Kriging method to create grid data of altitude variations for every observation day. (3) We apply
bilinear method to estimate altitude variations by the grid data at each benchmark to correct relative
elevations. (4) We conduct a net adjustment by using corrected relative elevations.
We evaluated the validity by comparing between altitude obtained by surveys and altitude estimated from
GEONET data in the areas where we recently conducted surveys twice. From the studies, we found that (1)it was possible to estimate altitude with 1 cm accuracy on average, and (2) it was impossible to estimate
local variation. These imply that we should compensate for GEONET's weakness. Fortunately, GSI has
InSAR technique that has an advantage to detect local variation economically. If time allows, we will show
the validation of Kumamoto earthquake with a combination of GEONET and InSAR.

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*G01-6-06
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Precise leveling, tide gauge and satellite altimetry for definition of Saudi
Arabia National Reference Frame (SANVRF) – Jeddah'2014* Rossen Grebenitcharsky 1) , George Vergos 2) , Othman Al-Kherayef 1) , Bandar Al-Musulmani 1) , Rene
Forsberg 3)
General Commission for Survey, Riyadh, Saudi Arabia 1) , Aristotle University of Thessaloniki, Thessaloniki,
Greece 2) , Technical University of Denmark, Copenhagen, Denmark 3)
Historically, in The Kingdom of Saudi Arabia several height reference systems have been developed andapplied by different organizations. To unify the vertical reference frame of the Kingdom, the General
Commission for Survey has developed and proposed for pre-definition a new national vertical reference
frame (VRF) named Jeddah'2014. It is based on the new National Vertical Network (NVN), National Gravity
Network (NGN), an analysis of 3.5 years of Tide Gauge Network data and an assimilation of all existing
Satellite Altimetry (SA) data in the Red Sea and Arabian Gulf region.
A Wavelet Multi-resolution analysis (WMRA) of TG data residuals (after eliminating periodic tide effects)
has been conducted for 11 TG stations in Red Sea and Arabian Gulf in order to determine the MSL,
necessary for vertical datum definition of KSA. This analysis has been supported by almost 30 years of SA
data and the most recent GOCE-based Global Geopotential Models (GGMs) for validation purposes. The
final SANVRF has been defined following a Least-Squares Adjustments (LSA) of NVN geopotential
numbers, assuming the height above Mean Sea Level (MSL) at Jeddah Tide Gauge Benchmark (JEDD-S) as
fixed. With the high NVN leveling precision achieved the new KSA VRF will also form the base of the new
precise KSA geoid model.
Details regarding the new SANVRF Jeddah'2014 are provided in this presentation, describing its
conceptual and specific characteristics.

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*G01-P-01
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Estimation of Post Seismic Deformation Model Using Monte Carlo Method* Takayuki Miyazaki
GSI of Japan, Ibaraki, JapanThe one of latest Global Geodetic Reference Frame (GGRF), ITRF2014 has been available since Jun. 2016.
In ITRF2014, Post Seismic Deformation (PSD) models were newly introduced to improve accuracy ofstation coordinates impacted by major earthquake. PSD models will improve accuracy of coordinates ofJapanese domestic GNSS observation network (GEONET) subject to active crustal deformation too. In thispaper, we has developed Bayesian estimation method that based on ensemble Marcov Chain Monte Carlo(MCMC) method to make PSD models of GEONET station. This method can estimate PSD model stably
avoiding local solution although PSD models includes non-linear functions. We compared estimated PSD
model and that of ITRF2014 products in TSKB station, which is one of IGS GNSS station. As a result, we
acquired s.d. of estimated PSD model and observation (E, N, U) = (10.1, 16.9, 1.7) mm. It is shown that
estimated PSD model sufficiently explain observation data. We also evaluated prediction power of the PSD
model in Miyako station, which has been impacted by the 2011 off the Pacific coast of Tohoku Earthquake.
We estimated the PSD model of Miyako station with coordinate time series spanning two years from theearthquake (fitting period) and compare that PSD model with observation of post-fitting period. As a result,
we found that their difference were smaller than 1cm for horizontal component, 2cm for verticalcomponent at 2 years after the end of fitting period when Log+Exp+Log model was used.

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*G01-P-02
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Impact of different TRF station coordinate parameterizations on VLBI
combined EOP
Sabine Bachmann , * Daniela Thaller
Federal Agency for Cartography and Geodesy (BKG), Germany
In the framework of the realization of the latest International Terrestrial Reference System, different
solutions using different TRF station coordinate parameterization have been published. Namely, theDTRF2014, published by the German Geodetic Research Institute (DGFI-TUM), using a piece-wise linear
station model with improved geophysical modeling, the ITRF2014, the official ITRF, using a piece-wiselinear station model and an additional post-seismic deformation model, and the JTRF2014, published by
Jet Propulsion Laboratory (JPL), using weekly estimations of station coordinates (epoch reference frames).
The combination on the normal equation level of EOP and station coordinates is well established within theInternational VLBI Service for Geodesy and Astrometry and in cooperation with other space geodetic
techniques (e.g. inter-technique combined TRF). In the combination process, the estimation of accurate apriori values for station coordinates plays an important role for the estimation of combined Earth
Orientation Parameters (EOP). In our study we compare the impact on the routinely combined VLBI EOP
by using the three different TRF solutions for a priori station coordinate estimation. The results of this study
and the comparisons of the different solutions will be presented.

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*G01-P-03
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Investigations on scale factor from VLBI observations* Hana Krasna 1) , Oleg Titov 2) , Igor Surkis 3) , Dmitrii Ivanov 3) , Alexey Melnikov 3)
TU Wien, Vienna, Austria 1) , Geoscience Australia, Canberra, Australia 2) , Institute of Applied Astronomy,
St. Petersburg, Russia 3)
The direct connection between the terrestrial and celestial reference frame as it is provided by the VeryLong Baseline Interferometry (VLBI) technique makes possible to gain an insight into astrophysical andcosmological studies. One of potentially informative cosmology-oriented evaluation of VLBI astrometricsurveys is based on the analysis of the scaling factor that is derived as a partial derivative of the observed
group delay to the theoretical geometrical delay. If the observations would perfectly match the theoreticalprediction, the scaling factor would be equivalent to unity. Otherwise, some deviation from unity can bedetected. Our estimates from two independent software packages OCCAM and VieVS show that the scale
factor from the VLBI measurements estimated for each radio source individually discloses a clear
systematic aligned with the direction to the Galactic center-anticentre. Therefore, the radio sources locatednear Galactic anticentre may cause a strong systematic effect on the terrestrial reference frame, especially,in early VLBI years. Furthermore, we investigate a potential dependence of the scaling factor on the radiosource redshift. We analyse geodetic VLBI observations carried out within the routine International VLBI
Service (IVS) activity extended by selected sessions of the KVAZAR network.

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*G01-P-04
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

IGRS2013 Deformation Model: Linear Velocities and Co-seismic
Deformation* Susilo Susilo 1) 2) , Hasanuddin Z. Abidin 1) 2) , Irwan Meilano 2) , Endra Gunawan 2) , Benyamin Sapiie 3) ,Dina A. Sarsito 2) , Heri Andreas 2) , Dhota Pradipta 2) , Antonius B. Wijanarto 1) , Joni Efendi 1)
Geospatial Information Agency, Bogor, Indonesia 1) , Bandung Institute of Technology, Faculty of Earth
Science and Technology, Geodesy Research Group, Bandung, Indonesia 2) , Bandung Institute ofTechnology, Faculty of Earth Science and Technology, Geodynamic Research Group, Bandung, Indonesia 3)
On October 11st, 2013, a new geodetic datum for Indonesia was defined by Geospatial Information Agency
of Indonesia. The datum name is Indonesian Geospatial Reference System 2013 (IGRS2013). This is a semi
dynamic datum which the reference epoch of geodetic control coordinate defined at 2012.0 and thechange of coordinate due to plate tectonic motion and earthquakes should be accommodated by adeformation model. In this study we estimate a linear GPS velocities from time series coordinates startingfrom 1999 until end of 2016. We include also several earthquakes that have magnitude > M7 starting from
01 January 2000 until 12 December 2016 to estimate the co-sesimic deformation. Our estimate of linear
velocities suggest that the GPS velocities shows the characterized of plate/block tectonic motion in theregion. Moreover, our co-sesimic deformation suggest that most of Indonesia region affected by co-seismic
deformation due to 2004 Sumatran-Andaman earthquake, 2005 Nias earthquake and 2012 Wharton Basinearthquake. The deformation model that consists a linear velocity and co-seismic deformation used totransform the coordinates from observation epoch to or from reference epoch of IGRS2013.
Keywords: Indonesia, IGRS2013, deformation model, linear velocities, co-sesimic deformation

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*G01-P-05
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Investigating the performance of the GNSS-SLR co-location on-board GNSS
satellites for reference frame determination* Sara Bruni 1) , Paul Rebischung 2) , Susanna Zerbini 1) , Zuheir Altamimi 2) , Maddalena Errico 1) , Efisio
Santi 1)
University of Bologna, Department of Physics and Astronomy, Bologna, Italy 1) , Institut National del'Information Geographique et Forestiere (IGN), Laboratoire de Recherche en Geodesie (LAREG), Paris,
France 2)
The International Terrestrial Reference Frame (ITRF) is realized by combining data provided by four space
geodetic techniques, namely the GNSS, SLR, VLBI and DORIS. Since the technique-specific groundnetworks do not share any common point, the combination requires some additional information
establishing their reciprocal spatial distribution. In the current computation strategy, the inter-techniqueconnection is provided by the so-called terrestrial ties which result from topometric surveys performed atthose ITRF sites where the instruments of at least two different techniques are co-located. A possible
alternative is provided by satellites equipped with the positioning payloads of different techniques. In
principle, the co-location in space could overcome major limitations, such as, poor spatial distribution ofground local ties, their infrequent updates and their discrepancies with space geodesy estimates due totechnique systematic errors. However, actual operational conditions are likely to impact the performance ofthe co-location in space and should be carefully assessed. In this study, we investigate the potential of thespace ties on-board GNSS satellites for the realization of a homogeneous GNSS-SLR frame. We analyzed
four years (2011-2014) of data collected by a ground network of about 100 GNSS receivers and 40 SLR
stations. The computations were operated to determine long-term and quasi-instantaneous (9 days)
reference frames. The resulting fully combined frames were compared to the GNSS-only and LAGEOS-only
solutions in order to test the efficiency of the selected space ties in transferring frame information between
the different subnetworks. The effect of possible future improvements in SLR tracking performances was
also investigated by means of simulations. According to our results, the space ties on-board GNSS satellites
do not realize, at present, a homogeneous GNSS-SLR frame.

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*G01-P-06
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Developing a semi-dynamic datum for Nepal after the April 25 Gorka
Earthquake
Christopher Pearson 1) , Niraj MANANDHAR 2) , * Paul DENYS 1)
School of Surveying University of Otago 1) , Survey Department of Nepal 2)
Along with the damage to buildings and infrastructure, the April 25, 2015 Mw7.8 Gorkha earthquake
caused significant deformation over a large area in central Nepal, with displacements of over 2 m recordedin the vicinity of Kathmandu. In order to correct the resulting distortions in the geodetic reference system,
Nepal is in the process of introducing a new semi-dynamic datum that is aligned with ITRF2014 (epoch
2016.0). The new geodetic datum will incorporate a national deformation mode (NDM) that will have thecapacity to correct for earthquake displacements as well as ongoing tectonic deformation associated with
Nepal's location on the India/Eurasian plate boundary. The NDM discussed here contains models of thevelocity field and both co-seismic and post seismic deformation for the Gorka earthquake plus co-seismic
deformation for the Mw 7.3 12 May Aftershock. The velocity model for Nepal is based on a compilation of
published velocity measurements from previous studies for Nepal and adjacent regions of China and India
combined with new velocity estimates for the Nepal GNSS array stations. We have developed a preliminary
velocity field by combining these studies and aligning them with the published ITRF2014 velocities for IGS
stations. The co-seismic deformation associated with the Gorkha earthquake and its 12th May Mw7.3
aftershock are modelled using published dislocation models. In order to estimate the post-seismic
relaxation, we used an exponential function with a uniform 43 day time constant. The model is
implemented as a series of grid files allowing the secular velocities, co-seismic displacements for the April
25, 2015 Mw7.8 Gorkha earthquake and the 12th May Mw7.3 aftershock and the post-seismic relaxation
coefficients for the Gorkha earthquake to be estimated. Using these grid files it is possible to estimate thedeformation as a function of time for any point in Nepal and correct both survey measurements andcoordinates to a common reference epoch.

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*G01-P-08
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Assessment of displacement models used in time-dependenttransformations. The particular case of California.
* Daphne Lercier
Trimble, Nantes, France
The support of time-dependent transformations for surveying and GIS is becoming a critical issue. The
main challenge is to calculate the accurate displacement of a station between two epochs. We focus on theuncertainties of station velocities used. In a first approximation, we use a global tectonic plate model tocalculate point velocities. We show the impact of the velocity model on the coordinate accuracies.
Several countries, particularly in active regions, are developing semi-dynamic reference frames. Theseframes include local displacement models updated regularly and/or after major events (such as
earthquakes). We study the particular case of California and the Horizontal Time-Dependent Positioning
model developed by the NGS. We show it improves greatly accuracy of estimated displacements.
The integration of these local deformation models into surveying or GIS applications is an upcoming
challenge. We want also to encourage the geodetic community to develop and use standard formats.

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*G01-P-09
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Verification of accelerated vertical crustal movements in the Tohoku region
prior to the 2011 Tohoku-Oki earthquake by reanalysis of GEONET datausing Precise Point Positioning* Yo Kawashima , Takeshi Sagiya
Nagoya University, Nagoya, Japan
Homogeneous coordinate time series data over a decade from GNSS analysis is essential for investigationof various phenomena preceding massive earthquakes such as the Tohoku-Oki earthquake. Kurokawa(2016) found a significant difference between vertical velocities obtained from GNSS and those from tidal
record during 2003~2011. This suggests that the long-term homogeneity of the GNSS result is questioned.
Routine processing of GEONET, the GNSS continuous observation network in Japan, currently adopts the
network analysis strategy (F3 solution). However, such strategy may generate bias in analysis result
because the combination of baselines has changed in response to the increase of the number of stations. In
this study, we reanalyze the daily coordinate of 30 GEONET stations along the coast of Tohoku region forthe last 20 years by using Precise Point Positioning method (PPP) in order to get rid of bias due to network
analysis. We compare the velocities obtained from the F3 solution and our PPP result. In the horizontal
components, the differences are about 1~1.5 mm/yr before the Tohoku-Oki earthquake. In the verticalcomponent, large differences of about 2~3 mm/yr are found before 2003, and gradually decrease to smaller
than 0.5 mm/yr just before the Tohoku-Oki earthquake. Even if the difference is small, there exist
systematic differences in many cases. We estimate the vertical acceleration before the Tohoku-Oki
earthquake. Our PPP result shows no significant change along the Japan Sea coast, and accelerated
subsidence along the Pacific coast (about -0.3 mm/yr^2). This result is consistent with the horizontal
acceleration indicated by Mavrommatis et al. (2014) and the accelerated subsidence by Kurosawa (2016).
Furthermore, this suggests that the construction of a network for the F3 solution is one of the causes of thecommon mode error, because Mavrommatis et al. (2014) and Kurokawa (2016) eliminated such errors byusing spatial filtering technique.

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*G01-P-10
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

Modeling vertical displacements at stations of the Geocentric Reference
System for the Americas (SIRGAS) due to hydrological load
Claudio Brunini 1) 2) 3) , * Laura Sanchez 4) , Romina Galvan 2) 3) , Hermann Drewes 4) 5) , Mauricio Gende 2)
3)

Argentinean - German Geodetic Observatory, Argentina 1) , Consejo Nacional de Investigaciones Cientificas
y Tecnicas, Argentina 2) , Facultad de Ciencias Astronomicas y Geofisicas de la Universidad Nacional de La
Plata, Argentina 3) , Deutsches Geodaetisches Forschungsinstitut, Technische Universitaet Muenchen,
Germany 4) , International Association of Geodesy, Germany 5)
The usual assumption of constant station velocities in reference frame realizations has proved to beinefficient for many sites where geophysical processes cause significant non-linear motions, either
seasonally (e.g., due to oceanic, hydrological or atmospheric loads) or episodically (e.g., due to co-seismic
and post-seismic processes). Seasonal displacements are usually described using harmonic functions withannual and sub-annual periods. This work presents an alternative description based on the modelling of thehydrological process underlying the seasonal displacement. The study focuses in a first stage on thevertical displacements of the SIRGAS stations associated with the seasonal variations of the hydrologicalload. The developed methodology combines two sources of information: GNSS normal equations of the
SIRGAS network (NEQ) to describe the geometric displacements; and monthly grids of equivalent waterheight (EWH) provided by GRACE to describe the hydrological load. The proposed model relates the
response of the Earth's crust to the hydrological load and relies on a numerical solution of the static
equilibrium equation for an elastic medium (i.e. the Earth's crust) characterized by an 'elastic parameter',which results from the combination of the Poisson ratio and the Young modulus. The NEQ are calculated
on a weekly basis and remain weakly constrained to avoid deformations of the network geometry. Theseequations are then combined with the EWH values and some fiducial station positions are constrained todefine the datum of the network. This leads to a common adjustment of 7 parameters per station, namely: 3
positions at a certain epoch, 3 velocities, and 1 elastic parameter. The vertical positions calculated after the
adjustment agree with the weekly vertical positions published by SIRGAS within +/- 3 mm at the one sigma
level, which is interpreted as a first satisfactory evaluation of the method here presented.

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*G01-P-11
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

SIRGAS: the core geodetic infrastructure in Latin America and the
Caribbean
Victor Cioce 1) , * Laura Sanchez 2) , Marco Aurelio de Almeida 3) , Jose Guillermo Gasca 4) , Hernan Guagni, Alfonso Morillo 6) , Hector Parra 7) , Oscar Rodriguez 8) , Norbertino Suarez 9) , Jose Francisco Valverde

5)

10)

Universidad del Zulia, Maracaibo, Venezuela 1) , Technische Universitaet Muenchen, Munich, Germany 2) ,Instituto Brasileiro de Geografia e Estatistica, Rio de Janeiro, Brazil 3) , Instituto Nacional de Estadistica yGeografia, Aguascalientes, Mexico 4) , Instituto Geografico Nacional,Buenos Aires, Argentina 5) , Instituto
Geografico Militar, Quito, Ecuador 6) , Instituto Geografico Militar, Santiago de Chile, Chile 7) , Instituto
Geografico Agustin Codazzi, Bogota, Colombia 8) , Servicio Geografico Militar, Montevideo, Uruguay 9) ,Universidad Nacional, Heredia, Costa Rica 10)
Studying, understanding, and modelling geophysical phenomena, such as global change and geodynamics,
require geodetic reference frames with (1) an order of accuracy higher than the magnitude of the effects wewant to study, (2) consistency and reliability worldwide, and (3) a long-term stability. The definition,
realisation and maintenance of the ITRS are oriented to guarantee a globally unified geometric reference
frame (i.e., the IRTF) with reliability at the mm-level. The densification of the global ITRF in Latin America
and The Caribbean is given by SIRGAS (Sistema de Referencia Geocentrico para Las Americas), primaryobjective of which is to provide the most precise coordinates in the region. At present, SIRGAS is the
backbone for all regional projects based on the generation, use, and analysis of geo-referenced data atnational as well as at international level. Besides providing the reference for a wide range of scientificapplications such as the monitoring of Earth's crust deformations, vertical movements, sea level variations,
atmospheric studies, etc., SIRGAS is also the platform for practical applications such as engineering
projects, digital administration of geographical data, geospatial data infrastructures, etc. However, thereliability of SIRGAS as reference frame is being affected by the frequent occurrence of seismic events
deforming the geometry of the network and by the omission of non-lineal station movements including
systematic errors in epoch coordinates. In this context, this presentation summarises the main challenges
faced currently by SIRGAS: (1) A high-resolution monitoring of the reference frame deformation by meansof more reference stations and improved analysis standards; (2) Co-seismic deformation models for thetransformation of station positions between pre- and post-seismic frame realisations; (3) Reliable modellingof non-lineal station movements in the reference frame computation to improve the estimation of epoch
coordinates.

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*G01-P-13
IAG Symposium / IAG01. Reference Frames / G01. Reference frames

IDS DORIS analysis centre Geodetic Observatory Pecny: development andresearch* Petr Stepanek , Michal Buday , Vratislav Filler
Research Institute of Geodesy, Topography and Cartography, Zdiby, Czech republic
Geodesy Observatory Pecny (GOP) provides one of the International DORIS Service (IDS) analyses centers,
participating on the combined IDS products including the solution for ITRF2014. As the unique approach,
GOP employs a DORIS-developed version of the Bernese GPS Software. Besides the routine operating, therecent research focuses on several topics as preprocessing strategy and observation weighting, estimationof Earth rotation parameters, station clock modeling from the DORIS/pseudorange measurements, satellite
attitude modeling and orbit parametrization. We demonstrate that observation weighting cos (Z) reduces
the scale bias respect to ITRF2014 by about 3 ppb. Combination of this observation weighting and new
preprocessing strategy has significant positive impact on the station repeatability and weekly station RMS
with respect to DPOD/ITRF, as well as on the precise orbit determination.

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*G02-1-01
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Rectangular rotation of spherical harmonic expansion of arbitrary highdegree and order* Toshio Fukushima
National Astronomical Observatory, Tokyo, Japan
In order to move the polar singularity of arbitrary spherical harmonic expansion to a point on the equator,
we rotate the expansion around the y-axis by 90 degrees such that the original x-axis becomes a new pole.
The spherical harmonic expansion coefficients are transformed by multiplying a special value of Wigner's Dmatrix and a normalization factor. Thanks to the choice of not the x- but the y-axis as the rotation axis, thespecial value becomes a real-valued function: Wigner's d-function of the angle as 90 degrees. Its realness
results the transformation of Cnm and Snm completely separated. The transformation matrix is unchanged
whether the coefficients are fully-normalized or Schmidt quasi-normalized. This is because the rotation isrestricted within the coefficients of the same degree, and therefore the difference in the normalization
factors do not alter the transformation formula. The d-function is stably computed by an increasing-degree
fixed-orders three-term recurrence formula. The two seed values can be also computed recursively. The
underflow problem during the recursions is effectively resolved by the so-called X-number formulation(Fukushima, 2012, J. Geodesy, 86, 271--285). As an example, we obtained 2190x2190 coefficients of therectangular rotated spherical harmonic expansion of EGM2008. The obtained coefficients are of the 15
digits consistency with the original one because the transformation is conducted by the quadruple
precision X-number formulation. A proper combination of the original and the rotated expansions isrealized by switching them at the parallels of 45 degrees latitude. The combined spherical harmonic
expansions will be useful in (i) integrating the polar orbits of artificial satellites precisely, and (ii)synthesizing/analyzing the gravitational/geomagnetic potentials and their derivatives accurately in the highlatitude regions including the arctic and antarctic area.

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*G02-1-02
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Gravitational contribution of a spherical tesseroid by means of mapping it
into sectors of spherical band
* Anna Maria Marotta 1) , Riccardo Barzaghi 2)
Universita' degli Studi di Milano, Department of Earth Sciences Ardito Desio, Milano, Italy 1) , Politecnico di
Milano, DICA, Milano, Italy 2)
We present a new methodology for computing the gravitational effect of a spherical tesseroid, based on therotation from the global Earth-Centred Rotational reference frame to the local Earth-Centred P-Rotationalreference. After rotation, the gravitational effect of the tesseroid is computed via the effect of a sector of
spherical zonal band. In this respect, two possible procedures to handle the rotated tesseroids have been
proposed and tested, one based on the re-orientation of the rotated tesseroids, and the other based on asecond-order tesseroidal decomposition. Sensitivity tests show that the RT procedure is adequate inestimating the gravitational effects at distances greater than 0.1 degree from the computation point; themore accurate ST procedure is required at closer distances. The implemented procedure has been tested
against other methods known in literature. In particular, benchmark tests have been carried out withrespect to the methods proposed by Heck and Seitz (2207), Hirth and Kuhn (2014) and Uieda et al. (2015).
The comparative analysis showed that the new devised methodology is in good agreement with all theabove-mentioned methods and can be thus used within future more general benchmark studies.

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*G02-1-03
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Boundary complexity in classical and variational concepts of solving
geodetic boundary value problems* Petr Holota 1) , Otakar Nesvadba 2)
Research Institute of Geodesy, Topography and Cartography, 250 66 Zdiby 98, Prague-East, Czech
Republic (e-mail: petr.holota@pecny.cz) 1) , Land Survey Office, Pod Sidlistem 9, 182 11 Prague 8, Czech
Republic (e-mail: otakar.nesvadba@gmail.com) 2)
In gravity field studies the complex structure of the Earth's surface makes the solution of geodetic boundary
value problems quite challenging. This equally concerns classical methods of potential theory as well as
modern methods often based on a (variational or) weak solution concept. The aim of this paper is to seek abalance between the performance of an apparatus developed for the surface of the Earth smoothed up to acertain degree and an iteration procedure used to bridge the difference between the real and smoothed
topography. The approach is applied to the solution of the linear gravimetric boundary value problem ingeopotential determination. Within the classical concept a transformation of coordinates is used that offers
a possibility to solve an alternative between the boundary complexity and the complexity of the coefficientsof the partial differential equation governing the solution. Also the oblique derivative boundary condition istaken into account in this way. The use of modified spherical and also modified ellipsoidal coordinates isdiscussed. The complexity of the boundary is reflected in the structure of Laplace's operator. Green's
function representation is applied and the structure and convergence of the iteration steps is analyzed. The
weak solution concept has different features. The aim here is to simplify the bilinear form that defines the
problem under consideration and to justify the use of Galerkin's matrix constructed for an approximation
solution domain. The approach focuses on the use of a sphere or an ellipsoid of revolution in quality of an
approximation boundary. Also in case of the weak solution the simplification is compensated by successive
approximations. The related functional analytic and numerical aspects are discussed. In both the cases
attention is also paid to the question concerning the possible (hidden or explicit) role of analyticalcontinuation.

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*G02-1-04
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

MRR and LSC – A mutual benefit for advanced regional gravity fieldmodeling* Michael Schmidt , Verena Lieb , Martin Willberg , Roland Pail
Technical University of Munich, Munich, Germany
Various regional gravity field modeling approaches exist next to each other – everyone revealing individual
strengths and weaknesses depending on the methods themselves and on the fields of application. For
instance, in order to establish precise height systems in developing countries with sparse data availability
and/or low-quality, Multi-Resolution Representation (MRR) using spherical basis functions and Least
Squares Collocation (LSC) are suitable approaches. Drawing mutual benefit from both is the innovative key
aspect of our study and enables an advanced modeling of the gravity field in the specific regions by
optimally combining heterogeneous data sets.
The common theoretical base of MRR and LSC is that in- and output functionals are described by series
expansion in terms of Legendre Polynomials. For formulating observation equations, LSC incorporates fullcovariance information of the observations, and thus, provides coherent error estimates of the resulting
models; MRR manages a well-balanced relative weighting of heterogeneous input data by variancecomponent estimation, and a consistent spectral combination by appropriate filtering.
We study in detail the differences of LSC and MRR, learn from each other and finally bring together thestrengths of both approaches: by (1) matching the mathematical fundamentals, (2) analyzing closed-loop
scenarios with simulated data, and finally (3) setting up an optimal regional modeling strategy. We focus ona study area in South America with different topographic features and combine heterogeneous data setsobtained in varying measurement heights and with different quality, spectral and spatial resolutions. From
the findings of these comprehensive studies, we plan to derive a generalized concept which provides
developing countries the opportunity of establishing physical height systems. Those have a high socioeconomic impact for various applications in science, infrastructure and administration.

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*G02-1-05
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Properties and applications of gravity-field curvatures in geodesy* Pavel Novak
University of West Bohemia
Recently reported developments in experimental physics suggest that gravity-field curvatures could
become observable one day through, e.g., atom interferometers or satellite constellations. This contribution
reviews basic properties of these functionals of the gravity potential (third-order directional derivatives)and discusses their possible applications in geodesy given their signal-to-noise-ratio reaches an acceptablevalue in order to facilitate these small values in geodetic applications. Discussed issues include spectral
and stochastic properties of Earth's gravity-field curvatures given currently available geopotential models,
links to other commonly used gravity-field parameters in geodesy, and applicability for local and global
gravity field modelling.

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*G02-1-06
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Direct topographical effect on the airborne gravity disturbance for Helmert's
second method of condensation* Jianliang Huang , Marc Veronneau , John W. Crowley
Natural Resources Canada, Ottawa, Canada
Helmert's second method of condensation removes the topographical mass and compensates using a thinmass layer on the geoid, transforming the Earth's gravitational potential to a harmonic field in the space
between the geoid and topographical surface. Consequently, the Helmert(ized) gravity anomaly can becontinued from the Earth's surface downward to the geoid to meet the requirement of Stokes's integral forthe determination of the geoid in the harmonic Earth's gravity field. Finally the geoid can be determined byrestoring the topography from the Helmert mass layer. In this process, the Helmert gravity anomaly isdetermined from the Molodensky-type free-air anomaly by evaluating and correcting for the direct andsecond indirect topographical effects (DTE and SITE) on the Earth's surface. The Molodensky-typeanomaly is defined by the difference between the gravity value at a point on the Earth's surface and thenormal gravity at the corresponding point on the telluroid. This approach is suitable when the gravity
observation and orthometric/normal height are available on the Earth's surface. The airborne gravity
observations provide the gravity disturbance, as ellipsoidal height is generally measured at flight level. To
apply Helmert's second method of condensation to the gravity disturbance, only the direct topographicaleffect is required at flight level. In this paper, we first formulate the direct topographical effect on thegravity disturbance at flight level in terms of both Newton's integral and spherical harmonic series, thennumerically determine the requirements on spatial and spectral resolutions of digital elevation model(DEM) for the evaluation of DTE at various flight levels.

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*G02-2-01
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Closing the GOCE polar gap in Antarctica from airborne gravity and derived
gravity gradients* Rene Forsberg 1) , Arne Olesen 1) , Tom Jordan 2) , Fausto Ferraccioli 2) , Kenichi Matsuoka 3) , Hasan Yildiz
4)

DTU-Space, Lyngby, Denmark 1) , Bristish Antarctic Survey, Cambridge, UK 2) , Norwegian Polar Institute,
Tromso, Norway 3) , General Command of Mapping, Ankara, Turkey 4)
GOCE has mapped the global gravity field with hitherto unprecedented accuracy and resolution, except forthe polar gaps north and south of latitude 83.3 degree. While the Arctic gap has been filled since a decadeby Arctic Gravity Project data, filling the Antarctic polar gap has been a major challenge. An ESA-supported
airborne gravity survey was carried out to do this in a major, challenging field campaign 2015/16. This
“Polar Gap project" used a Twin-Otter aircraft equipped with several gravity sensors (spring gravimeterand iMAR IMU), magnetometers, ice penetrating radar, and scanning lidar, to collect a complete suite of
airborne remote sensing data over the essentially unmapped region of the polar gap. The PolarGap logistics
involved two deep interior field camps, as well as flights the Amundsen-Scott South Pole station, thanks to a
special arrangement with NSF. In the talk we outline the Antarctic field operations, and show final resultsof the campaign, including performance of the gravity sensors, the gravity reference network, and thecomparison to the limited existing gravity data in the region. We also show results of computations ofgravity field gradients at altitude, computed by least-squares collocation, and compared to GOCE gradientsalong the outer rim of the polar gap. Examples of other acquired geophysical and lidar data are also given,
including discoveries of hitherto unknown major subglacial valleys and mountains in the survey region.

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*G02-2-02
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

A Comparison of Airborne Vector Gravimeter Measurements with the NOAA
Geoid Slope Validation Survey 2014
Stephen Ferguson 1) , * Yan Ming Wang 2) , Stefan Elieff 1) , Simon Holmes 3) , Xiaopeng Li 4) , Kevin Ahlgren, Ruifeng Xi 1)
Sander Geophysics Ltd., Ottawa, Canada 1) , The National Geodetic Survey, Silver Spring, MD USA 2) , SGT
Inc. Greenbelt MD USA 3) , DST Inc. Silver Spring MD USA 4)
2)

Gravity measurements made from aircraft are becoming widely used in combination with satellite andterrestrial data for geoid computation. At present, only measurements of the vertical component of thegravity vector are used for this purpose. Incorporation of the horizontal components of the vector offers theopportunity to strengthen the geoid solution, and minimize edge effects at the survey boundaries. Most
airborne gravity meters do not offer the possibility of measuring all three components of gravity, however
the AIRGrav system developed by Sander Geophysics has shown the ability to routinely obtainrepeatability at the sub-milliGal level, with suitable processing.
This presentation will focus on a direct comparison of airborne measurements flown on a repeat track overthe GSVS2014 test line located in Iowa, USA. The high-accuracy GSVS2014 ground data will be upward
continued to the flight elevation for comparison with the measured airborne gravity components(equivalent to magnitude and deflection of the vertical). The airborne data will also be compared with thelatest gravity models, including EGM2008, EIGEN6c4, and the current NOAA model xGEOID17. The
vector airborne data will also be incorporated into a gravity model to assess their contribution.

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*G02-2-03
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Evaluation of the contribution of optical clocks to gravity field modelling* Juergen Mueller , Hu Wu
Leibniz Universitaet Hannover, Hannover, Germany
In the past decade, the performance of optical clocks and frequency transfer techniques have been largely
improved. These technical developments allow to measure relative frequency differences with aninaccuracy of 1 x 10^-18 in the near future. According to the formula of relativistic gravitational redshift,
the frequency difference can be transformed to a geopotential difference with an error of 0.1 m^2/s^2, i.e.
approximately 1 cm in terms of height changes. Hence, optical clocks present a new and promisingtechnique for determining the Earth's gravity field and related quantities.
In this context, the present work aims to evaluate the contribution of optical clocks to gravity fieldmodelling in a combined analysis of different types of gravimetric observations. Here, gravity anomalies,
gravity gradients and potential differences are used for a simulation study, taking Germany as a test case.
With this simulation study, we attempt to answer the following research questions: 1) How much can
optical clocks help improving gravity field recovery? 2) How many clock measurements are required to
improve a combined gravity field model? 3) How should a clock network be arranged to achieve an optimal
gravity field solution?

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*G02-2-04
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Cold Atom Interferometers Used In Space (CAIUS) for measuring the Earth's
gravity field
Olivier Carraz , Luca Massotti , Christian Siemes , Roger Haagmans , Linda Mondin , Pierluigi Silvestrin , *Michael Kern
European Space Agency
In the past decades, it has been shown that atomic quantum sensors are a newly emerging technology thatcan be used for measuring the Earth's gravity field. Whereas classical accelerometers typically suffer fromhigh noise at low frequencies, Cold Atom Interferometers are highly accurate over the entire frequency
range.
There are two ways of making use of that technology: one is a gravity gradiometer concept, which relies ona high common mode rejection that relaxes the drag free control compare to GOCE mission; and the otherone is in a low-low satellite-to-satellite ranging concept to correct the spectrally colored noise of theelectrostatic accelerometers in the lower frequencies. We will present for both concepts the expected
improvement in measurement accuracy and for the gravity gradiometer concept the expected improvementof Earth gravity field models, taking into account the different type of measurements (e.g. single vs. 3 axis,
integration time, etc.) and different mission parameters such as attitude control, altitude of the satellite,
time duration of the mission, etc.

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*G02-2-05
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

An innovative tool for marine Gravimetry: results of a survey with a cold
atom gravimeter* Marie-Francoise Lalancette 1) 3) 4) , Didier Rouxel 1) 4) , Yannick Bidel 2) , Alexandre Bresson 2) , Nassim
Zahzam 2) , Sylvain Lucas 1) 4) , Cedric Blanchard 2) , Gildas Delachienne 1) 1)
Shom, Brest, France 1) , ONERA, Paris, France 2) , IUEM/LGO/UMR6538 3) , GRGS 4)
Measurements of marine gravimetry are usually carried out by relative shipborne gravimeter. We present
the development and the tests of an absolute onboard gravimeter for marine applications that highlights areal technological breakthrough. This instrument is based on the measurement of the acceleration of acloud of cold atoms in free fall with an atom interferometry method. This technology has already shown
excellent performances for static gravimeters and compares favorably with the best classical mechanicalabsolute gravimeters. Here the challenges were to develop a cold atom gravimeter able to measure gravity
in a mobile platform where the gravimeter is subject to accelerations and rotations. For this purpose, thesensor head has been miniaturized and placed in a gyrostabilized platform. The gravimeter has also been
adapted to work with strong vibrations and accelerations which occur in a ship. We report the gravity
marine survey realized by strong swell and bad weather in the bay of Biscaye during the winter 2015-2016.
After laboratory tests, the prototype has been successfully tested on the French Shom N/O vessel "Beautemps-Beaupre " during two campaigns of few days and compared to the commercial spring marine
gravimeter KSS32-M. We present the results and the benefit of such a technology for marine surveyors.

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*G02-2-06
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Development of a high-accuracy gravity measurement system onboard amoving autonomous underwater vehicle* Takemi Ishihara 1) , Masanao Shinohara 1) , Akito Araya 1) , Tomoaki Yamada 1) , Toshihiko Kanazawa 2) ,Hiromi Fujimoto 3) , Satoshi Tsukioka 4) , Shinobu Omika 4) , Kenji Uehira 2) , Masashi Mochizuki 2) ,Tsuyoshi Yoshiume 4) , Kokichi Iizasa 5)
Earthquake Research Institute, The University of Tokyo, Tokyo, Japan 1) , National Research Institute for
Earth Science and Disaster Prevention, Tsukuba, Japan 2) , Tohoku University, Sendai, Japan 3) , Japan
Agency for Marine-Earth Science and Technology, Yokosuka, Japan 4) , Institute of Industrial Science, The
University of Tokyo, Tokyo, Japan 5)
We have developed an underwater gravity measurement system onboard the autonomous underwater
vehicle (AUV) Urashima (JAMSTEC). The gravimeter is mounted on a gimbal unit and housed in a pressureproof sphere vessel made of titanium alloy. The gravity sensor is kept at a constant temperature of 60.4
degree C and covered with a sheet of permalloy for magnetic shielding. In order to obtain precise gravity
data, a Gaussian low-pass filter with the width of 100-300 s is applied to 100 Hz output of the gravity
sensor, and corrections are made using various measurements: correction of vertical acceleration with highaccuracy water pressure gauge data, Eotvos and free water corrections with the AUV's navigation data,
correction of location difference between the gravimeter and water pressure gauge with the AUV's pitch
and roll angle data, and Bouguer correction with the detailed topographic data collected by the Urashima's
multi-beam bathymetric system. A detailed and high-accuracy gravity survey of seafloor mineral deposit
area can be carried out by moving the AUV along planned track lines 50-100 m above the seafloor. Afterthe first successful sea experiment in September 2012, good quality data were collected by threeexperiments in mineral deposit areas in the Okinawa Trough and the Izu-Ogasawara Arc. Almost noiselessgravity anomalies were obtained by the above data processing of the collected data including those fromconstant altitude track lines above rough seabottom topography, where large amplitude verticalacceleration was observed. We obtained a good result with an rms crossover error of about 0.1 mGal in afavorable survey condition: measurements at a constant depth of 1550 m in relatively flat Izena Caldera of
the Okinawa Trough. High anomalies with amplitudes < a few mGal, which suggest occurrences of highdensity material, possibly mineral deposits, are observed in the Bouguer anomaly map of the southern partof Izena Caldera.

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*G02-3-01
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

An improved gravimetric geoid model for Japan based on the
Stokes–Helmert scheme with a deterministically modified Stokes' kernel* Koji Matsuo 1) , Takayuki Miyazaki 1) , Basara Miyahara 1) , Yuki Kuroishi 2)
Geospatial Information Authority of Japan, Ibaraki, Japan 1) , The University of Tokyo, Tokyo, Japan 2)This study developed an improved gravimetric geoid model for Japan on a 1 * 1.5 arc-minute grid, based on
the remove–compute–restore with Helmert's second method of condensation (the Stokes–Helmert
scheme). A GOCE (the Gravity field and steady-state Ocean Circulation Explore)-related global geopotential
model was used with 309,992 land gravity data and an updated altimetry-derived marine gravity model. To
minimize the truncation error and appropriately combine each gravity data, the hybrid Meissl–Molodensky
modified spheroidal kernel was employed with modification parameters regionally tuned. Thus, we createda gravimetric geoid model for Japan corresponding to GNSS/leveling geoid heights with a standard
deviation of 5.91 cm, an improvement of 2.63 cm compared with the previous model (JGEOID2008). This
remarkable improvement was particularly evident in the long-wavelength component of the geoid
undulation. The north–south tilted trend of the difference between the gravimetric and GNSS/levelinggeoid heights was reduced significantly from 0.18 to 0.06 ppm. Gravimetric geoid model improvements
provide the possibility of generating a new standard and convention for the height reference system inJapan, currently realized by spirit leveling and tide-gauge observation.

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*G02-3-02
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

AFRGDB_V2.0: The Gravity Database for the Determination of the Earth's
Mathematical Surface in Africa* Hussein Abd-Elmotaal 1) , Kurt Seitz 2) , Norbert Kuehtreiber 3) , Bernhard Heck 2)
Minia University, Minia, Egypt 1) , Karlsruhe Institute of Technology, Karlsruhe, Germany 2) , Graz
University of Technology, Graz, Austria 3)
In the framework of the activities of the IAG sub-commission on the gravity and geoid in Africa, it is needed
to have a uniform gridded gravity data set to determine the earth's mathematical surface (the geoid) in
Africa using Stokes' integral in the frequency domain. The available gravity data set consists of land point
gravity data as well as shipborne and altimetry derived gravity anomalies data. The available gravity data
set has a lot of significant gaps, while in some particular areas the distribution is very dense, besides thefact that the shipborne and altimetry data have a line structure (along tracks). This leads to a problem indetermining a reasonable empirical covariance function, and consequently reduces the capability of theused least-squares prediction technique. Filtering the available gravity data and degrading the ocean
gravity data took place to overcome this problem. The establishment of the gravity database for Africa has
been carried out using an iterative process employing an ultra high-degree tailored reference model andweighted least-squares prediction technique. The land gravity data got the highest precision, while the
shipborne and altimetry gravity data got a moderate precision. In each iteration step, the data gaps arefilled with the ultra high-degree tailored reference model computed at the previous iteration step, getting
the lowest precision within the prediction technique. The weighted least-squares prediction technique isthus carried out to estimate gridded gravity anomalies, which are used to estimate a new ultra high-degree
tailored reference model employing a least-squares harmonic analysis technique. The iterative processcontinues till the solution stabilizes. The AFRGDB_V2.0 gravity database on a uniform 5' x 5' grid has been
established by the developed process. The precision of the developed gravity database is tested. A
comparison with the previous AFRGDB_V1.0 is made and extensively discussed.

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*G02-3-03
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Terrestrial gravity data for a new Russian quasigeoid model* Ilya Oshchepkov
Center of Geodesy, Cartography and SDI, Moscow, Russia
A new quasigeoid model for Russia is planned to be calculated in the next few years.
For this purpose the gravity database was created from the geological gravity surveys whichwere carried out from the late 1940s to the 2000s. This means there are on the average 0.1-0.25 points per
squared kilometre with an accuracy of the Bouguer anomalies 0.8-1.0 mGal. Usually, but not always, eachgravity point has geodetic coordinates, the normal height, the free-air anomaly, the Bouguer anomaly with adensity of 2.3 g/cm^3, the refined Bouguer anomaly with a density of 2.67 g/cm^3 and the terrain
correction. These values are strictly related to each other and can be easily checked for inconsistencies
and errors, but unfortunately they don't cover the whole Russian territory, because not all the surveys weredigitized yet.
In 1980th the mean Bouguer (with a density of 2.67 g/cm^3) and the Faye gravity anomalies with theresolution of 5'x7.5' were calculated directly from the gravity maps for the whole USSR territory and around
its borders. These gridded data are almost complete for the whole area, but they have not been evaluatedsince the creation, which is done in this work by comparing them with the database points and the global
gravity field models.
The new gridded Bouguer anomalies for Russia were created with GMT software by concatenating after
gridding the point database with the old grid data to fill-in the gaps. The Faye anomalies were derived bysubtracting the Bouguer plate reduction calculated with the RuDTM2014 digital elevation model.

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*G02-3-04
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

DRUKGEOID15: The new geoid of Bhutan
Machiel Bos 1) , * Rui Fernandes 1) 2) , Kinzang Thinley 3) , Jamphel Gyeltshen 3)
SEGAL (UBI/IDL), Covilha, Portugal 1) , TU Delft, Delft, The Netherlands 2) , NLC, Thimphu, Bhutan 3)
In this research we present a new regional geoid for Bhutan, a land-locked country in the Himalayas. For
this mountainous area only few terrestrial gravity data are available which can explain the metre level
differences for this region between two recent global geopotential models: EGM2008 and EIGEN-6C4. To
improve this situation, a new terrestrial gravity campaign was performed from November 2014 to May
2015. In total 255 new gravity points were observed together with their coordinates using GPS using two
SCINTREX CG5 gravimeters.
Using the standard remove and restore technique, together with the residual terrain correction a new
regional geoid, called DRUKGEOID15, was computed. EIGEN-6C4 together with the Shuttle Radar
Topography Mission (STRM) digital terrain model a smooth residual gravity field was obtained in theremove step. Using standard least-squares collocation, this was converted into a residual height anomaly
field after which the effect of EGM2008 and the terrain model on the height anomalies were restored. The
height of the mountains can reach five kilometres which causes the height anomaly to geoid corrections toreach values of a few metres. Furthermore, we demonstrate that the height anomaly to geoid corrections
provided by the EGM2008 model differ up to one metre with our more refined computed values following
the method of Flury and Rummel (2009). Finally, we present a comparison of our geoid with orthometricheights observed at benchmarks that also were observed with GPS, demonstrating the improved accuracyof the new regional geoid compared to EGM2008 and EIGEN-6C4.

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*G02-3-05
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Combining airborne and terrestrial gravity data to improve the geoid modelin Brazil* Gabriel do Nascimento Guimaraes 1) , Ana Cristina Oliveira Cancoro de Matos 2) , Denizar Blitzkow 2)
Federal University of Uberlandia, Monte Carmelo, Brazil 1) , University of Sao Paulo, Sao Paulo, Brazil 2)
Brazil is a country of continental proportions and with different geographic characteristics. From its coastof nearly 7,400 km, where it houses 25% of the population, up to the 5,500,000 km² that form the Amazon
region, this country has great challenges for Geodesy. One of these challenges is linked to the improvementof the geoid model quality to meet the needs related to the areas of knowledge, besides having
homogeneous geoid undulation precision in most of the Brazilian territory. The country has about 450,000
ground gravimetric stations. While the South and Southeast regions have a regular distribution, the North(Amazon) and Northeast regions lack terrestrial gravimetric data. In this sense, this work aims to combine
terrestrial and airborne gravity data to improve the Brazilian geoidal model. Two areas were selected. The
first is bounded by 20S and 24S in latitude and 48W and 54W in longitude and has terrestrial and airborne
gravity data. The second area is located in the Amazon region and is limited by 05N and 05S in latitude
and 50W and 75W in longitude and does not have regular distribution of terrestrial data, only airborne
data. The computation are being conducted using the GRAVSOFT package. The geoid models computed
were based on EIGEN-6C4 up to degree and order 200 as a reference field. The oceanic region wascompleted with the mean free-air gravity anomalies derived from a satellite altimetry model from theDanish National Space Center, called DTU10. The short wavelength component was estimated via FFT. It is
expected that the result will be aggregated to the calculation of the new Brazilian geoid model predicted for2018.

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*G02-3-06
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

The gravimetric component of AUSGeoid2020 and its error model* Sten Claessens 1) , Jack McCubbine 1) , Will Featherstone 1) , Nick Brown 2)
Curtin University 1) , Geoscience Australia 2)
As Australia is moving from the Geocentric Datum of Australia 1994 (GDA94) to the new datum GDA2020,a new accompanying quasigeoid model has been computed: AUSGeoid2020. The 2020 designation is
because ITRF velocities have been used to predict the location of the datum so as to prolong its useful life.
Like its predecessor AUSGeoid09, AUSGeoid2020 is built up of a gravimetric quasigeoid model that has
subsequently been distorted to fit the Australian Height Datum (AHD) using cross-validated least-squares
collocation. AUSGeoid2020 includes many improvements over AUSGeoid09 including use of new data andimproved numerical integration routines. Another major improvement is that AUSGeoid2020 isaccompanied by an error model with geographic specificity, so that users no longer need to rely on crude
error estimates taken from a single nationwide comparison to GNSS-levelling data. The error estimates arepropagated from uncertainties in the GNSS-levelling, terrestrial and altimeter-derived gravity anomalies
and gravimetric terrain corrections. This presentation outlines the development of the gravimetriccomponent of AUSGeoid2020 and its associated errors. Results of various numerical tests used to optimise
the model are shown. Special emphasis is placed on the influence of data uncertainty on quasigeoid error
estimates. The model is validated through comparison to ~7,000 GNSS-levelling data and ~1,000 historicaldeflections of the vertical, showing the error propagation to be realistic.

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*G02-4-01
IAG Symposium / IAG02. Gravity field / G02. Static gravity fieldNGS Annual GRAV-D enhanced Geoid Models – xGEID2017: What is newand the results* Yan Ming Wang 1) , Simon Holmes 2) , Xiaopeng Li 3) , Kevin Ahlgren 1)
National Oceanic and Atmospheric Administration, Silver Spring MD USA 1) , SGT Inc. Greenbelt MD USA
2), DST Inc. Silver Spring MD USA 3)
The United States National Geodetic Survey [NGS] has been computing experimental gravimetric geoid
models annually. For these models, the latest satellite gravity models are combined with terrestrial gravity
data, and with airborne gravity data collected through the “Gravity for the Redefinition of the American
Vertical Datum" [GRAV-D] effort over the USA and its territories. To date, over 50% of this area has been
flown. Both the airborne and terrestrial gravity data are cleaned and their accuracies are estimated for
combination in the least squares sense. This paper outlines the methods used for data cleaning, editing anderror estimation, and the data combination. Results from using independent data sets to validate the geoid
models are also presented.

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*G02-4-02
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

High-resolution modelling of the static gravity field from the GOCE gravity
gradients using meshless boundary collocation techniques* Robert Cunderlik
Dept. of Mathematics, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Slovakia
Meshless boundary collocation techniques like the method of fundamental solutions (MFS) or singularboundary method (SBM) can be efficiently used to model the static gravity field purely from the GOCE
gravity gradients. These numerical methods use the fundamental solution of the Laplace equation as basis
functions. Hence, the system matrix is created by the second radial derivatives of the fundamental solutionthat depend solely on geometrical parameters, i.e. on 3D positions and direct distances between the GOCE
observations and source points located on the Earth's surface. Such a configuration is free of singularities
and MFS can be applied to derive unknown coefficients in the source points. From these coefficients thedisturbing potential and gravity disturbances can be evaluated in any point above the Earth's surface. To
obtain their values directly on the Earth's surface, e.g. at the source points, SBM can be applied. The key
idea of SBM is to isolate singularities of the fundamental solution and its derivatives using someappropriate regularization techniques.
The numerical experiments present results of processing several datasets of the GOCE measurements,
each for a different semi-annual period. To obtain "cm-level" precision, the source points are regularly
distributed over the Earth's surface with the high-resolution of 0.05 deg (12,960,002 points). For every
dataset the disturbing gravity gradients as input data are filtered using the nonlinear diffusion filtering.
Large-scale parallel computations are performed on the cluster with 1.2 TB of the distributed memory. A
combination of numerical solutions obtained for different datasets/periods yields the final static gravity
field model which is compared with the SH-based satellite-only geopotential models like
GO_CONS_GCF_2_DIR_R5. Finally, the geopotential evaluated on the DTU13 mean sea surface model isused to derive velocities of the ocean geostrophic surface currents.

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*G02-4-03
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Satellite gravimetry from tracking: do it right, and for better* Peiliang Xu
Kyoto University, Kyoto, Japan
Satellite gravimetry from tracking has played a key role in precise recovery of global Earth's gravity models.
In this talk, (1) We will prove that the standard numerical integration method to reconstruct a precise
global Earth's gravity model from satellite tracking measurements, as currently used to produce almost all
standard global Earth's gravity models by major institutions worldwide (NASA Goddard Space Flight
Center, GFZ, JPL and University of Texas CSR, for example), is incorrect mathematically; (2) Bearing in
mind that gravity satellites can be precisely tracked almost continuously by using global navigation satellite
systems, we develop a new, measurements-based perturbation method for precise reconstruction of global
Earth's gravity model from satellite tracking measurements. This new measurement-based perturbation
method is uniformly convergent from the mathematical point of view for arcs of any length and cantheoretically extract any small forces from long arc measurements with a very high resolution; (3) We
develop three different local solutions to the Newton's nonlinear different differential equations of satellite
motion. As a result, the new solutions can serve as starting foundations for global satellite gravitationalmodelling from satellite tracking measurements; and finally, (4) By directly turning the nonlinear
differential equations of satellite motion into the nonlinear integral equations, and recognizing the fact thatsatellite orbits can now be measured almost continuously at the level of random errors, we further
reformulate the links between satellite tracking measurements and the global uniformly convergent
solutions to the Newton's governing differential equations as a condition adjustment model with unknown
parameters. With all the efforts, we have finally constructed solid mathematical foundations for the next
generation of global satellite gravitational models of high precision and high resolution.

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*G02-4-04
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Evaluation of Dynamic Heights on the Great Lakes* Daniel Roman 1) , Xiaopeng Li 2)
U.S. National Geodetic Survey, Silver Spring, USA 1) , DST Inc., Silver Spring, USA 2)
The National Geodetic Survey (NGS) supports the Center for Operational Oceanographic Products andServices (CO-OPS) in the maintenance and access to the International Great Lakes Datum of 1985 (IGLD
85). IGLD 85 is expressed as a dynamic height and is informally considered as a height equivalent (basedon work to raise a unit mass) above mean sea level. IGLD 85 is also based on an adopted elevation at Point
Rimouski/Father's Point as well as mean water levels at a set of master water level stations on the Great
Lakes. Due to various observational, dynamical, and steric effects, there will be slight departures between adynamic height and an IGLD 85 height. These departures are known as hydraulic correctors and can range
from a few cm's to a couple dm's. With cm-level accurate orthometric heights planned as a part of the new
US datums in 2022, an update to the dynamic height datum for the Great Lakes is also planned. This paper
focuses on assessment of the accuracy of the current experimental geoid height models for use indeveloping updated dynamic heights. Fourteen CORS sites and an additional 39 water level sites occupied
by campaign GPS were evaluated. The GPS-derived geometric coordinates were transferred via second
order leveling to the 53 water level stations that continuously monitor the Great Lakes. Using the geometriccoordinates for the mean water level surfaces, a geopotential model was applied to determine dynamic
heights for comparison around each Lake. The CORS sites showed the best agreement as random errors
are significantly lower, but overall agreement was in the 2-5 cm range with Lake Superior providing thebest results and Lake Erie showing the worst. Differences appeared to due to standing water topography
arising from hydrologic factors, such as the persistent westerly wind direction along the length of Lake Erie.

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*G02-4-05
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Results from GOCE++ Dynamical Coastal Topography and tide gauge
unification using altimetry and GOCE
Ole Andersen 1) , * Per Knudsen 1) , Karina Nielsen 1) , Chris Hughes 2) , Rory Bingham 3) , Michael Kern 4) ,Guy Woppelmann 5) , mederic Garvelle 5) , Luciana Fenoglio-Marc 6)
DTU Space 1) , University of Liverpool 2) , University of Bristol 3) , ESA Estec 4) , University La Rochelle 5) ,University of Bonn 6)
ESA has initiated the GOCE ++ study on the investigation and using ocean levelling as a novel approach tothe study of height system unification across the oceans taking the recent development in geoid accuracy
through GOCE data into account.
The suggested investigation involves the use of measurements and modelling to estimate Mean Dynamic
Topography (MDT) of the ocean along a coastline, which contributes/requires reconciling altimetry, tidegauge and vertical land motion. Close to the coast the determination of the MDT is problematic due to i.e.,
the altimeter footprint, land motion or parameterization/modelling of coastal currents.
The objective of this activity is to perform a consolidated and improved understanding and modelling ofcoastal processes and physics responsible for sea level changes on various temporal/spatial scales. The
study runs from October 2015 to march 2017 and involves the following elements
Develop an approach to estimate a consistent DT at tide gauges, coastal areas, and open ocean; Validate
the approach in well-surveyed areas where DT can be determined at tide gauges; Determine a consistent
MDT using GOCE with consistent error covariance fields; improving altimetry (SAR) along the coast for
MSS/MDT improvement and finally connecting the global set of tide gauges and investigate trends

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*G02-4-06
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

A new OGMOC mean dynamic topography model – DTU17MDT.
* Per Knudsen 1) , Ole Andersen 1) , Thomas Gruber 2) , Thomas Fecher 2) , Nikolai Maximenko 3)
DTU Space, Technical University of Denmark, Geodesy 1) , Institute of Astronomical and Physical Geodesy,Technical University of Munich, Germany 2) , University of Hawaii at Manoa, IPRC, Honolulu, USA 3)
Within the ESA supported Optimal Geoid for Modelling Ocean Circulation (OGMOC) project a new geoid
model have been derived. It is based on the GOCO05C setup though the newer DTU15GRA altimetricsurface gravity has been used in the combination. Subsequently the model has been augmented using the
EIGEN-6C4 coefficients to d/o 2160.
The new DTU17MDT has been derived using this new geoid model and the DTU15MSS mean sea surface.
Compared to other geoid models the new OGMOC geoid model has been optimized to avoid striations andorange skin like features. Finally, the filtering was re-evaluated by adjusting the quasi-gaussian filter width
to optimize the fit to drifter velocities. Subsequently, the drifter velocities were integrated to enhance theresolution of the MDT. The results show that the new MDT improves the resolution of the details of theocean circulation.

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*G02-5-01
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

The GEOMED2 project: Geoid estimation in the Mediterranean Area
* Riccardo Barzaghi 1) , Georgios Vergos 2) , Alberta Albertella 1) , Daniela Carrion 1) , Ilias N. Tziavos 2) ,Vassilios N. Grigoriadis 2) , Dimitrios A. Natsiopoulos 2) , Sean Bruinsma 3) , Sylvain Bonvalot 3) , Lucia
Seoane 3) , Franck Reinquin 3) , Marie-Francoise Lequentrec-Lalancette 4) , Corinne Salaun 4) , Pascal
Bonnefond 5) , Per Knudsen 6) , Ole Andersen 6) , Mehemet Simav 7) , Hasan Yildiz 7) , Tomislav Basic 8) ,Matei Varga 8) , Olga Bjelotomic 8)
Politecnico di Milano, Milano, Italy 1) , Aristotle University of Thessaloniki, Thessaloniki, Greece 2) , GET
UMR 5563, Toulouse, France 3) , SHOM, Brest, France 4) , OCA/Géoazur, Sophia-Antipolis, France 5) , DTU
Space, Kopenhagen, Denmark 6) , General Command of Mapping, Ankara, Turkey 7) , University of Zagreb,
Zagreb, Croatia 8) , University of Jaén, Jaén, Spain 9)
The GEOMED2 project has been set up in order to compute an updated estimate of the geoid in the
Mediterranean area. In this work, the geoid computation based on gravity data collected in the area
29o<lat.<48o -10o<lon.<41o, covering the entire Mediterranean basin, is presented. Outlier rejection anddata homogenization have been carefully performed on the entire database. Low frequency components ofthe gravity field have been modelled using the more recent global geopotential models, such as EIGEN-6c4
and satellite only derived models (namely those based on the GOCE mission). Reduction for the terrain
effect has been also accounted for using the SRTM Digital Terrain Model that has been complemented withbathymetric data. In computing the geoid, different methods have been considered. Collocation, Fast
Collocation, Stokes and Stokes/FFT have been applied and discrepancies among the different estimateshave been evaluated and discussed. The obtained geoid solution will then allow estimating a refined SST,
both over open-sea and coastal areas, which will be used to compute permanent and seasonal currents in
the Mediterranean Sea that are relevant to many physical phenomena (e.g. climate changes).

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*G02-5-02
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Geomed2: gravimetric versus combined geoid model* sean bruinsma 1) 2) , sylvain bonvalot 2) , franck reinquin 1) 2) , lucia seoane 2)
CNES-Space Geodesy, Toulouse, France 1) , OMP/GET, Toulouse, France 2)
Computation of the geoid of the Mediterranean Sea is challenging due to the combination of poor marine
gravity data coverage and their non-homogeneous quality with gravity and geoid slopes that reachsignificant values with high variability. The GEOMED 2 project aims at the determination of a highaccuracy and resolution marine geoid model based on the availability of improved models for gravity,
thanks to GRACE and GOCE in particular, for land topography and bathymetry, and the compilation of acleaned-up gravity database of the Mediterranean area based on BGI and SHOM data. GEOMED 2 uses
land and marine gravity data, the latest satellite-only and combined GOCE/GRACE based Global
Geopotential Models and a combination of MISTRALS, EMODnet and SRTM/bathymetry terrain models in
the geoid computation. Marine gravity data is not available for large parts of the Mediterranean andconsequently a gravimetric geoid solution will be significantly less accurate there. Gravity inferred fromaltimetry data, or a mean sea surface corrected for mean dynamic topography, can be used to fill the gaps.
However, ocean dynamic signal always contaminates the derived gravity or synthetic geoid, which is why agravimetric solution is preferred.
The effect on the geoid solution of using several altimeter-based models, such as DTU10, DTU13 andDTU16 gravity and mean sea surface, a new DTU model for the Mediterranean, as well as the CNES-CLS15
mean sea surface, in weighted combinations with the gravimetric data will be evaluated and quantified. To
that purpose, test models will be constructed and compared to the gravimetric geoid solution. The(localized) uncertainty due to the data gaps, and the subsequent uncertainty in the ocean mean dynamic
topography and geostrophic currents, can be estimated via the results of all comparisons. The processing
methodology is based on the remove-compute-restore method and the fast collocation method has beenused to construct all test models.

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*G02-5-03
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Overview of the FAMOS efforts to improve the Baltic Sea geoid model by
new marine gravity measurements* Jonas Agren 1) , Joachim Schwabe 2) , Gabriel Strykowski 3) , Rene Forsberg 3) , Gunter Liebsch 2) ,Christoph Foerste 4) , Franz Barthelmes 4) , Mirjam Bilker-Koivula 5) , Artu Ellmann 6) , Silja Maerdla 6)
Lantmateriet, the Swedish mapping, cadastral and land registration authority, Gavle, Sweden 1) , Bundesamt
fur Kartographie und Geodasie, Leipzig, Germany 2) , Technical University of Denmark, National Space
Institute, Copenhagen, Denmark 3) , GFZ German Research Centre for Geosciences, Potsdam, Germany 4) ,Finnish Geospatial Research Institute, National Land Survey of Finland, Masala, Finland 5) , Tallinn
University of Technology, School of Engineering, Tallinn, Estonia 6)
The Baltic Sea Hydrographic Commission (BSHC) has decided to introduce the Baltic Sea Chart Datum
2000 as new common reference system for the Baltic Sea nautical charts from 2020. The Baltic Sea Chart
Datum 2000 is a geodetic height reference system that uses an equipotential surface as zero level. It isbased on the definition of the European Vertical Reference System (EVRS) as well as on the European
Terrestrial Reference System 89 (ETRS89). The reference epoch for the postglacial land uplift is 2000.0. On
land, the Baltic Sea Chart Datum 2000 will – for the time being – primarily be realized by the national
levelling height reference frames. Offshore, it will be realized by GNSS (relative to networks of permanentreference stations) and a height reference surface constructed based on a gravimetric geoid model.
One of the key tasks of activity 2 in the FAMOS (Finalizing Surveys for the Baltic Motorways of the Sea)
project is to improve the gravimetric geoid model over the Baltic Sea, aiming at the above realization. It is
required that the model is ready by 2020 and has a well corroborated standard uncertainty better than 5
cm. This will be reached mainly (but not only) by validating and complementing the existing gravity data,with new marine gravimetry measurements made from the FAMOS hydrographic surveying vessels. Up to2016, eight marine gravimetry campaigns have been finalized, and new FAMOS gravity and GNSS/levelling
databases have been set up. It is the intention in the project to compute many interim geoid models using
different computation methods on a successively improving gravity dataset. The purpose of thiscontribution is to give an overview of the marine gravimetry campaigns performed, present the status of the
FAMOS databases and shortly describe the computation of the first FAMOS preliminary interim geoid
models.

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*G02-5-04
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

The altimetry-derived marine gravity field for enhanced geodetic andgeological studies around Taiwan* Xiaoli Deng 1) , Cheinway Hwang 2) , Ole B. Andersen 3) , Mark G. Stewart 1)
School of Engineering, The University of Newcastle, New South Wales, Australia 1) , Department of Civil
Engineering, National Chiao Tung University, Taiwan 2) , Danish National Space Centre, Technical
University of Denmark, Copenhagen, Denmark 3)
There are, every year, earthquakes occurring around Taiwan, which can sometimes cause destruction andloss of life. As such, it has become increasingly important to understand surface deformations insouthwestern Taiwan and the northern South China Sea. This paper investigate how satellite altimetry
contributes to this understanding of neotectonic fields. Waveform data from the satellite altimetry geodetic
mission Jason-1 are retracked. Together with data from the repeat mission Cryosat-2, the derived altimetersea surface heights are used to model a regionally optimal marine gravity field around Taiwan. The
methodologies and techniques traditionally used for local and regional gravity determination areinvestigated. The modelled gravity field over the study region is compared to the latest global marine
gravity models (e.g., DTU15 and Sandwell's 2014 model), as well as the ship-track gravity measurements
around Taiwan. The results show that accuracy of the recovered marine gravity ranges from ~3 mGal to~7.5 mGal depending on coastal zones. The vertical gravity gradient field is also generated to detect
potentially hidden geological features around Taiwan. It is shown that oceanic areas around Taiwan canbenefit from this new and detailed altimetry-derived gravity field, especially in waters offshore eastern
Taiwan.

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*G02-5-05
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Towards a new Global marine gravity field based on SARAL/ALtiKa, Jason-1
and Cryosat-2 Geodetic Missions.
Ole Andersen , * Per Knudsen , Carsten Ludwidsen , Adil Abulaitijiang
DTU Space
A latest steps towards a new global high resolution global marine free air gravity field called DTU17 ispresented in this presentation. Data from the latest generation of high-class geodeit miccions creates thebasis for this new global marine gravity field. A total of 9 years grom three geodetic missions including (7years of Cryosat-2 (369 days repeat mission) as well as one year of Jason-1 end-of-life mission and one yearof SARA/AltiKa geodetic mission). Older geodetic missions (ERS-1 and GEOSAT) are now nearly retired in
DTU17 and provide marginal information in a very few regions.
In the Arctic Ocean we will present results from several new developments in high resolution gravity fieldmodelling. One is a a new dual-pass retracking of SARAL/AltiKa together with an new combined
empirical/physical retracking system for Cryosat-2 that uses physical retracking of the LRM data n
combination with empirical retracking of the SAR and SAR-In data.
A new medium wavelength correction based on altimetry and GOCE have been introduced to deal withproblems in the older remove restore technology based on EGM2008. This is particularly important for
Cryosat-2 due to its ability of provide new accurate sea surface height information for gravity field
determination all the way up to 88N where no altimeters have measured before.

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*G02-5-06
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Comparing marine gravity and satellite altimetry in the Mediterranean area
* R. Barzaghi 1) , D. Carrion 1) , C. De Gaetani 1) , A. Albertella 1) , G. Vergos 2) , A. Abulaitijiang 3) , O.
Andersen 3) , P. Knudsen 3) , I. N. Tziavos 2) , M.-F. Lequentrec-Lalancette 4) , C. Salaun 4)
Politecnico di Milano, Milano, Italy 1) , Aristotle University of Thessaloniki, Thessaloniki, Greece 2) , DTU
Space, Lyngby Denmark 3) , SHOM, Brest, France 4)
The combination of altimeter data and gravity allows an effective estimation of the Mean Dynamic
Topography (MDT) at sea. The MDT allows then estimating the oceanic currents, a crucial information inhydrological analysis and oceanographic studies. This is of particular interest in closed seas, such as theMediterranean Sea, due to the impact that marine physical phenomena can have in such a heavily
populated area. In this work, detailed computations are carried out for comparing marine gravity data andsatellite altimeter observations. Particularly, Cryosat-2 data are compared with marine gravity data in the
Mediterranean area. This is done by collocation in the framework of the remove-compute-restore
procedure. Different data reduction procedures based on different Global Geopotential Models andbathymetric models have been carried out in order to evaluate their impact on the final MDT and current
estimates. The results have been discussed also in the framework of the Geomed2 project in view of theestimation of a refined and updated MDT surface in the entire Mediterranean basin.

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*G02-6-01
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Establishing an IHRS reference station* Georgios S. Vergos , Ilias N. Tziavos
GravLab, Department of Geodesy and Surveying, Aristotle University of Thessaloniki, Thessaloniki,
GR-54124, Greece
The definition of an International Height Reference System (IHRS) and its realization to an International
Height Reference Frame (IHRF) is gaining increased importance given the outstanding results offered by
the GOCE mission. Additionally, the availability of satellite altimetry data close to the coastline from the
Cryosat2 SAR and SARin modes, allow the collocated determination with shipborne gravity of marine
gravity anomalies not only for purely marine areas but close to the sea-land boundary as well. Finally, theexistence of GOCE-derived Global Geopotential Models (GGMs), historic and current land gravity
measurements, GNSS-derived ellipsoidal heights at Continuously Operating Reference Stations (CORS),
and first-order levelling data set the field for the proper determination of the Earth's potential on
benchmarks (BMs) that will serve as IHRF reference network stations.
The main scope of the current work is to present the theoretical aspects and practical results ofdetermining the Earth's potential Wi at a GNSS reference station that belongs to the EUREF network. To
that respect, all available gravity observations within a distance of 210 km around the AUT1 CORS
reference station are collected and combined through a remove-compute-restore procedure to determine
the residual disturbing potential of that specific BM. The long wavelengths are represented by the
GOCE/GRACE GGM GOCO05s/GOCO05c, band-limited to d/o 250, and the high-frequencies by the SRTM
3 arcsec DTM. Least squares collocation (LSC) is used as an optimal predictor while error propagation
utilizes the GGM commission error, DTM errors and the a-priori variances of the gravity data. Various
configurations of the spatial distribution of the input gravity data are investigated and their influence on the
final Wi prediction is outlined. Finally, conclusions on the most rigorous local/satellite/terrain data
configuration are drawn along with proposals for the needed improvements and requirements.

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*G02-6-02
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

The permanent tide and the International Height Reference System IHRS
* Jaakko Makinen
Finnish Geospatial Research Institute (FGI), National Land Survey, Masala, Finland
The IAG in its resolution No. 1 at the 26th General Assembly of the IUGG in Prague in 2015 adopted themean-tide system for the International Height Reference System (IHRS). This was a partial reversal ofearlier recommendations: IAG resolutions 9 and 16 at the XVIII General Assembly of the IUGG in
Hamburg in 1983 had recommended the zero-tide system for handling the permanent tide in geodetic
quantities.
In practice, the treatment of the permanent tide has been highly variable even after 1983. So is there
anything new in the IHRS from this viewpoint? After all, we are well accustomed to mean-tide heightsystems at the national level. The reductions that are needed when we combine them with say 3-D
positions in a conventional tide-free system and gravimetric geoid heights in the zero-tide system are also
well-established.
However, there is a tidal novelty in the IHRS and that is its reference level. The national mean-tide heightsystems depended on a physically defined reference, usually traceable to the mean sea level at some tidegauge(s). The reference level of the IHRS is an equipotential surface where the geopotential has theconventional value W0=62636853.4 m^2/s^2. This value was first determined empirically to wellapproximate the global mean sea level and then adopted as a convention.
In which way does the W0 depend on the tidal system used, first in the determination, and then in theapplications after the adoption as a convention? Or is there any dependence at all? This is the main subjectof the presentation. I also provide a summary of reduction formulas between different tidal systems,
consistent with the current IERS Conventions, and a compendium of older approximate formulas used inlegacy geodetic systems.

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*G02-6-03
IAG Symposium / IAG02. Gravity field / G02. Static gravity fieldOn the practical realization of the fixed GBVP approach for a unification ofheight systems in Central Europe* Thomas Grombein , Lucas Porz , Kurt Seitz , Bernhard Heck
Karlsruhe Institute of Technology, Geodetic Institute, Karlsruhe, Germany
By using tide gauge observations, national height reference systems have conventionally been linked to the
local mean sea level. Due to variations in the sea surface topography, different tide gauges do not realize
the same height reference level in terms of a global equipotential surface. The resulting discrepancies
cause height datum offsets with a magnitude of about +- 1-2m at a global scale.
To achieve a height system unification of high precision, an approach based on the solution of the fixed
Geodetic Boundary Value Problem (GBVP) is proposed. On the basis of gravity disturbances and theirrigorous transformation into gravity anomalies, Hotine's integral formula is solved at GNSS/leveling
benchmarks in different height datum zones, which allows to estimate datum offsets as unknown
parameters in a least squares adjustment.
Based on the analysis of several case studies, this contribution presents first results of a practicalrealization of the fixed GBVP approach for a unification of height systems in Central Europe. To this end,
several practical aspects have to be considered and taken into account. Due to the limited availability ofgravity data of the necessary resolution and accuracy, it is not possible to evaluate Hotine's integral formula
to its global extent. Therefore, the integration area is restricted to a near zone around the respective
GNSS/leveling benchmarks, where regional high-resolution gravity anomaly data is available. In order toaccelerate the convergence rate of the resulting truncation error, a suitable modification of the Hotinekernel is applied. Furthermore, to reduce systematic errors, the terrestrial gravity data is combined with theinformation of a satellite-based global geopotential model as well as topographic effects within a removecompute-restore procedure.
In order to evaluate the obtained height datum offsets, results are compared to the transformation
parameters of the unified European Vertical Reference Frame EVRF2007.

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*G02-6-04
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Height datum unification by patching local geoid models
Mirko Reguzzoni 1) , Georgios S. Vergos 2) , Giovanna Sona 1) , * Riccardo Barzaghi 1) , Ilias N. Tziavos 2) ,Alberta Albertella 1) , Daniela Carrion 1) , Carlo I. De Gaetani 1) , Lorenzo Rossi 1)
Department of Civil and Environmental Engineering, Politecnico di Milano, Milan, Italy 1) , GravLab,
Department of Geodesy and Surveying, Aristotle University of Thessaloniki, Thessaloniki, Greece 2)
National geoid models are frequently used in engineering applications to transform GNSS derived
ellipsoidal heights into orthometric heights. The establishment of a unique International Height Reference
System (IHRS) among neighboring countries requires the verification of the consistency between national
geoids. The choice of different reference tide gauges, reference frames and ellipsoids causes biases and ingeneral systematic effects making local geoid models inconsistent to each other. These effects can be
estimated and removed by exploiting modern satellite-only models.
In the present work, a unification strategy is presented, firstly estimating biases and systematic effects by aleast-squares adjustment of the local geoid residuals with respect to a satellite-only model, and thencorrecting the remaining geoid distortions along the national borders by collocation. The advantage is thatthe resulting unified geoid includes both the low frequencies of the satellite-only global model and the highfrequencies of the local ones. These high frequencies are expected to be more accurate in the definition of
the equipotential than those coming from a "terrestrial" global geopotential model combined with theresidual terrain effect. Moreover, this procedure allows for a fast update of the unified model when a new
geoid is available.
The local models to be used as test data come from the archive of the International Service for the Geoid(ISG) and the result is compared with existing global and continental geoid models. It is expected that, if
the used gravity data were not preliminarily reduced by biases, these models are more affected by
distortions due to the different national reference systems.
This study is performed in the frame of the Joint Working Group 2.2.1 "Integration and validation of local
geoid estimates" of IAG Commission 2 . The output will represent a new product of ISG and aims to be acontribution in the frame of GGOS for the establishment of an IHRS.

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*G02-6-05
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

NGS' Gravity for the Redefinition of the American Vertical Datum Project
Update and Developments* Vicki Childers , Monica Youngman , Theresa Damiani
NOAA/National Geodetic Survey, Silver Spring, MD, USA
NOAA's National Geodetic Survey (NGS) defines latitude, longitude, and heights for the nation. NGS has
recognized the need to update both our geometric and geopotential reference frames and plans to release
updated frames in 2022. Our current vertical datum, the North American Vertical Datum of 1988 (NAVD
88), is a height system based upon geodetic leveling and realized at more than 500,000 monuments. NGS
has chosen to replace this datum with one based upon a gravimetric geoid. The goal is to allow the user
community to determine orthometric heights accurate to 2 cm through GNSS measurement plus a geoid
height model. To create a geoid accurate to the needed 1 cm, the gravity field must be recovered at
sufficient accuracy across the entire nation and its territories. NGS designed the Gravity for the
Redefinition of the American Vertical Datum (GRAV-D) project to accomplish this purpose. GRAV-D
involves a nationwide airborne gravity campaign designed to capture medium wavelength gravity data (20– 500 km) to allow proper spectral blending with long-wavelength satellite gravity data from the GRACE
and GOCE satellites with short-wavelength gravity information from terrestrial and shipborne
measurements. From this blended gravity field we will create the gravimetric geoid that will be the basis of
the new geopotential datum. This project has been underway for almost 9 years and is nearly 59% done asof February.
The GRAV-D project also includes long-term monitoring of geoid change over time so that the vertical
datum will change as the Earth changes. NGS will monitor how gravity and hence the geoid changes overtime and will update the vertical datum accordingly. We have named this effort the Geoid Monitoring
Service (GeMS) and the research plan is currently under development.
In this presentation, we will present updates on the status of the GRAV-D project, discuss results of proof-ofconcept experiments, and plans for the Geoid Monitoring Service.

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*G02-6-06
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

SAR and SARIN contribution to Height System Unification in Greece
Ourania Altiparmaki 1) , * Georgios S. Vergos 1) , Ole Andersen 2)
GravLab, Department of Geodesy and Surveying, Aristotle University of Thessaloniki, Greece 1) , DTU
SPACE, National Space Institute, Technical University of Denmark, Denmark 2)
One of the most important research topics in physical geodesy nowadays, is height system unification(HSU), at both national and global levels. The innovative Cryosat-2 satellite mission and mainly the SAR
and SARin drifting modes, offer dense cross-track spacing, which contributes to the improvement of spatial
resolution in both open sea and coastal zones. Taking advantage of the above, this work focuses on theprediction of Sea Level Anomalies (SLAs) and Sea Surface Heights (SSHs), close to the coastline andspecifically on tide gauges/GNSS benchmarks at the land/sea boundaries. The Greek region was chosen as
the study area, as its complex structure with many isles and islands constitutes an interesting area of
research for the evaluation of SAR and SARin data close to coastline. Furthermore, SAR and SARin data forthis region are available from the mission start (April 2010) to the end of 2016. Two different cases areinvestigated in this work. First, the prediction at the TG BMs is achieved via interpolation on a grid andsmoothing algorithms using the total set of SAR and SARin data. Then, only the along-track data close toeach point of interest are used and contribute to the prediction using simple polynomial models (first to
second order), splines and Least Squares Collocation. Different prediction cases are investigated based on
the general structure of the prediction area, the distribution of points which act as input data and thecorresponding accuracy of the SAR and SARin SLAs and SSHs. Finally, interpolation and prediction iscarried out to ‘bridge' the data between SAR-SARin and LRM-SAR modes using novel algorithms, as wellas to detect the existence of possible biases during the alternation of the mask mode.

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*G02-P-02
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

What is the real meaning of the Secondary Indirect Effect?
Petr Vanicek 1) , Robert Kingdon 1) , Peter Vajda 2) , * Jianliang Huang 3)
University of New Brunswick, Fredericton, Canada 1) , Academy of Sciences, Bratislava, Slovakia 2) , Natural
Resources Canada, Ottawa, Canada 3)
Researchers who are faced with the task of transforming the free-air gravity anomalies from real space tothe Helmert or the NT space would have met with a term called Secondary Indirect Topographical Effect,
SITE for brief. Here the spaces are defined by their distribution of topographical mass density and theyshare the normal gravity field as well as the coordinate systems used for describing the processes that takeplace in these spaces. The Helmert space is defined by the two-dimensional distribution of a condensed
topographical mass layer on the geoid in terms of Helmert's second method of condensation. Anotherspace is the NT space in which the entire topographical mass is removed, i.e. it has a zero topographicaldensity distribution. The SITE is one term in the sequence of terms applied to a gravity anomaly in the“from space", say the real space, to obtain gravity anomaly in the “into space", say, the Helmert space.
The origin of all the terms in the sequence can be intuitively understood, except for the SITE, which is also
missing in the transformation equations/sequences for other gravity related quantities.
On the other hand, people who deal with these different spaces, speak of the direct transformation from the“from space" to the “into space" and the inverse transformation from the “into space" to the “fromspace". The direct transformation is associated with the “direct effects" while the inverse transformation isassociated with the “indirect effects". So, is the SITE associated with the inverse transformation? It turns
out that it is not. Instead, the SITE must be understood as transforming from one space to another the ruleof computing gravity anomalies. This means transforming the rule of identifying the “corresponding"equipotential surfaces in the real gravity field and the normal gravity field. This study explains the physicalmeaning and formulates mathematical transformations of the SITEs between the Helmert and NT spaces.

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*G02-P-03
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Regional geoid computation by Least Squares Modified Hotine's formulawith Additive Corrections
Silja Mardla 1) , Artu Ellmann 1) , * Jonas Agren 2) , Lars E. Sjoberg 3)
Tallinn University of Technology, Tallinn, Estonia 1) , Lantmateriet, The Swedish Mapping, Cadastral andLand Registration Authority, Gavle, Sweden 2) , KTH, Royal Institute of Technology, Stockholm, Sweden 3)
Geoid and quasigeoid modelling from gravity anomalies by the method of Least Squares Modification of
Stokes' formula with Additive Corrections (LSMSA) is adapted for the usage with gravity disturbances andHotine's formula. The biased, unbiased and optimum versions of least squares modification are considered.
Equations are presented for the four additive corrections that account for the combined (direct plus
indirect) effect of downward continuation (DWC), topographic, atmospheric or ellipsoidal corrections in
geoid or quasigeoid modelling. The geoid or quasigeoid modelling scheme by the least squares modified
Hotine formula is numerically verified, analysed and compared to the Stokes counterpart in aheterogeneous study area.
Both, the approximate geoid models (before the combined corrections) and the additive corrections
computed for use with Stokes' or Hotine's formula differ most in areas of high elevation. Over the study
area with elevations up to 2 km, the approximate geoid models differ by 7 mm on average with a 3 mmstandard deviation (STD) and a maximum of 1.3 cm. The additive corrections, out of which only the DWC
correction differs significantly, improve the agreement between respective geoid or quasigeoid models toan average difference of 5 mm with a 1 mm STD and a maximum of 8 mm.

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*G02-P-04
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Establishment of the new Japan Gravity Standardization Network(JGSN)
2016* KENJI YOSHIDA , Toshihiro Yahagi
Geospatial Information Authority of Japan, Japan
Geospatial Information Authority of Japan (GSI) has released a new JGSN2016 in March 2017 for the firsttime in 40 years using the latest land gravity data over Japan measured by highly accurate gravimeters.
Before that, JGSN75, which is established by GSI in 1976, has been used as a gravity standard in Japan. It
is the gravity network decided by only relative gravity measurements based on IGSN71 and has been
widely utilized in both social and scientific fields such as determining domestic altitude standards,
correcting the results of leveling surveys, exploring underground structures reflected hidden active faults
and calibration of measuring instruments. On the other hand, due to mainly active crustal movements, thegravity values vary both spatially and temporally in Japan according to the redistribution of theunderground mass. In fact, the difference between the gravity value of JGSN75 and current one reached
0.1mGal at maximum. In addition, along with the recent advancement of gravity measuring instruments andtechnologies, more accurate gravity standard had been required.
JGSN2016 was conducted by both absolute and relative gravity data carried out by GSI between 2002 and2016, including gravitational changes accompanying big earthquakes such as 2011 Tohoku earthquake.
Especially, in order to obtain absolute gravity values which are consistent with international standards, wecalibrated our FG5 absolute gravimeter once a year to the one owned by National Institute of Advanced
Industrial Science and Technology (AIST)which participated in the international comparative observation
supported by BIPM so that we could. Furthermore, weestablished 33 absolute gravity points with precise position coordinates and reviewed and unified analysis
parameters such as tidal correction as new attempts. With this kind of ingenuity, we realize a highly
accurate and reliable gravity network covering all over Japan.

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*G02-P-05
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Local hydrological disturbances on gravity revealed by simultaneous
observation with a gPhone and a superconducting gravimeter* Kazuma Mochizuki 1) 3) , Kazunari Nawa 1) , Yuichi Imanishi 2)
Geological Survey of Japan, AIST, Tsukuba, Japan 1) , The University of Tokyo, Tokyo, Japan 2) , Shizuoka
University, Shizuoka, Japan 3)
In August 2016, continuous gravity observation with a gPhone gravimeter (# 133) was started at the F-net
IGK (Ishigaki) station of the National Research Institute for Earth Science and Disaster Resilience (NIED),
in order to supplement the superconducting gravimeter CT36 at the VERA Ishigakijima station of the
National Astronomical Observatory of Japan. The F-net station is about 900 meters away from the VERA
station. In spite of some initial problems, the gPhone gravimeter has been producing high-quality records
since late November, 2016, thanks to the stable condition inside the observation vault free from the effects
of solar radiation and ambient temperature changes. From the comparison of two month long data, it isshown that the gravity records from the two gravimeters are in agreement to within 5 microgals. The small
difference in the observed gravity is highly likely to reflect the different responses of gravity to local
precipitation at the two sites. Detailed investigation of this signal in comparison with meteorological data
will be useful for precise modeling and correction of hydrological disturbances on gravity, and thenretrieving deep underground signals (i.e. slow slip events).

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*G02-P-06
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Combined use of a superconducting gravimeter and Scintrex gravimeters forhydrological correction of precise gravity measurements - A superhybrid
gravimetry* Yuichi Imanishi 1) , Kazunari Nawa 2) , Yoshiaki Tamura 3) , Hiroshi Ikeda 4) , Ryo Honda 5) , Takashi Okuda, Makoto Okubo 7)
The University of Tokyo, Tokyo, Japan 1) , AIST, Tsukuba, Japan 2) , Mizusawa VLBI Observatory, NAOJ,
Oshu, Japan 3) , Tsukuba University, Tsukuba, Japan 4) , MFRI, Fujiyoshida, Japan 5) , Nagoya University,
Nagoya, Japan 6) , Kochi University, Kochi, Japan 7)
6)

Precise gravity observations are often subject to influence of temporally variable distribution ofunderground water near the observation sites. It is in general difficult to model and correct such effects
from the observed gravity series, because it requires knowledge of the hydrological nature of theunderground which varies from place to place. The superconducting gravimeter CT36 at Ishigakijima,
Okinawa, Japan also experiences very complicated effects of underground water, apparently combined withthe atmosphere and the ocean. Effects of the fluids near the surface on gravity must be precisely corrected
so that the possible gravity signals associated with the long-term slow slip events occurring near the
Ryukyu trench can be detected.
To overcome this difficulty, we employ combined use of the superconducting gravimeter (SG) and Scintrex
CG-5 gravimeters. The latter are used as mobile instruments, measuring relative gravity values with respect
to the SG pier as in a local gravity survey. One of the advantages of the CG-5 gravimeter is that it enables
continuous measurements and therefore comparison with the SG, thus greatly mitigating the problems of
instrumental drift inherent to mobile gravimeters. Under the assumption that temporal gravity changes arecommon within the survey area, using the SG data as reference helps improving estimates of the local
gravity field significantly.
We made an experiment of this kind of measurements (which we term superhybrid gravity measurements)using two CG-5's at Ishigakijima in January 2017. Preliminary analysis of the data has shown that relative
gravity values at a particular point measured on different days were in agreement at 1 microgal precision.
We will present further results and discuss temporal changes of gravity in relation to the dynamics ofunderground water.

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*G02-P-07
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Application of Local Functions in Airborne Gravimetry for Regional Geoid
Improvement* Xiaopeng Li , Yan Ming Wang
NGS, USA
Local functions such as the Radial Basis Functions (RBF) have been extensively studied and applied inphysical geodesy in the recent decade, such as in Schmidt et al (2007) and Klees et al (2008), and in manyother studies that focused mainly on satellite mission related applications. Considering that airborne
gravity data is usually limited in both the space domain and the frequency domain, it is a perfect match tothe characteristics of the RBF. Thus, it is a natural choice to process and model the airborne gravity datawith RBF, though in the literature for airborne gravimetry various other methods such as Least Squares
Collocation and the inverse of Abel-Poisson's integral (the Fredholm integral equation of the first kind) areoften used to take advantage of the airborne data for local geoid improvement. In this study, first, a series ofsimulation tests are carried out to demonstrate the reliability and versatility of using RBF to model and to
downward continue the airborne data, as well as to detect outliers and systematic bias in problematic flightlines typically find in an airborne campaign. Then the final verified (in term of closed loop simulation tests)
algorithm is applied to the real airborne flight data in the area of Puerto Rico and US Virgin Islands for
local gravity field modeling.

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*G02-P-09
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Topographic correction and covariance function modelling over the coastal
regions* ADILI ABULAITIJIANG 1) , Riccardo Barzaghi 2) , Ole Baltazar Andersen 1) , Per Knudsen 1)
DTU Space, Technical University of Denmark, Copenhagen, Denmark 1) , Department of Civil andEnvironmental Engineering, Politecnico di Milano, Milano, Italy 2)
Using the conventional remove-compute-restore (only removing the Global Geopotential Models)
technique, the theoretical assumption of homogeneity and isotropy in the Least Square Collocation (LSC)
algorithm is not always satisfied in the coastal regions and mountainous regions. High resolution
bathymetry data (e.g., SRTM30, spatial resolution of around 1 Km) is used to account for the strong
correlation in the short wavelength (1~10 km) gravity features with topography and bathymetry. Hence, theTopographic Correction (TC) is a critical step in the reduction of the gravity functionals (e.g., heightanomaly and gravity anomaly), to comply with the theoretical assumption of LSC.
DTU has been working on the improved coastal marine gravity from satellite altimetry (mainly CryoSat-2).
Previous studies show that the terrain correction using Residual Terrain Model (RTM) w.r.t. residual gravity
anomalies are slightly different w.r.t the residual height anomalies over the shallow regions close to thecoast (or regions including islands). This should be well examined when the (sea level) height anomalies
are to be reduced by TC and further the marine gravity field is derived using LSC. In this work, the TC
computation (both w.r.t. the height anomalies and gravity) will be conducted in several regions (patches)around Mediterranean, Chile, islands of Indonesia where the true gravity data is available for validation.
Both the spatial integration and FFT approach will be tested due to the steep topographic changes in theselected regions. The reduction performance is then evaluated through proper covariance function
modelling and analysis before the LSC.

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*G02-P-10
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Geoid and Moho-depth modeling in Cyprus
Ilias N. Tziavos 1) , * Georgios S. Vergos 1) , Vassilios N. Grigoriadis 1) , Efstratios Stylianidis 2)
GravLab, Department of Geodesy and Surveying, Aristotle University of Thessaloniki, Thessaloniki,
GR-54124, Greece 1) , School of Spatial Planning & Development, Aristotle University of Thessaloniki,
Thessaloniki, GR-54124 2)
A high-resolution gravimetric geoid determination was carried out for the wider area of Cyprus using
gravity data from national and international databases, local and global digital elevation and bathymetry
models and satellite altimetry data for the surrounding sea areas. The EGM08 global geopotential model
was used as a reference surface to model long to medium frequencies of the gravity field spectrum. Terrain
and bathymetry effects on gravity anomalies have been studied through different reduction schemes andvarious validation procedures were applied in order to finally produce a reliable gravity grid of 1 arcmin
resolution. Geoid solutions were computed by Least Squares Collocation (LSC) and Stokes integral
employing Fast Fourier Transform (FFT) techniques using the rigorous 1D spherical kernel, within aRemove-Compute-Restore (RCR) approach. The geoid solutions show an absolute accuracy at the level of
4cm for the continental area of Cyprus, after comparison with GPS/leveling derived geoid heights, and a
relative accuracy at the level of about 8ppm over baselines of 10km. These accuracies meet the nowadays
requirements of a wide spectrum of geodetic, geophysical and engineering projects. In a second step, Moho
depths were estimated for both land and marine areas following the inversion of the previously compiled
gravity grid complemented with density and GOCE data. The geoid and Moho models computed in thisstudy show the strong signature and peculiar futures of the gravity field in the test area and the wider
eastern Mediterranean basin. To this respect, further geodetic and geophysical considerations form thebasis for future important research in the area under study.

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*G02-P-11
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Preliminary Results of Mass Redistribution from Repeated Campaigns ofPrecision Gravimetry in the Wandan Mud Volcano, Taiwan* Kai-chien Cheng 1) , Ling-Ho Chung 1) , Ricky Kao 2) , Yuan-Hsi Lee 1)
National Chung Cheng University, Chiayi, Taiwan 1) , National Chiao Tung University, Hsinchu, Taiwan 2)
The Wandan mud volcano, classified as an intermittent one, is located in the coastal plan of Kaohsiung andPingtung, SW Taiwan. Although its past eruptions are not regular, it has erupted at least once a year, except
for 1999, since 1988. Despite the exceptional consistency of eruptions, the amount and period of eruptions
and the mass redistribution underneath the area have been little known by far. In this study, we conducted
repeated campaigns of precision gravimetry to monitor the temporal gravity change once a few months
since 2015 with Microg LaCoste FG5 absolute gravimeter and Scintrex CG-5 relative gravimeter. We
arranged the before and after gravity measurements for eruptions. Preliminary result reveals that there's a
30 μGal absolute gravity increase near the crater before an eruption on April 28, 2016 and a 150 μGal
drop after that. The spatial feature of the absolute gravity increases in the western area and decreases inthe southern part. The result confirms that the temporal gravity change and possibly the mass
redistribution caused by the Wandan mud volcano is sensible to the precision gravimetry. Though somedifficulties such as hydrology and other corrections need to be overcome, the promising result is
anticipated to be helpful to the understanding of the activities of the Wandan mud volcano and diapirs in
the area.

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*G02-P-12
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Determination of Moho depth models for Greece using different gravity
inversion methods* Vassilios Grigoriadis , Ilias Tziavos
GravLab, Department of Geodesy and Surveying, Aristotle University of Thessaloniki, Thessaloniki, Greece
In this study, three of the most common methods of determining the Mohorovicic (Moho) discontinuity are
employed towards the development of new Moho-models for the area of Greece by gravity inversion. The
first method is conducted in the spectral domain and is based on an iterative approach following the ParkerOldenburg formula and applying a low-pass filter for the stabilization of the finally produced solution. The
background of the second method is in line with the well-known Bott's method combined with a GaussNewton formulation and a regularization technique focusing on a well-controlled solution. The entire
procedure incorporates tesseroids in the modelling part and an adaptive iterative scheme for the optimal
approximation of the finally determined Moho-depth surface. The solution of Vening-Meinesz and Moritz
inverse isostatic problem is carried out by the third method along with non-isostatic corrections applied to
the Moho-height differences estimated by the gravity data and the seismic constrained information
incorporated in the inversion algorithm. The gravity data used in the computations of the three methods
were derived from GOCO05s and EGM08 global geopotential models. The aforementioned methods arereviewed in terms of their computational efficiency as well as the assumptions and limitations required fortheir numerical evaluation. The Moho models derived by the three methods are inter-compared andcompared also with a model derived for the test area by a previous study, which is based on high resolution
local gravity databases. An external validation test of the new models was performed by comparing with
Moho depths derived by seismic data in a number of stations in the area under consideration. Someremarks, conclusions and suggestions are finally drawn mainly related to the performance of each method
and taking into account the strong features of the gravity field in the area under study.

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*G02-P-13
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Towards the best GOCE gravity gradients
Christian Siemes , Roger Haagmans , * Michael Kern
European Space Agency
The GOCE gravity gradients show perturbations that correlate with the geomagnetic field. In particular the
cross-track gravity gradient is significantly perturbed in the regions around the geomagnetic poles.
Recently, it was found that the perturbing effect is due to an unmodelled quadratic factor that occurs in theconversion from the electrode control voltages to accelerations, which caused the highly dynamic
acceleration signal from cross-track drag to map onto the cross-track gravity gradient. Fortunately, it ispossible to model and completely remove the perturbing effect, arriving at a more accurate, “clean" crosstrack gravity gradient, which is demonstrated in this presentation.
Also the other gravity gradients show perturbations that correlate with the magnetic field. Those
perturbations are much smaller than the perturbation of the cross-track gravity gradient, but appear
systematic and are therefore important to remove as well. We will show in this presentation to which extent
these perturbation can be removed from the gravity gradients by re-calibrating the accelerometer data andassess the impact on the gravity field retrieval from GOCE data.

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*G02-P-15
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Evaluation of the gravity and altimetry data in the Baltic Sea region andcomputation of the new quasi-geoid model for the territory of Poland
Adam Lyszkowicz 1) , * Joanna Kuczynska-Siehien 2)
Polish Air Forces Academy, Department of Air Navigation, Deblin, Poland 1) , University of Warmia andMazury in Olsztyn, Faculty of Geodesy, Geospatial and Civil Engineering, Olsztyn, Poland 2)
The gravimetric quasi-geoid models in Poland were computed using FFT, collocation and KTH methods. In
all cases the same gravity data from the southern part of the Baltic Sea, geopotential model EGM2008, andthe same digital terrain model, were used. The accuracy of the computed models was estimated using
GPS/levelling data from the POLREF network.
Marine gravity anomalies used in the quasi-geoid model computations cover the very limited southern partof the Baltic Sea. The currently available gravity data from the satellite altimetry, e.g. the DNSC08GRA
global marine gravity field, are covering the whole Baltic Sea. The usage of this data source should improve
the quality of existing quasi-geoid models.
The first aim of the work is the comparison and validation of gravity anomalies from the DNSC08GRA
model and the shipborne gravity anomalies along the Polish coast and in the Gulf of Bothnia. The next step,is the computation of new gravimetric quasi-geoid model for the territory of Poland, using gravity data fromthe satellite altimetry, the EIGEN-6C4 and GECO geopotential models, and the chosen DTM. The accuracyof the computed new model is estimated using the high precision ASG-EUPOS network connected to the
new vertical datum PL-EVRF2007-NH.

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*G02-P-16
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

PCA and along track filtering of Crysoat2 SSH for DOT modeling in the
Mediterranean* Dimitrios Natsiopoulos , Georgios Vergos , Ilias Tziavos
GravLab, Department of Geodesy and Surveying, Aristotle University of Thessaloniki, Thessaloniki,
GR-54124, Greece
With the availability of an abundance of earth observation data from satellite altimetry missions, monitoringof the sea level variations is gaining increased importance. Given the availability of altimetric sea surface
heights (SSHs) one can employ all such available data to estimate the mean dynamic ocean topography(DOT) as well as its time varying, part. ESA's Cryosat2 mission with its orbit characteristics, measurements
mode and accuracy can be used for sea level anomaly (SLA), geoid and DOT modeling over the entire
Mediterranean basin. The main goal of this work is to use the altimetry data of Cryosat2 from the mission
start until the end of 2016 for the determination of the DOT for the Mediterranean Sea. To this respect,along-track filtering of the Cryosat2 SLAs, derived from the combination of the original SSHs with the
GOCO05c GOCE-based Global Geopotential Model (GGM) is investigated, while through a Principal
Component Analysis the structure of the data variability will be explored. Principal Component Analysis(PCA) is used to investigate the temporal spatial variations of DOT and derive annual and secular trends.
For the along-track filtering, spectral filters will be examined, based on various options of FIR and IIR
filters. Filtering is applied along the whole passes of the satellite in order to remove/reduce the effects ofgeoid omission and commission errors still remaining in the DOT due to the limited representation offeredby the GGM. Finally, for the evaluation of the new filtered DOT models, the RIO_MED and SMDT synthetic
models for the Mediterranean and DTU10 have been used.

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*G02-P-17
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

The GEOMED2 project: Multi-resolution aspects and aliasing in topographic
effects for geoid and gravity determination* Riccardo Barzaghi 1) , Georgios S. Vergos 2) , Alberta Albertella 1) , Daniela Carrion 1) , Ilias N. Tziavos 2) ,Vassilios N. Grigoriadis 2) , Dimitrios A. Natsiopoulos 2) , Sean Bruinsma 3) , Lucia Seoane 3) , Franck
Reinquin 3) , Marie-Françoise Lequentrec-Lalancette 4) , Corinne Salaun 4) , Pascal Bonnefond 5) , Per
Knudsen 6) , Ole Andersen 6) , Mehmet Simav 7) , Hasan Yildiz 7) , Tomislav Basic 8) , Matej Varga 8) , Olga
Bjelotomic 8) , Antonio J. Gil 9)
Politecnico di Milano, Italy 1) , GravLab, Department of Geodesy and Surveying, Aristotle University ofThessaloniki, University Box 440, GR 54-124 Thessaloniki, Greece 2) , GET UMR 5563, Toulouse, France 3) ,SHOM, Brest, France 4) , OCA/Géoazur, Sophia-Antipolis, France 5) , DTU Space, Kopenhagen, Denmark 6) ,General Command of Mapping, Ankara, Turkey 7) , University of Zagreb, Zagreb, Croatia 8) , University of
Jaén, Jaén, Spain 9)
One of the key aspects of the GEOMED2 project is the determination of a high-accuracy and highresolution geoid model for the Mediterranean Sea along with the generation of gravity grids for various
types of gravity anomalies like free-air, complete Bouguer, isostatic, etc. A crucial point in both geoid
determination and gravity reductions, using the remove-compute-restore method, is the proper modellingof the topography/bathymetry effects on the available gravity anomalies. When estimating the highfrequency content of the gravity field spectrum the robustness and rigorousness of the determined
topographic effects relies on both proper theoretical treatment and the soundness of the Digital Terrain andBathymetry Model (DTM/DBM) used. Over land areas, the latest SRTM-based DTMs offer high-accuracy
and high-resolution information on the topographic variations, in the sense that they properly manage tomodel the high-frequency contributions of the topographic masses. Over marine regions the situation isquite different, since the resolution of the DBMs available is not capable to remove the high-frequencies
present in shipborne marine gravity data. Moreover, marine gravity data themselves do not have in manycases the necessary spatial resolution to rigorously model the high-frequencies depicted in the DBM. The
main focus of the present work is on treating the aforementioned problems, i.e., to investigate and properly
determine topographic effects over both land and marine areas to efficiently reduce land and marine
gravity data towards geoid determination. Additionally, aliasing effects on the estimated topographic effects
are investigated and the corresponding errors introduced in gravity anomalies and geoid heights are
determined. Then, the DTM/DBM combination that provides the overall best results, in terms of thesmoothness of the residual gravity anomalies, is outlined along with the final topographically corrected
gravity anomalies and geoid indirect effects.

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*G02-P-18
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

The GEOMED2 project: Geoid and circulation in the Mediterranean Sea* R. Barzaghi 1) , G. S. Vergos 2) , A. Albertella 1) , D. Carrion 1) , I.N. Tziavos 2) , V. N. Grigoriadis 2) , D. A.
Natsiopoulos 2) , S. Bruinsma 3) , S. Bonvalot 3) , L. Seoane 3) , F. Reinquin 3) , M.-F. Lequentrec-Lalancette 4) ,C. Salaun 4) , P. Bonnefond 5) , P. Knudsen 6) , O. Andersen 6) , M. Simav 7) , H. Yildiz 7) , T. Basic 8) , M. Varga
8), O. Bjelotomic 8)
Politecnico di Milano, Milano, Italy 1) , Aristotle University of Thessaloniki, Thessaloniki, Greece 2) , GET
UMR 5563, Toulouse, France 3) , SHOM, Brest, France 4) , OCA/Géoazur, Sophia-Antipolis, France 5) , DTU
Space, Kopenhagen, Denmark 6) , General Command of Mapping, Ankara, Turkey 7) , University of Zagreb,
Zagreb, Croatia 8) , University of Jaén, Jaén, Spain 9)
The main scope of the GEOMED2 project is the determination of a high-accuracy and high-resolution geoid
model for the Mediterranean Sea using land and marine gravity data and the more recent Global
Geopotential Models, those based on GOCE/GRACE data. The processing methodology is based on thewell-known remove-compute-restore procedure and both stochastic and integral/spectral methods for thedetermination of the geoid and the rigorous combination of heterogeneous data. All the available gravity
observations for the wider Mediterranean basin were collected, validated, homogenized and unified interms of their horizontal coordinates and gravity systems, so as to derive a reliable gravity data base to be
used for the determination of the geoid. The so-determined geoid model can form the basis for heightsystem unification in the Mediterranean area. Also, by comparison with altimeter data, this geoid can beused to derive high-resolution models of the Mean Dynamic Topography that will allow estimating themarine circulation in the Mediterranean Sea.
The final delivered products of this project will be the geoid estimate in the Mediterranean area, the Mean
Dynamic Topography of the Mediterranean Sea and the implied circulation model.

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*G02-P-19
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

CryoSat-2-only gravity model of the Arctic ocean: case study in Greenland
Sea* ADILI ABULAITIJIANG , Ole Baltazar Andersen , Per Knudsen
Technical University of Denmark, Copenhagen, Denmark
The Arctic marine gravity has not been well mapped due to weather conditions or political interests. The
polar orbiting satellite altimetry mission (e.g., CryoSat-2) covers the Arctic up to latitude 88 and has thegreat potential of achieving the Arctic marine gravity maps from altimetry. Combined with the dense acrosstrack and improved along track resolution achieved by synthetic aperture processing, the arctic sea ice
freeboard and sea level can be achieved and further transformed to the gravity anomalies using the Least
Square Collocation (LSC).
In this work, we will derive the marine gravity for Greenland Sea using the remove-compute-restore
technique and LSC algorithm. The data preparation is challenging due to the changing operating mask of
CryoSat-2 and presenting sea ice in the footprints. A careful data editing scheme combined with sea ice
flags will addressed. The existing bathymetry chart of Arctic Ocean, known as IBCAO will be introduced tofurther reduce the altimetric data. Earlier studies show that using the FFT method, a 4 mGal accuracy canbe achieved and with 6 years of data, a better accuracy is expected.

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*G02-P-20
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

Local vertical datum validation through the incorporation of GOCE varianceand covariance information
Vassilios D. Andritsanos 1) , Vassilios N. Grigoriadis 2) , * Georgios S. Vergos 2) , Thomas Gruber 3) , Thomas
Fecher 3)
Geospatial Technology Research Lab, Department of Civil Engineering and Surveying & Geoinformatics
Engineering, Technological and Educational Institute of Athens, 12210 Athens, Greece 1) , GravLab,
Department of Geodesy and Surveying, Aristotle University of Thessaloniki, University Box 440, GR 54-124
Thessaloniki, Greece 2) , Institute for Astronomical and Physical Geodesy, Technical University of Munich,
Arcisstrasse 21, 80333 Munich, Germany 3)
After the completion of the GOCE mission, the information on height system validation and unification has
been enriched, especially in the low to medium frequency of the gravity field spectrum. GOCE information
is used for estimating height and/or geopotential offsets with respect to a conventional reference
geopotential value, employing available GNSS/Leveling observations on trigonometric BMs and a GOCEbased geoid model. The scope of this work is to investigate the influence of GOCE errors in thedetermination of the Hellenic LVD. This is facilitated through a least-squares (LS) based adjustment of
collocated GNSS/Leveling and GOCE geoid heights over a network of 1542 BMs in mainland Greece. The
latest TIM-R5 and GOCO05s GOCE and GOCE/GRACE global geopotential models are used to represent
the contribution of GOCE and GRACE to the Earth's gravity field. Four different weighting scenarios areused including standard a-priori error for the BMs heights, the GNSS heights and the geoid undulations,
cumulative errors for the geoid heights and variance/covariance information from GOCE geoid models. The
local geopotential offset Wo(LVD) is also calculated utilizing the weighting scenarios. Finally, variancecomponent estimation is performed to evaluate the height (h, H, N) variance/covariance matrices using the
GPS/leveling errors from the above weighting schemes.

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*G02-P-22
IAG Symposium / IAG02. Gravity field / G02. Static gravity field

International Digital Elevation Model Service (IDEMS): A Revived IAG
Service* Kevin Kelly 1) , Christian Hirt 2) , Michael Kuhn 3) , Riccardo Barzaghi 4)
Environmental Systems Research Institute (Esri), Redlands, CA, USA 1) , Technical University of Munich,
Munich, Germany 2) , Curtin University, Perth, Western Australia 3) , Politecnico di Milano, Milano, Italy 4)
A newly developed International Digital Elevation Model Service (IDEMS) is now available under theumbrella of the International Gravity Field Service of the International Association of Geodesy. Hosted andoperated by Environmental Systems Research Institute (Esri) (http://www.esri.com/), the new IDEMS
website is available at: https://idems.maps.arcgis.com/home/index.html.
IDEMS provides a focus for distribution of data and information about various digital elevation models,
including spherical-harmonic models of Earth's global topography and lunar and planetary DEM. Related
datasets, such as representation of inland water within DEMs, and relevant software which are available in
the public domain are also provided.
Currently, IDEMS serves as repository of links to providers of global terrain and bathymetry, terrain related
Earth models and datasets such as digital elevation data services managed and maintained by Esri (Terrain
and TopoBathy), Bedmap2-Ice thickness and subglacial topographic model of Antarctica and Ice, Cloud,and Land Elevation ICESat/GLAS Data, as well as planetary terrain data provided by PDS Geosciences
Node at Washington University, St. Louis. These services provide online access to a collection of multiresolution and multi-source elevation and bathymetry data, including metadata and source information.
In addition to IDEMS current holdings of terrestrial and planetary DEMs, some topography related
products IDEMS may include in future are: dynamic ocean topography, 3D crustal density models, Earth's
dynamic topography, etc. IDEMS may also consider terrain related products such as quality assessments,
global terrain corrections, global height anomaly-to-geoid height corrections and other geodesy-relevant
studies and products.
IDEMS encourages contributions to the site from the geodetic community in any of the product types listed
above. Please contact the authors if you would like to contribute or recommend content you think
appropriate for IDEMS.

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*G03-1-01
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Current Status of the GRACE Mission* Byron Tapley 1) , Frank Flechtner 2) , Michael Watkins 3) , Srinivas Bettadpur 1)
University fo Texas Center For Space Research 1) , German Research Centre for Geosciences - GFZ, 2) ,NASA Jet Propulsion Laboratory 3)
The twin satellites of the Gravity Recovery and Climate Experiment (GRACE) were launched on March 17,
2002 and have operated for over 15 years. The mission objectives are to sense the spatial and temporalvariations of the Earth's mass through its effects on the gravity field at the GRACE satellite altitude. The
major cause of the time varying mass is water motion and the GRACE mission has provided a continuous
decade long measurement sequences which characterizes the seasonal cycle of mass transport between
the oceans, land, cryosphere and atmosphere; its inter-annual variability; and the climate driven secular, or
long period, mass transport signals. In 2012, a complete reanalysis of the mission data, referred to as the
RL05 data release, was initiated. The monthly solutions from this effort were released in mid-2013 with themean fields following in subsequent years. The mission is entering the final phases of operations withmission end expected to occur before July 1, 2017. The current mission operations strategy emphasizes
extending the mission lifetime to minimize the break in the measurements before the GRACE Follow-On
Mission is launched. This presentation will review the mission status and the projections for mission
lifetime, describe the issues that influence the operations philosophy, discuss the approaches to bridge thegap between GRACE and GRACE FO and discuss the content of the science data products during thisphase of the mission.

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*G03-1-02
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

GRACE Follow-On: Overview and Current Mission Status* Felix Landerer 1) , Frank Flechtner 2) , Frank Webb 1) , Michael Watkins 1) , Christoph Dahle 2) , Srinivas
Bettadpur 3)
Jet Propulsion Laboratory / Caltech, Pasadena, CA, USA 1) , GFZ Posdam, Germany 2) , Center for Space
Research, University of Texas, Austin, TX, USA 3)
The GRACE Follow-On Mission has now advanced to the Assembly and Test Phase with the delivery ofessentially all satellite subsystems and science instruments. The two spacecraft have been transferred to
Ottobrunn near Munich for several months of operational testing in the IABG test center. The project teamis conducting tests of satellite and instrument operation and performance and putting together updated
simulations of expected performance on-orbit, including intersatellite ranging (both microwave and laser),accelerometer, thermal variability and deformation, and other errors. In addition, all required ground
analysis software of the Science Data System is in development and testing at JPL, UTCSR, and GFZ, in
preparation for fully integrated end-to-end (international) testing from Level-1 through Level-3 data within2017. Recently, the GRACE Follow-On launch was confirmed in a rideshare agreement between GFZ and
Iridium Satellite LLC. GRACE Follow-On is expected to launch in the period from December 2017 to
February 2018, together with 5 Iridium-Next satellites, on a Space-X Falcon-9 from Vandenberg Air Force
Base in California.
In this presentation, we will provide the detailed status of project integration and test, the latest results of
expected science performance, and schedule for remaining project milestones before and after launch.

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*G03-1-03
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Towards deriving temporal sampling requirements for future satellite
gravimetry missions* David Wiese , Christopher McCullough
Jet Propulsion Laboratory, Pasadena, California, USA
Studies have shown that future satellite gravimetry missions utilizing low-low satellite-to-satellite tracking(LL-SST) that have an improved onboard measurement system relative to the Gravity Recovery and Climate
Experiment (GRACE) will be limited by temporal aliasing errors. The improved measurement system comesprimarily in the form of improved electrostatic accelerometers to measure nonconservative forces as well
as a laser interferometer to measure changes in distance between the satellites. Temporal aliasing errors
are accumulated primarily because of deficiencies in models of high frequency mass variations (ocean
tides, atmosphere and ocean mass variations), which are required in the first place because of the limited
temporal sampling of a single pair of satellites. It has been shown that the impact of temporal aliasing
errors on the gravity retrieval can be reduced substantially by implementing a mission architecture
consisting of two pairs of satellites; however, even in this case the temporal aliasing errors remain as thedominant source of error. In this study, we make a first attempt to define temporal sampling requirements
for future satellite gravimetry missions to go beyond the performance that two pairs of satellites can offer.
We probe both the spatial and temporal characteristics of temporal aliasing errors to understand theirimpact on the gravity retrieval using numerical simulations. Through such studies, we can hypothesize as towhat spatial and temporal scales of gravity field variations must be directly observed to gain specified
improvements in accuracy and spatio-temporal resolution with which mass flux in the Earth system can be
resolved.

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*G03-1-04
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Constellations of Next Generation Gravity Missions: mapping and mitigationof ocean tide model errors* Pieter Visser
Delft University of Technology, Delft, The Netherlands
The GRACE and GOCE satellite missions have shown the great potential of using space-borne gravimetry
for observing mass transport in the system Earth. However, for meeting future user needs, it is crucial toenhance both the spatial and temporal resolution. This can be achieved by a Bender-type Next Generation
Gravity Mission (NGGM) that consists of a constellation of two GRACE-type satellite tandems, with one pairflying in a (near-)polar orbit and the other in an inclined orbit. In addition, GRACE-type satellites will be
implemented with improved sensor packages, including laser-based low-low satellite-to-satellite tracking (llSST) instruments, more precise accelerometers and state-of-the-art star trackers.
The European Space Agency (ESA) study “ADDCON" (ADDitional CONstellations) aims at investigating
the impact of several orbit design choices on the performance of temporal gravity field retrieval by Bendertype NGGMs. Simulation studies have indicated that for such constellations aliasing of errors in ocean tidemodels is a dominant error source in retrieved temporal gravity field. As part of the ADDCON study, ocean
tide model errors are mapped first in terms of ll-SST range-rate residuals for several Bender-type NGGMs,
with orbits varying in altitude, repeat period and inclination (prograde and retrograde). This provides
among others insight in the geographical distribution of ll-SST observation residuals due to errors in ocean
tide models. Second, the ocean tide model errors are mapped to gravity field errors in terms of sphericalharmonic (SH) expansions for retrievals ranging from one day to a month and for maximum SH degrees
ranging from 10 to 120. Third and finally, the possibility of mitigating the impact of ocean tide model error
on gravity field retrieval by tuning the set of estimated parameters has been explored (including estimationof empirical accelerations, so-called Wiese approach, etc.).

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*G03-1-05
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Status of development on the future accelerometers for next generation
gravity missions* Bruno Christophe , Francoise Liorzou , Damien Boulanger , Bernard Foulon , Vincent Lebat , Phuong-Anh
Huynh , Nassim Zahzam , Yannick Bidel , Alexandre Bresson
ONERA The French Aerospace Lab, Chatillon, France
The GRACE FO mission, led by the JPL and GFZ, is an Earth-orbiting gravity mission, continuation of the
GRACE mission, which will produce an accurate model of the Earth's gravity field variation providing
global climatic data during five years at least. Europe and US propose new gravity missions beyond GRACEFO, with performance improved thanks to laser interferometry and better accelerometers. ONERA has
procured the accelerometers for the previous geodesic mission (CHAMP, GRACE, GOCE and now GRACEFO) and continue to improve the instruments to answer to the challenge of the future missions according to
two main axes:
Firstly, a new design of electrostatic accelerometer is proposed, based on MicroSTAR configuration, a3-axes ultra-sensitive accelerometer, with a cubic proof-mass. This new design gives, beyond the linear
acceleration, the 3 angular accelerations for a better satellite attitude control. For linear acceleration, theperformance is improved by at least an order of magnitude with respect to GRACE-FO.
Secondly, ONERA studies the hybridization of such electrostatic accelerometer with cold atominterferometer technology. Each of these two types of instruments presents their own advantages whichare, for the electrostatic sensors, their demonstrated short term sensitivity and their high TRL, and for atominterferometer, the absolute nature of the measurement and therefore no need for calibration processes.
These two technologies are very complementary and a hybrid sensor could be the opportunity to make a
big step in this context of gravity space missions. We present here the first experimental association on
ground of an electrostatic accelerometer and an atomic accelerometer and underline the interest ofcalibrating the electrostatic sensor with the atomic interferometer.

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*G03-2-02
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Time variable gravity from kinematic orbits of LEO satellites – A 15+ years
series of monthly solutions without gaps
* Norbert Zehentner , Torsten Mayer-Guerr , Sebastian Strasser
Institute of Geodesy, Graz University of Technology, Graz, Austria
Gravity field recovery from high-low satellite to satellite tracking has been applied successfully to former
gravity missions like CHAMP and GOCE. The process to derive gravity field estimates from GNSS
observations is separated into two steps. First kinematic orbits for the LEO satellite are derived from the
GNSS measurements. Subsequently the kinematic orbit positions are introduced as pseudo-observations
estimate the gravity field. We make use of a precise point positioning approach based on raw GNSS
observations to retrieve kinematic orbits with accuracies of a few centimeters. Some special aspects of theapproach are: antenna center variations for phase and code observations, azimuth and nadir angle
dependent antenna center variations for transmitters, and azimuth and nadir angle dependent accuracy
information for each observation type. In this contribution we will show the impact of these specificprocessing aspects on the orbit quality and on derived gravity field estimates. The method has been applied
to a number of LEO missions, including non-gravity missions like Swarm, Terra-SAR-X, TanDEM-X, MetOp,
or Jason 1&2. Based on kinematic orbits from more than 10 satellite missions a time series of individual
and unconstrained monthly gravity field solutions has been produced. The series starts in January 2002
and spans more than 15 years without gaps. We demonstrate that it is possible to observe mass variations
for regions like Greenland, the Antarctic, the Amazon basin, and other large river basins, down to areas as
small as the Caspian Sea.

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*G03-2-03
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Near real-time gravity and its applications in the era of Next Generation
Gravity Missions - Insights on the ESA-ADDCON project
Ilias Daras 1) , Pieter Visser 3) , * Nico Sneeuw 2) , Tonie van Dam 4) , Roland Pail 1) , Thomas Gruber 1) ,Qiang Chen 4) , Wei Liu 2) , Mohammad Tourian 2) , Johannes Engels 2) , Peyman Saemian 2) , Christian
Siemes 5) , Roger Haagmans 5)
Technical University of Munich, Munich, Germany 1) , University of Stuttgart , Stuttgart, Germany 2) , Delft
University of Technology, Delft, Netherlands, 3) , University of Luxembourg, Luxembourg 4) , European
Space Agency, ESTEC 5)
Next Generation Gravity Missions (NGGMs) expected to be launched in the mid-term future have set highanticipations for an enhanced monitoring of mass transport in the Earth system, establishing their products
applicable to new scientific fields and serving societal needs. The European Space Agency (ESA) has
issued several studies on concepts of NGGMs. Following this tradition, the project “Additional
Constellations & Scientific Analysis Studies of the Next Generation Gravity Mission" picks up where theprevious study ESA-SC4MGV left off.
One of the ESA-ADDCON project objectives is to investigate the impact of different orbit configurations
and parameters on the gravity field retrieval. Given a two-pair Bender-type constellation, consisting of apolar and an inclined pair, choices for orbit design such as the altitude profile during mission lifetime, thelength of retrieval period, the value of sub-cycles and the choice of a prograde over a retrograde orbit areinvestigated. Moreover, the problem of aliasing due to ocean tide model inaccuracies, as well as methods
for mitigating their effect on gravity field solutions are investigated in the context of NGGMs.
The performed simulations make use of the gravity field processing approach where low-resolution gravity
field solutions are co-parameterized in short-term periods (e.g. daily) together with the long-term solutions(e.g. 11-day solution). This method proved to be beneficial for NGGMs (ESA-SC4MGV project) since theenhanced spatio-temporal sampling enables a self-de-aliasing of high-frequency atmospheric and oceanic
signals, which may now be a part of the retrieved signal. The potential added value of having such signals
for the first time in near real-time is assessed within the project.

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*G03-2-05
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Amplitude-phase representation of GRACE spherical harmonic spectra* Nico Sneeuw 1) , Balaji Devaraju 2)
Institute of Geodesy, University of Stuttgart, Stuttgart, Germany 1) , Institute of Geodesy, Leibniz Universityof Hannover, Hannover, Germany 2)
Representing the spherical harmonic spectrum of a field on the sphere in termsof its amplitude and phase is termed as its polar form. While the polar formof the Fourier spectrum, especially in time-series analysis and image
processing, is well understood, it is an alien concept in geodesy. To thisextent, we first show that spherical harmonic synthesis can be interpreted asa weighted (by amplitude) sum of rotated (by phase) spherical harmonics. As an
example, we explore the polar forms of the monthly GRACE time-variable gravity
field data before and after filtering. The impact of filtering on amplitude iswell understood, but that on phase has not been studied previously. Here, we
demonstrate that certain class of filters only affect the amplitude of thespherical harmonic spectrum and not the phase, but the others affect both theamplitude and phase. Further, we also demonstrate that the filtered phasehelps in ascertaining the efficacy of decorrelation filters used in the
GRACE community.

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*G03-2-06
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Using Swarm and Sentinel observations for time-variable hl-SST gravity field
determination* Christoph Dahle 1) 2) , Daniel Arnold 2) , Adrian Jaeggi 2) , Ulrich Meyer 2) , Rolf Koenig 1) , Grzegorz
Michalak 1) , Karl Hans Neumayer 1)
GFZ German Research Centre for Geosciences, Potsdam, Germany 1) , Astronomical Institute, University ofBern, Bern, Switzerland 2)
Equipped with geodetic-grade on-board GPS receivers and star trackers, the three satellites of the Swarm
mission can be used to determine the long-wavelength part of the Earth's gravity field including its time
variations by means of high-low satellite-to-satellite tracking (hl-SST). This is also true for ESA's Sentinel
satellites, although their slightly higher orbital altitude degrades their sensitivity to the gravity field. Hl-SST
based gravity field solutions are of special interest to fill the gap between the dedicated gravity missions
GRACE and GRACE-FO.
In this contribution the latest results obtained at the Astronomical Institute of the University of Bern (AIUB)
as well as at the German Research Centre for Geosciences (GFZ) are presented focusing on the following
topics: (1) Systematic errors in Swarm gravity field solutions along the Earth's geomagnetic equator caused
by ionospheric disturbances and their mitigation by GPS data screening and/or updated tracking loop
settings of the GPS receivers. (2) Comparison of monthly AIUB and GFZ Swarm solutions that are
generated with different approaches. (3) Added value of Sentinel-1A, -2A, and -3A satellites (which are notaffected by the aforementioned systematic degradations) to the very low degrees of the Swarm gravity field
solutions.

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*G03-3-01
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Preliminary results from CSR RL06 GRACE gravity solutions* Himanshu Save
Center for Space Research, The University of Texas at Austin
The GRACE mission data will be reprocessed in order to be consistent with the first gravity products
released by the GRACE-FO project. The improvements in the next generation GRACE Release-06 (RL06)
gravity products will come from the improvements in GRACE Level-1 data products, background models
and processing methodology. This paper will discuss the planned and realized improvements for CSR –RL06 gravity products and present the preliminary results. This paper will discuss the evolution of thequality of the GRACE solutions and characterize the errors, especially over the past few years. We will also
discuss the possible challenges associated with connecting the GRACE time series with that from GRACEFO.

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*G03-3-02
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Combination of monthly gravity field solutions – transition from an EGSIEM
prototype service into an IAG service* Adrian Jaggi , Ulrich Meyer , Yoomin Jean , Daniel Arnold
University of Bern, Bern, Switzerland
One of the main objectives of the project European Gravity Service for Improved Emergency Management(EGSIEM) is to establish a prototype service to combine monthly gravity field solutions from the current
GRACE and the future GRACE-FO mission in order to deliver improved gravity field solutions forapplications in Earth and environmental science research. Five analysis centers are currently contributing
to these prototype service activities, where combinations on the solution level and more rigorous
combinations on the normal equation level are performed. We report on the current achievements and thetransition from the prototype phase into regular service operation under the umbrella of IAG's International
Gravity Field Service (IGFS), which will ensure continuation beyond the EGSIEM project ending after three
years of funding by the end of 2017.

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*G03-3-03
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity fieldOn computation of along-track potential and Line-of-Sight (LOS)
acceleration difference using GRACE inter-satellite ranging data for timevariable gravity analysis* Khosro Ghobadi Far 1) , Shin-Chan Han 1) , Bryant Loomis 2) , Scott Luthcke 2)
School of Engineering, University of Newcastle, Callaghan, New South Wales, Australia 1) , Geodesy andGeophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA 2)
In situ along-track potential difference and LOS acceleration difference can be computed from GRACE
orbit and inter-satellite range-rate and range-acceleration data. We study the systematic errors in deriving
along-track potential difference from inter-satellite range-rate and LOS acceleration difference from intersatellite range-acceleration. Since GRACE can be considered as a long single-axis gradiometer,
approximating gradiometric observable (i.e. LOS acceleration difference divided by inter-satellite range) byalong-track gravitational gradient is also discussed. In all three cases (potential, gravity and gravity
gradient), we formulate the errors explicitly in terms of cross-track and radial components of the intersatellite velocity vectors. Based on a simulation study, we found that, except for low frequency part of thespectrum (0-1.85 mHz, or equivalently, spherical harmonic degrees <10), for which the radial component ofinter-satellite velocity vector is the main source of the errors, the approximation error of range-rate andrange-acceleration remains <8% of the signal. Considering the KBR ranging noise, it is feasible toaccurately compute the along-track potential and LOS acceleration difference directly from band-passfiltered range-rate and range-acceleration, respectively, and employ them for analyses concerning the local
time-variable gravity fields of the Earth. We present the results from real GRACE KBR data analysis andapplications to local refinement of the GRACE monthly gravity solutions. We also discuss the increased
sensitivity to gravity signals by virtue of altitudes lowered down to 350 km in 2016 from the nominal
altitude of 500 km.

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*G03-3-04
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Evaluating strategies for mitigating aliasing errors in GRACE-like satellite
missions
Balaji Devaraju , Matthias Weigelt , * Juergen Mueller
Leibniz Universitaet Hannover, Hannover, Germany
The aliasing of tidal and non-tidal geophysical signals with frequencies of less than one month into themonthly time-variable GRACE gravity field solutions is an often observed but only partially understoodphenomenon. With increasing sensor accuracy (for example, GRACE-FO), the aliasing errors have been
identified as the major stumbling blocks for the geophysical applications of satellite gravimetry data.
While aliasing affects all spherical harmonic coefficients, their impact on the higher harmonic degrees andorders can be reduced via parameter pre-elimination of low-degree sub-monthly (two-day) solutions often
denoted as the Wiese-approach. In this study, we specifically look at how the Wiese-approach handles thealiasing errors, thereby analysing its mechanism in reducing aliasing errors. The Wiese-approach is
implemented in the gravity field recovery process via the acceleration approach. In preceding studies, only
the along-track acceleration has been used. Here, we demonstrate the benefit of the cross-track and theradial components of the acceleration vector in mitigating the aliasing errors. By using a noise-free
simulation, we are able to specify upper bounds for the aliasing errors.

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*G03-3-05
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

GRACE de-striping by biharmonic thin-plate splines on the sphere* Wolfgang Keller
University Stuttgart, Stuttgart, Germany
If gravity field solutions are deduced from satellite observations, the gravity field information is only
available along the ground tracks of the satellite.
Implicitly, a global spherical harmonics solution leads to polynomial interpolation between these tracks.
The oscillation tendency of polynomial interpolation contributes to the undesired striping effect in monthly
GRACE solutions.
In the paper an alternative interpolation strategy is tested, which fulfills two requirementsi) It reproduces the observations along the tracks andii) it is as smooth as possible between the tracks.
If smoothness is understood as minimal bending energy of an elastic membrane, the strategy results in an
spherical thin-plate spline interpolation.
The interpolation problem is solved in two independent ways:
1) As the direct solution of the variational problem and2) as the solution of the corresponding Euler equation.
In our case the Euler equation is the biharmonic equation on the sphere. For this equation a consistent
finite differences approximation is developed and numerically implemented.
Compared to Gaussian smoothed spherical harmonics solution the thin-plate spline solutions shows abetter consistency with the observations along the tracks.

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*G03-3-06
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

SLR monthly gravity solutions using the C5++ software* Koji Matsuo 1) , Toshimichi Otsubo 2)
Geospatial Information Authority of Japan, Ibaraki, Japan 1) , Hitotsubashi University, Tokyo, Japan 2)This study presents monthly gravity solutions up to degree and order 4 for the period 1993-2015 derived
by Satellite Laser Ranging (SLR) data using the C5++ software [Otsubo et al., 1994]. Here, we apply thefollowing modifications to the previous solutions by Matsuo et al. (2013). First, Range bias is estimated forper station and per satellite. Secondly, station coordinates are solved for using no-net-rotation constraints.
Thirdly, non-tidal effects for atmosphere, ocean, hydrology are corrected using geophysical fluid models.
Last, one-per-rev empirical accelerations are estimated in along-track and cross-track. Consequently, our
new SLR solutions exhibited better consistency with those from Gravity Recovery And Climate Experiment(GRACE) than the previous solutions in the degree 3 and 4 components. The improvements of SLR gravity
solutions provides further insight into the mass variability of the earth prior to the launch of GRACE in
2002.

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*G03-4-01
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Mapping probabilities of extreme continental water storage changes fromspace gravimetry* Juergen Kusche 1) , Annette Eicker 2) , Ehsan Forootan 3) , Anne Springer 1) , Laurent Longuevergne 4)
University of Bonn, Germany 1) , HafenCity University Hamburg, Germany 2) , University of Cardiff, UK 3) ,University of Rennes, France 4)
Using data from the Gravity Recovery and Climate Experiment (GRACE) mission, we derive statisticallyrobust 'hotspot' regions of high probability of peak anomalous - i.e. with respect to the seasonal cycle -water storage (of up to 0.7 m one-in-five-year return level) and flux (up to 0.14 m/mon). Analysis of, andcomparison with, up to 32 years of ERA-Interim reanalysis fields reveals generally good agreement of thesehotspot regions to GRACE results, and that most exceptions are located in the Tropics. However, asimulation experiment reveals that differences observed by GRACE are statistically significant, and further
error analysis suggests that by around the year 2020 it will be possible to detect temporal changes in thefrequency of extreme total fluxes (i.e. combined effects of mainly precipitation and floods) for at least
10-20% of the continental area, assuming that we have a continuation of GRACE by its follow-up GRACEFO.
J. Kusche et al. (2016): Mapping probabilities of extreme continental water storage changes from spacegravimetry, Geophysical Research Letters, 43, 8026–8034

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*G03-4-02
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Glacier melting and GIA in Alaska estimated from joint GPS, ICESat and
GRACE measurements* Shuanggen Jin , Tengyu Zhang
Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai, China
The Alaskan Mountain glacier is one of the largest glaciers on the Earth excluding the polar ice sheets over
Antarctica and Greenland. However, it is difficult to quantify of the glacier melting in Alaska due to thelimited and high-cost traditional observations of the glaciers. Although Gravity Recovery and Climate
Experiment (GRACE) can estimate the glacier mass change, but with large uncertainty in GIA, while ICESat
needs the density of Alaskan glacier volume change. In this paper, GPS, ICESat and GRACE measurementsfrom 2003 to 2009 are for the first time jointly used to estimate average density, GIA and glacier mass loss.
An optimal density of glacial volume change with 750 kg/m3 is estimated to fit the measurements. The
glacier mass loss is -57.5 6.5Gt by converting the volumetric change from ICESat. Furthermore, the GIA isalso estimated after correcting the ice mass loss signal in GPS and GRACE measurements.

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*G03-4-03
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Spatio-temporal downscaling of GRACE water storage changes data at
catchment scale* Mohammad J. Tourian , Nico Sneeuw
Institute of Geodesy, University of Stuttgart
The launch of the gravity mission GRACE satellites in 2002, caused a quantum leap both in hydrologicalunderstanding continental scale systems and their interactions as well as for applications. GRACE captureswater storage change over landmasses, which is a useful indicator of climate variability and human impacts
on the environment. The application of time variable gravity from GRACE for hydrological purposes has
been growing. Recent achievements about the dynamic changes in groundwater highlight the importanceof GRACE for hydrological applications. However, the spatio-temporal resolution remains the biggest
bottleneck in applying GRACE-derived water storage changes to a wider hydrological use on regional
catchments and shorter time scales as often needed for river basin management.
Although the spatio-temporal resolution of GRACE is limited by its orbit configuration, one can downscalewater storage variation at catchment scale by assimilating the data of different storage compartments with ahigher temporal and spatial resolution. This study attempts to develop a statistical based algorithm toachieve a realization of GRACE water storage with better temporal (less than a week) and spatial scales(~100 km), consistent with auxiliary observations. We use observations of hydrological and hydrometeorological fluxes e.g. precipitation, runoff and moisture flux divergence. We also use surface water
storage and soil moisture storage products. We estimate surface water storage by combining water levelfrom satellite altimetry with the surface water extent from satellite imagery. We obtain spatio-temporalvariable soil moisture storage from dedicated satellites e.g. SMOS ASCAT.

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*G03-4-04
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

The potential of GRACE gravimetry to detect heavy rainfall-induced
impoundment of a small reservoir in the upper Yellow River* Shuang Yi 1) 2) , Chunqiao Song 3) , Qiuyu Wang 2) , Linsong Wang 4) , Kosuke Heki 1) , Wenke Sun 2)
Department of Natural History Sciences, Hokkaido University, Sapporo, Japan 1) , Key Laboratory ofComputational Geodynamics, University of Chinese Academy of Sciences, Beijing 100049, China 2) ,Department of Geography, University of California, Los Angeles, Los Angeles, CA 90095, United States 3) ,Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan, Hubei, China 4)
Artificial reservoirs are important indicators of anthropogenic impacts on environments, but their gravity
effects have been seldom studied. Here, satellite gravimetry Gravity Recovery and Climate Experiment(GRACE) is utilized to detect the gravity effect of the Longyangxia Reservoir (LR) situated in the upperstream of the Yellow River. Heavy precipitation in the summer of 2005 caused the LR water storage toincrease 37.9 m in height or 13.0 Gt in mass. Three different GRACE solutions from CSR, GFZ and JPL andthree different filters (an anisotropic decorrelation filter DDK4, Gaussian filter and a decorrelation filter)
are compared here. In this case, CSR solutions have the highest signal-noise-ratio and DDK4 shows thebest ability to reveal the expected gravity signals. We obtained 109 combinations of inundation area
measurements from satellite imagery and water level changes from laser altimetry and in situ observations
to derive the area-height ratios in the LR, which agrees well with an alternative method based on the digital
elevation model. After removing simulated gravity signals caused by mass changes in the LR, the root meansquare of GRACE series in the LR is reduced by 31.1%. If the residuals are totally attributed to GRACE
errors, the standard deviation of GRACE observation in this study spot is estimated to be 3.1 cm. With anarea of 383 km2, the Longyangxia Reservoir is the smallest signal source reported to be detected by
GRACE.

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*G03-4-05
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Detection and interpretation of multi-annual mass variation in GRACE
monthly gravity solutions* Lorant Foldvary 1) 2) , Annamaria Kiss 3)
Institute of Geoinformatics, Obuda University, Szekesfehervar, Hungary 1) , Geodetic and GeophysicalInstitute, Research Centre of Astronomy and Earth Sciences, Hungarian Academy of Science, Sopron,
Hungary 2) , Budapest University of Technology and Economics, Budapest, Hungary 3)
The GRACE mission provides monthly gravity field solutions for nearly 15 years with very few gaps in theconsecutive series of gravity field models. The time series of gravity field models provides primarily a tool
for annual and sem-annual mass variations. The length of the data already enables investigations ofvariations on multi-annual periods. The non-unique sampling of the epochs calls for an appropriate methodfor determining the multi-annual signal; for the purpose Burg spectrum, modified periodogram, Thompson's
multitaper method and Lomb–Scargle periodogram has been adapted. Regions of statistically convincing
variations in the 2-10 year periods has been identified. In most cases at these regions the mass variation
was found to be related to the El Nino/La Nina events.

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*G03-5-01
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

What GRACE/GRACE-FO satellite gravity may tell about the atmosphere(and what not)* Annette Eicker 1) , Anne Springer 2) , Andreas Hense 2) , Isabelle Panet 3) , Juergen Kusche 2)
HafenCity University, Hamburg, Germany 1) , University of Bonn, Bonn, Germany 2) , Institut National del'Information Geographique et Forestiere, Paris, France 3)
In this presentation we would like to discuss the present benefit and future potential of satellite gravity
observations, as obtained from the satellite mission GRACE and its successor GRACE-Follow-On (GRACEFO), for studying the atmospheric water cycle. In the first part of the presentation, we will show recent
results of using GRACE to constrain atmospheric water budgets. GRACE-derived water storage changes (incombination with observed runoff) can be used to solve for the vertical water flux deficit of precipitation (P)minus evapotranspiration (E), which links the terrestrial and the atmospheric water balance equations. This
relates gravity change to moisture flux divergence and water vapor change and thus provides, in principle,
a link between GRACE/GRACE-FO and (area-averaged) GNSS integrated water vapor observations that
may be exploited in the future. We will show that such an independent estimate of P minus E can be used
to constrain land-atmosphere fluxes from monthly time scales to decadal trends and even provides
meaningful flux information down to daily time steps.
In the second part of the presentation, we would like to give an outlook towards the potential of using
satellite gravity data directly for the estimation of atmospheric water mass changes. On the basis of ERAInterim data, we provide a first assessment which suggests that an anticipated future double-pair gravity
mission would be sensitive to 'feeling' atmospheric water mass (water vapor) variations. However, whether
these (faster) variations could be separated from dry air mass variations through modeling needs to beinvestigated. If possible, this would offer a completely new tool for validating atmospheric analyses and for
improving engergy and mass budgets in models.

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*G03-5-02
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Uncertainty of GRACE-borne long periodic and secular ice mass variations
in Antarctica* Lorant Foldvary 1) 2) , Annamaria Kiss 3)
Institute of Geoinformatics, Obuda University, Szekesfehervar, Hungary 1) , Geodetic and GeophysicalInstitute, Research Centre of Astronomy and Earth Sciences, Hungarian Academy of Science, Sopron,
Hungary 2) , Budapest University of Technology and Economics, Budapest, Hungary 3)
Glacial ice mass balance of Antarctica can be determined by monthly gravity field solutions derived fromGRACE observations. The present investigation delivers an error estimation of the long-periodic andsecular variations by determining the linear trend of the observed surface mass anomaly series. The
analysis focuses on unavoidable error sources and disregards the consequences of the methodology.
Among the error sources, the error of the timing of the trend fitting, the error of the glacial isostatic
adjustment correction, and the error of the atmospheric correction of the GRACE monthly solutions are
discussed. The investigation concludes that apart from West Antarctica, Wilkes Land, Queen Maud Landand Enderby Land no reliable trend estimates of ice mass variation can be expected, thus any results
should be treated with care.

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*G03-5-03
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Ocean tide alias spectrum estimation for satellite gravity missions* Wei Liu , Nico Sneeuw
University of Stuttgart, Stuttgart, Germany
Spaceborne gravimetry missions like GRACE suffer from ocean tide alias errors which can be understood
into two steps: undersampling of the ocean tides from satellite orbit and recombination of the satellite
measurements over time and space while recovering the gravity field. Although ocean tide models are used
for de-aliasing during the gravity field retrieval, the uncertainty in those models will directly alias into therecovered gravity field. If the aliasing frequencies of each tidal constituent would be known, ocean tide
alias errors can be mitigated in a post-processing mode. Hence, it is crucial to evaluate the alias periods
with respect to the type of satellite mission and to field recovery strategy. Here we develop an approach toestimate the alias spectrum of ocean tide errors based on the abovementioned two steps, taking bothsatellite orbit sampling and recovery process into consideration. Apart from a GRACE-type single-pairmission, the alias spectrum of a so-called Bender formation is investigated. The latter double pair formationis considered to be the most promising type for future gravity missions and deserves a closer look.

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*G03-5-04
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Seasonal water mass variation in the Japan Sea from satellite gravimetry:
Comparison with GNSS and seasonality in earthquake occurrences
Suguru Doto , * Kosuke Heki
Hokkaido University, Hokkaido, Japan
Since the launch in 2002, most researches with the GRACE satellites have focused on gravity changes onland, but its increasing time span enables us to discuss time-variable gravity in the ocean, e.g. seasonal
water mass changes in the Red Sea (Wahr et al., 2014). Here, we study seasonal mass changes in the Japan
Sea (the East Sea of Korea) using the GRACE data 2002-2016 (Level-2 RL-5 data from CSR). By analyzing
the GSM files, we found the gravity maximum and minimum in November and June, respectively, with thepeak-to-peak amplitude ~10 cm in equivalent water depth. Then we added back the GAD files to recover
the original gravity changes in the ocean. Oddly, GSM + GAD resulted in a smaller seasonal change withamplitude of ~4 cm. This means that the non-tidal ocean mass change model used for the GAD files isincorrect in the Japan Sea.
We compared the GRACE data with the tide gauge records in the Japan Sea, and found that tide gauge
showed amplitudes several times as large and the maximum in late summer. This suggests that the seasonalsea surface height changes mainly reflect thermal expansion of warm water above the thermocline rather
than the real water mass changes. Winter snow also causes seasonal gravity changes in NE Japan with asharp peak in February. GNSS stations in NE Japan show complicated seasonal movements coming partly
from the sea water and partly from the snow. We further discuss the causal relationship between seasonal
water mass changes in the Japan Sea and seasonal changes in seismicity in the plate boundary runningalong the eastern margin of the Japan Sea, i.e. major earthquakes occur during three months May, June andJuly there.

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*G03-5-05
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Seismic gravity changes of the 2004 Sumatra-Andaman earthquake andstatic gravity anomaly* Yusaku Tanaka , Kosuke Heki
Hokkaido University, Hokkaido, JapanThe 2004 Sumatra-Andaman earthquake is the first very large earthquake after the launch of the GRACE
satellites in 2002. In this study, we analyzed the time series of the gravity changes using the latest GRACE
data sets. The result suggests that the postseismic gravity changes of the 2004 Sumatra-Andaman
earthquake have almost ended. The observation data can help us determine time scales of the postseismic
gravity changes and constrain viscosity structure of the upper mantle. Moreover, it may allow us toresearch interseismic gravity changes because the static gravity anomaly is formed by the repeat of inter-,co-, and postseismic gravity changes and the static anomaly and co- and postseismic gravity changes arebeing revealed.

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*G03-5-06
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity fieldContinuous time variations in relative gravity and tilt, observed by a CG-3M
gravimeter during the inflation event at Sakurajima Volcano on August 15,
2015* Takahito Kazama , Keigo Yamamoto , Masato Iguchi , Yoichi Fukuda
Kyoto University, Kyoto, Japan
Continuous gravity observation is one of the most powerful methods to monitor mass redistributions involcanoes. In Japanese volcanoes, absolute gravimeters have detected gravity changes of less than 10
microGal originating from volcanism, with those time period of more than a few days (e.g., Kazama et al.,
JGR, 2015). However, absolute gravimetry cannot precisely detect short-period (< one day) gravity changes
due to the low signal-to-noise ratio in the high frequency domain. On the other hand, broadband volcanic
phenomena have been monitored by other geodetic observations at many active volcanoes (e.g., Iguchi etal., JVGR, 2008). If the short-period volcanic gravity signals can be detected by continuous gravity
observations other than absolute gravimerty, volcanic phenomena will be minutely discussed in terms ofmass redistributions.
We were thus motivated to monitor continuous relative gravity changes at high time resolution in
Sakurajima Volcano, one of the most active volcanoes in Japan. We installed a CG-3M relative gravimeter(serial number: 9403248) in September 2010, and started collecting relative gravity values at one-minuteinterval. After the corrections of gravity disturbances such as instrumental drift and tidal gravity changes,
we succeeded in detecting a rapid gravity decrease of -5.86 microGal during the rapid inflation event on 15
August 2015. This gravity change is smaller than the typical observation error of relative gravimeters (~10
microGal), but the high-frequency measurements of relative gravity contributed to the detection of the small
gravity change in the case of Sakurajima Volcano. We also found that the gravity change was consistent
with one of the dike intrusion models provided by Geospatial Information Authority of Japan (2015) if thedensity value of 0.97 +/- 0.37 g/cm3 was assumed, which implies the drastic foaming of the intruded
magma.

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*G03-P-01
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

ESA's Studies of Next Generation Gravity Mission Concepts
Luca Massotti , Christian Siemes , Olivier Carraz , Roger Haagmans , Pierluigi Silvestrin , * Michael Kern
European Space Agency
The presentation addresses the preparatory studies of future ESA mission concepts devoted to improve ourunderstanding of the Earth's mass transport phenomena causing temporal variations in the gravity field, atdifferent temporal and spatial scales, due to ice mass changes of ice sheets and glaciers, continental water
cycles, ocean masses dynamics and solid-earth deformations.
The ESA initiatives started in 2003 with a study on observation techniques for solid Earth missions andcontinued through several studies focussing on the satellite system, technology development for propulsion
and distance metrology, preferred mission concepts, the attitude and orbit control system, as well as the
optimization of the satellite constellation. These activities received precious inputs from the in-flightlessons learnt from the GOCE and GRACE missions. More recently, several studies related to new sensor
concepts based on cold atom interferometry were initiated, mainly focussing on technology development
for different instrument configurations (GOCE-like and GRACE-like).
The latest results concerning the preferred satellite architectures and constellations, payload design andestimated science performance will be presented as well as remaining open issues for future concepts.

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*G03-P-02
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Combination of monthly gravity fields on normal equation level
Ulrich Meyer , * Adrian Jaeggi , Yoomin Jean , Daniel Arnold
University of Bern, Bern, Switzerland
In the frame of the Scientific Combination Service of the European Gravity Service for Improved
Emergency Management (EGSIEM), monthly gravity fields of different analysis centers are combined on
normal equation (NEQ) level. While common standards for reference frame, Earth rotation and satellite
geometry ensure consistency of the NEQs, the different processing centers are free to apply their own
processing strategies and to select different background models for de-aliasing and signal separation. The
applied noise models are very inhomogeneous, too, and consequently standard procedures for NEQ
combination like Variance Component Estimation fail. We present an alternative NEQ combination strategy
where relative weights are defined based on the solution noise, as determined by pairwise comparisons of
the individual contributions on solution level. We further investigate combination approaches where theindividual NEQs are scaled prior to combination, with the goal to reach homogeneous levels of formal
errors.

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*G03-P-03
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

GNSS-based calibration of GRACE accelerometers
Igor Koch , Akbar Shabanloui , Jakob Flury , * Juergen Mueller
Leibniz University of Hannover, Hannover, Germany
In this study, two approaches for the determination of total non-gravitational accelerations acting on
GRACE were investigated. To investigate two approaches, GRACE Level-1B data including accelerometer
sensor data, GNSS based positions and star camera data was used. In the first approach, usual surface
accelerations acting on the satellite were taken into account. In a second approach, the total acceleration,
consisting of a gravitational and non-gravitational contribution, was first determined from the GNSS-based
precise orbit data by means of smoothing polynomial and differentiation. Then the gravitational
contribution determined by state of art models was removed to determine the non-gravitational part.
The results of these two methods were used to calibrate the linear acceleration measurements on-board
GRACE. Daily constraint-free biases and scale factors were determined for two time periods including threemonth data with a different solar activity. The quality of the results, especially of the second approach ishighly dependent on the solar activity and therefore the magnitude of the non-gravitational reference
acceleration. The results show that calibration parameters for along track direction can be determined
more precise without any information about satellite properties and atmospheric conditions. Constraints
have to be applied to get more realistic calibration parameters for axes with a smaller contribution.

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*G03-P-04
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Comparison of short-term iGrav superconducting gravimeter observations
with local and global hydrological models
Hojjat Kabirzadeh , Dimitrios Piretzidis , Jeong Woo Kim , * Michael G. Sideris
Department of Geomatics Engineering, University of Calgary, AB, Canada
Hydrological mechanisms have been identified as the most complicated environmental effect on gravity
signals. In this study, several sources of local and global hydrological observations are used and comparedin order to obtain the 10 nms-2 accuracy for the iGrav's measurements needed in many geophysicalapplications. Six months of stationary measurements with Canada's first iGrav superconducting gravimeter(SG), collected from 31st October 2011 to 1st May 2012 at the University of Calgary, supported by A10
absolute measurements for calibration purposes, are processed and corrected for environmental
interferences. After calibration, unwanted signals due to human activities, and natural environmental
effects such as Earth tides, ocean loading, atmospheric pressure, polar motion, seismic events, etc., were
removed from the iGrav's raw gravity signal. Residual gravity values increased by 50 nms-2, which agrees
with the gravity effect of accumulated precipitation obtained by using an empirical admittance factor of 4.2
nms-2/cm. Groundwater level changes also demonstrated high correlation with the high frequency gravity
variations. The gravity effect of groundwater level changes was calculated from a Bouguer slab model. The
temporal variations of the integrated gravity signal are compared with filtered CSR GRACE monthly masschange solutions. Average soil moisture contributions from global land hydrology models, such as the
GLDAS NOAH model with spatial resolution of 0.25 degrees and temporal resolution of 3 hours, are also
analyzed. The results indicate that the monthly variations of groundwater storage effect in the iGrav's
residual signal can be recovered perfectly by GRACE observations or local and global hydrological models
with an accuracy of 8.5 nms-2.

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*G03-P-05
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

Evaluation and Analysis of Ground Water Level Changes and Water Budget
in the Northeast Poland* Joanna Kuczynska-Siehien 1) , Zofia Rzepecka 1) , Monika Birylo 1) , Ewa Andrasik 2) , Jolanta Nastula 3)
University of Warmia and Mazury in Olsztyn, Olsztyn, Poland 1) , Warsaw University of Technology, Warsaw,
Poland 2) , Space Research Centre Polish Academy of Sciences, Warsaw, Poland 3)
Water is one of the most important component of the environment, having a direct effect on themaintenance of life on the Earth. In this paper, the analyses of changes of groundwater level, water budget
and all the parameters included in these quantities, were performed on the area of northeastern Poland, inthe period of 2003 – 2016.
The groundwater level (GWL) changes were computed on the basis of the mean Terrestrial Water Storage(TWS) values determined from GRACE observations, completed with data acquired from the Global Land
Data Assimilation System (GLDAS). TWS data have spatial resolution of one degree, and temporal
resolution of one month, therefore the calculated changes of GWL do also refer to such resolution. The
obtained results were evaluated by the comparison with the data acquired from the Hydrological Annual
Reports of Polish Hydrological Survey.

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*G03-P-06
IAG Symposium / IAG02. Gravity field / G03. Time variable gravity field

A novel approach to study ice mass change by integration of satellite data inGreenland and Antarctica* Mohammad Bagherbandi 1) 2) , Nureldin Gido 2) 1) , Lars E. Sjoberg 2)
Faculty of Engineering and Sustainable Development, University of Gavle, SE-801 76 Gavle, Sweden 1) ,Division of Geodesy and Satellite Positioning, Royal Institute of Technology (KTH), SE-100 44 Stockholm,
Sweden 2)
For the time being there is an exceptional opportunity of achieving simultaneous and complementary datafrom a multitude of geoscience and environmental near-Earth artificial satellites. These satellite missions
allow significant contributions in understanding the climate change. There are many indications for climatechange, e.g. sea level rise, ice melting and temperature change. Ice melting is one of the most important
indicators in the context of global warming. Therefore, modelling of the Earth's mass distributions due tothe ice melting and the temporal changes of such masses, are very important in studying sea level rise.
Such study will improve our capability to understand, monitor and predict geophysical/geologicalprocesses which are affected by mass changes. The overall goal of this study is to specifically study Earth's
surface mass changes due to ice melting in Greenland and Antarctica. The goals will be achieved byanalyzing GRACE data, ICEsat data and integrating the results with other In-situ data. For this study weused the GRACE data during the years of 2003 to 2017 and then we determined the rate of the ice masschange, using time series analysis explained in Sjoberg and Bagherbandi (2017). Using the obtained ice
melting rate from GRACE data we are able to model near Earth surface mass density changes, according to
Sjoberg and Bagherbandi (ibid). Preliminary results show average surface mass changes are -413+-23.9
and 26+-5.9 kg/m^2 per year in Greenland and Antarctica, respectively. The changes will affect the sea
level, hence the mass changes are compared with sea level rise obtained from satellite altimetry missions(e.g. Jason 1 and 2). Also the results will be verified by In-situ data like GLDAS (Global Land Data
Assimilation System), land surface temperature (Rodell et al. 2004 and Swenson et al. 2006) and otherremote sensing satellite missions such as the ICEsat mission.

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*G04-1-01
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Limited True Polar Wander as evidence that Earth's non-hydrostatic shape ispersistently triaxial* Bernhard Steinberger 1) 2) , Miriam-Lisanne Seidel 3) , Trond Torsvik 2) 4) 1)
GFZ German Research Centre for Geosciences, Potsdam, Germany 1) , Centre for Earth Evolution and
Dynamics, University of Oslo, Oslo, Norway 2) , Werner-von-Siemens Gymnasium, Berlin, Germany 3) ,Geological Survey of Norway (NGU), Trondheim, Norway 4) , University of Witwatersrand, Wits, South
Africa 5)
Earth's spin axis follows the maximum moment of inertia axis of mantle convection, with some delay due toadjustment of the rotational bulge. Here we compute this axis for geodynamic models based on subduction
history, assuming constant slab sinking speed, with another contribution due to thermochemical piles. Fora wide range of parameters, a large shift of approximately 90 degrees is predicted around 80 − 90 Ma. It
can be largely attributed to a change in circum-Pacific subduction from predominantly in the North andSouth towards East and West. Actual amounts of true polar wander are much smaller, pointing towards
additional inertia tensor contributions, possibly due to slabs in the lowermost mantle below both polar
regions. These slabs would have been subducted before approximately 150 Ma, when plate motions in thePanthalassa basin are largely unknown. Matching predicted and observed true polar wander can serve atconstraining such plate motions.

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*G04-1-02
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Short-term Angular Momentum Forecasts for Polar Motion Prediction* Maik Thomas 1) , Robert Dill 1) , Henryk Dobslaw 1) , Christian Bizouard 2)
GFZ German Research Centre for Geosciences, Potsdam, Germany 1) , Observatoire de Paris, Paris, France
2)

The Earth System Modelling group at GeoForschungsZentrum (GFZ) Potsdam provides operational 6-day
forecasts of Earth rotation excitation due to atmospheric, oceanic, and hydrologic angular momentum
changes. These EAM forecasts extend the 40 years long EAM series for 6 days into the future with atemporal resolution of 3 hours for both AAM and OAM. A set of 6-day EAM hindcasts from 2016 to 2017
for Earth rotation forecasts reveals positive prediction skills for up to 8 days into the future. Compared to
the IERS predictions of bulletin A, the introduction of the 6-day EAM forecasts improves the prediction for
more than 10 days into the future for both polar motion and length of day variations. Thus, not only the
AAM forecasts as currently used for UT1 predictions in bulletin A, but also OAM forecasts and to a smaller
extent HAM forecasts improve polar motion prediction, in particular for lead-times between 2 and 8 days.
We will also report about early results obtained at Observatoire de Paris to predict polar motion from theintegration of GFZ's 6-day EAM forecasts into the Liouville equation in a routine setting that fully takes into
account the operational latencies of all required input products.

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*G04-1-03
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Geophysical interpretation of long-term polar motion* Jianli Chen
Center for Space Research, University of Texas at Austin, Austin, Texas, USA
Polar motion represents the constant motion of the Earth rotation pole position in the terrestrial reference
frame, and is driven by mass movement and redistribution within the Earth system, under the conservationof angular momentum. Polar motion has been accurately measured by a multi-technique observing programof international scope, with an accuracy reaching ~0.03 milliarcsecond (mas) over variations of up to few
hundred mas. Observed polar motion at different temporal scales can be used to study mass changes indifferent components in the Earth system, including the atmosphere, ocean, hydrosphere, cryosphere andsolid Earth. While at interannual and shorter time scales, polar motion is mainly driven by air and watermass redistribution and movement in the atmosphere, ocean and hydrosphere, ice mass change from polar
ice sheets and mountain glaciers and non-steric global eustatic sea level change play an important role indriving polar motion at decadal and longer time scales. Solid Earth mass redistributions associated with
Glacial Isostatic Adjustment (GIA) and tectonic movement are believed to be the dominated contributors tolong-term polar motion (i.e., linear trends in most studied time frames). Using over 14-years of GRACE
satellite gravity measurements and climate model predictions, here we provide a comprehensive analysis ofgeophysical excitations of polar motion from different components of the Earth system, with a focus oninterannual and longer time scales. The extended record of GRACE time-variable gravity measurements
offer a unique means for people to better understand geophysical excitations of polar motion at a broadband of frequencies, and provide observational constraints on model predicted polar motion excitations,such as those from GIA and pole tide (i.e., rotational deformation).

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*G04-1-04
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Hydrological excitation of polar motion by different representations ofEarth's gravity field* Jolanta Nastula 1) , Malgorzata Winska 1) 2) , Waldemar Popinski 3)
Space Research Centre Polish Academy of Sciences, Warsaw, Poland 1) , Warsaw University of Technology,
Faculty of Civil Engineering, Warsaw, Poland 2) , Department of Methodology and Standards, Central
Statistical Office, Warsaw, Poland 3)
The impact of continental hydrological loading from land water, snow and ice, on polar motion excitation, isdifficult to estimate and is strongly needed for a full understanding of the excitation of polar motion. These
global circulation of surface geophysical fluids induces Earth's gravity field changes.
Mass concentrations parameters and spherical harmonics have been widely used to model variations inplanetary gravity fields. Variations in water storage on land affect the time dependent Earth's gravity field
as well and can be estimated from Gravity Recovery and Climate Experiment (GRACE) satellite mission
and hydrological models.
Firstly, the geographical patterns of terrestrial water storage (TWS) variations determined from GRACE
data, as a global mascon solutions and from spherical harmonics coefficients, will be compared to eachother and to TWS determined from Global Land Data Assimilation System (GLDAS) hydrological model.
Next, different estimations of hydrological excitation functions of polar motion (Hydrological AngularMomentum - HAM) will be investigated using either monthly TWS data, spherical harmonics as well as
mascon parameters representations of Earth's gravity field derived from GRACE mission. Simultaneously,
estimations of HAM from GLDAS hydrological model will be done.
Afterwards, we estimate the hydrological signal in geodetically-observed polar motion excitation as aresidual by subtracting the atmospheric - AAM and oceanic - OAM contributions. Finally, the hydrologicalexcitations are compared to these hydrological signal from the observed polar motion excitation series
residuals.
In this study, linear trend, decadal, inter-annual, and seasonal variations of hydrological excitation
functions of polar motion, determined from different representations of Earth's gravity field, are comparedto each other. This way, a comparison of HAM estimation strategies from mass concentrations, harmonics
coefficients and TWS changes will be investigated.

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*G04-1-05
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Global and regional comparison of hydrological excitation functions of polar
motion by GRACE data and climate models* Justyna Sliwinska , Jolanta NastulaSpace Research Centre of Polish Academy of Sciences, Warsaw, Poland
Explaining the hydrological part of the observed polar motion excitation has been a major challenge over adozen years. The terrestrial water storage (TWS) excitation of polar motion - hydrological angularmomentum (HAM), has been investigated widely using global hydrological models, mainly at seasonal
timescales. However, the results from the models do not agree among themselves and do not fully explain
the role of hydrological signal in polar motion excitation. Throughout the past decade, the Gravity Recovery
and Climate Experiment (GRACE) has given an unprecedented view on global variations in TWS.
Our investigation is focused on the influence of Terrestrial Water Storage (TWS) variations obtained from
Gravity Recovery and Climate Experiment (GRACE) satellite mission as well as from hydrological andclimate models on polar motion excitation functions at decadal, inter-annual and seasonal timescales. The
global and regional trend, seasonal cycle as well as some extremes in TWS variations are considered here.
Here TWS are obtained from the monthly mass grids land GRACE Tellus data: GRACE CSR RL05, GRACEGFZ RL05 and GRACE JPL RL05. As a comparative dataset, we also use TWS estimates determined fromthe World Climate Research Programme's Coupled Model Intercomparison Project Phase 5 (CMIP5)
climate models and Global Land Assimilation Data System (GLDAS) hydrological models. The TWS is
estimated in two ways: firstly, as a difference of total precipitation, evapotranspiration and total water runoff
and secondly, as the sum of soil moisture in all layers, accumulated snow, and plant canopy surface water.
Our studies include two steps: first, the determination and comparisons of regional patterns of TWS
obtained from GRACE data, climate and hydrological models, and second, comparison of the regional andglobal hydrological excitation functions of polar motion with a hydrological signal in the geodetic excitation
function of polar motion.

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*G04-2-01
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

On application of the Kalman filter for high resolution estimation of Earthorientation parameters using the ring laser and VLBI data
* Monika Tercjak 1) , Aleksander Brzezinski 1) 2) , Tobias Nilsson 3) , Harald Schuh 3)
Warsaw University of Technology, Warsaw, Poland 1) , Space Research Centre, Polish Academy of Sciences,
Warsaw, Poland 2) , GFZ German Research Centre for Geosciences, Potsdam, Germany 3)
Ring laser gyroscope (RLG) is a promising new technology for directly and continuously measuringchanges in Earth orientation; see, e.g., (Schreiber and Wells, 2013, Review of Scientific Instruments 84,
041101) for details. The Sagnac frequency observed by a RLG is sensitive to temporal variations of theinstantaneous rotation pole (IRP), while the space geodetic techniques report the terrestrial and celestial
motions of the conventional Celestial Intermediate Pole (CIP). The two poles are close to each other when
considering variation with periods of the order of weeks and longer, but behave differently at daily andsubdaily periods. Here we discuss the possibility of a simultaneous use of the observations of ring laser andvery long baseline interferometry (VLBI) for determination of Earth Orientation Parameters with hourly
resolution. The combination of RLG and VLBI data is done by a Kalman filter which incorporates the firstorder kinematical relationships between the motions of the CIP and IRP.

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*G04-2-02
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Corrections to IAU2000 nutation series for consistency with IAU2006
precession* Alberto Escapa 1) 2) , Jose Manuel Ferrandiz 1) , Tomas Baenas 1) , Juan Getino 3)
Dept. Applied Mathematics. University of Alicante. Spain 1) , Dept. Aerospace Engineering. University of
Leon. Spain 2) , Dept. Applied Mathematics. University of Valladolid. Spain 3)
A central issue in modern nutation and precession theories is to guarantee consistency among theirdifferent parts. This fact is motivated because IAU standards considered in the last decades tackle
precession and nutation as separated models that are interconnected, but just partially. However, current
accuracies in the determination of the EOPs require, at least, adopting some corrections aimed at
suppressing the inconsistencies that have been found between IAU2000 nutation and IAU2006
precession. In fact, IERS Conventions (2010) already includes some corrections to amend the IAU2000
nutation series, but they only cover a small part of the inconsistencies discovered so far.
We will present various corrections that must be accounted for to ensure full consistency and discuss theirsources. They can be separated into two groups. The first one is due to the changes of the value of the
dynamical ellipticity of the Earth, resulting from components of the precession theory not considered ormodeled with insufficient accuracy. These changes induce indirect variations of the nutation amplitudes. In
addition the change of ellipticity has a part related with the redistribution of mass within the Earth of tidal
and centrifugal nature.
The second group stems from some differences assumed for the Earth model in IAU2006 precession withrespect to IAU2000 nutation. The main one was the consideration of a constant J2 rate acting on theprecession motion. Its incorporation to the nutation model introduces some out–of–phase and mixed
secular nutations. Besides, it is also necessary to consider other effects like those related to the changes insome precession quantities, the time–dependent part of the orbital coefficients, etc.
These corrections should be considered in the updating of the IAU/IAG models of the Earth Rotation orincorporated in the most important standards like IERS Conventions to prevent the appearance ofsystematics associated to these inconsistencies.

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*G04-2-03
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

EOP prediction based on the Copula method using multi-source data
* Sadegh Modiri 1) 2) , Robert Heinkelmann 1) , Santiago Belda 3) , Jose M. Ferrandiz 3) , Harald Schuh 1) 2)
GFZ German Research Centre for Geosciences, Potsdam, Germany 1) , Technische Universitat
Berlin,Institute for Geodesy and Geoinformation Science, Berlin, Germany 2) , University of Alicante, EPS II,
Applied Mathematics Alicante, Spain 3)
Prediction of the Earth Orientation Parameters (EOP) is provided by the International Earth Rotation andReference Systems Service (IERS) Rapid Service Prediction Centre in USNO, Washington DC. Different
methods have been developed and applied for the EOP prediction. However, the accuracy of EOP
prediction still is not satisfactory even for a few days in the future. Therefore, new methods or a
combination of the existing methods need to be investigated for improving the accuracy of the predicted
EOP. Thus, the stochastic methods which analyze and exploit the dependency structure between
multivariate data should be studied due to the stochastic nature of the EOP. There is a well-introduced
method called Copula and we want to apply it for EOP prediction. The Copula method exploits linear andnon-linear dependency between variables and it is a very powerful and efficient tool for dealing withmultidimensional data and modeling the relation between parameters.
In this study, we analyze the impact of mass redistribution and movement within the Earth system e.g. solid
Earth, atmosphere, ocean, hydrosphere, and cryosphere on EOP to get a more precise and reliable
forecasting model. Our preliminary studies illustrate that Copula can be applied for capturing thedependency structure between EOP and angular momentum data. Finally, EOP will be predicted moreaccurately based on the derived dependency structure by evaluating the conditional distribution function
given by the Copula model in the appropriate resolutions.

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*G04-2-04
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Excitation study of the observed Chandler wobble based on GRACE and SLR
gravity data
* Aleksander Brzezinski 1) 2) , Jolanta Nastula 2)
Warsaw University of Technology, Department of Geodesy and Cartography, Warsaw, Poland 1) , Space
Research Centre of the Polish Academy of Sciences, Warsaw, Poland 2)
We investigate the excitation of the free Chandler wobble by the large-scale processes taking place in theexternal fluid layers including the atmosphere, the oceans and the land hydrology. The mass term of
excitation is expressed by the so-called gravimetric excitation function estimated from time variation ofdegree-2, order-1 harmonics of the Earth gravity field, derived from Gravity Recovery and Climate
Experiment (GRACE) and the Satellite Laser Ranging (SLR) data. Our first results (Brzezinski and Nastula,presented at GAGER2016 Symposium in Wuhan) indicated that the Chandler wobble observed during
2003–2014 can be fully explained by the GRACE-derived mass term of excitation. Here we extend thatstudy by considering alternative GRACE data sets which are publicly available, like the CNES/GRGS and
Tongji solutions. In addition, we include also in the analysis the motion term of excitation taken fromdifferent geophysical models.

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*G04-2-05
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Determination of accuracy information for effective angular momentum
functions derived from gravity field observations
Franziska Goettl , Mathis Blossfeld , Alexander Kehm , * Michael Schmidt , Florian Seitz
Deutsches Geodaetisches Forschungsinstitut der Technischen Universitaet Muenchen, Germany
Variations of Earth rotation are caused by the redistribution and motion of masses within the Earth system.
Since 2002, the satellite mission GRACE observes variations of the Earth's gravity field which are caused
by mass displacements. Therefore, time variable gravity field models can be used to determine effective
angular momentum functions which describe mass-related excitation mechanisms of Earth rotation. By
applying suitable filter techniques and masks, not only the integral mass effect on Earth rotation but also
the mass effects of the oceans, continental hydrosphere and cryosphere can be studied. The effective
angular momentum functions derived from gravity field observations suffer from uncertainties due to (1)the destriping and filtering of the GRACE data, (2) the separation of the individual contributions (leakage
effect), (3) the reduction of glacial isostatic adjustment (GIA) and (4) an appropriate replacement of the
Stokes coefficients C10, C11, S11 and C20.
In this study we will present a new method to reduce the leakage effect, and via closed loop analysis theimpact on effective angular momentum functions is estimated. In order to reduce the GIA effect, different
GIA models will be used and compared to evaluate the uncertainties. Due to the fact that the GRACE dataprocessing is performed in the Earth's center-of-mass (CM) frame, the degree-1 Stokes coefficients are zeroby definition. But processes at the Earth's surface and interior are referred to a coordinate system attachedto the Earth's crust which moves relative to the CM. Therefore, external solutions for C10, C11 and S11 areused to investigate the impact on derived effective angular momentum functions. Due to the low sensitivityof the GRACE K-band measurements on the Earth's flattening the Stokes coefficient C20 obtained fromGRACE data are inaccurate. Thus external solutions will be used for C20 to estimate the uncertainties ofderived effective angular momentum functions.

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*G04-2-06
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Empirical approach to the consistency and accuracy of the current IAU
2006/2000A precession-nutation modelSantiago Belda 1) 2) , * Jose M. Ferrandiz 1) , Robert Heinkelmman 2) , Maria Karbon 2) , Tobias Nilsson 2) ,Harald Schuh 2)
University of Alicante, Alicante, Spain 1) , GFZ German Research Centre for Geosciences, Potsdam,
Germany 2)
Due to the gravitational attractions from the Moon, Sun, and planets, the Earth rotation axis shows various
periodical motions w.r.t its figure axis. The forced nutations can be precisely modelled and predicted using
the IAU 2006/2000A precession-nutation model which relates the International Celestial Reference Frame(ICRF) to the International Terrestrial Reference Frame (ITRF). Currently IAU 2000A/20006 only contains
the easiest to predict astronomically forced terms, and thus, the Free Core Nutation (FCN), caused by thefluid outer core and the exchange of angular momentum among the Earth's components, is not included. It
causes deficiencies in the IAU 2006/2000A precession-nutation model up to the order of 0.2 mas.
In order to empirically evaluate the consistency and deviations of the aforementioned model we computed
several time series of Celestial Pole offsets (CPO) derived from the global analysis of the VLBI sessions
since 1990 with varied settings to reflect the impact on the CPO estimates. These series were used torecalculate and adjust the precession constant offset and rate, as well as the main nutation amplitudes of
the IAU 2006/2000A precession-nutation model, trying to empirically improve and update theconventional values adopted by the International Astronomical Union (IAU) and the International
Association of Geodesy (IAG) and used by the International Earth Rotation and Reference Systems Service(IERS) Conventions 2010. Amplitudes of the FCN were also included in the previous adjustment andcompared with other empirical FCN models.

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*G04-3-01
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Long-baseline laser strainmeter constructed at the underground KAGRA sitein Kamioka as a new tool for monitoring crustal dynamics* Akito Araya 1) , Akiteru Takamori 1) , Wataru Morii 2) , Kouseki Miyo 3) , Masatake Ohashi 3)
ERI, The University of Tokyo, Tokyo, Japan 1) , DPRI, Kyoto University, Kyoto, Japan 2) , ICRR, The
University of Tokyo, Tokyo, Japan 3)
Ground motion and its deformation have been monitored by various instruments with very wide ranges inamplitudes and timescales. Strainmeters measure deformation of the ground by sensing distance between
two separated points, and cover crustal observation of small strain changes at low frequencies. However,the strainmeters tend to suffer from local disturbances and instabilities of reference for the distancemeasurement. Long-baserline laser strainmeters that measure distance of separation of 10-1000m based onhighly stable optical wavelength of laser can avoid some of the problems.
A 100-m laser strainmeter [1] at an underground site in Kamioka, Gifu Prefecture, Japan, showed reliable
detection of coseismic crustal deformation associated with remote earthquakes and provided estimation ofseismic moment based on far-field geodetic observation [2]. It also showed the baseline (100m) was notenough for long-term strain observation because groundwater pressure of seasonal timescale affected theground strain.
In 2016, a new laser strainmeter with a 1.5-km baseline was constructed at an underground site along
KAGRA gravitational wave detector [3] in Kamioka and started test observation. With the long baseline, thestrainmeter clearly detected earth tides which almost agreed with theoretical calculations. We discuss its
detectability for long-term strain changes in comparison to the 100-m laser strainmeter and prospect formonitoring crustal dynamics using the long-baseline strainmeter.
[1] S. Takemoto et al., A 100 m laser strainmeter system installed in a 1 km deep tunnel at Kamioka, Gifu,
Japan, Journal of Geodynamics, 38, 477-488, 2004.
[2] A. Araya et al, Analyses of far-field coseismic crustal deformation observed by a new laser distancemeasurement system, Geophys. J. Int., 181, 127-140, 2010.
[3] Y. Aso et al, Interferometer design of the KAGRA gravitational wave detector, Phys. Rev. D, 88, 043007,
2013.

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*G04-3-02
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

First year of gravity signal records with the iGrav-027 superconducting
gravimeter* Przemyslaw Dykowski , Marcin Sekowski , Jan Krynski
Institute of Geodesy and Cartography, Warsaw, Poland
The new iGrav-027 superconducting gravimeter was successfully installed in early spring 2016 at theBorowa Gora Geodetic-Geophysical Observatory. Since last decade of April a complete gravity signal isrecorded providing high quality gravity data for a wide range of applications. The instrument supplements a
A10-020 gravimeter as well as a group of LaCoste&Romberg (LCR) gravimeters operating in the
Observatory.
This work presents the results of analysis of gravity signal records with the iGrav-027 from the first year of
its operation, starting from the scale factor determination and drift characteristics. Scale factor of theiGrav-027 was determined with the use of data acquired with A10-020 and FG5-230 absolute gravimeters
as well as LCR relative gravimeters. The instrumental drift will be evaluated by co-location of the iGrav-027
data with conducted on monthly basis absolute gravity determinations with the A10-020 gravimeter.
A comprehensive tidal analysis of the iGrav-027 record along with a more than a 5 year time seriesacquired with a LCR G1036 gravimeter was performed to obtain a reliable residual signal. Residual signal
will be compared with known and available models providing time series corrections for atmospheric andhydrological loading. Residual signal will also be compared with monthly regular absolute gravity
determinations with the A10-020 as well as with local hydrological models developed with the use of datafrom hydrological sensors operating at the Borowa Gora Observatory.
Results of the presented work will be a comprehensive basis for evaluation of long term gravity changes at
the Borowa Gora Observatory and for further improvement of the quality of data submitted from theObservatory to IGETS and AGrav databases.

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*G04-3-03
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Loading effects caused by storm surges in the Rio de La Plata / Argentina: A
model proof by a high resolution gravity time series* Hartmut Wziontek 1) , Fernando Oreiro 2) 3) , Ezequiel Antokoletz 4) , Enrique D'Onofrio 2) 3) , Monica Fiore
2) 3), Claudia Tocho 4) 5)
Federal Agency for Cartography and Geodesy (BKG), Leipzig, Germany 1) , Facultad de Ingenieria,
Universidad de Buenos Aires, Ciudad Autonoma de Buenos Aires, Argentina 2) , Servicio de Hidrografia
Naval, Ministerio de Defensa, Ciudad Autonoma de Buenos Aires, Argentina 3) , Departamento deGravimetria, Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, La Plata,
Argentina 4) , Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC), La Plata,
Buenos Aires, Argentina 5)
In December 2015, the Superconducting Gravimeter SG038 was put into operation at the Argentine –German Geodetic Observatory (AGGO) located near the city of La Plata, Argentina. Since then, gravity
variations are continuously recorded with highest precision and temporal resolution.
By careful preprocessing of the gravity time series of the first year applying a remove-restore procedure,
spikes and high frequency disturbances and one step caused by a power failure were corrected. The series
was then filtered and downsampled to hourly resolution and atmospheric effects were removed using
numerical weather models. Now a detailed Earth tide analysis was performed separating more than 50
wave groups and a treating degree three tide generating potential independently by making use of thecapabilities of the latest version V60 of the Eterna software package. Despite these efforts, the residual
gravity time series still shows significant non-tidal variations reaching up to several microGal which could
not be explained by the applied models but are correlated with extreme weather events.
Wind effects are causing surges at the Rio de La Plata during these events. By using tide gauge
observations around the river and a simple empirical astronomical tide model (SEAT) it was possible tocompute the propagation of the storm surges landwards from the estuary. The resulting loading effect interms of gravity shows excellent agreement with the residual gravity time series. This proofs both, the highquality of the gravity time series and the validity of the storm surge model, which allows to isolate gravity
effects due to local water storage changes in the gravity record. Perspectively, this model can be used tocorrect these loading effects also in terms of position changes, which becomes essential as a correction of
the results from space geodetic techniques (GNSS, SLR, VLBI) currently established at the observatory.

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*G04-3-04
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Constraining vertical land motion of tide gauges (IAG JWG 3.2):
combination of velocity fields* Alvaro Santamaria-Gomez 1) , Matt King 2) , Tilo Schone 3) , Tonie van Dam 4) , Guy Woppelmann 5)
Universite de Toulouse, GET, OMP, Toulouse, France 1) , University of Tasmania, School of Land and Food,
Hobart, Australia 2) , Helmholtz Centre Potsdam GFZ, Potsdam, Germany 3) , University of Luxembourg,
Faculte des Sciences, de la Technologie et de la Communication, Luxembourg 4) , LIENSs, Universite de La
Rochelle/CNRS, La Rochelle, France 5)
The Joint Working Group 3.2 of the International Association of Geodesy aims at providing contrasted
vertical land motion estimates at tide gauges commonly used for long-term sea-level change and forcalibration/validation of satellite altimeters.
We present the combination and comparison of available global vertical velocity solutions from GPS andDORIS techniques. Up to 20 individual and 4 combined solutions have been compiled; they include
solutions using different GPS processing approaches (differenced and undifferenced), different time series
lengths and different approaches to assess velocity uncertainty. The combined vertical velocity solution
contains 1132 stations for which at least 3 different estimates were available. After aligning and weighting
the solutions, the repeatability of the vertical velocity estimates varies among the stations between 0.1
mm/yr and more than 1 mm/yr, with a median station repeatability of 0.3 mm/yr. These velocity
repeatability estimates represent an empirical approach to assess velocity uncertainty and their medianvalue is in agreement with uncertainty assessments accounting for the auto-correlation of the time series.

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*G04-3-05
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Estimates of vertical velocity errors for IGS ITRF2014 stations by applying
the improved singular spectrum analysis method and environmental loading
models* Janusz Bogusz 1) , Marta Gruszczynska 1) , Anna Klos 1) , Machiel S. Bos 2) , Jean-Paul Boy 3)
Military University of Technology, Warsaw, Poland 1) , University of Beira Interior, Beira Interior, Portugal 2), University of Strasbourg, Strasbourg, France 3)
An accurate removal of the seasonal signals from the Global Positioning System (GPS) position time series
is beneficial for the accuracy of the derived velocities. In this research, we propose a two-stage solution of
the problem of reliable subtraction of seasonal changes. Firstly, we employ the environmental loading
models (atmospheric, hydrologic and ocean non-tidal) and study the seasonal signal (annual and semiannual) estimates that changes over time using the Improved Singular Spectrum Analysis (ISSA) approach.
Then, this model is subtracted from GPS position time series. We studied data from 376 permanent IGS(International GNSS Service) stations, derived as the official contribution to ITRF2014 (International
Terrestrial Reference Frame) to measure the influence of applying environmental loading models on theestimated vertical velocity. These loading models show a dominant annual signal and their superpositon
reveals amplitudes of up to 12 mm. Having removed the environmental loadings directly from ITRF2014
position time series we noticed the evident change in the power spectrum of GPS time series forfrequencies between 4 and 80 cpy. Therefore, we modeled the seasonal signal using the ISSA approach inenvironmental models and subtracted it from GPS position time series. Finally, we estimated the Dilution ofPrecision (DP) of the vertical velocities of the ITRF2014 series. For a total number of 298 out of the 376
stations analyzed, the DP was lower than 1. This indicates that when the ISSA-derived curve was removed
from the GPS data, the error of velocity becomes lower than it was before.

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*G04-3-06
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Vertical velocity profile and possible velocity changes in SW Japan from
GNSS data over the last 20 years* Yutaro Iwasa , Kosuke Heki
Hokkaido University, Hokkaido, Japan
Although GNSS (Global Navigation Satellite System) observations can measure 3-D crustal movement, paststudies have focused on horizontal components, i.e. the vertical component has not been well utilized. Thisis due mainly to the lower signal-to-noise ratio of the vertical components. However, vertical movements
are not much influenced by plate motions, and are more straightforward in their interpretation. In Japan,
Aoki and Scholz (2003) analyzed vertical crustal movements in the Japanese Islands for 1996-1999. Here
we present 20 years of vertical crustal movement data in 1996-2016 from the Japanese dense GNSS array
GEONET. Using such long-period data, we analyzed the interplate coupling in the Nankai Trough,Southwest Japan, and estimated the coupling of individual segments of the interface between thePhilippine Sea Plate and the Amurian Plate.
Such interplate coupling, in the Japan Trench, is reported to have gradually weakened over 7-8 years
before the 2011 Tohoku-Oki earthquake. Classical studies of viscous flow contribution in subduction zones
have also suggested that crustal deformation rate may change within an earthquake cycle. In the Nankai
Trough, the next inter-plate earthquake is anticipated to occur within the coming years/decades. With thedata spanning ~20 years, we could study temporal changes of the vertical velocities. Here we modeled
them using quadratic functions of time, and discuss the significance of the quadratic terms. We compared
the linear trend and the quadratic components of stations with various distances from the trench, andexamined if the quadratic terms show real crustal movements or just a leakage from the movement of thereference point.

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*G04-4-01
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Actual Continuous Kinematic Model (ACKIM) of the Earth Crust based on
ITRF2014* Hermann Drewes
Technical University Munich, Munich, Germany
The global kinematics of the Earth crust is traditionally represented by geophysical rigid plate models (e.g.
NUVEL-1A, DeMets et al. 1994) integrating their motions linearly over geologic time scales (millions ofyears). The present-day plate motions and deformations in boundary zones are based on these models
deriving the plate rotation poles from geodetic station velocities as actual plate kinematic models (e.g.
APKIM, Drewes 2009). The denser the geodetic station distribution becomes, the more different plates andinter-plate and/or intra-plate deformation zones are detected. The model PB2002 (Bird 2003) includes 52
plates (instead of 14 in NUVEL-1A) and 13 orogenic zones. But even this increasing structure does notreflect the true crustal deformation obtained from geodetic observations. Larger plates (e.g. North
American, Caribbean) do not move rigidly but they are split and present significantly varying motions indifferent regions. Smaller plates (e.g. Peru, Puna Sierras-Pampeanas, Okhotsk) show strong regional
deformations. This paper presents an actual continuous kinematic model (ACKIM) instead of a rigid platemodel. Crustal motions in a global 1 deg. x 1 deg. grid are derived from ITRF2014 station velocities in aleast squares collocation approach. A no-net-rotation condition with respect to horizontal motions over theentire Earth's surface is included in order to get the model consistent with Earth rotation. The model
reflects much better the present-day deformations of the Earth crust than any plate kinematic model.

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*G04-4-02
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Comparing Global and Dedicated Plate Angular Velocity Models: the casesof Arabia and South America* Rui Fernandes 1) 2) , Machiel Bos 1) , Abdulaziz Alothman 3) , Hector Mora-Paz 4)
SEGAL (UBI/IDL), Covilha, Portugal 1) , TU Delft, Delft, The Netherlands 2) , KACST, Riyadh, Saudi Arabia 3), SGC, Bogota, Colombia 4)
Angular velocities models are necessary to analyse inter- and intra-deformations due to plate tectonics.
They permit quantify the magnitude and direction of relative displacement between different tectonic units.
The use of inaccurate models can produce incorrect conclusions, particularly at plate boundaries.
In the last decades, many angular velocity models have been produced based on geological/geophysicaland/or geodetic measurements. The first ones (e.g., NUVEL-1A and MORVEL) average the motions oftectonic models in the last 3My whereas the geodetic ones (e.g., REVEL and GEODVEL) are representativeof the present-day tectonic motions.
Due to the used methodology and data, geologic/geophysical models are only able to be estimated byinverting data for pairs of (or multiple) tectonic plates. This implies that the estimation is always relative toa reference plate. This is not the case for the geodetic models where the used data (normally velocities
derived from space-based techniques, particularly GNSS observations) are estimated with respect to a NoNet-Rotation reference frame. Consequently, both approaches are possible: to estimate the angular motionof each plate individually or by inverting a global dataset of velocities.
In this work, we discuss the differences of both approaches by looking at two particular tectonic plates:
Arabia and South America. We compare our own dedicated estimations of the plate angular velocities forthese plates with the predicted motions given by global plate models and other recent published models.
We show that the differences can still be significant when different plate models are considered for thesame plate, which can lead to incorrect interpretations.

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*G04-4-03
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Modelling of Time-Varying Seasonal Signals in GNSS Time Series* Anna Klos 1) , Machiel Bos 2) , Janusz Bogusz 1)
Military University of Technology, Faculty of Civil Engineering and Geodesy, Warsaw, Poland 1) , Universityof Beira Interior, Instituto D. Luis, R. Marques d'Avila e Boloma, Portugal 2)
Most GNSS (Global Navigation Satellite System) coordinate time series contain oscillations of annual andsemi-annual periods that are routinely modelled by two periodic signals with constant amplitudes. In
reality, the amplitudes of these seasonal signals varies slightly over time. The stochastic properties of the
GNSS coordinate time series are well described by power-law noise. Subtracting of the time varying
seasonal signals is crucial, since each residual periodicity which is still left in the data naturally will make it
appear to be autocorrelated. In this research, we employed 174 IGS (International GNSS Service) stations
processed by JPL (Jet Propulsion Laboratory) and showed that the mean variation of the annual amplitude
has a standard deviation of 0.8 mm and that for c.a. 15% of stations these variations are larger than 1.0 mm.
We performed a quantitative comparison of Wavelet Decomposition (WD), Singular Spectrum Analysis(SSA), Chebyshev Polynomial (CP) or Kalman Filter (KF). Using synthetic time series with realistic powerlaw noise we showed that ignoring the variations in the amplitude of the seasonal signal results in too large
estimates of the spectral index κ of 0.1-0.2 (bias towards flicker noise) and an overestimation of the noise
amplitude of about 0.4-1.0 mm/yrκ/4. When the flicker noise amplitude is very low relative to the size ofthe variations in the seasonal signal, estimating a constant seasonal signal performs worse than any of themethods that try to model varying seasonal signal and can produce an estimated trend error that isoverestimated by 0.03 mm/yr. When the noise level is average, the varying seasonal signals can no longer
be estimated accurately and one can continue to estimate only a constant seasonal signal. For the JPLderived GPS data, we noticed a decrease in spectral indices for all coordinates of -0.14 in average and adecrease of trend error of 0.05 mm/yr when time-varying seasonal curves were modelled.

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*G04-4-04
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Distribution of interplate coupling in the south of Central and Eastern Java
from GPS observation* Irwan Meilano 1) , Endra Gunawan 1) , Dina Sarsito 1) , Rahma Hanifa 1) , Bambang Setyadji 1) , Hasanuddin
Abidin 1) , Susilo Susilo 2)
Faculty of Earth Science and Technology, Institut Teknologi Bandung, Indonesia 1) , Agency for Geospatial
Information (BIG), Indonesia 2)
Java is one of the many islands at the Eurasian margin in Indonesia in which subduction has been an
important influence on its tectonic condition. The subduction process or plate coupling at the Java Trench
was considered to be weak. However, two tsunami earthquakes, accompanied by tsunamis have occurred
off the south coast of Java, the 1994 Mw7.8 and the 2006 Mw7.8 earthquakes. Given the evidence of thisearthquake, it is very important to have detail information of the interplate coupling in particular off theCentral and Eastern .
Interplate seismogenic zones in the south of Central and Eastern Java were estimated by using campaign
and continuous GPS observation. The observation period is strarting from 2008 to 2016. The GPS analysis
indicates that present-day deformation in the south of Central and Eastern Java from is controlled byrotation of Sunda land, postseismic deformation of the 2006 earthquake and the coupling between IndoAustralian plate and Sunda land. The estimated interplate coupling in the Java trench is larger than 50
percent in the Central Java and become bigger to the East.

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*G04-4-05
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Seismo-geodetic Behavior of Basic Tectonic Elements in Anatolian Region
and Surroundings* Haluk Ozener 1) , Asli Dogru 1) , Bahadir Aktug 2) , Soner Ozdemir 3)
Bogazici University, Kandilli Observatory and Earthquake Research Institute, Cengelkoy, 34684, Istanbul,
Turkey 1) , Ankara University, Geophysics Department, 06830 Golbasi, Ankara, Turkey 2) , General
Command of Mapping, Geodesy Department, 06100, Ankara, Turkey 3)
Understanding earthquake and faulting processes requires investigating tectonic-related surface and subsurface movements through the Earth's crust. In this context, we jointly investigate geodetic andseismological data in Anatolia and surroundings, representing seismically the most active region of Europe.
We combine GPS measurements and seismicity between 2006-2016 in order to characterize physical stageof the upper crust at different fault sections. Velocity field has been provided by CORS-TR consisting of 146
GPS stations. Earthquake catalogue has been provided by KOERI at a magnitude detection threshold of 3.0.
We produced grid-based distribution of residual velocity field in order to map major inter-plate faults/intraplate tectonic regimes and their role in whole tectonic process. We also produced a map of seismicitygenerated slip distribution along the entire target region. Integrating geodetic and seismological data leads
us to quantitatively verify following features: 1-The North Anatolian Fault (NAF) and The East Anatolian
Fault (EAF) are the major plate boundaries surrounding the Anatolian Plate. 2- NAF is the most active plateboundary accommodating a slip rates ranging between 7-23.5 mm/yr. 3-The slip rates systematicallyincrease from the east to the west along the fault zone. 4-EAF accommodates relatively a slower inter-platedeformation at an annual slip rate range of 6-9 mm/yr. 5-Anatolian plate reflects internally a very stabletectonic behavior almost for decade. 6- Western Anatolia is however internally deformed as suggested by avariety of slip rates. This probably due to complex fault network developed under large-scale extensional
regime. 7-We captured four prominent creeping sections of NAF. 8-In the Sea of Marmara region, where a
M>7 earthquake is expected in near future, northern branch of NAF accommodates most of the tectonic
slip. 9-Southern branch is however almost inactive based on geodetic and seismological observations.

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*G04-P-01
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Length of the Day estimated from DORIS observations* Petr Stepanek 1) , Michal Buday 1) , Vratislav Filler 1) , Urs Hugentobler 2)
Research Institute of Geodesy, Topography and cartography, Zdiby 1) , Technische Universitat Munchen 2)
The Length of the Day (LOD) can be estimated from the DORIS data, when cross track orbit harmonics are
not adjusted in the same solution. Our experiment, based on 9 years of the processed DORIS data
(2006-2014) , demonstrates a possibility to reach LOD standard deviation around 0.10 msec per day(compared to reference IERS C04 model). The LOD bias is varying between the time periods and reaches
the level of low hundredths msec in maximum. We also discuss the accuracy of the single satellite solutions
and the multi satellite solution bias variations relations to the changes in the satellite constellation. We
present the parameter correlation analysis and the relations between LOD estimation accuracy based on
the solution covariance matrix and on the application of time variable gravity field, as well as the impact of
the simultaneous estimation of LOD and gravity field coefficient C20.

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*G04-P-02
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Revisiting the indirect effect of the triaxiality on the polar motion libration of
the non-rigid Earth* Alberto Escapa 1) 2) , Jose Manuel Ferrandiz 1) , Juan Getino 3) , Tomas Baenas 2)
Dept. Applied Mathematics. University of Alicante. Spain 1) , Dept. Aerospace Engineering. University of
Leon. Spain 2) , Dept. Applied Mathematics. University of Valladolid. Spain 3)
The gravitational action of the Moon and Sun acting on the triaxial Earth gives rise to high-frequency forced
nutations of diurnal and subdiurnal periods. Accordingly to IAU 2000 Resolution B1.7 this motion must be
described as a part of the evolution of the pole with respect to ITRS, usually referred to as libration in polar
motion (IERS Conventions 2010).
One part of that libration is due to the indirect effect of the triaxiality. This effect is related with the fact thatthe response of the Earth to the lunisolar perturbation, even the zonal one, depends on its structure. It was
shown by Escapa et al. (2002, 2003) that the triaxiality of the Earth and its core originate diurnal terms dueto their crossing with the (2, 0) harmonic of the gravitational potential. Although the magnitude of some ofthose contributions was greater than the adopted cut-off level (0.5 microarcseconds), they were notconsidered in the modelling of polar motion libration due to the uncertainty in the value of the triaxiality of
the core existing in that epoch.
In the last years, however, there have been published comprehensive investigations by Chen and Shen
(2010), and Sun and Shen (2016), among others, providing accurate estimations of the triaxiality of the
Earth and its core. Taking advantage of these results, we recalculate the contributions of the indirect effectof the triaxiality on the libration in polar motion. Our preliminary computations show that these updated
amplitudes present a noticeable amplification with respect to their earlier values for some of the newly
proposed sets of triaxiality parameters.
Chen, W., Shen, W. 2010, J. Geophys. Res., 115, B12419
Escapa, A., Getino, J., Ferrandiz, J. M. 2002, Astron. Astrophys., 389, 1047
Escapa, A., Ferrandiz, J. M., Getino, J. 2003, Proc. of the Journees 2002 Systemes de Reference Spatiotemporels, 152
IERS Conventions 2010, ed. G. Petit and B. Luzum. IERS Technical Note 36
Sun, R., Shen, W. B. 2016, J. Geophys. Res., 121, 7570

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*G04-P-03
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

The influence of mantle anelasticity on load response functions
Volker Klemann , Robert Dill , * Maik Thomas
GFZ German Research Centre for Geosciences, Potsdam, Germany
Predefined response functions are applied to parametrize the effect of load deformation due to seasonalmass redistribution in geodetic correction models, e.g., for GRACE or GPS networks. The correction models
are usually based on accepted 1D earth structures like PREM, iaspr or ak135. All these structures represent
global means, where, at most, oceanic and continental lithospheric structures are distinguished. One aspectpresent in the earth's mantle but usually not considered is the impact of anelasticity. As a temperature andmaterial dependent behaviour, anelastic attenuation shows significant lateral variability, especially in the
mantle asthenosphere, e.g., at active plate boundaries (Andes, Himalaya) versus passive cratonic regions(North American shield).
In this study, we consider attenuation according to seismological inferences. In order to predict therelaxation of the shear modulus on tidal and seasonal time scales, we extrapolate the constant Q model,
which is defined for the seismic band, to these longer time periods.
Based on this approach, we assess the impact on the load Love number spectrum and on the resulting
Green's functions. Furthermore, this approach is applied in order to analyse the effect on ocean andatmospheric loading products.

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*G04-P-05
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

GPS Observation to Identify Bali Back Arc Thrusting* Dina A. Sarsito 1) , Sri Hidayati 1) , Susilo Susilo 3) , Cecep Sulaiman 2) , Irwan Meilano 1) , Endra Gunawan, Estu Kriswati 2) , Hasanuddin Z. Abidin 1) , Heri Andreas 1)
Geodesy Research Group – Institut Teknologi Bandung, Ganesa 10, Bandung , Indonesia 1) , Geological
Agency of Indonesia, Diponegoro, Bandung, Indonesia 2) , Geospatial Information Agency, Jl. Raya JakartaBogor Km. 46, Cibinong, Indonesia 3)
1)

Historically Bali has been influenced by several destructive earthquakes that caused widespread damages
in the south of island and more than 1500 casualties especially from 1917 M 6.6 earthquake disaster. The
island is the part of Sunda Shelf which is separated from Java Island by narrow strait called Bali Strait.
Although Indo-Australian plate is subducting highly frontal beneath Bali, it should be considered to have
low interpolate coupling indicating a low possibility of stress accumulation associated with the plateinterface to the south of this island.
This research uses continuous-GPS and campaign-GPS which are distributed over Bali. By using combine
analysis of GPS vector velocity, azimuth slip vector from earthquake data and simple inversion modeling,
we try to infer interplate coupling on the southern subduction zone and also possible back arc thrusting in
the northern part. Our preliminary results show that the combination of moderate coupling on subduction
and thrusthing on the back arc contribute to the deformation pattern of the island.

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*G04-P-06
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Earth rotation in sight of climate modulations
Leonid Zotov 1) 2) , Nikolay Sidorenkov 3) , Christian Bizouard 4) , * Alexey Lyubushin 5)
National Research University Higher School of Economics, Moscow, Russia 1) , Sternberg AstronomicalInstitute, MSU, Russia 2) , Hydrometeorological Centre of Russia 3) , Paris Observatory, SYRTE 4) , Schmidt
Institute of Physics of the Earth, Moscow, Russia 5)
We draw attention to the length of day (LOD) and amplitude of the Chandler wobble changes, which show
70-year modulations similar to what can be observed in the mean Earth temperature and sea level. We
analyze Chandler wobble phase and amplitude changes, as well as LOD, and their excitation sources, trying
to bridge this traditional subject of geodesy with contemporary climatological observations over ocean,
atmosphere, and land mass transport. We believe, our epoch of precise observations of the Earth system isalready providing an evidence of interconnection between climate processes and Earth rotation changes.

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*G04-P-07
IAG Symposium / IAG03. Earth rotation and Geodynamics / G04. Earth rotation andgeodynamics

Identifying the land subsidence attributed to the natural gas mining in GNSS
time series in Japanese actively crustal deformed area
* Takuya Harada , Tomochika Tokunaga , Seiichi Shimada
The Unversity of Tokyo, Tokyo, Japan
Large-scale land subsidence has been observed in the regions of Kujukuri and Shimousa, Kanto District,Japan, caused by continuous mining of groundwater which is refined for natural gas and iodine uses since1950's. In terms of advanced sustainable development of the mining, urgent research from the view pointof geodesy is highly required to evaluate the amount of subsidence caused by the mining. We havesuccessfully identified the land subsidence attributed to the groundwater mining for refining natural gas
and iodine from the pumping of groundwater for the agricultural usages and crustal deformations driven by
tectonic factors; secular tectonic dynamics, co-seismic offsets, slow earthquake wandering, and the postseismic deformations of huge earthquakes, applying the time series of GNSS observations analyzed
applying GAMIT/GLOBK software. We detach the land subsidence due to groundwater pumping for
agriculture uses by focusing their annual periodicity. Then we represent the comparatively short period oftime slow earthquakes as Markov process, and segregate it from other causes. We evaluate the amount ofcrustal subsidence originated from plate collisions under the Kanto District, which widely seen in the Kanto
plane before the 2011 Mw9.0 Tohoku-Oki earthquake, and we disregarded it since this kind of land
subsidence is an order of magnitude smaller than them caused by the human activities. Finally, we express
the time series of the post-seismic activities after the 2011 Tohoku-Oki earthquake as logarithmic,
exponential, or combined logarithmic and exponential function models. Thus we enable complicatedcrustal deformations arising around Kujukuri and Shimousa area to be segregated into the artificial and thetectonic factors, and evaluate the amount of the subsidence originated by the groundwater mining forrefining natural gas and iodine.

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*G05-1-01
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Constrained Differential Wi-Fi and UWB Measurements for Indoor
Cooperative User Localization
Guenther Retscher 1) , Hannes Hofer 1) , Allison Kealy 2) , * Vassilis Gikas 3) , Andreas Ettlinger 1) , Franz
Obex 4)
TU Wien Vienna University of Technology, Vienna, Austria 1) , The University of Melbourne, Melbourne,
Australia 2) , National Technical University of Athens, Athens, Greece 3) , Freelancer, Vienna, Austria 4)
Many personal mobility scenarios require the localization of users within a group or neighbourhood. A
solution to this problem is Cooperative Positioning (CP) where the end user localization is performed using
its own measurements plus any additional information coming from neighbouring users in the form of internodal ranges or other means. In this study, new differential Wi-Fi positioning approaches based either on
DGPS or VLBI are applied for (tri)lateration. By the use of reference station (RS) observations the received
signal strength (RSS) measurements of the access points (APs) is corrected to reduce short- and long-time
variations of the RSS at the user side. A low-cost implementation is realized using a number of Raspberry Pi
units, which serve simultaneously as both APs and RSs emitting and scanning Wi-Fi signals. For the datacollection a smartphone application (Android App) has been developed. Furthermore, the use of UWB andits combination with Wi-Fi is investigated to form a networked solution. In the practical evaluation, staticand kinematic tests using six users carrying different smartphones are conducted in an indoor lab ofapproximately 400m2. Five Raspberry Pi's served as reference stations and APs together with another three
additional Wi-Fi routers. One user enabled the hotspot function on his mobile device so that the other users
can measure the RSS to derive inter-nodal ranges. Additional five UWB units were carried by the users
serving as either a reference for the derivation of the inter-nodal ranges or in order to be integrated into theoverall positioning solution. Ground truth for these experiments was measured using a robotic total station.
It is proven that both DWi-Fi approaches outperform conventional RSS lateration and the integration withUWB further strengthens the CP solution.

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*G05-1-02
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Static and kinematic experimental evaluation of a UWB ranging system for
positioning applications
Harris Perakis , * Vassilis Gikas , Panos Sotiriou
National Technical University of Athens, Greece
Ultra Wideband (UWB) is a rapidly evolving radio-based technology leading to low range uncertainty (< 10cm) even at long (up to hundreds of meters) ranges. Compared to other radio-based technologies, such as
RFID and Wi-Fi, the bandwidth characteristics of UWB offer remarkable NLoS functionality and increased
multipath resistance which are of great importance for complex indoor environments. This study presents
the results of the analyses undertaken for a number of tests using a commercial UWB system both in staticand dynamic conditions. Static experiments involve assessing the capabilities of the system in terms of
position accuracy (precision and trueness), availability, maximum range operation, as well as examining theinfluence of antenna orientation and the surrounding environment (e.g. the Fressnel zones) in distancemeasurements. Kinematic positioning is performed by implementing the multi-lateration technique on aroving UWB node, while vehicle kinematics are recorded using a geodetic (tactical) grade GNSS/INS
system to provide the reference trajectory. The UWB position solution is improved through range
calibration while range error maps are generated to support statistical analyses. Both an Extended Kalman
Filter (EKF) and an Unscented Kalman Filter (UKF) are implemented for trajectory extraction andcompared against the reference trajectory to assess their impact on the position solution.

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*G05-1-03
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

The Database Referenced Navigation Algorithms : A new attempt at
combining geophysical DBs and navigation algorithms* Jisun Lee , Jay Hyoun Kwon
University of Seoul, Seoul, South Korea
Recently, an alternative navigation method which uses various geophysical database is being studied forcompensating for inertial navigation system (INS) errors against the non-global navigation satellite system(GNSS) environment. In virtue of precise geophysical sensors and databases, the precision of the databasereferenced navigation (DBRN) system is known to be from the few tens, even hundreds of meters. However,the stability of the DBRN dramatically decreases due to the inconsistency of the geophysical DBs.
Especially, filter based navigation algorithm sometimes diverges once wrong or over correction occur.
Therefore, the way to develop more robust navigation algorithm is still an important question in the DBRN.
In this study, two new attempts to combine geophysical DBs or navigation algorithms are tried to improve
the stability. Since geophysical DBs show different local characteristics, both terrain and geophysical DBs
are applied to estimate the position of the vehicle in the extended Kalman filter (EKF)-based navigation
algorithm. Then, the profile matching algorithm which uses stacked terrain information is realized toevaluate the stability of the EKF-based algorithm. Once, two solutions show large differences, the position
from the profile matching is selected or used to estimate the new position. The effects of applying two
geophysical DBs in the EKF-based algorithm and combining navigation algorithms are evaluated throughsimulation tests. Especially, the stability of the navigation performance is verified when geophysical DBschanges abruptly or diminutively. Finally, Some discussions on the future works are also included.

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*G05-1-04
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

The Estimation of Error Models of MEMS-IMU and its application to develop
the GNSS/MEMS-IMU/On-board Vehicle sensor based positioning System* Yong Lee , Jay Hyoun Kwon
University of Seoul
The determination of the precise position and attitude of a vehicle is an essential issue in ensuring thesafety of the driver and pedestrian. Recently, vehicles equipped with various sensors have been introduced
to support the safety of drivers. In addition, GNSS/INS integration technology is broadly applied in the fieldof the mobile mapping system (MMS) and unmanned aerial vehicle (UAV) due to the development of lowcost micro-electro-mechanical system (MEMS). MEMS-based inertial measurement unit (IMU) has anadvantage in terms of the small size as well as the low cost, but its error rapidly increases in a short time.
Especially, the stability of the position could not be guaranteed in the case of the GNSS signal outage.
Therefore, it is necessary to model the behavior of the MEMS-based IMU to maintain the stability ofpositioning. Also, the way to compensate the error of MEMS-based IMU using supplement sensors is
required to improve the precision of the position in the GNSS/INS integration.
In this study, three types of error models, random constant, 1st order Gauss-Markov and 3rd order
Autoregressive, were applied to estimate the MEMS-based IMU error. The estimated models were applied
as a form of closed-loop in the extended Kalman filter (EKF) based navigation algorithm to compensate theerror, and the effect of the models were evaluated based on the static and kinematic experiments. Also, theposition, velocity and attitude estimated from various on-board sensors are applied to improve theperformance of the navigation when GNSS signal is blocked

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*G05-1-05
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Global GNSS processing based on the raw observation approach* Sebastian Strasser , Norbert Zehentner , Torsten Mayer-Guerr
Institute of Geodesy, Graz University of Technology, Graz, Austria
High-quality global navigation satellite system (GNSS) products, such as precise satellite orbits and clocks,
are a requirement for many GNSS applications, e.g. Precise Point Positioning. These products are routinely
determined by analysis centers of the International GNSS Service (IGS). In their GNSS processing, theseanalysis centers make use of the ionosphere-free linear combination to reduce the ionospheric influence.
Some of the analysis centers also form observation differences, in general double-differences, to eliminate
several additional error sources. The raw observation approach is a new GNSS processing approach thatwas developed at Graz University of Technology for kinematic orbit determination of low Earth orbit (LEO)
satellites and for processing a global ground station network. The raw observation approach offers somebenefits compared to well-established approaches, such as a straightforward incorporation of new
observables due to the avoidance of observation differences and linear combinations. This becomes
especially important in view of the changing GNSS landscape with two new systems, the European system
Galileo and the Chinese system BeiDou, currently in deployment.
Graz University of Technology currently generates the following GNSS products using the raw observation
approach: precise satellite orbits and clocks, station positions and clocks, code and phase biases, and Earthrotation parameters. The new approach is evaluated by comparing products generated using the Global
Positioning System (GPS) constellation and observations from the global IGS station network to the GNSS
products of IGS analysis centers. The comparisons show that the products determined at Graz University ofTechnology are on a similar level of quality to the IGS analysis center products. This confirms that the raw
observation approach is applicable to global GNSS processing. Some areas requiring further work havebeen identified, enabling future improvements of the method.

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*G05-1-06
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Improving GNSS RTK and kinematic PPP positioning through extended
Kalman filter tuning
Marco Aurelio Moraes de Mendonca , * Marcelo C. dos Santos
University of New Brunswick, Fredericton, NB, Canada
In the past decades, the number of global GNSS data analysis centers and reference stations has
consistently increased – from about 100 reference stations in 1995 to more than 500 nowadays. The
quality of the orbits, clocks and atmospheric behavior modeling products increased at the same pace. As of
February 2017, the final IGS orbits are believed to be accurate at a 2.5 cm level and the clocks at a 75 ps
RMS level. Considering as well the increasing quality of GNSS receivers and antennas, often the fine-tuningof positioning estimation for applications demanding high-precision lies in the correct parameterization of
the filter. The Extended Kalman Filter (EKF) allows users to set stochastic variations for the parameters tobe estimated, such as antenna acceleration, ionospheric, and tropospheric delays random-walk. By underconstraining those parameters with generic values, the error budget is ill-distributed between the different
effects on the final estimated position. Also, over-constraining them will force the mathematical model toapportion the same error budget wherever the system allows, often resulting in significant positioning
errors. The often overlooked EKF tuning is hereby addressed by a short review of the problem
mathematics, followed by experiments. The first dataset is composed of one month of data from the stations
UNB3 and UNBJ where different scenarios in RTK and kinematic PPP are analyzed in order to find thespecific tuning in a well-known position. The second experiment uses data collected by a GNSS receiver on
the top of a vehicle while riding in an urban/suburban environment. The results show 5-10% improvementsin accuracy in both RTK and kinematic PPP solutions for the first experiment and indicate a better
performance on reconvergence and challenging environments for the second experiment. In conclusion,
guiding the EKF with information about the platform and atmosphere can be the difference between
achieving or not the desired accuracy.

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*G05-2-01
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Impact of Multi-GNSS analysis on precise geodetic applications* Elmar Brockmann 1) , Daniel Ineichen 1) , Simon Lutz 1) , Stefan Schaer 1)
Federal Office of Topography swisstopo, Berne, Switzerland 1) , Federal Office of Topography swisstopo,
Berne, Switzerland 2)
Today, many GNSS Permanent networks are enhanced from GPS or GPS/Glonass networks to Multi-GNSS
networks supporting also the signals of the European Galileo and the Chinese BeiDou satellite system. The
additional signals are beneficial to many applications. This paper focus on the impact on precise geodetic
applications, such as precise coordinate determination based and daily solutions and also improvements
on kinematic precise PPP solutions. Here, results from the complete processing chain are shown – fromdata collection to analysis.
Swisstopo, the Swiss Mapping agency enhanced its permanent network to Multi-GNSS beginning 2015. A
complete MULTI-GNSS data flow based on RINEX3 is established parallel to the RINEX2 data flow
mid-2015. Parallel to these developments also the field equipment was replaced after conducting atechnical evaluation. All 200 reference stations were measured in 2016 by static Multi-GNSS observationsof about 48 hours.
On the analysis side the scientific Bernese Software was updated enabling multi-GNSS capability andmaking use of the IGS MGEX products (especially the CODE-derived Multi-GNSS orbits). Thesedevelopments were used to analyse the Multi-GNSS data from the field campaigns as well as to analyse thepermanent networks. As first analysis centre in Europe the contribution of daily and weekly solutions to theEuropean Permanent Network (EPN) of EUREF was switched to Multi-GNSS mid-2016.
Intersystem parameters are an important indicator of the compatibility of the coordinates and troposphereparameters between the various satellite systems. Examples will show the order of magnitude theseparameters can reach and will demonstrate its impact on the final results.
On the way towards real-time, we show results of kinematic PPP solutions, addressing the possible gainusing additional satellite systems.

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*G05-2-02
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Assessment of PPP quality for high speed kinematic application.
* Joao Francisco Galera Monico 1) , Haroldo Antonio Marques 2) , Italo Tsuchiya 1) , Mauricio Cardoso 3)
Universidade Estadual Paulista UNESP, Pres. Prudente, Brazil 1) , Instituto Militar de Engenharia IME, Riode Janeiro, Brazil 2) , Embraer 3)
Precise Point Positioning (PPP) has been used in several applications and showed quite high accurate
results. Normally, such applications are either in static mode or in a quite stable kinematic mode. In thispresentation we will access the results of a PPP experiment accomplished during an aircraft flight, in which
the velocity reached up to 700 km/h. The reference trajectory was determined using multi relative
positioning, providing precision better than 20 cm. The PPP results from the two flights were comparedwith the reference trajectory. We will present details of the flights, determination of the reference trajectory
and the in-house PPP software developed for such application together with the results. From the results
obtained so far, we can conclude that, as expected, the quality deteriorates with the aircraft velocity andthat most of time accuracy better than 80 cm was obtained for the height component.

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*G05-2-03
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Statistical Analysis of Multi-GNSS Inter-System Biases for Precise Point
Positioning Ambiguity Resolution
Shuyang Cheng , * Jinling Wang
School of Civil and Environmental Engineering, UNSW Sydney, Australia
Compatibility and interoperability among multi-GNSS constellations are the necessity for reliable multiGNSS positioning and navigation, thus, attracting great attention from the satellite navigation community
over recent years. There are inter-system biases affecting precise point positioning (PPP) ambiguity
resolution. While it has been well known that differenced integer ambiguities between satellites areresolvable. in the current PPP ambiguity resolution procedures, due to the multi-GNSS Inter-System Biases,
the integer carrier phase ambiguities between satellites within a single constellation are formed, forexample, GPS ambiguities and Galileo ambiguities are separate. Such a situation will certainly reduce theperformance of multi-GNSS ambiguity resolution due to a relatively weaker geometry than the scenario in
which integer ambiguities between any satellites within multi-constellations can be resolved.
In this paper, we will investigate the statistical characteristics of multi-GNSS Inter-System Biases, especiallyin the carrier phase domain, and design procedures to estimate and accommodate these biases towards thegoal to resolve the integer ambiguities between any satellites within the multi-constellation GNSS. For
example, in conventional PPP-AR methods, one GPS and one Galileo satellites are chosen as reference
satellites to form inner-system between-satellite-single-differencing (BSSD). In this new method, only one
GPS satellite will be selected as the pivot satellite to form GPS-GPS inner-system BSSD and GPS-Galileointer-system BSSD. Experimental results will be presented to show the time variability of these ISBs andcompare the PPP-AR performance of this new method and traditional methods.

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*G05-2-04
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Quality of GPS, GLONASS, Galileo and BeiDou real-time orbits and clocks* Kamil Kazmierski , Krzysztof Sosnica , Tomasz Hadas
Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
A constantly increasing number of satellites of Global Navigation Satellites Systems (GNSS) and theircontinuous modernization allow improving the positioning accuracy and enables performing the GNSS
measurements in demanding environments. In order to take advantage of all GNSS and their frequencies it
is necessary to get precise orbits and clocks also for new systems. To provide such products Multi-GNSS
experiment (MGEX) has been established by the International GNSS Service (IGS). Products ensured by
IGS may be used only in post-processing mode due to the latency of these products.
IGS Real-Time Service (RTS) was launched in April 2013 in order to pave the way for obtaining the position
in real-time. Products provided currently by IGS-RTS are available only for GPS and GLONASS. Therefore,
to enable real-time users to take advantage of all GNSS observations it is necessary to provide orbit andclock corrections for all available GNSS via streams. Centre National d'etudes Spatiales (CNES) is one ofanalysis centers that provides freely available corrections for all GNSS, including new systems.
The presented work evaluates the availability and quality of real-time corrections. The final products
provided by the Center of Orbit Determination in Europe (CODE) and Satellite Laser Ranging (SLR) areused as a reference for the evaluation of real-time products. The 3D orbit RMS, when compared to CODE
products, is 5, 10, 19, 18 and 37~cm for GPS, GLONASS, Galileo, BeiDou MEO and IGSO, respectively. The
insufficient quality of BeiDou geostationary orbits that reaches above 1~m is inadequate for precise
positioning applications. The conducted works are a background for further studies related to the real-time
Multi-GNSS processing, e.g. using the proper system-specific weighing of observations in order to achieve
reliable multi-GNSS solutions.

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*G05-2-06
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

High-rate RTK and PPP for precise dynamic displacements determination* Jacek Paziewski , Rafal Sieradzki , Radoslaw Baryla , Pawel Wielgosz
University of Warmia and Mazury in Olsztyn
The measurement method applied for the monitoring of the ground and engineering structures'
displacements ought to satisfy the highest requirements in terms of accuracy, reliability and availability.
These specific demands may be met by the GNSS technique and suited method of signal processing. High
precision and availability of high-rate GNSS observations predestine this technology to be applied to themost demanding applications such as small-scale dynamic displacements determination. Thus, GNSS
positioning may be used as a reliable source of information on dynamic, different origin deformations, also
in real time applications.
In this study both RTK and PPP positioning techniques have been implemented and employed in order toretrieve small-scale high-rate site displacements. Methodology and algorithms applied in self-developed
software allowing for precise absolute and relative multi-GNSS positioning were given and supported by
the results of conducted experiment. In the experiment were used the GNSS observations derived fromhigh-rate (50 Hz) geodetic receivers and processed using several established scenarios in a RTK and PPP
modes. The dynamic displacements were simulated using constructed device responsible for generation of
GNSS antenna oscillations with dedicated amplitudes and frequencies. The results indicate on applicabilityof both relative and absolute positioning techniques to detection of dynamic displacements of the GNSS
antenna even at the level of few millimetres after suitable signals processing.

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*G05-3-01
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Higher Order Ionospheric modelling campaigns for precise GNSS
applications* Tomasz Hadas 1) , Jan Kaplon 1) , Anna Krypiak-Gregorczyk 2) , Manuel Hernandez-Pajares 3) , Pawel
Wielgosz 2) , Alberto Garcia-Rigo 3) , Jacek Paziewski 2) , Kamil Kazmierski 1) , Jaroslaw Bosy 1) , Krzysztof
Sosnica 1) , Dawid Kwasniak 3) , Marcin Pucilowski 4) , Robert Szyszko 4) , Raul Orus Perez 5)
Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland 1) , University of Warmia andMazury, Olsztyn, Poland 2) , Universitat Politecnica de Catalunya, Barcelona, Spain 3) , Leica Geosystems
Poland, Warsaw, Poland 4) , European Space Research and Technology Centre, Noordwijk, Netherlands 5)
The first order ionospheric term (I1) is the main contributor to the ionospheric delay of GNSS observations,compared with the less than 0.1% corresponding to the higher order ionospheric terms. However, higher
order ionospheric effects (I2+) are one of the main limiting factors in very precise GNSS processing, forapplications where millimetre accuracy is demanded. The consortium of LGP, WUELS, UWM and UPC
deals with higher order ionospheric mitigation under the HORION (Higher Order Ionospheric modelling
campaigns for precise GNSS applications) project, supported by the European Space Agency. ThisHORION project is focused on the development of the HORION-PL web service for mitigation of higher
order ionospheric terms, thus improving precise GNSS processing.
Within this project we also investigated the impact of I2+ on troposphere delay estimation, long-range
relative positioning and autonomous positioning. We selected three networks (global, Polish and Brazilian)
and three test period (each one week long, reflecting solar minimum conditions, solar maximum conditions
and geomagnetic storm). We also estimated GPS and GLONASS orbit and clock products, that were further
used in GNSS processing. We performed each processing in two variants 1) with original RINEX files, and2) with I2+ corrected RINEX files, to assess the impact of I2+ effects on the results.
The initial analysis of I2+ impact on orbit modelling showed the following RMS of residuals: 1.1 mm, 3.7mm and 3.3 mm for radial, along and out-of-plane component respectively. For troposphere, the average
ZTD difference was -0.06 mm with 0.20 mm of standard deviation, with the extreme ZTD differences
reaching 3.4 mm and -4.4 mm. ZTD differences obtained in Brazilian network fluctuates following daily I2+
correction oscillations. In Poland this effect is smaller, due to shorter baselines and lower ionosphereactivity.

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*G05-3-02
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Crustal deformation in response to the changing climate* Shimon Wdowinski 1) , Paulo Setti 2) , Tonie van Dam 3)
Florida International University 1) , Sao Paulo State University 2) , University of Luxembourg 3)
Vertical crustal movements induced by atmospheric, hydrological, cryospheric, and oceanic load changes
are detectable with sub-cm accuracy by precise continuous GPS measurements. Areas subjected to rapid
load changes due to icesheet melt, drought, massive groundwater extraction, or lake level drop, arecharacterized by a dominant non-linear uplift signal. In other areas, seasonal load changes often mask thelonger-term climatic signal. Here we present a new method for removing the seasonal signal and extracting
the climatic signal from long GPS time series (>15 years). Applying the method to GPS records form
western and eastern North America indicates different load change characteristics. In the western US, theseasonal and climatic signals are dominated by hydrological load changes and, consequently, the GPS
climatic signal correlates well with the Palmer Severe Drought Index calculated for the same region. In
eastern North America the GPS climatic signal in some stations correlates with the North Atlantic
Oscillation (NAO) index, suggesting a linkage between decadal scale weather patterns in the Northern
Atlantic region and vertical crustal movements, possibly due to ocean and atmospheric load changes. Our
results suggest that long continuous GPS observations of vertical crustal movements can serve as
independent measures of regional-scale climate change.

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*G05-3-03
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Variometric approach for displacement analysis using Galileo data
Francesca Tesolin 1) , Alfonso Vitti 1) , Augusto Mazzoni 2) , * Mattia Giovanni Crespi 2)
University of Trento, Trento, Italy 1) , Sapienza University of Rome, Rome, Italy 2)
The Variometric Approach for Displacement Analysis Standalone Engine (VADASE)* was successfully
applied for seismological and monitoring purposes using GPS observations. The Galileo system, recently
entered in the Initial Services operation phase, supplies GPS inter-operable and specific observations thatcan be used by VADASE.
In this work, the Galileo derived VADASE solutions are inspected to evaluate the impact of the European
system. In particular, the combined GPS and Galileo variometric model has been improved in order toconsider two receiver clock variations for both the systems. VADASE solutions were, at first, computed
using single and iono-free observations from a set of IGS-MGEX sites in order to evaluate the sensitivity ofthe solutions with respect a static scenario. After, real displacements were investigated using U-blox single
frequency receivers. The comparison with the GPS derived solutions was carried out selecting GPS
constellations with the same number of satellites and the closest PDOP values to that of the Galileo
constellations inspected. The analysis was carried out using broadcast and precise orbits. Standard
statistics of the Galileo derived solutions are provided and commented. In general, the solutions are ofgood quality and essentially comparable to or better than the GPS derived solutions.
The preliminary results enhance the contribution of Galileo system and pave also the way to a wider use of
low-cost single frequency receivers for monitoring applications.
Furthermore, a WebApp version of the VADASE software is presented in order to give to the scientificcommunity the possibility to run the variometric approach on RINEX files.
*Colosimo, G., Crespi, M., Mazzoni, A. Real-time GPS seismology with a stand-alone receiver: A preliminary
feasibility demonstration (2011) JGR Solid Earth, 116 (11)Powered by TCPDF (www.tcpdf.org)

*G05-P-01
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Assessment of GNSS and map integration for lane-level applications in thescope of Intelligent Transportation Location Based Services (ITLBS)
Emerson Cavalheri , * Marcelo Santos
University of New Brunswick
To enable safe and robust Intelligent Transportation Systems (ITS) applications, the integration of different
sensors and techniques will certainly be a common reality. One application in this context is the lanekeeping techniques for autonomous driving systems. These systems normally use imagery sensors for lane
identification, however imagery systems always depend on light and well structured roads. One potential
worldwide autonomous driving technique without any other lane and road detection/identification sensor
would be GNSS positions along with accurate map information. However, this fusion depends on theaccuracy and reliability of both GNSS positions and map information. The positioning accuracy that
Intelligent Transportation Location Based Services (ITLBS) requires for where-in-lane and active control
applications are 0.5 m and 0.1 m, respectively. To evaluate the potential of a such fusion, this work
proposes an integration of GNSS and map information in the attempt to address the lane-keeping problem.
This integration is performed by merging GNSS solutions and lane centerline positions, acquired fromaerial orthophotos, into a Kalman Filter and a map-matching approach. To measure the positioning error, or
off-track performance, a conversion of positions to the “road domain" is necessary. To evaluate the results,
a positioning accuracy limit, considering the road, vehicle dimensions, and the requirements for ITLBS is
also proposed. The results showed that 95% of the time the proposed methodology off-track performanceswere within 1.89 m, in an average of 4 runs. Half of the runs were within 0.75 m, in average, at 95% of thetime. Compared to an accurate GNSS Post Processed Kinematic (PPK) mode, an improvement of 10% wasachieved.

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*G05-P-02
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Evaluation of digital surface models created from LiDAR and optical sensor
data collected with unmanned aerial systems* Andrzej Borkowski , Grzegorz Jozkow , Agata Walicka , Mateusz Karpina , Przemyslaw Tymkow
Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
Unmanned aerial systems (UASs) are becoming more popular in local scale topographic mapping. The
state of the art in topographic UAS mapping is the use of consumer-grade RGB cameras, however, sensor
development caused that laser scanners started to be used for this purpose. This work aims on comparative
assessment of digital surface models (DSMs) created form data collected with 3 various UAS sensors:
Nikon D800 RGB camera, Optris PI Lightweight 450 thermal camera, and Velodyne HDL-32E laser
scanner. The evaluation focused on assessing the impact of georeferencing method to created DSM. Alldata was processed using standard methods. In the case of imagery data a bundle block adjustment (BA)was executed and was followed by image dense matching to create point cloud necessary for DSM
modeling. Three types of georeferencing constraints in BA were investigated: ground control point (GCPs)
measured with GNSS-RTK technique, image projection centers obtained from onboard GNSS-RTK
measurements, and from onboard navigational GNSS solution. In the case LiDAR data, direct
georeferencing of the point cloud using post-processed kinematic GNSS/INS solution was executed.
Obtained DSMs were compared to the most accurate DSM created from high resolution RGB images
georeferenced using GCPs. Results showed that georeferencing method has higher impact to the DSM
accuracy than the quality of the sensor. Low quality thermal images georefer-enced using GCPs resulted in
DSM of vertical RMSE equal to 17 cm, while good quality RGB images georeferenced with other methods
resulted in vertical RMSE equal to 60 cm, however, a significant bias of about 50 cm was observed. It
proved that internal accuracy of the point cloud created from RGB images is very high. In the case of
LiDAR data, obtained RMSE was equal to 47 cm, but the internal accuracy of the point cloud was much
lower than for RGB data. It was caused by lower quality of GNSS/INS solution, especially the orientation.

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*G05-P-03
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Improving low-cost GNSS navigation in urban areas using multiconstellation receivers and integrating a Kinect device
Diana Pagliari 1) , Carlo Iapige De Gaetani 1) , Eugenio Realini 2) , Mirko Reguzzoni 1) 2) , Lorenzo Rossi 1) ,Livio Pinto 1) , * Riccardo Barzaghi 1)
Department of Civil and Environmental Engineering, Politecnico di Milano, Milan, Italy 1) , GReD srl,
Lomazzo (CO), Italy 2)
In the last decades, low-cost GNSS receivers have been widely used for navigation purposes. Some of themdeliver also raw data, allowing for a more sophisticated processing, such as the double difference approach,and therefore a more accurate positioning, typically at the decimeter level. However, these accuracies canbe generally achieved only with a good sky visibility, that is a critical issue in urban areas even using lowcost receivers equipped with a high-sensitive antenna. In this respect, a significant contribution comes fromthe multi-constellation signal that increases the number of visible satellites. An additional possibility is theintegration of the GNSS receiver with a camera or a laser scanner. In fact, the external orientation of theacquired digital images or dense point clouds ultimately provides an estimate of the sensor kinematic
position.
In this work, we have first studied the contribution of the different GNSS constellations to the accuracy andthe temporal continuity of the estimated trajectory in outdoor urban environment by a low-cost receiver,such as u-blox or NVS devices. The free and open source goGPS software has been used to process thereceiver raw data. Then, we have studied the integration of the Kinect device into the navigation system.
This device is endowed with a depth camera, as well as a RGB camera, at a cost of about 200$, thus
maintaining our main target of realizing a low-cost system. A proper Kalman filter has been implemented
for jointly processing the GNSS estimated coordinates and the images of the Kinect cameras. An outdoor
experiment has been arranged with the aim of testing the hardware and software system. The results showthat the obtained improvement is more significant for the temporal continuity of the trajectory rather thanfor its accuracy.

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*G05-P-04
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Multi GNSS attitude estimation of UAVs during landing* Marton Farkas 1) 2) , Szabolcs Rozsa 2) , Balint Vanek 1)
Systems and Control Lab, Hungarian Academy of Sciences Institute for Computer Science and Control,
Budapest, Hungary 1) , Department of Geodesy and Surveying, Faculty of Civil Engineering, Budapest
University of Technology and Economics, Budapest, Hungary 2)
Sensor fusion methods are becoming increasingly important in all aspects of commercial aviation,
especially in the challenging phases of flight like landing, where ILS, GNSS and vision based sensor
sources can be fused. If we would like to enhance the safety of air transport, then it is necessary to improve
the navigation system and built -in fault detection of these functions. The attitude estimation has aprominent role of this improvement. The inertial measurement units (IMU) provide data necessary to allnavigation tasks, but the drift of the gyroscope and accelerometer sensors decreases the reliability of thesemeasurements, particularly at the low-cost devices.
The main objective of the H2020 VISION project (Validation of Integrated Safety-enhanced Intelligent
flight cONtrol) is to validate smarter technologies for aircraft Guidance, Navigation and Control. Within theframework of the project we would like to present an algorithm which estimates the attitude of the aerial
vehicle based on single frequency, single baseline, multi GNSS code and phase measurements, to provide a
redundant alternative for IMU based attitude data.
The baseline coordinates between the two GNSS antennas and the single-differenced integer ambiguities
are estimated by an Extended Kalman Filter (EKF). This EKF algorithm is supplemented with a Baseline
Constrained Least-Squares Estimator of the Integer Ambiguities. The heading and the elevation angles of
the aircraft are estimated with this method within one degree precision, significantly enhancing the inertial
based attitude determination. The method also has the advantage, that the solution is drift free unlike theattitude of the IMU.
This study discusses the computational algorithm and the validation experiment.
Based on the real flight test data, it is examined how single frequency GNSS attitude solution can improve
the Guidance and Navigation during landing of the aircraft, which is one of the most hazardous phase of
the flight.

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*G05-P-05
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Short-Term Prediction of IGS Real Time Service Data for Continuous GNSS
Positioning* Jeongrae Kim , Mingyu Kim
Korea Aerospace University, Goyang-City, Korea
For precise global navigation satellite system (GNSS) positioning, GNSS error components such as satellite
orbit and clock errors need to be corrected. The international GNSS service (IGS) provides a real-time orbit
and clock estimates (real-time service, RTS) for real-time precise positioning. The real-time performance of
the RTS, i.e. accuracy and stability, are analyzed with a long-term data. And the RTS correction availability
for the GPS satellites observed in East Asia is analyzed. Since the IGS RTS provides the real-timecorrections via the internet, intermittent data loss can occur due to software or hardware failures. In orderto make up for possible RTS data loss or delays, several prediction algorithms for the RTS data aredeveloped, which include polynomial extrapolation, autoregressive moving average (ARMA), and machinelearning algorithms (neural network and genetic algorithm). The prediction interval is set from 10s to 900s,
and the performance of those methods are evaluated and compared. The machine learning algorithms
yields a substantial improvement, greater than 25%, over the simple extrapolation algorithms. The error
reduction is more significant in the clock prediction than in the orbit prediction. The clock correction has amore stochastic variation than the orbit correction, and the machine learning algorithm is efficient forpredicting such a stochastic variation.

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*G05-P-07
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Multiplicative random error models: Parameter estimation and error analysis* Yun Shi , Jing Zhang , Peng Chen , Jie Lv , Chao Li
Xi'an University of Science and Technology
Conventional geodetic adjustment theory has been almost always developed on the linear and/or
linearized model of measurements. The most important feature of these conventional adjustment methods
and theory are that the random errors of measurements are added to the functional models. In other words,
the sizes or magnitudes of random errors are independent of the true values of measured quantities.
However, in geodetic practice, we know that this assumption is not necessarily always true. For example,
we know that the accuracy of an EDM, GPS and/or VLBI baseline is proportional to the length of thebaseline itself, which clearly indicates that the random errors of this type are proportional to the measured
quantities. From the statistical point of view, such random errors should be multiplied to the functionalmodels and are not additive any more. In this talk, we will extend the conventional model of geodetic
adjustment to account for multiplicative errors and/or mixed additive-multiplicative errors. We will address
the parameter estimation and error analysis in the linear/linearized model of measurements with mixed
additive-multiplicative random errors. More specifically, we will first discuss three least-squares-based
methods to estimate the model parameters, namely, least squares, weighted least squares (LS) and biascorrected weighted least squares. We will then analyze these three methods from the statistical point ofview. We construct five estimators of the variance of unit weight in association with the three LS-based
methods and compare them, statistically and through numerical simulations. Although LiDAR data havebeen proved to be of multiplicative nature, they have been treated as if they were of additive random errors.
Thus, as a final part, we will simulate a landslide example, which is supposed to be surveyed with LiDAR, todemonstrate how the methods discussed here works and how they can be applied to DEM construction fordisaster monitoring.

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*G05-P-07
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

MINIMUM MEAN SQUARE ERROR ADJUSTMENT, Part 2: The Empirical
BLE and the reproBLE for multivariate positioning
Burkhard Schaffrin 1) , * Peiliang Xu 2)
Ohio State University, Columbus, USA 1) , Kyoto University, Kyoto, Japan 2)
Abstract:
A little while ago, in 2000, Schaffrin showed how the weighted Least-Squares solution (LESS) within amodel of direct observations (univariate case) may be improved by applying the minimum Mean Square
Error (MSE) principle, either leading to the well established Empirical BLE (Best Linear Estimate) or thenovel reproBLE. Here, an attempt will be made to generalize the concept to cover the multivariate case inform of a Gauss-Markov Model. First steps in this direction had been undertaken by Schaffrin in 2008
already, but with emphasis on the optimal choice for the Tykhonov-Phillips regularization parameter. Now,
new aspects of any solutions of type reproBLE regarding questions of positioning will be the focus of thiscontribution.
Reference:
Schaffrin, B. (2000) Minimum mean squared error adjustment, Part I: The empirical BLE and the repro-BLE
for direct observations. J Geod Soc Japan 46:21–30
Schaffrin, B. (2008) Minimum mean squared error (MSE) adjustment and the optimal Tykhonov–Phillips
regularization parameter via reproducing best invariant quadratic uniformly unbiased estimates (reproBIQUUE). 2008, 82(2): 113–121

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*G06-1-01
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

GNSS Remote Sensing at GFZ: Overview and Recent Results* Jens Wickert 1) 2) , Fadwa AlShawaf 1) , Christina Arras 1) , Milad Asgarimehr 1) , Galina Dick 1) , Stefan
Heise 1) , Kristine Larson 3) , XingXing Li 1) , Cuixian Lu 1) , Markus Ramatschi 1) , Maximilian Semmling 1) ,Torsten Schmidt 1) , Tzvetan Simeonov 1) 2) , Sibylle Vey 1) , Florian Zus 1) , Harald Schuh 1) 2)
German Research Centre for Geosciences GFZ, Germany 1) , Technische Universitaet Berlin, Germany 2) ,University of Colorada, Boulder, U.S. 3)
GNSS atmospheric remote sensing was successfully established during the last two decades and evolved
into a major application for high precision GNSS. Globally distributed vertical profiles of refractivity,
temperature and water vapour are derived from satellite based GNSS data (Radio Occultation, RO). Groundbased measurements, provided by GNSS networks, allow for the derivation of vertically (IWV) or along theline-of-sight integrated water vapour (SWV). Another important GNSS remote sensing technique, theexploitation of Earth reflected signals (GNSS Reflectometry, GNSS-R) exhibits a huge potential for Earth
Observation.
The status of the GNSS-RO experiments aboard the satellites GRACE-A, TerraSAR-X and TanDEM-X isreviewed. Examples of GNSS RO applications are given, as, e.g. climatological investigations of the global
vertical temperature structure or the detection of ionospheric irregularities in the E-region. We also focus
on ground based activities for GNSS water vapour monitoring. Observations of a global and regionallydensified German network, with about 600 stations in total, are processed in near-real time to operationallyprovide IWV data. These data are assimilated into atmospheric models by several European weather
centers. Current research activities are focused on the generation and meteorological application of GNSS
based slant data, on real-time and multi-GNSS meteorology. In addition, climatological investigations aredescribed to analyse long-term trends of the atmospheric water vapour over Germany but also as part of
the Global Climate Observing System (GCOS) of the WMO (World Meteorological Organization).
Multipath data from standard GNSS receivers are used to derive information on soil moisture, vegetationand snow properties. We introduce selected research examples. We also review results from GNSS
receivers aboard flight and ship platforms using the GNSS-R phase altimetry technique.

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*G06-1-02
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

A new baseline processing strategy for GNSS meteorology* Katarzyna Stepniak 1) , Olivier Bock 2) , Pawel Wielgosz 1)
University of Warmia and Mazury in Olsztyn, Poland 1) , IGN LAREG, University Paris Diderot, France 2)
Though GNSS data processing has been significantly improved over years it is still commonly observed that
tropospheric parameters (ZTD and gradients) contain many outliers. Detection and removal of outliers in
GNSS time series is an important step before their use in meteorology and climatology. We show thatoutliers in double difference processing are often caused by defects in the baseline strategy. We elaborate
and test a new baseline strategy which solves this problem and significantly reduces the number of outliers.
One year of data is analyzed from a network of 136 GNSS stations. Three baselines strategies are intercompared: 1) a strategy commonly used for positioning (e.g. determination of national reference frame) inwhich the pre-defined network is composed of a skeleton of reference stations to which secondary stations
are connected in a star-like structure; 2) the widely-used “obs-max" strategy available in Bernese GNSS
software (e.g. for processing of regional to global networks); and 3) our new baselines strategy.
It is shown that many outliers are due to data gaps at reference stations which cause disconnections ofclusters of stations from the reference network. These outliers are common–mode biases due to the strong
correlation between stations in short baselines. They can reach a few centimeters in ZTD and can bedetected by a jump in formal errors. The magnitude and sign of the bias is impossible to predict, because it
depends on different errors in the observations and on the geometry of the baselines. Several cases areillustrated. This defect is shown to strongly impact the 2 most widely used strategies. Our new strategy
ensures that no station is disconnected from the main network and that all clusters include long baselines
necessary to estimate absolute tropospheric parameters. This strategy might help to improve significantly
the quality of GNSS tropospheric parameters estimated in national to regional networks for meteorology.

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*G06-1-03
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Impact of advanced ZTD estimate method – Separation from site coordinates
estimation –* Seiichi Shimada 1) 2) , Shingo Shimizu 3) , Kazuhisa Tsuboki 4) , Yusuke Morimoto 4)
The University of Tokyo, Tokyo, Japan 1) , Nippo Co. Ltd., Kawasaki, Japan 2) , The National ResearchInstitute for Earth Science and Disaster Prevention (NIED), Tsukuba, Japan 3) , Nagoya University 4)
We introduce the new procedure to estimate zenith total delay (ZTD) to obtain GPS precipitable water(PWV) for the assimilation of the numerical weather models (NWM). In general, the major systematic error
source of the ZTD estimation is the trade-off between the ZTD and the coordinate solutions usuallysimultaneously estimated in the GNSS analysis. In the analysis of the ZTD estimation, we fix the accuratesite coordinates and exclude the trade-off systematic errors.
In the first step of the procedure, we estimate site coordinates as well as hourly ZTD, every four-hourly
atmospheric gradient, and independent ambiguities of all of the GEONET network sites as well as the IGS
fiducial sites applying the GAMIT program. In the second step, we estimate the accurate present-day site
coordinates of the GEONET sites, estimating from the recent 30-days' time series of the site coordinates
solutions applying the Kalman filtering of the GLOBK program, constraining the IGS fiducial site
coordinates. Then in the final step of the procedure, we estimate every hourly ZTD and every four-hourly
gradients of the GEONET sites fixing the site coordinates obtained in the second step.
To evaluate the advanced ZTD estimation, we compare the PWV values calculated from the three kind of
ZTDs obtained by three different analysis procedures. We assimilate the PWVs to the CReSS NWM, andexamine the impact of the PWVs in the heavy rain in the Southern Gifu Prefecture, Central Japan, on July
15 2010. Examining the wide area distribution of water vapor in the objective analysis, only the ZTDs
obtained applying the procedure mentioned above (advanced ZTDs) shows the sharp contrast of the mixing
ratio. coincides significantly The heavy rain phenomena calculated using the advanced ZTDs only
significantly coincides with the observation.

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*G06-1-04
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

Main achievements of the Working Group 1 “Advanced GNSS Processing
Techniques" of the COST Action ES1206: GNSS for Severe Weather andClimate (GNSS4SWEC)* Galina Dick 1) , Jan Dousa 2) , Michal Kacmarik 3) , Pavel Vaclavovic 2) , Eric Pottiaux 4) , Florian Zus 1) ,Hugues Brenot 5) , Jan Kaplon 6) , Gregor Moeller 7) , Rosa Pacione 8) , Andrea Stuerze 9) , Norman Teferle10), Laurent Morel 11) , Pawel Hordyniec 6)
GFZ German Research Centre for Geosciences, Potsdam, Germany 1) , Geodetic Observatory Pecny, RIGTC,
Ondrejov, The Czech Republic 2) , Technical University of Ostrava, Ostrava, The Czech Republic 3) , Royal
Observatory of Belgium, Brussels, Belgium 4) , Belgian Institute for Space Aeronomy, Brussels, Belgium 5) ,Institute of Geodesy and Geoinformatics, Wroclaw University of Environmental and Life Sciences, Wroclaw,
Poland 6) , Vienna University of Technology, Vienna, Austria 7) , E-GEOS, s.p.a. & ASI, Matera, Italy 8) ,Federal Agency for Cartography and Geodesy,, Frankfurt am Main, Germany 9) , University of Luxembourg,
Luxembourg 10) , GeF Laboratory, ESGT – CNAM, Le Mans, France 11)
The COST Action ES1206 GNSS4SWEC addresses new and improved capabilities from developments inboth the GNSS and meteorological communities. The synergy of all GNSS systems (GPS, GLONASS, Galileo
and BeiDou) are used to develop advanced tropospheric products, exploiting the full potential of multiGNSS water vapour estimates on a wide range of temporal and spatial scales, from real-time monitoring
and forecasting of severe weather, to climate research. The Working Group 1 (Advanced GNSS processing
techniques) deals with implementing and assessing new methods for GNSS tropospheric monitoring andprecise positioning exploiting all modern GNSS constellations, signals, products etc. Besides other goals,
WG1 coordinates development of advanced tropospheric products in support of weather numerical andnon-numerical nowcasting.These are ultra-fast and high-resolution tropospheric products available in realtime or in a sub-hourly fashion and parameters in support of monitoring an anisotropy of the troposphere,
e.g. horizontal gradients and tropospheric slant path delays.
We give an overview of WG1 activities and focusing on achievements within Benchmark and Real-time
Demonstration campaigns. For the Benchmark campaign a complex data set of GNSS observations andvarious meteorological data were collected for May-June 2013 which included severe weather events incentral Europe. An initial processing of data sets from GNSS and numerical weather models (NWM)
provided independently estimated reference parameters – ZTDs and tropospheric horizontal gradients. The
Benchmark data set is used for development of an optimal strategy for real-time processing and a validationof tropospheric horizontal gradients and line-of-sight tropospheric slant total delays from GNSS, NWMraytracing and Water Vapour Radiometer solutions. Real-time campaign is used to demonstrates products
achieved in operational GNSS real-time analysis.

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*G06-1-05
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Heterogeneity of residuals from GNSS and ray-traced tropospheric delays as
an indicator of hydrometeors* Pawel Hordyniec , Witold Rohm , Jan Kaplon
Wroclaw University of Environmental and Life Sciences, Institute of Geodesy and Geoinformatics, Wroclaw,
PolandWe attempt to indicate hydrometeors content along ray-path trajectories between ground-based receivers
and respective GNSS satellites. Using tropospheric delays retrieved from GNSS data in Precise Point
Positioning (PPP) and associated ray-traced delays in Numerical Weather Prediction (NWP) model, we areable to calculate residuals resulting from different processing approaches. When precise satellite orbits andclocks are applied, GNSS post-fit residuals carry the troposphere information except of multipath andresidual antenna Phase Centre Variations (PCVs). After post-fit residuals are reduced by site-dependent
systematic effect, they are introduced to GNSS-based delays increasing discrepancies with respect to raytraced delays. Assuming the hydrometeor information in GNSS solution is correct, we expect the effect tobe significant during severe weather events since ray-traced tropospheric delays exclude aerosols
contributions. We conducted spatial and temporal correlation analysis of the slant delay residuals (GNSS
minus ray-traced) with weather phenomena recorded during the COST ES1206 GNSS4SWEC benchmark
period (May 5th - June 29th, 2013). We also discuss results that arise from different GNSS PPP slant delay
estimation approaches related to coordinates constraining and inclusion of ZTD horizontal gradients.

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*G06-1-06
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Analysis of systematic effects in slant total delay estimation with PPP* Jan Kaplon , Pawel Hordyniec , Witold Rohm
Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
Slant total delay (STD) of GNSS signal estimated during the PPP procedure is a sum of a priori slant
hydrostatic delay, estimated wet delay, asymetry introduced by the estimated zenith total delay (ZTD)
horizontal gradients and a post-fit residual reduced by the systematic (site-dependant) effect. The main
systematic influence on STD is the multipath error. It can be determined from the long time series of postfit residuals as their average value calculated in equal-area bins or calculated from the raw GNSS
observables.
Paper presents the review and comparison of systematic effect maps (mainly multipath) obtained from PPP
slant delay estimation post-fit residuals for a set of GNSS stations gathered in the COST ES1206
GNSS4SWEC benchmark database. We are presenting as well the systematic effect influence on estimated
STD values through the results of comparison with STDs from WRF model raytracing.

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*G06-2-01
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

High-resolution troposphere models based on Numerical Weather Prediction
for GNSS real-time Precise Point Positioning* Karina Wilgan , Tomasz Hadas , Pawel Hordyniec , Jaroslaw Bosy
Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
Tropospheric delay is highly correlated with the receiver clock and receiver height. To efficiently decorrelate these parameters in Precise Point Positioning (PPP), a change in constellation geometry is
required. An alternative approach is to introduce the external high-quality regional tropospheric delay
model to constrain tropospheric estimates. In this study, we present a high-resolution troposphere model
based on Numerical Weather Prediction (NWP) model and Global Navigation Satellite Systems (GNSS)
data, suitable to support PPP. We investigate the impact of different tropospheric models and mapping
functions on the position accuracy and convergence time. We propose a routine to constrain the
tropospheric estimates, which we implemented in the in-house developed real-time PPP software. We takeadvantage of the spatial high-resolution NWP Weather Research and Forecasting (WRF) model toreconstruct troposphere delay from WRF model and near real-time GNSS data combined by the leastsquares collocation technique. We also present mapping functions calculated from WRF model using the
ray-tracing technique. We compare commonly used troposphere models such as UNB3m or VMF1-FC andthe high-resolution GNSS/WRF-based troposphere model with the reference EUREF Permanent Network(EPN) data on 14 Polish stations during three weeks of different tropospheric conditions: calm, standard
and severe. The application of the high-resolution model results in the best agreement with the official EPN
coordinates. In both static and kinematic mode this approach results in average reduction of 3D bias by 20
and 10 mm respectively. The application of high-resolution tropospheric model also shortens theconvergence time by 13% for horizontal components and 20% for vertical component compared to thestandard models.

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*G06-2-02
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Optimum stochastic modeling for GNSS tropospheric delay estimation in
real-time* Tomasz Hadas 1) , Felix Norman Teferle 2) , Kamil Kazmierski 1) , Pawel Hordyniec 1) , Jaroslaw Bosy 2)
Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland 1) , University of Luxembourg,
Luxembourg, Luxembourg 2)
In GNSS data processing, the station height, receiver clock and tropospheric delay (ZTD) are highly
correlated to each other. Although the zenith hydrostatic delay of the troposphere can be provided with
sufficient accuracy, zenith wet delay (ZWD) has to be estimated, which is usually done in a random walkprocess. Since ZWD temporal variation depends on the water vapor content in the atmosphere, it seems to
be reasonable that ZWD constraints in GNSS processing should be geographically and/or time dependent.
Rather than performin a prior empirical testing for each station, we propose to take benefit from numerical
weather prediction (NWP) models to define optimum random walk process noise. In the first approach, weused archived VMF1-G data to calculate a grid of yearly means of the difference of ZWD between two
consecutive epochs divided by the root square of the time lapsed, which can be considered as a random
walk process noise. Alternatively, we used the Global Forecast System NWP model from National Centres
for Environmental Prediction to calculate random walk process noise dynamically in real-time, byperforming ray-tracing through the two shortest available forecasts.
We performed two representative experimental campaigns with 20 globally distributed International GNSS
Service (IGS) stations and compared real-time ZTD estimates with the official ZTD product from the IGS.
We have shown that a single random walk processing noise (RWPN) value should not be applied globally toall stations, because it may lead to significant degradation of solution quality. With RWPN yearly grid wewere able to reconstruct the wet RWPN value obtained from empirical testing with a mean error of
1mm/sqrt(h). A superior result was obtained with dynamical NWP-based apporach, in which we obtained
an improvement of up to 10% in accuracy of the ZTD estimates compared to any uniformly fixed random
walk process noise applied for all stations.

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*G06-2-03
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Impact assessment of regional versus global Numerical Weather
Model–derived tropospheric corrections for GPS and VLBI
* Thaleia Nikolaidou 1) , Felipe Nievinski 2) , Kyriakos Balidakis 3) , Marcelo Santos 1)
University of New Brunswick 1) , Federal University of Rio Grande do Sul 2) , Technische Universitat Berlin
3)

Mapping functions based on Numerical Weather Models (NWM) have been developed in the recent years
to model tropospheric delay in Global Positioning System (GPS) and Very Long Baseline Interferometry(VLBI).Their limited accuracy however, requires the estimation of residual tropospheric delay for results ofhigh accuracy.
Correlation between the tropospheric delay, the receiver clock offset and the station height prolongs thetime required for the solution to converge and impacts directly the accuracy of the results. Althoughobservation in low elevation angles, help the parameters to de-correlate, they amplify the noise, are notalways adequate and it is a highly demanding prerequisite for real-time applications.
In this study, we applied tropospheric corrections proceeding from high resolution NWM in Precise Point
Positioning (PPP), in an attempt to acquire rapid and accurate positioning results, particularly useful for
kinematic applications, positioning in non-standard weather conditions and obstructed environment, where
estimation of tropospheric delay/height/clock offset is ambiguous.
Although regional NWM have outperformed standard atmosphere parameters and global models, it is thefirst time they were compared against other NWM-derived corrections; such as the state-of-art Vienna
Mapping Function 1 (VMF1) parameters.
To eliminate processing systematic effects, a consistent VLBI solution was generated.
The results were assessed in terms of their formal errors, convergence time, station coordinate andbaseline repeatability respectively, for the PPP and VLBI analysis.
Results shown minimal improvement in convergence time in “non-demanding" conditions, but “cm"height differences in kinematic mode and cases of tropospheric disturbances for specific sites. The qualityof the corrections and the filter a-priori variance, are barometrical for the final solution.

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*G06-2-04
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

A Study of Severe Storm Monitoring and Prediction using High Spatiotemporal GNSS Water Vapor Information Retrieved with RTKLIB and
MADOCA* Yoshinori Shoji 1) , Kazutoshi Sato 2) , Masanori Yabuki 3) , Toshitaka Tsuda 3)
Meteorological Research Institute, Tsukuba, Japan 1) , Japan Aerospace Exploration Agency, Tsukuba,
Japan 2) , Research Institute for Sustainable Humanosphere, Kyoto University, Kyoto, Japan 3)
Water vapor plays a significant role on development of hazardous cumulus convection. Water vapor
monitoring with high temporal and spatial resolution is indispensable for both predicting and monitoring ofsuch disastrous weather phenomenon. In Japan, a nationwide dense continuous ground based GNSS
network named GEONET (http://www.gsi.go.jp/ENGLISH/page_e30030.html) has also been utilized as acontinuous water vapor monitoring network by the Japan Meteorological Agency since 2009.
In order to capture finer water vapor variation, we have been developing two new applications, as (1) GNSS
slant-path delay (SPD) utilization to detect strong horizontal water vapor gradient within several kilometer
which associated with convective activities [1][2], and (2) observation system of water vapor over the oceanusing GNSS receivers equipped on top of floating buoys and vessels [3].
One of the most important point of these application is its real-time availability. We have tested "MADOCA(Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis)" real-time ephemerides(https://ssl.tksc.jaxa.jp/madoca/public/public_index_en.html) applied to the program package for GNSS
positioning “RTKLIB (http://www.rtklib.com/)" version 2.4.2 (patch 11). The results so far show great
potential of RTKLIB with MADOCA for severe weather prediction and monitoring.
References:[1] Sato, K., E. Realini, T. Tsuda, M. Oigawa, Y. Iwaki, Y. Shoji, and H. Seko, “A High-resolution,
Precipitable Water Vapor Monitoring System Using a Dense Network of GNSS Receivers", Journal ofDisaster Research, 8, 37-47, 2013.
[2]Shoji, Y., Hiroshi Yamauchi, Wataru Mashiko, and Eiichi Sato, “Estimation of Local-scale Precipitable
Water Vapor Distribution Around Each GNSS Station Using Slant Path Delay", SOLA, 10, 29-33, 2014.
[3]Shoji Y., K. Sato, M. Yabuki, and T. Tsuda, “PWV Retrieval over the Ocean using Shipborne GNSS
Receivers with MADOCA Real-time Orbits", SOLA, 12, 265-271, 2016.

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*G06-2-05
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Integrated water vapor trends from VLBI analysis, and their validation with
GNSS and numerical weather models
Kyriakos Balidakis 1) , Tobias Nilsson 2) , * Robert Heinkelmann 2) , Susanne Glaser 1) , Florian Zus 1) ,Zhiguo Deng 1) , Harald Schuh 1) 2)
Technische Universitaet Berlin, Institute of Geodesy and Geoinformation Science, Berlin, Germany 1) , GFZ,
German Research Centre for Geosciences, Potsdam, Germany 2)
We assess the impact of different modeling and parametrization of the propagation delay in the electricallyneutral atmosphere on the estimates of geodetic very long baseline interferometry (VLBI). Erroneous
meteorological observations applied to mitigate the tropospheric delay, as well as unsuitable constraints
imposed on the a priori gradients, especially in VLBI sessions with poor geometry, corrupt the data analysis
and thus distort the VLBI estimates. Hence, these issues affect the long-term integrated water vapor (IWV)
trends estimated from these results. The explicit purpose of this work is to address the impact of themeteorological data source, and of the a priori non-hydrostatic delays and horizontal gradients employed inthe VLBI analysis, on the estimated IWV trends. We explore the effect of employing pressure andtemperature from (i) homogenized in situ records, (ii) the model level data of ERA interim and (iii) an own
empirical model in the style of GPT2w with enhanced parametrization, employing the latter data set as
input. Moreover, we apply non-hydrostatic delays and gradients stemming from (i) a GNSS reprocessing at
German Research Centre for Geosciences Potsdam, after accounting for troposphere ties and (ii) direct raytracing through ERA interim. For the evaluation we modified the least-squares module of the VieVS@GFZ
VLBI software to produce two series of solutions. We study the noise characteristics of the non-hydrostaticdelays and horizontal gradients estimated from our VLBI analysis as well as from GNSS and ray-tracing. We
modified the Theil-Sen estimator appropriately to robustly deduce IWV trends from VLBI and GNSS
observations, as well as ray-tracing and direct numerical integration in ERA interim.

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*G06-2-06
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

Tropospheric ties for inter-technique comparisons and combinations
Jan Dousa 1) , * Robert Heinkelmann 3) , Kyriakos Balidakis 2)
Research Institute of Geodesy, Topography and Cartography, Czech Republic 1) , Technische Universitaet
Berlin, Institute of Geodesy and Geoinformation Science, Germany 2) , GFZ Potsdam 3)
Tropospheric parameters are necessarily part of the adjustment process within space geodetic highprecision geodetic processing when using GNSS, DORIS or VLBI data. The intra-/inter-techniquecomparisons of tropospheric parameters, resulting as by-products of the analyses, provide a usefulfeedback for the evaluation of the state-of-the-art models and strategies in the reprocessing. The
development of combining space geodetic techniques at an observation level suggests external
computation of tropospheric ties in order to estimate a single tropospheric correction for two or more
collocated stations of different techniques.
The tropospheric ties are optimally separated into two components - zenith dry and wet delays. Several
models have been used in the past for calculating tropospheric ties for inter-technique comparison of
tropospheric parameters. Recently, we have developed a new method particularly improving verticalscaling of the wet component. Different strategies require different external meteorological data or otherspecific tropospheric parameters fitted specifically for vertical scaling. The tropospheric ties may be
calculated using actual numerical weather data field. Both the accuracy and the simplicity of calculating
tropospheric ties will play a key role in a practical implementation of tropospheric ties in future intertechnique comparison and combination activities.
We evaluated different strategies for calculating or approximating tropospheric ties within two basic
scenarios: a) using numerical weather reanalysis data fields (ERA-Interim) for an assessment of optimal
strategy for the vertical scaling of dry and wet tropospheric components independently, b) assessing theimpact of tropospheric ties in comparison of GNSS and radiosonde tropospheric parameters, and c)evaluating tropospheric ties specifically for GNSS, VLBI and selected DORIS collocated stations in order toassess the impact of tropospheric ties in inter-technique comparison.

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*G06-3-01
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Detection of both icecap and crustal deformation associated with the
2014-2015 Bardarbunga rifting episode* Yuji Himematsu , Masato Furuya
Hokkaido University, Sapporo, JapanThe 2014-2015 Bardarbunga rifting episode is one of the largest event in Iceland. Previous studies havealready reported that the earthquake swarm migrated from Bardarbunga to Holhraun where the fissure
eruptions occurred at northern edge of Vatnajokull icecap. There were few ground-based GPS observation
points near the epicenters of the swarm. While the nearby crustal deformation associated with the episodehave also been detected by using satellite InSAR-data, phase decorrelation problems have hampered
detecting the icecap deformation during the rifting episode. Although the icecap has been known to flow
steadily, one of our motivations is to see if the rifting episode affected the flow speed of ice in light of thewell-known Jokulhlaups event by subglacial eruption. Moreover, phase-based InSAR measurement does
not allow for the detailed measurement of the subsidence over the graben, which is indispensable toconstrain the volume and geometry of intruded dike.
In this study, we processed COSMO-SkyMed images to simultaneously detect both the flow signals on theicecap and the crustal deformation associated with the rifting event. The offset tracking data derived fromCOSMO-SkyMed images showed the displacement signals that consist of both the crustal deformation overland and the icecap flow. Two displacement discontinuities were detected not only on the land but also on
the icecap, while we could not capture the entire image of the both deformations due to the limited SAR
image coverage. The 3D displacements revealed a graben structure with over 8 m subsidence at the graben
floor. At the graben floor, approximately 1 m of the rift-parallel motion which caused by the dog-boneseismicity was detected. Using these observation results, we will estimate the dike intrusion model anddiscuss the possible interaction between the ice and the crustal deformation during the 2014-2015
Bardarbunga rifting episode.

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*G06-3-02
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

Taiwan/TriG Radio Occultation Process System (TROPS)* Cheng-Yung Huang 1) , Wen-Hao Yeh 1) , Tzu-Pang Tseng 2) , Linton Chen 1) , Jing-Mei Wu 2) , Hsiu-Wen Li
2)

National Space Organization, National Applied Research Laboratories, Taiwan 1) , GPS Science andApplication Research Center, National Central University, JhongLi, Taiwan 2)
ABSTRACT
Global Positioning System (GPS) Radio Occultation (RO) technique has been used to investigate the Earth's
atmosphere since 1990. In 2006, Taiwan has launched six low Earth orbit (LEO) satellites as a RO
constellation mission, named FORMOSAT-3 /COSMIC (F-3/C). F-3/C mission can release 1500-2500 data
sets per day for both neutral atmosphere and ionosphere. With the advent of Global Navigation Satellite
System (GNSS) in ten years and FORMOSAT-7/COSMIC-2 (F-7/C-2) mission, 12 LEO satellites areplanned to be launched and deployed in two clusters of 6-satellites into the designated low and highinclination orbits in 2017 and 2019 (TBD), respectively. The amount of RO data set will increase to about
8000 set per day with the using of GNSS TriG (GPS, Glonass, Galileo) receivers. The first phase of F-7
mission is designed to low inclination (24 deg) orbit to improve the ability of server weather forecasting,like typhoon and monsoon rainfall around tropical region. The second is high inclination (72 deg) for
global distribution. This report will introduce the constellation of F-7/C-2 mission, the distribution of RO
profiles, and the status of FORMOSAT-7 Taiwan/Trig RO process System (TROPS) including
Determination(POD), ionospheric and atmospheric data process.

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*G06-3-03
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

Global and regional high resolution VTEC Representations using B-Splines
and Kalman filtering* Michael Schmidt 1) , Andreas Goss 1) , Eren Erdogan 1) , Denise Dettmering 1) , Florian Seitz 1) , Klaus
Boerger 2) , Sylvia Brandert 2) , Barbara Goerres 3) , Wilhelm Kersten 3) , Volker Bothmer 4) , Johannes
Hinrichs 4) , Niclas Mrotzek 4)
Technical University of Munich, Munich, Germany 1) , German Space Situational Awareness Centre,
Uedem, Germany 2) , Bundeswehr Geoinformation Centre, Euskirchen, Germany 3) , Institut für Astrophysik
der Universitaet Goettingen, Goettingen, Germany 4)
The project OPTIMAP is a joint initiative of the Bundeswehr Geoinformation Centre (BGIC), the German
Space Situational Awareness Centre (GSSAC), the German Geodetic Research Institute of the Technical
University of Munich (DGFI-TUM) and the Institute for Astrophysics at the University of Goettingen (IAG).
The main goal of the project is the development of an operational tool for ionospheric mapping andprediction. The tool will consider all available observation techniques (GNSS, satellite altimetry, radio
occultations and DORIS) which are sensitive for the ionosphere and provide global and regional VTEC
products with a high spatial and spectral resolution within a two-level model (TLM).
Since the ionospheric observations from space-geodetic missions are distributed rather unevenly over the
globe, an appropriate modeling approach has to be developed. Our approach is based on a two-levelstrategy with a global modeling part as the first and a regional modeling part as the second level. To be
more specific, the global VTEC model contains moderate regional and spectral resolution, while in areas
with a dense measurement distribution, a regional VTEC model with a higher resolution is set up.
The global VTEC model part is based on a series expansion in terms of polynomial B-Splines in latitude
direction and trigonometric B-Splines in longitude direction whereas the regional model part is set up bypolynomial B-splines for both directions.
In terms to avoid dependencies between the global and the regional models a data selection by means of a"thinning out" procedure, based on station positions, is applied. The two selected subsets of observations
are exploited within multiple Kalman filtering processes which are running in parallel mode in order toestimate the unknown B-spline series coefficients. Additional technique-dependent unknowns such as the
GNSS Differential Code Biases (DCBs) are considered. In this contribution we will present the firstnumerical results.

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*G06-3-04
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

The optimal regularization (alpha-weighted BLE via A-optimal design) and its
application in GNSS-based ionospheric tomography* Jianqing Cai 1) , Kun Qian 1) , Nico Sneeuw 1) , Cheng Wang 2) , Jiexian Wang 3)
University of Stuttgart, Stuttgart, Germany 1) , Wuhan University, Wuhan, China 2) , Tongji University,
Shanghai, China 3)
In this talk the optimal uniform Tykhonov-Phillips regularization (alpha-weighted BLE) by A-optimal design(minimizing the trace of the Mean Square Error matrix MSE) is reviewed. The determination of optimal
regularization parameter via A-optimal design is introduced and its comparison with the results derived bynumerical heuristic methods, such as by means of L-Curve, GCV and ridge trace is also performed. In
which the A-optimal design regularization parameter has been shown to have minimum trace of MSE andits calculation has better efficiency.
In the reconstruction of ionospheric tomography based on the GNSS observations, geometrical limitations(no horizontal ray path, incomplete viewing angles, a limited number of receiving stations, etc.) of the dataacquisition system cause the available data insufficient for ideal reconstruction tomography, which makes
ionospheric tomographic reconstruction an ill-posed problem. In order to overcome the non-uniqueness of
ionospheric tomographic reconstruction, many algorithms have been developed. For example, several kindof regularization algorithms have been applied in solving this kind of ill-posed problem. In theseapplications how to determinate an optimal regularization parameter is remaining an open problem. As acase study here the A-optimal design regularization will be implemented in solving the ill-posed problem of
GNSS-based ionospheric tomographic reconstruction. The reconstruction results will be also analyzed anddiscussed in the sense of optimal and efficient aspects.

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*G06-3-05
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensingContributions to real time and near real time Ionosphere Monitoring by
IAG's RTIM-WG* Alberto Garcia-Rigo 1) , David Roma-Dollase 2) , Manuel Hernandez-Pajares 1) , Zishen Li 3) , Michael
Terkildsen 4) , German Olivares 4) , Reza Ghoddousi-Fard 5) , Denise Dettmering 6) , Eren Erdogan 6) , Haris
Haralambous 7) , Yannick Beniguel 8) , Jens Berdermann 9) , Martin Kriegel 9) , Anna Krypiak-Gregorczyk 10) ,Tamara Gulyaeva 11) , Attila Komjathy 12) , Panagiotis Vergados 12) , Joachim Feltens 19) , Rene Zandbergen
13), Tim Fuller-Rowell 14) , David Altadill 15)
UPC-IonSAT research group, Technical University of Catalonia, Barcelona, Spain 1) , Department ofEngineering: Electronics, University of Barcelona (UB), Spain 2) , Academy of Opto-Electronics, Chinese
Academy of Sciences (CAS), China 3) , Bureau of Meteorology, Space Weather Services, Australia 4) ,Canadian Geodetic Survey, Natural Resources Canada (NRCan) / Government of Canada, Canada 5) ,Deutsches Geodatisches Forschungsinstitut der Technischen Universitat Munchen (DGFI-TUM), Germany
6), Frederick University Cyprus, Cyprus 7) , IEEA, France 8) , Institute of Communications and Navigation,
DLR, Germany 9) , Institute of Geodesy, UWM, Poland 10) , Institute of Terrestrial Magnetism, ionosphereand Radio Wave Propagation, Russian Academy of Sciences, Russia 11) , NASA - Jet Propulsion Laboratory(JPL), California Institute of Technology, USA 12) , Navigation Support Office, ESA-ESOC, Germany 13) ,NOAA affiliate, USA 14) , Observatori de l'Ebre (OE), CSIC - Universitat Ramon Llull, 43520 Roquetes, Spain
15), Planetology and Reference Systems, Royal Observatory of Belgium (ROB), Belgium 16) , Space RadioDiagnostics Research Centre, UWM (SRRC/UWM), Poland 17) , SYMBAN Limited c/o Navigation Support
Office, ESA-ESOC, Germany 18) , Telespazio VEGA Deutschland GmbH c/o Navigation Support Office, ESAESOC, Germany 19) , University of Massachusetts Lowell, Space Science Lab, USA 20)
The status and the research carried out within the International Association of Geodesy (IAG) Real Time
Ionosphere Monitoring Working Group (RTIM-WG), which is part of IAG's Sub-Commission 4.3
Atmosphere Remote Sensing, will be presented.
Of particular interest within the research community is the analysis of St. Patrick's Day 2015 geomagnetic
storm, which will be extended to account for correlations among the multiple independent real time andnear real time (global or regional) ionospheric approaches. In this regard, ionospheric parameters, such as
Total Electron Content (TEC), foF2, hmF2, B0, B1 and the ionospheric disturbance W-index, will beconsidered thanks to the complementary expertise of the WG members.
In addition, the analysis of real time and near real time VTEC Global Ionospheric Maps (GIMs) is anothermajor goal within the team. In this context, the comprehensive study carried out in Roma-Dollase 2016 (D.
Roma-Dollase, M. Hernandez-Pajares, A. Garcia-Rigo, D. Laurichesse, M. Schmidt, E. Erdogan, Y. Yuan,
Zishen Li, J. Ma. Gomez-Cama and A. Krankowski, Real Time Global Ionospheric Maps: a low latency
alternative to traditional GIMs. Beacon Satellite Symposium 2016, June 27 2016, Trieste, Italy) will be
extended based on existing real time and near real time ionospheric VTEC models within the WG,
supporting the IONEX format. In this context, validation based on external data from JASON dualfrequency altimeter will be performed.
Last but not least, experiences within the WG on dissemination and format of GIMs in order to properly
support real time usage will be outlined to promote discussion on this open topic.

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*G06-4-01
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

S4 index observations and global morphology of ionospheric scintillations
using FS3/COSMIC GPS radio occultation data
* Lung-Chih Tsai 1) , Shin-Yi Su 1) , Chao-Han Liu 2) 1)
National Central University, Taoyuan, Taiwan 1) , Academia Sinica, Taipei, Taiwan 2)
We report on the FormoSat-3/ Constellation Observing System for Meteorology, Ionosphere and Climate(FS3/COSMIC) limb-viewing observations of GPS L-band scintillations since mid-2006 and propose to
study global F-layer irregularity morphology. The FS3/COSMIC has generally performed >1000
ionospheric radio occultation (RO) observations per day. We reprocess 1-Hz amplitude data and obtaincomplete limb-viewing profiles of the undersampling-S4 scintillation index from about 80% of the RO
observations. There are a few percent of FS3/COSMIC RO observations having >0.09 undersampling
S4max values on average. However, seven identified areas Central Pacific Area (-20~20 deg dip latitude,
160 deg E~130 deg W), South American Area (-20~20 deg dip latitude, 100 deg W~30 deg W), African Area(-20~20 deg dip latitude, 30 deg W~50 deg E), European Area (30~55 deg N, 0~55 deg E), Japan Sea Area
(35~55 deg N, 120~150 deg E), Arctic Area (>65 deg dip latitude) and Antarctic Area (<-65 deg dip
latitude) have been designated to have a much higher percentage of strong limb-viewing L-band
scintillations. During these years in most of the last sunspot cycle from mid-2006 to the end 2014, thescintillation climatology, namely, its variations with each identified area, season, local time, magnetic
activity and solar activity have been documented.

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*G06-4-02
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

3-D Tomography of Daytime Mid-latitude Sporadic-E from GNSS Data
* Ihsan Naufal Muafiry , Kosuke Heki , Jun Maeda
The University of Hokkaido, Sapporo, Japan
We study ionospheric irregularities caused by daytime midlatitude sporadic-E (Es) in Japan using 3-D(three-dimensional) ionospheric tomography. Es is a thin layer of unusually high ionization that appears at
the altitude of ~100 km. In previous studies, we imaged the Es patches on 2-D maps over Japan (Maeda &Heki, 2014 Radio Sci.; 2015 EPS) using changes in the ionospheric Total Electron Content (TEC) observedwith Japanese GNSS receiver array, GEONET. They found that Es usually show frontal structure extending
hundreds of kilometers predominantly in east-west.
Using the slant TEC residuals as an input, we estimate the electron density anomalies within >2000 small
blocks with dimensions of a few tens of kilometers over a region of 300 x 500 km. We applyed a certain
continuity constraint to stabilize the solution. We considered the distribution of GNSS line-of-sights to know
which area will be properly resolved, and performed checkerboard resolution tests with synthesized data
before using the actual observation data.
We select two examples of clear Es irregularities, i.e. Case 1 over the Kanto District at ~8 UT on 21 May
2010, and Case 2 over the Kyushu District at ~4 UT on 22 May 2010. They are first studied by Maeda &Heki (2014) and Maeda & Heki (2015), respectively. We confirmed that the positive electron density
anomalies showed frontal shapes extending east-west at the E region altitude. In the first case, Es patch
slowly moved southward, and it moved rather rapidly northward in the second case. One interesting featurein their 3-D structures is that positive anomalies expand upward and northward in Case 1, and upward andsouthward in Case 2. The results suggest that the extension direction of the upward continuation of Es
patches might be controlled by their horizontal drift directions.

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*G06-4-03
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Dispersive and Non-dispersive Components in the L-band InSAR Data
Associated with Sporadic-E and Heavy Rain Episodes* Masato Furuya 1) , Takato Suzuki 1) , Youhei Kinoshita 2)
Hokkaido University, Sapporo, Japan 1) , The University of Tokyo, Tokyo, Japan 2)
In contrast to GNSS, SAR imaging is based on a single carrier frequency, andthus no operational ionospheric corrections have been performed in the interferometric
SAR (InSAR) data analyses. Recently, Gomba et al (2016) detailed theprocessing strategy of split-spectrum method (SSM) for InSAR, which splits the finite bandwidth of therange spectrum and virtually allows for dual-frequency measurements. We apply the SSM to the
L-band ALOS1/2 InSAR data to examine the contributions of dispersive and non-dispersive
components. Maeda et al (2016) succeeded in detecting the sporadic-E (Es) signals in both
GNSS/TEC and ALOS/PALSAR InSAR data. Meanwhile, Kinoshita and Furuya (2017)detected phase anomaly in ALOS/PALSAR InSAR data associated with heavy rain overNiigata area, Japan. In this paper, we apply the SSM to the L-band InSAR data that detected both Es andheavy rain episodes. Originally, we expected no anomalies in non-dispersive phases for Es and indispersive phases for heavy rain. To our surprise, however, we notice the presence of phase anomalies inboth dispersive phase in heavy rain and non-dispersive phase in Es. We discuss its geophysicalimplications.

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*G06-4-04
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

Remote sensing of ionospheric TEC using GNSS observations in relation to
space weather events and seismic activity in Bosnia and Herzegovina* Randa Natras 1) 2) , Medzida Mulic 2)
Department of Urban Planning, Construction, Cadastre and Property Affairs, Municipality of Travnik,
Travnik, Bosnia and Herzegovina 1) , Department of Geodesy, Faculty of Civil Engineering, University ofSarajevo, Sarajevo, Bosnia and Herzegovina 2)
Radio signals on their way from Global Navigation Satellite Systems (GNSS) to receiver on the Earth passthrough various layers of atmosphere where ionosphere has major influence on their propagation, which
affects accuracy of positioning and navigation. Monitoring of ionosphere above Bosnia and Herzegovina
was conducted using European Permanent Network (EPN) station SRJV in Sarajevo by investigating total
electrons content (TEC) variability with possible causes of its sudden variations, such as due to space
weather and seismic activities. Day to day variability, seasonal variations, solar activity dependence andlong term TEC trends were investigated for three years (2014 – 2016) from solar maximum to its next
minimum in the solar cycle 24. For statistical analysis lower and upper bounds were determined by 15-day
medians prior and after TEC anomaly ± 2*standard deviation. Results were combined with data of x-ray flux
from Geostationary Operational Environmental Satellites, magnetic activity indices (Kp Ap Dst),
observations of sudden ionospheric disturbances using SuperSID monitor. Transition of solar cycle from its
maximum to its minimum is evident in decreasing trend of TEC from 2014 to 2017. Although somepatterns of TEC variability could be observed, sudden anomalies caused major disturbances in ionospheremostly due to space weather. The strongest geomagnetic storm (Kpmax=8-, Ap=108) in current solar cycle(17/03/2015) increased TEC values for near 60% from monthly median and than decreased to 40% in
following days. Anomalous TECs were investigated for seismic activity of medium intensity (4<M<5). TEC
anomalies prior earthquakes were mainly caused by gap in data and effects of space weather, but the restof anomalies might be connected to seismic activities, such as negative anomalies to 5 TECU under lower
bound observed on the day before and few days after the earthquake with epicenter 13km far from EPN
station SRJV, which requires further investigations.

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*G06-4-05
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Assessment and comparisons of ionospheric vertical total electron content
products* Michael Schmidt 1) , Alberto Garcia-Rigo 2) , Eren Erdogan 1) , Andreas Goss 1) , David Roma-Dollase 3) ,Manuel Hernandez-Pajares 2)
Technical University of Munich (DGFI-TUM), Munich, Germany 1) , Technical University of Catalonia (UPCIonSAT), Barcelona, Spain 2) , University of Barcelona (Department of Engineering), Barcelona, Spain 3)
Accurate modelling of the ionosphere is crucial for GNSS-based applications in positioning and navigation
to mitigate the effect of ionospheric disturbances. Large volumes of GNSS data, which are acquired fromcontinuously operating terrestrial GNSS receivers and distributed worldwide, pave the way of monitoring
the Vertical Total Electron Content (VTEC) of the ionosphere with an increasing accuracy as time goes by.
In this context, many analysis centres are v providing VTEC products with different latencies (e.g. real-time,hourly, daily) and quality as well as they spent effort to improve their models.
The UPC-IonSAT group generates global VTECs maps both in real-time and in post-processing mode using
its Tomographic Model of the Ionosphere electron content (TOMION) software. This software works as anassimilative model of GPS data to create a global 2-layer voxel tomographic representation solved with a
Kalman filter.
The VTEC model of DGFI-TUM is based on tensor products of trigonometric B-spline functions in longitude
and polynomial B-spline functions in latitude for a global representation. The unknown parameters of themodel are sequentially estimated by assimilating GNSS observations using a Kalman filter.
In this study, the performance of the VTEC maps, particularly derived from UPC and DGFI-TUM, isassessed, using e.g. the differenced STEC analysis method and Jason-2 altimetry comparisons. We also
compare our results with other available products, e.g. IGS VTEC maps. Furthermore recent model
improvements are presented.

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*G06-5-02
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

IAG/GGOS inter-comparison campaign on SNR-based GNSS reflectometry
for sea level monitoring
Felipe Geremia-Nievinski 1) , Thomas Hobiger 2) , Karen Boniface 3) , Ruediger Haas 2) , Wei Liu 4) , Nicolas
Roussel 5) , Joakim Strandberg 2) , Sajad Tabibi 6) , Sibylle Vey 4) , * Jens Wickert 4) , Simon Williams 7)
Federal University of Rio Grande do Sul, Brazil 1) , Chalmers University of Technology, Sweden 2) ,Geosciences Environnement Toulouse, University of Toulouse, France 3) , GFZ Potsdam, Germany 4) ,University of Toulouse, France 5) , University of Luxembourg, Luxembourg 6) , National Oceanography
Centre, UK 7)
A joint working group (JWG 4.3.9) on GNSS reflectometry (GNSS-R) was established at the end of 2015
under the auspices of the International Association of Geodesy (IAG) and the Global Geodetic Observing
System (GGOS). Its goal is to foster the adoption of GNSS-R corrections (e.g., hydrological loading) in
geodetic positioning as well as the generation of environmental parameters (e.g., soil moisture and coastal
sea level) based on GNSS-R using conventional geodetic instrumentation. Of particular interest are sea
level estimates using existing GNSS networks by means of signal-to-noise ratio (SNR) analysis. Thisapplication has the potential to become a GGOS data product and an IAG data service in the near future.
JWG 4.3.9 initiated an inter-comparison campaign on SNR-based GNSS-R for sea level monitoring at theend of 2016. Its purpose is to assess retrieval solutions from independent research groups undercomparable conditions. One year of RINEX files with GNSS measurements collected at the Onsala Space
Observatory, Sweden, were made available to JWG 4.3.9 members. More than half participated submitting
single-signal solutions (GPS L1 C/A) as well as a dual-frequency (L1/L2) and dual-constellation(GPS/GLONASS) multi-signal solutions. In general, we found good agreement between the co-located tidegauge record and SNR-based GNSS-R retrievals from different groups. Most correlation coefficients exceed
0.9 and standard deviations are at sub-decimeter level, with some solutions approaching 0.99 and few-cm,
respectively. Systematic effects and/or dependency on meteorological conditions have been revealed andare subject of further discussion within JWG 4.3.9.

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*G06-5-03
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Sea level retrieval based on fitting model of GNSS SNR observations* Wei Liu 1) , Yuan Hu 2) , Maximilian Semmling 3) , Jens Wickert 3) 4)
Shanghai Maritime University 1) , Shanghai Ocean University 2) , German Research Centre for Geosciences(GFZ) 3) , Berlin University of Technology 4)Long-term water level monitoring in coastal regions is important to understand how the local sea level ischanging and affects the human life. This paper presents a new altimetric method for retrieving sea surface
heights by global navigation satellite signals reflected over the ocean surface. It uses SNR observations
from a single geodetic receiver. A detrended SNR fitting model depends on different impact factors of SNR
measurements is proposed. The fitting model searching process includes two steps: the coarse parametersof the detrended SNR model for the whole elevation period of different satellites are searched based on
optimization method firstly. Then, the fine model parameters for small temporal samples are refined basedon the estimated coarse parameters. Ground-based sea level measurements that was conducted at theOnsala Space Observatory from July 1, 2015 to June 30, 2016 demonstrate, that altimetric information
about the reflecting water surface can be obtained with a Root Mean Square Error of 9.29 cm with respect
to a reference tide gauge dataset. The sea surface changes, derived from our field experiment and thereference tide gauge, are highly correlated with a correlation coefficient of 0.93. Experimental results of the
SNR measurements show the proposed method can perform much higher temporal resolution and havehigher accuracy when compared to the previously spectral methods.

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*G06-5-04
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Observation of sea surface heights from moving ships based on analysis of
GNSS-SNR data
* Joerg Reinking
Jade University Oldenburg, Germany
Current studies investigate the possibilities to combine satellite altimetry and tide gauge readings with
GNSS-based observations from moving ships to derive precise information of the sea surface height (SSH).
The latter method requires determining the variable distance between the GNSS antenna and theundisturbed water surface. Commonly the distance is calculated based on hydrostatic and hydrodynamic
data. Since some of the necessary corrections are not always available or not easy to derive (draft changes
due to fuel consumption or ship squat), it would be desirable to connect the GNSS antenna and the sea
surface by direct and continuous observations.
It is well-know that GNSS-SNR data can be utilized to derive water surface heights. Up to now, existing
inversion techniques were only used for the analysis of SNR observations from static GNSS antennas. If
these techniques could be applied also to observations from moving ships, the resulting reflector height
could be used together with GNSS -derived antenna heights to directly observe the ellipsoidal height of thewater surface around the ship without the need of dynamic corrections.
To assure that the used SNR observations are not influenced by the wave system of the ship only data fromlow elevation angles should be analysed. The movements of the ship can be calculated from theobservations of at least three GNSS antennas aboard the ship and will be used to correct for the shortperiodic variations of reflector heights in the inversion step. Hence, the static reflector height together witha long-term variation due to draft change and squat effect can be modelled as 2D time depending function.
The inversion of the SNR data is carried out by global optimization based on interval analysis. This method
will be applied to a data set from a ship cruise in the North Sea. The results from this experiment will bepresented and future applications will be discussed.

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*G06-5-05
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensingWind Direction Retrieval in Airborne Experiments of a GNSS-R Receiver* Sheng-Hsiung Ma , Jyh-Ching Juang
National Cheng Kung University, Tainan, Taiwan
The GNSS reflected signals have been proposed for the remote sensing of sea surface altimetry, ocean
wind speed, salinity, soil moisture. A GNSS reflection receiver provides the delay-Doppler map (DDM) as
the raw measurement for the retrieval of remote sensing variables. Indeed, the spreading and geometry of
the DDM is related to geophysical property of ocean surface. In this paper, the experimental and retrieval
results by using a GNSS reflectometry (GNSS-R) receiver are described. The GNSS-R receiver is anindigenous design that is capable of processing reflected GNSS signals and generating the DDM in realtime. Two airborne experiment data sets are processed for the retrieval of wind direction. The retrieval
results are compared with the measurement result on buoys operated by the Central Weather Bureau of
Taiwan. In addition, different retrieval methods are discussed.

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*G06-5-06
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

GNSS Reflectometry onboard the International Space Station with GEROSISS: Review of activities and current status* Jens Wickert 1) 2) , Estel Cardellach 3) , Manuel Martin-Neira 4) , Ole Andersen 5) , Jorge Bandeiras 6) ,Laurent Bertino 7) , Adriano Camps 8) , Jan Saynisch 1) , Nuno Catarinho 6) , Christine Gommenginger 10) ,C.K. Shum 14) , Cinzia Zuffada 12) , Giuseppe Foti 10) , Jiping Xie 7) , Per Hoeg 5) , Adrian Jaeggi 11) , Michael
Kern 4) , Tony Lee 12) , Maximilian Semmling 1) , Hyuk Park 8) , Nazzareno Pierdicca 13)
GFZ Potsdam, Germany 1) , Technische Universitaet Berlin, Germany 2) , IEEC/ICE-CSIC, Institute of Space
Sciences, Barcelona, Spain 3) , European Space Agency, ESTEC, Noordwijk, The Netherlands 4) , Technical
University of Denmark, Copenhagen, Denmark 5) , DEIMOS Engenharia, Lisbon, Portugal 6) , Nansen
Environmental and Remote sensing Center, NERSC, Bergen, Norway 7) , IEEC/CTE-UPC, Center for SpaceTechnologies, Barcelona, Spain 8) , Ifremer, Paris, France 9) , National Oceanography Center, Southampton,
U.K. 10) , University Bern, Switzerland 11) , Jet Propulsion Laboratory, Pasadena, Caltech, USA 12) , Sapienza
University of Rome, Italy 13) , Ohio State University, Columbus, USA 14) , Collecte Localisation Satellites,
Ramonville St-Agne, France 15)
GEROS-ISS is an innovative ISS experiment of the European Space Agency (ESA) primarily focused on
exploiting reflected signals of opportunity from Global Navigation Satellite Systems (GNSS) at L-band tomeasure key parameters of ocean surfaces.
The primary mission objectives are: (1) to measure the altimetric sea surface height of the ocean usingreflected GNSS signals and (2) to retrieve scalar ocean surface mean square slope (MSS), which is related
to sea roughness, wind speed and direction.
Secondary mission objectives are related to further explore the potential of GNSS radio occultation data for
global atmospheric sounding and to assess the potential of GNSS scatterometry for land applications.
Two competitive industrial phase A studies were completed in 2016, complemented by the international
scientific study GARCA (GNSS-R – Assessment of Requirements and Consolidation of Retrieval Algorithms)
to develop an End2End Simulator for the preparation of the GEROS-Mission and to perform ObservingSystem Simulation Experiments (OSSE) to assess the oceanographic significance of the expected GEROSISS measurements. In parallel to these studies dedicated flight campaigns were carried out to monitor thesea surface height of the Baltic Sea around Helsinki, Finland utilizing the interferometric GNSSReflectometry approach, which is planned to be implemented for GEROS.
GEROS was originally foreseen to be launched in 2019. Following the Phase A industrial contracts and theparallel scientific study, ESA is now leading a mission reduction exercise aimed at bringing its cost
significantly down while keeping the most essential scientific objectives. We review the activities related to
the GEROS-ISS experiment and inform on the recent mission status.

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*G06-P-01
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Assessing Precise Point Positioning Derived Zenith Total Delays Using the
NIGNET
Omeiza Mayaki 1) , * Marcelo Santos 1) , Thaleia Nikolaidou 1) , Chukwuma Okolie 2)
University of New Brunswick 1) , University of Lagos 2)
Global Navigation Satellite Systems (GNSS) is increasingly being used worldwide in operational
meteorology with the estimation of parameters such as zenith total delay (ZTD). Due to its continuous
evolution, precise point positioning (PPP) has become an increasingly used technique for estimating ZTDfrom GNSS data. Many nations utilize dedicated GNSS receiver networks as continuously operatingreference stations (CORS) for operational weather and climate services. The focus of this research is toassess the quality of PPP derived ZTDs using data collected by the Nigerian GNSS Reference Network(NIGNET) and a local and nearby International GNSS Service (IGS) station. NIGNET is a network offourteen stations equipped with GPS and GLONASS dual frequency capable receivers. Data collected from
1st January 2011 to 9th November 2016 is used in the assessment. The estimates are compared with raytraced estimates from the global Numerical Weather Model (NWM) of the National Centre forEnvironmental Prediction (NCEP), and estimates from the IGS final troposphere product. A time series
analysis is performed to access the level of agreement of the products and identify possible systematiceffects arising from the different techniques. Results indicate a 3 cm root mean square value of thedifferences, and that the variation exhibited by the PPP ZTD estimates correlates with known annual
weather patterns across the country.

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*G06-P-02
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

Calibration of empirical thermospheric models by using laser observations
to near-Earth orbiting spherical satellites* Michael Schmidt 1) , Mathis Blossfeld 1) , Chao Xiong 2) , Hermann Luehr 2)
Technical University of Munich (DGFI-TUM), Munich, Germany 1) , Deutsches GeoForschungsZentrum
GFZ (Section 2.3), Potsdam, Germany 2)
The thermosphere causes by far the largest non-gravitational perturbing acceleration of near-Earth orbiting
satellites. Especially between 80 km and 600 km, the thermospheric density distribution and variations are
required to accurately model this force. So far, mainly accelerometers onboard of satellites are used tomeasure the thermospheric density. However, such type of satellite is usually of complex shape and any
error or miss-modelling of the satellite drag coefficients will directly propagate into the derived
thermospheric density values.
At GFZ, an empirical model of the thermospheric mass density has been developed by using 9 years of
CHAMP observations. The model is based on seven `key' parameters, namely height, solar flux, season,
magnetic local time, geographic latitude, and magnetic activity.
A completely different approach is to use satellite laser ranging (SLR) measurements to satellites equippedwith retro-reflectors to determine the most accurate satellite orbit. These measurements are sensitive tosmall perturbations acting on the satellite. In order to minimize the error induced by wrong satellite macromodels, we use ranging observations to satellites with a simple spherical shape. Therefore, the derived
thermospheric density values can be seen as `absolute' density values.
In this study, we use SLR observations at least to the four ANDE satellites with altitudes between 350 km
and 400 km to calibrate the empirical model developed at GFZ. The main features of the GFZ model arethen compared to standard thermospheric models for different solar activity conditions.

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*G06-P-03
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Impact of heat island effect on rainfall patterns under global warming: casestudy of Taipei City
* Ta-Kang Yeh 1) , Jing-Shan Hong 2) , Kuan-Chen Su 1) , Shih-Liang Chan 1)
National Taipei University, Taiwan 1) , Central Weather Bureau, Taiwan 2)
Sustained global development with the environmental issues have been repeatedly discussed andattention, while the Taipei region is also under the influence of climate change. In the past, it is known that
there are severe heat island effects in the urbanized area of Taipei, and the hydrological change is causedby temperature change. The city continues to develop, so for the suburbs to carry out comprehensive
weather detection and early warning is a matter of urgency. In this study, we observed the influence of heatisland effect on the temperature, Precipitable Water Vapor (PWV) and rainfall in the suburbs. According to
the results, the study confirmed that the urban area and the urban area have a rising trend during theperiod from 2006 to 2014, which is about 0.7 degree higher than that in the suburbs. The temperature in
the suburbs decreases by 1.1 degree, of the decline is greater than the urban areas. The average PWV
increased about 6.7 mm, the cumulative rainfall also increased about 54.7 mm. The other two hightemperature areas are gathered in the development zone, and in the northern mountain area presents a lowtemperature, heat island effect occurs obviously. Moreover, the rainfall is largest in the mountainous areasof the southern region in summer. While the winter due to wind direction, the rainfall falls in thenortheastern region of the windward side. The results show that there is a significant urban heat islandeffect in the Taipei region, and the overall increase in the amount of PWV increases with the global
warming and more rain falls in the urban area. In the face of future urban areas with more flooded
conditions due to climate change, we need to strengthen the attention and planning of hardware fordisaster prevention and flood prevention in urban areas to avoid irreparable disasters and losses.

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*G06-P-04
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensing

Ray-traced radio occultation profiles during tropical cyclones* Pawel Hordyniec 1) , Cheng-Yung Huang 2) , Witold Rohm 1)
Wroclaw University of Environmental and Life Sciences, Institute of Geodesy and Geoinformatics, Wroclaw,
Poland 1) , National Space Organization, HsinChu, Taiwan 2)
We used Global Forecast System (GFS) model as an environment to propagate microwave signal alongoccultation plane between GNSS satellite and low-Earth orbiter in order to assess ray-traced radio
occultation atmospheric products. We restored 2-dimensional structure of bending angle and associatedexcess phase by means of geometry optics in non-spherically symmetric atmosphere neglecting out-ofplane components. Since the spherical symmetry assumption is commonly applied for retrieval of radio
occultation profiles, we also considered the GFS refractivity above tangent point to be consistent withmedium along propagation paths. The Abel transform is used to prove correct simulations. Above
troposphere, where strong horizontal gradients usually are not observed, we were able to estimate signal
amplitude under geometry optics. However, tropospheric signal to noise ratio needs to be resolved in wave
optics due to multipath effect based on simulated bending angle profiles. The radio occultation data
provided by COSMIC Data Analysis and Archive Center (CDAAC) in atmPrf and wetPrf products wereconsidered as an additional source of reference for bending angle as well as atmPhs containing amplitude
and phase data. To demonstrate capability of the ray-tracer, simulations were conducted under severe
weather conditions on the example of tropical cyclones that passed through Taiwan in 2016. In such
events, significant horizontal irregularities can be observed, hence we calculated and analyzed residuals
between spherically symmetric and asymmetric ray-traced parameters together with amplitude variations.

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*G06-P-05
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sensingRegional Precipitation Prediction Based On Tropospheric Gradients andDelay Time Series
Janina Boisits 1) , Gregor Moeller 1) , Christoph Wittmann 2) , Robert Weber 1) , * Johannes Boehm 1)
TU Wien - Department of Geodesy and Geoinformation, Vienna, Austria 1) , Central Institution for
Meteorology and Geodynamics, Vienna, Austria 2)
Changes of temperature and humidity in the neutral atmosphere cause variations in tropospheric pathdelays and tropospheric gradients. Thus, time series of GNSS-based tropospheric parameters provide
information about spatial and temporal variations of water vapour in the atmosphere and, therefore, cancontribute to the forecast of regional precipitation events.
In a recently finalized master thesis at TU Wien the information content of tropospheric parameters forweather prediction was investigated. Two characteristics in ZWD and gradient time series can be
anticipated in case of an approaching weather front. First, an induced asymmetry in tropospheric delays
results in both, an increased magnitude of the gradient and in gradients pointing towards the weather front.
Second, an increase in ZWD reflects the increased water vapour concentration right before a precipitation
event. To investigate these characteristics exemplary test events were processed. Therefore, ZWD andgradient time series at selected GNSS reference stations were compared to precipitation data. All required
meteorological data was provided by the Central Institution for Meteorology and Geodynamics (ZAMG).
It can be deduced, that GNSS-based tropospheric parameters show high potential for predicting
precipitation events. The sequence of the anticipated increase in ZWD at each GNSS station indicates theorientation of the air mass boundary. Furthermore, the magnitude of ZWD increase at each stationsuggests, whether the station is affected by the precipitation event or not. Gradients rather indicate thedirection of movement of an approaching weather front. Additionally our investigations have shown, that
gradients are able to capture the characteristics of an approaching weather front twenty to thirty hours
before the precipitation event, which allows a first indication well in advance.

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*G05-P-06
IAG Symposium / IAG04. Positioning and Applications / G05. Multi-signal positio
ning: Theory and applications

Multiplicative random error models: Parameter estimation and error analysis* Yun Shi , Jing Zhang , Peng Chen , Jie Lv , Chao Li
Xi'an University of Science and Technology
Conventional geodetic adjustment theory has been almost always developed on the linear and/or
linearized model of measurements. The most important feature of these conventional adjustment methods
and theory are that the random errors of measurements are added to the functional models. In other words,
the sizes or magnitudes of random errors are independent of the true values of measured quantities.
However, in geodetic practice, we know that this assumption is not necessarily always true. For example,
we know that the accuracy of an EDM, GPS and/or VLBI baseline is proportional to the length of thebaseline itself, which clearly indicates that the random errors of this type are proportional to the measured
quantities. From the statistical point of view, such random errors should be multiplied to the functionalmodels and are not additive any more. In this talk, we will extend the conventional model of geodetic
adjustment to account for multiplicative errors and/or mixed additive-multiplicative errors. We will address
the parameter estimation and error analysis in the linear/linearized model of measurements with mixed
additive-multiplicative random errors. More specifically, we will first discuss three least-squares-based
methods to estimate the model parameters, namely, least squares, weighted least squares (LS) and biascorrected weighted least squares. We will then analyze these three methods from the statistical point ofview. We construct five estimators of the variance of unit weight in association with the three LS-based
methods and compare them, statistically and through numerical simulations. Although LiDAR data havebeen proved to be of multiplicative nature, they have been treated as if they were of additive random errors.
Thus, as a final part, we will simulate a landslide example, which is supposed to be surveyed with LiDAR, todemonstrate how the methods discussed here works and how they can be applied to DEM construction fordisaster monitoring.

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*G06-P-07
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Ionospheric parameters determination using integrated space geodetic data(case study: Iran)
Saeed Zare 1) , Mahdi Alizadeh 1) , * Michael Schmidt 2)
K.N.Toosi University of Technology 1) , Technical University of Munich 2)
Ionosphere is a layer of the upper atmosphere, between the thermosphere and the exosphere,
distinguished because it is ionized by solar radiation. As an important part of human living environment,
ionosphere affects our modern society in many ways, e.g. International broadcasters use this medium toreflect radio signals back toward the Earth. In last decade space geodetic techniques have turned into acapable tool for studying the ionosphere. Up to now, two dimensional models of vertical TEC have been
widely developed and used by different communities; however, due to the fact that these models provide
information about the integral of the whole electron content along the vertical or slant ray path, these maps
are not useful when information about the ionosphere at different altitude is required.
This paper includes the extraction of ionospheric parameters from radio signals observed by various spaceobservation techniques; i.e. Ionospheric Radio Occultations measurements from Low Earth Orbit satellites
and observations from Global Navigation Satellite Systems (GNSS). Due to the commonly heterogeneous
distribution of the data, the selection of suitable basis functions is an important issue. For this reason weapplied B-Spline basis functions. B-Spline basis functions are used for longitude and latitude variations of
the electron density and Chapman profile function for altitude variations. The required data for ourinvestigation are ground based measurements of permanent GPS stations over Iran and radio occultation
data from Formosat-3/Cosmic for region of interest.
The National Cartographic Center of Iran (NCC) has established a network of one hundred GPS stations:
The Iranian Permanent GPS Network for Geodynamics. By integrating observations from various
observation techniques, it is expected to have an increase in accuracy and reliability of final model ofelectron density.

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*G06-P-08
IAG Symposium / IAG04. Positioning and Applications / G06. Geodetic remote sens
ing

Ionospheric scintillation detection based on GPS observations, a case study
over Iran
Sahar Sobhkhiz 1) , Mahdi Alizadeh 1) , * Michael Schmidt 2)
K.N.Toosi University of Technology 1) , Technical University of Munich 2)
The earth's upper atmosphere –the ionosphere– is a highly variable region with complex physical structure
which is produced by ionizing radiations from the sun. a layer of ionosphere, extended from 250 to 400 km
above the earth's surface which contains the greatest amount of free electrons, is called F-region. Duringstrong geomagnetic activities, this region would be disturbed; also small-scale irregularities in electron
density would be developed. Signals from Global Positioning System (GPS), pass through this region before
reaching receivers on the Earth and therefore if the irregularities are sufficiently enough, signals may
experience rapid amplitude fluctuations or unexpected phase changes. This is referred to as ionosphericscintillation. Ionospheric scintillation is one of the dominant propagation disturbances at radio frequency
signals. These irregularities severely affect the accuracy and reliability of GPS measurements. Therefore itis necessary to investigate ionospheric scintillation and its effects on GPS observations.
The focus of this paper is to detect ionospheric scintillations over Iran's region, during different periods ofsolar activity and to investigate these effects on GPS observations in more detail. Furthermore the effects ofthese irregularities on regional modeling of ionosphere over Iran is also investigated. The results show that
effectiveness of this phenomenon depends on geographic location, local time and global geomagnetic
storm index (kp index).
The required data for this investigation are ground based measurements of permanent GPS stations overIran, established by the National Cartographic Center of Iran (NCC).

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*G07-1-01
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

The Contribution of Geodetic Observations to Science and Society* Richard Gross
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA
Earth observations are needed not only for scientific research but also for societal applications such as
disaster prevention and mitigation, managing resources like energy, water, and food, mitigating the effects
of climate change, and protecting the biosphere, the environment, and human health. Geodetic
observations provide the metrological foundation for Earth observations and provide the means todetermine mass transport in the Earth system. Geodetic observations are therefore a cornerstone of the
Earth observing systems needed for scientific research and societal applications. Geodetic observations
also provide the basis for realizing the reference systems that are required in order to assign coordinates topoints and objects in space and time and to describe the motion of the Earth in space. The International
Terrestrial Reference Frame (ITRF) determined by geodetic observations is the indispensable foundation
for all the sustainable Earth observations that are used by science and society for so many purposes,
including navigation, mapping, surveying, construction, land development, natural resource management
and conservation—in fact, all decision-making activities that have a geo-related component. It allows
different spatial information, such as imagery from different space and airborne platforms, to be georeferenced and aligned with each other. And it plays a key role in modeling and estimating the motion of
the Earth in space, in measuring change and deformation of all components of the Earth system, and inproviding the ability to connect measurements made at the same place at different times, a criticalrequirement for understanding global, regional and local change. In this presentation, selected examples of
the contribution of geodetic observations to science and society will be presented.

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*G07-1-02
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

The GGOS Bureau of Networks and Observations: Activities and Plans
Michael R Pearlmaan 1) , Chopo Ma 2) , Ruth Neilan 3) , Carey E Noll 2) , Erricos Pavlis 4) , Jerome Saunier 5) ,Tilo Schoene 6) , Riccardo Barzaghi 7) , Daniela Thaller 8) , Sten Bergstrand 9) , Juergen Mueller 10) , * Richard
Gross 3)
Center for Astrophysics, Cambridge, MA, United States 1) , NASA Goddard Space Flight Center, Greenbelt,
MD, United States 2) , Jet Propulsion Laboratory/CalTech, Pasadena, CA, United States 3) , University of
Maryland, Baltimore, MD, United States 4) , Institut Geographique National, Saint Mande Cedex, France 5) ,GeoForschungsZentrum, Potsdam, Germany 6) , Politecnico di Milano, Milan, Italy 7) , Bundesamt fuer
Kartographie und Geodaesie, Frankfurt, Germany 8) , SP Swedish Technical Research Institute, Boras,
Sweden 9) , Institut fuer Erdmessung, Hannover, Germany 10)
Working with the IAG geometric services (VLBI, SLR, GNSS, and DORIS) the Bureau continues to advocate
for the expansion and upgrade of the space geodesy networks for the maintenance and improvement of thereference frame and other application, and for the extension and integration with other techniques. New
sites are being established following the GGOS concept of “core" and co-location sites; new technologies
are being implemented to enhance performance in data yield as well as accuracy. Several groups areundertaking initiatives and seeking partnerships to update existing sites and expand the networks in
geographic areas currently void of coverage. The Bureau continues to meet with organizations to discusspossibilities of new and expanded participation and to promote the concept of partnerships. The Bureau
provides the opportunity for representatives from the services to meet and share progress and plans, and to
discuss issues of common interest. The Bureau monitors the status and projects the evolution of the
network based on information from the current and expected future participants. Of particular interest at
the moment is the integration of gravity and tide gauge networks. The Committees and Joint Working
Groups play an essential role in the Bureau activities: using simulation and analysis techniques to project
future network capability and to examine trade-off options, working on strategies for GGOS metadata
systems, enhancing communication with the space missions and advocating for missions that support
GGOS goals, working to enhance standardization in ground survey procedures and encouraging
participation of new survey groups.
The 2007–2018 Implementation Plan for the GGOS Bureau of Networks and Observations has been postedon the GGOS website. We will outline progress over the past two years and discuss the status of the
network and updated plan.

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*G07-1-03
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

GGOS Bureau of Products and Standards: Recent activities and future plans* Detlef Angermann 1) , Thomas Gruber 1) , Michael Gerstl 1) , Urs Hugentobler 1) , Laura Sanchez 1) , Robert
Heinkelmann 2) , Peter Steigenberger 3)
Technische Universitaet Muenchen, Muenchen, Germany 1) , GeoForschungsZentrum Potsdam, Potsdam,
Germany 2) , Deutsches Zentrum fuer Luft- und Raumfahrt, Germany 3)
The Bureau of Products and Standards (BPS) supports GGOS in its goal to obtain consistent products
describing the geometry, rotation and gravity field of the Earth, along with its variations in time. The main
purpose of the BPS is to keep track of adopted geodetic standards and conventions across all IAG
components as a fundamental basis for the generation of consistent geometric and gravimetric products.
The work of the BPS is primarily built on the IAG Service activities in the field of data analysis andcombinations. The BPS acts as contact and coordinating point regarding homogenization of standards and
IAG products. As a key activity the BPS has performed an assessment of the standards and conventions
currently adopted and used by the IAG and its components for the processing of geometric and gravimetricobservations and as a basis for the generation of IAG products. The results of this BPS inventory were
published in the IAG Geodesist's Handbook 2016.
In this contribution we present the role of the BPS and summarize the major findings of its recent activities.
Some examples of the product-based BPS inventory on standards and conventions will be highlighted. It
will also be discussed how to proceed with the recommendations given in the inventory and how to resolveinconsistencies and gaps in order to improve the consistency of IAG products. This presentation will also
give an overview of the contributions of the BPS towards the integration of geometric and gravimetricparameters and the development of new products, required to address important geophysical questions
and societal needs.

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*G07-1-04
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Space Geodetic Activities and GGOS Working Group in Japan* Toshimichi Otsubo 1) , Basara Miyahara 2) , Ryoji Kawabata 2) , Yuichi Aoyama 3) , Yuichi Fukuda 4) ,Yusuke Yokota 5) , Hiromi Yamao 2) , Shigaru Matsuzaka 6)
Hitotsubashi University, Kunitachi, Japan 1) , Geospatial Information Authority of Japan, Tsukuba, Japan 2) ,National Institute of Polar Research, Tachikawa, Japan 3) , Kyoto University, Kyoto, Japan 4) , Japan Coast
Guard, Tokyo, Japan 5) , (retired) Geospatial Information Authority of Japan, Tsukuba, Japan 6)
Japan has been actively involved in space geodetic observations, technical developments and data
analyses since 1970s. Eminent long-term examples are Shimosato Hydrographic Observatory for SLR(Satellite Laser Ranging), GSI (Geospatial Information Authority of Japan) Tsukuba Station and NIPR
(National Institute of Polar Research) Syowa Station for VLBI (Very Long Baseline Interferometry), and
NICT (National Institute of Information and Communications Technology) being one of the VLBI TechnicalDevelopment Centers. More institutes and individuals have a number of achievements.
Japanese geodetic activities had leaned a little to monitoring local and regional deformation. At the earlystage of IAG GGOS (Global Geodetic Observing System), Japan did not present much involvement, but the“GGOS Working Group" was formed in 2013. Helped by a number of institutes and organizations, theGeodetic Site List was assembled in 2014 where 10 geodetic sites in Japan and one geodetic site in
Antarctica were included. Each site has at least one VLBI or SLR station collocated with a GNSS station,and some of them has a DORIS antenna and a gravimeter. The list was submitted to the GGOS bureau andall sites were approved as a GGOS site. It should be noted that 5 different institutes own and operate thesesites. Each of them has its own backgrounds and missions but all of them have worked in collaboration.
Due to seismic deformation, especially the 2011 Tohoku Earthquake, the motion of the geodetic sites inJapan cannot be properly expressed by the conventional piecewise linear function. However, the use of
post-seismic deformation models newly introduced in ITRF2014 is expected to ease the problem, and theJapanese stations can contribute to global-scale geodetic products.
The GGOS WG of Japan strives to improve the quality and productivity of our geodetic stations, toencourage the collaboration beyond each technique, and to make/help strategic projects for the future.

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*G07-1-05
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Observing the Earth's gravity field as integral component of the Global
Geodetic Observing System
Roland Pail 1) , * Riccardo Barzaghi 2)
Technical University of Munich, Munich, Germany 1) , Poltecnico di Milano, DICA, Italy 2)
Observing the Earth's gravity field addresses in several aspects the mission of GGOS. It provides a) the
direct observation of mass variations (due to geophysical signals) and mass transport processes, b) a
physical height reference surface, with respect to which very small change processes can be described, andc) the definition of the datum of the terrestrial reference frame.
The first generation of satellite gravity missions (CHAMP, GRACE, GOCE) has revolutionized our picture of
the static and time-variable gravity field. However, due to signal attenuation with altitude gravity models
based on satellite data are restricted to 70-80 km wavelength, so that a combination with ground data is
still indispensable for high-resolution applications such as the definition and global unification of heightsystems. Service applications with significant societal benefit such as forecasting of floods and droughts orwater management require not only a higher spatial resolution, but also the provision of the temporalchanges of the gravity field in near real-time.
In this paper the achievements, but also limitations of the current observation of the Earth's gravity field are
discussed. An inventory of the GGOS satellite infrastructure, which is needed to achieve the GGOS 2020
goals, performed by the GGOS Standing Committee on Satellite Missions, has revealed that that gravity
field missions are the most critical component to be continuously maintained in the future. Therefore,
current international activities to advocate satellite gravity missions and thus to foster a sustained gravity
field observations system from space as integral component of the GGOS satellite infrastructure in the
future are presented, and the added value of improved measurement technology and innovative mission
concepts is discussed. Finally, special emphasis will be given to the gravity field contributions to a globallyunified height system as integral part of a Global Geodetic Reference Frame.

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*G07-1-06
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

A first approximation to the International Height Reference Frame (IHRF)* Laura Sanchez 1) , Heiner Denker 2) , Denizar Blitzkow 3) , Roland Pail 1) , Jianliang Huang 4) , Daniel
Roman 5) , Matt Amos 6) , Johannes Ihde 7) , Riccardo Barzaghi 8) , Michael Sideris 9) , Ilya Oshchepkov 10) ,Ana C.O.C. Matos 3) , Diego Pinon 11) , David Avalos 12) , Silvio R.C. Freitas 13)
Technische Universitatet Muenchen, Germany 1) , Leibniz Universitaet Hannover, Germany 2) ,Universidade de Sao Paulo, Brazil 3) , Natural Resources Canada, Canada 4) , National Geodetic Survey,
NOAA, USA 5) , Land Information New Zealand, New Zealand 6) , Helmholtz-Zentrum Potsdam, Deutsches
GeoForschungsZentrum, Germany 7) , Politecnico di Milano, Italy 8) , University of Calgary, Canada 9) ,Center of Geodesy, Cartography and SDI, Russia 10) , Instituto Geografico Nacional, Argentina 11) , Instituto
Nacional de Estadistica y Geografia, Mexico 12) , Universidade Federal do Parana, Brazil 13)
The International Height Reference System (IHRS) is defined as a geopotential reference system corotating with the Earth. Coordinates of points attached to the solid surface of the Earth are given by (1)geopotential numbers C(P) referring to the equipotential surface defined by the conventional W0 value
62636853.4 m2s-2 and, (2) geocentric Cartesian coordinates X referring to the International Terrestrial
Reference System (ITRS). The determination of the coordinates C(P) and X(P) includes their variation withtime. As W0 is a conventional constant value, C(P) basically depends on the potential value W(P). Thus,
W(P) may be understood as a main coordinate of the IHRS. The present challenge is the realization of the
IHRS; i.e., the establishment of the International Height Reference Frame (IHRF). This comprises, among
others, (1) the selection of a global well-distributed set of stations as the IHRF core network, and (2) the
development of strategies for the precise computation of the coordinates W(P) and X(P) at those corestations. While X(P) may be determined following the standards and conventions of the International Earth
Rotation and Reference Systems Service, the estimation of the potential values W(P) is not a standardized
procedure so far. Consequently, the establishment of the IHRF also includes the identification ofharmonized standards for the consistent determination of W(P) and X(P), the precise modelling of the timedependent changes of the coordinates, and the implementation of strategies for the collocation of IHRF
reference stations with other reference frames (like the GGRF, the ITRF, geodetic observatories, timelaboratories, etc.). This contribution presents the first approximation to the IHRF: it describes thepreliminary IHRF core network and the criteria applied to select its reference stations. It also discusses andcompares different approaches for the computation of the potential values W(P) at the IHRF core stations.

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*G07-2-01
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Activities of the UN GGIM on the Global Geodetic Reference Frame
Gary Johnston 1) , Laila Lovhoiden 2) , Anne Jorgensen 2) , * John Dawson 1)
Geoscience Australia 1) , Norwegian Mapping Authority 2)
The United Nations initiative on Global Geospatial Information Management (UN-GGIM) plays a leadingrole in setting the agenda for the development of global geospatial information and promoting its use inaddressing key global challenges. It provides a forum for liaison and coordination between Member States,
and also between Member States and international organizations. Recognizing the importance of the Global
Geodetic Reference Frame (GGRF) for science and societal applications the UN GGIM facilitated a groupof interested member nations and international organisations, including the IAG, to commence cooperation
on global geodesy under the auspices of the UN. This presentation will detail the achievements so far
including the adoption of a UN General Assembly Resolution on Geodesy and the development of aRoadmap for the sustainability and enhancement of GGRF. It will also discuss plans for the development of
an implementation plan for the GGRF Roadmap.

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*G07-2-02
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Roadmap to implement the UN resolution on Global Geodetic Reference
Frame in Europe* Markku Poutanen
Finnish Geospatial Research Institute FGI, Masala, Finland
In February 2015 the United Nations General Assembly adopted the resolution on a Global Geodetic
Reference Frame for Sustainable Development (A/RES/69/266), recognizing the importance of a globally
coordinated approach to geodesy. The plan and the roadmap were formulated by the working group on the
Global Geodetic Reference Frame (GGRF) of the United Nations Committee of Experts on Global
Geospatial Information Management (UN-GGIM).
UN-GGIM has regional entities, including UN-GGIM:Europe. In connection with the implementation of the
GGRF roadmap it is assumed beneficial that the regions contribute through regional GGRF working groups.
The UN-GGIM: Europe working group “GRF-Europe" (Geodetic Reference Frames – Europe) wasestablished in 2016 to prepare and implement the plan in Europe. GRF-Europe will be working with a close
connection to geodesy-related organizations in Europe and actively contribute to the work of the subcommittee on Geodesy in UN. GRF-Europe will provide a link between the geospatial community, scientists
and policy makers. In this presentation we will describe current status and plans of GRF-Europe.

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*G07-2-03
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Recent Activities of the GGOS Standing Committee on Performance
Simulations and Architectural Trade-Offs (PLATO)* Benjamin Maennel 1) , Daniela Thaller 2) , Markus Rothacher 3) , Johannes Boehm 4) , Juergen Mueller 6) ,Mathis Blossfeld 5) , Alexander Kehm 5) , Susanne Glaser 1)
Deutsches GeoForschungsZentrum GFZ, Potsdam, Germany 1) , Bundesamt fuer Kartographie undGeodaesie, Frankfurt am Main, Germany 2) , ETH Zurich, Zurich, Switzerland 3) , TU Vienna, Vienna, Austria
4), Deutsches Geodaetisches Forschungsinstitut - TU Muenchen, Munich, Germany 5) , Leibnitz
Universitaet Hannover, Hanover, Germany 6)
The terrestrial reference frame (TRF) is the foundation for virtually all space-based and ground-based Earthobservations. The commonly used global TRF is the International Terrestrial Reference Frame (ITRF) thatis generated by combining the observations of GNSS, VLBI, SLR and DORIS. GGOS has determined thatthe accuracy and stability of the ITRF, suitable for a global society on a changing planet, needs to be better
than 1mm and 0.1mm/y, respectively. As these goals are not yet reached, several improvements areneeded:Developing next generation space-geodetic stations with improved technology and system performance;
Improving the ground network configuration in view of global coverage and co-locations;Improving the number and accuracy of surveys between co-located stations;
Deploying, improving and optimizing space-based co-locations.
In order to support these activities, GGOS established the Standing Committee "Performance Simulations
and Architectural Trade-Offs (PLATO)“. To achieve progress in the topic mentioned above the PLATO
members develop improved analysis methods using all existing observation data and co-locations of spacegeodetic techniques. In addition, extensive simulations are carried out in order to investigate future
improvements and optimization of the ground network, the space segment and different observation
scenarios. These simulations will help to assess future data product quality based on projected network
configuration and performance. Since 2015, PLATO acts also as Joint Working Group under IAG's SubCommission 1.1.
This presentation summarizes the activities within the Standing Committee PLATO and gives an overview
on our ongoing studies. Preliminary results will be highlighted and first recommendations will be given.

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*G07-2-04
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Simulated multi-technique TRFs for GGOS with focus on enhanced SLR and
VLBI ground network architecture* Susanne Glaser 1) , Rolf Koenig 2) , Karl-Hans Neumayer 2) , Tobias Nilsson 2) , Robert Heinkelmann 2) ,Harald Schuh 1) 2) , Frank Flechtner 1) 2)
Technische Universitaet Berlin, Berlin, Germany 1) , GFZ German Research Centre for Geosciences,
Potsdam, Germany 2)
One of the key tasks of the Global Geodetic Observing System (GGOS) is the provision of high quality andconsistent global terrestrial reference frames (TRFs) to accurately monitor and reliably interpret importantgeophysical processes such as the global sea level rise. The GGOS requirements of 1 mm accuracy and 0.1
mm/yr stability in the long-term are not achieved so far by the currently available TRFs due to, e.g., thelacking of an optimal architecture of the ground networks of the Satellite Laser Ranging (SLR) and VeryLong Baseline Interferometry (VLBI) space-geodetic techniques. In this study we address this issue by
assessing the merit of enhanced SLR and VLBI networks. We simulate all four space geodetic techniques(Doppler Orbitography and Radiopositioning Integrated by Satellite - DORIS and Global Navigation
Satellite Systems - GNSS besides SLR and VLBI) contributing to the TRF in the time span 2008-2014 andcombine them by applying simulated local ties (LTs). From the combination of SLR and VLBI we conclude
that the precision of the LTs should be 1 mm or better. Simulating LTs with systematic errors indicates thatthe stations Wettzell, Badary and AGGO play a key role in the combination and should definitely be precise
to 1 mm or better. Simulating enhanced VLBI networks, which are expected to be operational in 5 and 10
years from now, demonstrate that the anticipated network in 10 years fulfills the 1 mm GGOS goal in termsof the TRF defining parameters. In the end, our simulation tool allows to assess the impact of the LT
accuracies and their monitoring intervals and to identify beneficial new co-location sites to improve the
TRF in order to achieve the GGOS goals.

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*G07-2-05
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Effective expansion of satellite laser ranging network for improving geodetic
products and satellite orbits* Toshimichi Otsubo 1) , Koji Matsuo 2) , Yuichi Aoyama 3) , Keiko Yamamoto 4) , Thomas Hobiger 5) ,Toshihiro Kubo-oka 6) , Mamoru Sekido 6) , Urs Hugentobler 7) , Rolf Koenig 8)
Hitotsubashi University, Kunitachi, Japan 1) , Geospatial Information Authority of Japan, Tsukuba, Japan 2) ,National Institute of Polar Research, Tachikawa, Japan 3) , National Astronomical Observatory of Japan,
Mitaka, Japan 4) , Chalmers University of Technology, Gothenburg, Sweden 5) , National Institute ofInformation and Communications Technology, Kashima, Japan 6) , Technical University of Munich, Munich,Germany 7) , Deutsches GeoForschungsZentrum, Wessling, Germany 8)
About 35 satellite laser ranging stations are being operational all over the world but huge regions on the
globe are not covered. We assume a new station is going to be added to the existing station network andtherefore we like to evaluate the effectiveness of each location. Realistic numbers of observations for a newstation are numerically simulated, based on the actual data acquisition statistics of the existing stations.
Multiple-satellite-combined orbit determination is then conducted with and without a new station, and theestimated errors are investigated.
A new station placed in the Southern hemisphere is found to be effective in general. It is revealed that themost effective place differs according to the geodetic parameter. The X and Y components of the geocenterand the sectoral terms of the Earth's gravity field are largely improved by a station in the polar regions. A
middle latitude station best contributes to the tesseral gravity terms, and, to a lesser extent, a low latitude
station best performs for the Z component of the geocenter and the zonal gravity terms. With the existingstations the quality of satellite orbits is found to be relatively poor in the Southern hemisphere, but a newhigh latitude station in Antarctica enhances locally the accuracies so they behave close to uniform over one
orbit.

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*G07-2-06
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Benefits for GGOS from SLR tracking of GLONASS, Galileo, BeiDou, and
QZSS satellites* Krzysztof Sosnica , Grzegorz Bury , Radoslaw Zajdel , Kamil Kazmierski , Mateusz Drozdzewski , Tomasz
Hadas
Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
One of the fundamental goal of GGOS is to improve the consistency level between different space geodetic
techniques, such as Global Navigation Satellite Systems (GNSS) and Satellite Laser Ranging (SLR). In the
SLR solutions, the station coordinates are typically derived on the basis of SLR tracking of four sphericalgeodetic satellites: two LAGEOS and two Etalons. The GNSS orbits are, on the other hand, solely derived
from microwave GNSS observations. The International Laser Ranging Service (ILRS) initiated four
intensive SLR tracking campaigns for Galileo and three campaigns devoted to tracking all GNSS spacecraft
between 2014 and 2016. As a result, the number of SLR observations and the number of tracked GNSS
satellites have dramatically increased allowing for determining GNSS orbits, SLR station coordinates, andEarth Rotation Parameters (ERPs) solely on the basis of SLR tracking of GNSS satellites.
We will present a solution in which the GNSS orbits, SLR station coordinates, geocenter coordinates, and
ERPs are determined using the SLR observations to 26 GLONASS, 14 Galileo, 2 BeiDou IGSO, 2 BeiDou
MEO, and 1 QZSS satellite. We compare the SLR station coordinate stability derived from GNSS-based
results to the LAGEOS-only solution and from a combined 'SLR to GNSS+LAGEOS' solution. We compare
as well the SLR-derived GNSS orbits to the microwave-derived results. We found that the coordinate
stability of those SLR stations which provide a large number of SLR observations of GNSS s/c canremarkably be improved. The Length-of-day parameter can be derived from SLR-GNSS solutions with amuch better accuracy than from the LAGEOS-only solutions. The benefits for ITRF of SLR tracking of GNSS
satellites are much greater than the SLR tracking of two Etalons. Eventually, we show that the SLR tracking
of GNSS satellites improves the consistency between SLR and GNSS solutions, which is fundamental for
fulfilling the GGOS goals.

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*G07-3-01
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Implementing the GGOS Decadal Vision for Geohazards Monitoring* John LaBrecque
University of Texas, Center for Space Research. Austin, Texas
The Global Geodetic Observing System of the IAG identified present and future roles for Geodesy in thedevelopment and well being of the global society. The GGOS is focused upon the development of
infrastructure, information, analysis, and educational systems to advance the International Global
Reference Frame, the International Celestial Reference System, the International Height Reference System,
atmospheric dynamics, sea level change and geohazards monitoring. The geohazards initiative is guided byan eleven nation working group initially focused upon the development and integration of regional multiGNSS networks and analysis systems for earthquake and tsunami early warning. The opportunities andchallenges being addressed by the Geohazards working group include regional network design, algorithm
development and implementation, communications, funding, and international agreements on data access.
This presentation will discuss in further detail these opportunities and challenges for the GGOS focus uponearthquake and tsunami early warning.

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*G07-3-02
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Global Navigation Satellite System Tsunami Early Warning Project* Gerald Bawden 1) , John Rundle 2) , John Labrecque 3)
National Aeronautics and Space Administration, Washington, DC 1) , University of California, Davis,
California 2) , University of Texas, Austin, TX 3)
The past decade has witnessed a terrible loss of life from large earthquakes and resultant tsunamis in the
Indo-Pacific region. Algorithms based on real-time GNSS data and science now exist to rapidly determine
the likelihood that a tsunami will be generated from a large earthquake, to predict their extent, inundation,and runup, and to track the tsunami as it propagates through the ocean basins. The algorithms use realtime GNSS in combination with other sensors to measure ground displacements generated by large
earthquakes to quickly estimate critical parameters (magnitude, depth, length, spatially slip distribution
along strike and dip of the fault, rupture direction) used to assess the likelihood that earthquake generated
a tsunami and then to measure disturbances in the ionosphere generated by the propagating tsunamis. An
experimental prototype GNSS-based tsunami early warning system could be developed that would initiallyincorporate real-time data from existing networks in economies around the circum- and intra- Pacific andIndian Ocean basins. This prototype requires access to real-time GNSS data distributed throughout
earthquake and tsunami prone regions. In this talk, we discuss this technology and its considerable
promise. We also report on a workshop, funded by NASA, to understand the feasibility of deploying such asystem around the Pacific Rim during the next decade. The workshop, to be held in Sendai during July
25-27, 2017, has the goals:- Identify what GNSS resources (networks, processing centers, telecommunication, etc.) will be necessary
to develop real-time GNSS early warning capabilities throughout the entire Pacific Rim region- Assess data gaps in the current Pacific-wide networks, develop strategies on the best approaches to fill thegaps- Review the state-of-the-art early warning approaches with an eye towards emergency response
community.
We conclude with a summary of actionable items to be carried out following this workshop.

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*G07-3-03
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

GNSS Buoy Array in the Ocean for a Synthetic Geohazards Monitoring
System* Teruyuki Kato 1) , Yukihiro Terada 2) , Keiichi Tadokoro 3) , Akira Futamura 4) , Morio Toyoshima 5) , Shinichi Yamamoto 5) , Mamoru Ishii 6) , Takuya Tsugawa 6) , Michi Nishioka 6) , Kenichi Takizawa 7) , Yoshinori
Shoji 8) , Tadahiro Iwasaki 9) , Naoyuki Koshikawa 9)
Earthquake Research Institute, the University of Tokyo, Tokyo, Japan 1) , National Institute of Technology,
Kochi College, Kochi, Japan 2) , Graduate School of Environmental Studies, Nagoya University, Nagoya,Japan 3) , National Institute of Technology, Yuge College, Ehime, Japan 4) , Wireless Networks ResearchCenter, National Institute of Information and Communications Technology, Tokyo, Japan 5) , Applied
Electromagnetic Research Institute, National Institute of Information and Communications Technology,
Tokyo, Japan 6) , Resilient ICT Research Center, National Institute of Information and Communications
Technology, Tokyo, Japan 7) , Meteorological Research Institute, Japan Meteorological Agency 8) , Satellite
Applications and Operation Center, Japan Aerospace Exploration Agency, Ibaraki, Japan 9)
The GNSS buoy system for tsunami early warning has been developed and is now operational as a national
wave monitoring system since 2008 in Japan. It was used to update the tsunami warning at the 2011
Tohoku-oki tsunami, Japan. Yet, the buoys are placed less than 20km from the coast and are not far enoughfor effective evacuation. We are thus trying to improve the system for putting the buoys much farther fromthe coast. For this purpose, we employ a new PPP-AR analysis algorithm, instead of conventional RTK-GPS,for positioning. In addition, a two-way satellite data transmission in contrast with current surface radio
system is introduced. We have conducted a series of experiments using the upgraded system in 2013 and2014, using a buoy located about 40km south of Cape Muroto, southwest Japan. GEONET data were used
to obtain precise orbits and clocks of satellites, and the information was sent to the buoy using a satellite.
The information was used for real-time PPP-AR analysis for every second. The estimated buoy position wasthen sent back to the ground base through another satellite. The received data was disseminated to publicthrough internet. These experiments indicate that the GNSS buoy can be placed at nearly anywhere in theocean. Given this success, we made up a new research plan in which we test a commercially available
satellite communication system and try to develop a new GNSS-acoustic system for continuous monitoringof ocean bottom crustal movements. Moreover, we are trying further applications of GNSS data forionospheric and atmospheric researches. A new project started in June 2016 which tries to establish a
GNSS buoy array in the western Pacific, which will be a powerful tool for monitoring geohazards in theregion. The newly designed GNSS system is deployed at another buoy located about 40km south of Cape
Ashizuri, southwest Japan. The system is now under testing. We are adding a GNSS-acoustic system in2017 to the same buoy.

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*G07-3-05
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Global and regional sea level budgets from joint analysis of space gravimetry
and altimetry data sets
Bernd Uebbing , Christina Lueck , Roelof Rietbroek , * Juergen Kusche
University of Bonn, Germany
Partitioning of altimetric sea level change in contributions from ocean steric expansion, ice-sheet andglacier mass imbalance, the water cycle, and crustal uplift is important for developing sea level predictions
at the regional scale, but as yet our understanding is incomplete even on the global scale.
Here we will present updated results following the ‘inverse' method developed at the University of Bonn,where budget closure is imposed on altimetric and gravimetric data in a least-squares forward modelling inversion scheme (Rietbroek et al., 2016). Starting with GRACE normal equations and along-track binned
Jason-1 and -2 altimetry, we derive an ocean mass rate at the lower end of the spectrum of contemporary
studies (-0.3 mm/a hydrology, 1.4 mm/a ice sheets and glaciers, 2002-2014) that would suggest a larger
steric rate than found from conventional ‘direct' GRACE ocean mass estimates before, but consistent withseveral modelling studies. As an aside, geocenter motion (difference between the center of common mass,CM, and the center of surface figure, CF) is resolved for within the method itself and can be extracted as a
byproduct; i.e. we do not rely on external data for it.
In particular, we will discuss the sensitivity of these inversion results with respect to GRACE and altimetry
data sets: we will present new results that incorporate Envisat altimetry and Swarm satellite gravimetry(which may be relevant in case a gap between GRACE and GRACE-FO cannot be avoided).
Rietbroek R. et al. (2016): Revisiting the contemporary sea-level budget on global and regional scales, Proc.
Nat. Acad. Sci. U.S.A. 113(6):1504–1509

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*G07-3-06
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

The International DORIS Service: Current Status and Future Plans
Laurent Soudarin 1) , Pascale Ferrage 2) , Jerome Saunier 3) , * Frank Lemoine 4)
CLS, Ramonville, France 1) , CNES, Toulouse, France 2) , IGN, Saint-Mande, France 3) , NASA Goddard
Space Flight Center 4)
The International DORIS Service (IDS) was created in 2003 under the umbrella of the International
Association of Geodesy (IAG) to foster scientific research related to the French DORIS tracking system andto deliver scientific products, mostly related to the International Earth rotation and Reference systems
Service (IERS). Since its start, the organization has continuously evolved, leading to additional andimproved operational products from an expanded set of DORIS Analysis Centers.
IDS is now based on a reinforced structure with two Data Centers, six Analysis Centers, several associatedgroups and a Combination Center. Using the experience gained in the preparation of the ITRF2008 and
ITRF2014, many improvements were made both in data analysis and on technical aspects.
This presentation addresses the organizational aspects of the IDS and the recent achievements made by its
components. We also discuss the future plans in terms of new products and activities.

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*G07-4-01
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Activities of the Wettzell station in Germany* Daniela Thaller 1) , Torben Schueler 1) , Thomas Kluegel 1) , Johann Eckl 1) , Alexander Neidhardt 2) ,Christian Ploetz 1) , Gerhard Kronschnabl 1) , Hartmut Wziontek 1) , Jan Kodet 2) , Ulrich Schreiber 2)
Bundesamt fuer Kartographie und Geodaesie, Frankfurt, Germany 1) , Technische Universitaet Muenchen,
Germany 2)
The geodetic observatory in Wettzell (Germany) has a long tradition in geodetic observations for VLBI, SLR,GNSS and gravimetry, and the observatory has recently been augmented with a DORIS beacon. By thisadditional instrumentation, Wettzell is one of only four global geodetic observatories that are equipped withall four space geodetic techniques. Such kind of geodetic stations are of great importance for generating astable global geodetic reference frame because co-locations of the four geodetic space techniques are
crucial for consistently combining the contributions by all observing techniques.
With three VLBI telescopes – the “old" RTW with one of the longest observing history, and the new TWIN
telescopes – Wettzell is a key player in the international VLBI community. The participation in diverse
24-hour sessions guarantees a stable and continuous contribution to the global reference frame.
Additionally, the almost continuous participation in the Intensive sessions is the basis for a reliable andcontinuous determination of Universal Time with low latency, which is required for every navigation
application and every satellite mission.
An important aspect at co-located sites is the determination and monitoring of the co-location network.
Besides local survey campaigns in regular intervals, Wettzell is installing an inter-technique calibration
target which does not only function as geometric reference for all techniques but also allows to monitor the
potential differences in the timing system between the individual instruments.

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*G07-4-02
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Geodetic activities at Syowa Station, East Antarctica* Yuichi Aoyama 1) , Koichiro Doi 1) , Yoichi Fukuda 2) , Hiroshi Ikeda 3) , Hideaki Hayakawa 1) , Yoshihiro
Fukuzaki 4) , Mamoru Sekido 5) , Toshimichi Otsubo 6) , Yoshifumi Nogi 1) , Kazuo Shibuya 1)
National Institute of Polar Research, Tokyo, Japan 1) , Kyoto University, Kyoto, Japan 2) , University ofTsukuba, Ibaraki, Japan 3) , Geospatial Information Authority of Japan, Ibaraki, Japan 4) , National Instituteof Information and Communications Technology, Tokyo, Japan 5) , Hitotsubashi University, Tokyo, Japan 6)
Syowa Station, the main wintering base of the JARE (Japanese Antarctic Research Expedition), is locatedon East Ongul Island, Dronning Maud Land, East Antarctica. Three space geodetic observations with VLBI
(Very Long Baseline Interferometry), GNSS (Global Navigation Satellite System) and DORIS (Doppler
Orbitography and Radiopositioning Integrated by Satellite) have been carried out at Syowa Station sincethe 1990s and these observation sites are all distributed within 400m each other. We have also conducted
repetitive absolute gravity measurements with FG-5 and temporal gravity change measurements with three
serial superconducting gravimeters since early 1990s. For monitoring ocean tides and sea level, tidal
observation with bottom pressure gauges has been continuing at Nisi-no-ura Cove, 700 m far from GNSS
sites, since 1976. Their local ties have been surveyed with accuracy less than a few millimeter, except thatvertical offset vector between GNSS and VLBI was determined with an uncertainty of 1 cm.
Those continuous geodetic observation data contributed to maintain international terrestrial reference
frame and to detect crustal movement induced by glacial isostatic adjustment and recent surface masschanges on East Antarctic ice sheet. To enhance the geodetic observations, we start a feasibility study for
installing SLR (Satellite Laser Ranging) system at Syowa Station.
In this study, we report the current geodetic activities of JARE at Syowa Station, and the future plans forcontributing to GGOS as a co-location site in Antarctic region.

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*G07-4-03
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Development of New Analysis Strategy for GNSS Observation Network inJapan* Satoshi Abe , Naofumi Takamatsu , Norihiko Ishikawa , Kazunori Yamaguchi , Yuki Kamakari , Satoshi
Kawamoto , Yohei Hiyama , Yuki Hatanaka , Hiromichi Tsuji
Geospatial Information Authority of Japan, Ibaraki, Japan
Geospatial Information Authority of Japan (GSI) has been operating Continuous Operating Reference
Stations (CORS) called GEONET (GNSS Earth Observation Network System), since 1996. We currently
operate more than 1,300 stations to cover whole Japan, with an average spacing of about 20km. With thetotal number and density, GEONET is one of the largest GNSS CORS systems in the world. After 20 yearsof successful operation, it becomes vital infrastructure for surveying and mapping, precise positioning,disaster management, and even for weather forecast in Japan.
We calculate the daily coordinates for each GEONET station by using Bernese GNSS software to monitor
the crustal deformation in Japan. The analysis strategy was updated three times. Latest version wasestablished in 2009. We are now developing new strategy because the software, reference frame, and otherphysical models have been obsolete.
In this paper, we focus on the GPS and GLONASS integration. Only GPS was used for older strategy.
However, the receivers and antennas in GEONET were updated into the multi-frequency type in 2013.
Furthermore, the final orbit for GLONASS provided by IGS has reached almost the same accuracy incomparison with the one for GPS. We process GPS and GLONASS data independently to estimate theambiguities, and then combine the solutions with normal equations. The result based on GLONASS
observations data show the apparent fluctuation with the period of 8 days that was not found on the GPS
result. Which is significant for the stations apart from the reference station, but it is systematic which can
explain, for example, frame rotation. IGS analysis centers using GLONASS observations reported the same
phenomenon that seemed to be caused by the GLONASS constellation geometry (Ray et al., 2013,
Rebischung et al., 2016). We have tried ways to set transformation parameters and absorb systematicfluctuation. We discuss the method to suppress the apparent fluctuation in our presentation.

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*G07-4-04
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Performance of various homogenization tools on a synthetic benchmark
dataset of GPS and ERA-interim IWV differences* Anna Klos 1) , Roeland Van Malderen 2) , Eric Pottiaux 3) , Olivier Bock 4) , Janusz Bogusz 1) , Barbara
Chimani 5) , Michal Elias 6) , Marta Gruszczynska 1) , Jose Guijarro 7) , Selma Zengin Kazanci 8) , Tong Ning 9)
Military University of Technology, Warsaw, Poland 1) , Royal Meteorological Institute of Belgium (RMI),
Brussels, Belgium 2) , Royal Observatory of Belgium (ROB), Brussels, Belgium 3) , IGN LAREG, University
Paris Diderot, Sorbonne Paris, France 4) , Central Institute for Meteorology and Geodynamics, Austria 5) ,Research Institute of Geodesy, Topography and Cartography, Czech Republic 6) , AEMET (Spanish
Meteorological Agency), Spain 7) , Karadeniz Technical University, Turkey 8) , Lantmäteriet, Sweden 9)
Within the COST Action ES1206 “Advanced Global Navigation Satellite Systems tropospheric products formonitoring severe weather events and climate" (GNSS4SWEC), a sub-Working Group (WG) on “Data
Homogenization" has been set up. The aim of this group is to homogenize a worldwide Integrated Water
Vapour (IWV) dataset retrieved from Global Positioning System (GPS) observations, the IGS repro 1
tropospheric product (1995-2010), by correcting for (artificial) break points due to e.g. instrumental
changes. As at most stations, the ERA-interim IWV field output correlates well with the IWV retrieved byGPS, the former one is used as reference and the IWV differences between both sets are considered. The
characterization of these IWV differences provided us typical trend values, seasonal oscillations and noisemodels, to build a synthetic benchmark IWV dataset of differences. We simulated these IWV differences
over a period of 16.4 years with two different noise types: white, as well as the combination of white andautoregressive process. Then, we simulated offsets, trends and seasonal oscillations, as characterized fromthe real IWV differences. We created three variants of synthetic datasets referred to as: EASY, LESSCOMPLICATED and FULLY-COMPLICATED, depending on the level of complexity. All synthetic datasets
were then subjected to homogenization: various detection methods (e.g. HOMOP, CLIMATOL, PMTred,STARS and non-parametric rank tests) were blindly employed to deliver the epochs of simulated offsets. In
this presentation, we show the detection scores for each synthetic dataset type and each detection method
We analyze the sensitivity of each detection method w.r.t. the complexity of the synthetic datasets. We alsopresent the trend differences between before and after homogenization by the different approaches.

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*G07-4-05
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

A comparison of precipitable water vapor retrieved with novel ground-based
microwave radiometer, GPS and analysis data in Tsukuba during a cold front
passage* Ryuichi ICHIKAWA 1) , Hiroshi TAKIGUCHI 1) , Taketo NAGASAKI 2) , Osamu TAJIMA 2) , Kentaro ARAKI3)

National Institute of Information and Communications Technology 1) , High Energy Accelerator Research
Organization (KEK) 2) , Meteorological Research Institute 3)
We have developed a state-of-the-art microwave radiometer named KUMODeS (KEK Universal Moisture
and Oxygen Detection System) using the technology of millimeter-wave spectroscopy for the highresolution and high-precision monitoring of water vapor behavior. We have carried out comparative
measurements of precipitable water vapor (PWV) in order to investigate the potential of KUMODeS/PWV
measurements.
KUMODeS measures spectra using two receivers with frequency bands of 20–30 GHz and 50–60 GHz. The
low-noise amplifier of the first receiver and a cold calibration source are implemented in a cryostat, which
is maintained at 10 K in order to improve the sensitivity in the detection of the characteristic broad peak ofwater vapor at around 22 GHz. The second receiver is used to measure the absorption peaks of oxygen(~60 GHz).
The GPS-based PWV is estimated reliably with 1–2 mm accuracy according to previous studies. The GPS
PWV values are retrieved from zenith wet delays (ZWDs), which are computed by subtracting the zenithhydrostatic delays (ZHDs) from GPS-based zenith total delays (ZTDs). In this procedure, the ZHDs are
obtained from the surface pressure and temperature.
We analyzed the PWV variation in Tsukuba, Japan, derived from three techniques, i.e., using KUMODeS,
GPS and JMA operational local analysis (LA), during a cold front passage. The PWV measurements derived
from GPS and KUMODeS have temporal resolutions of 30 s and about 2 min, respectively. The estimatesfrom the LA have a temporal resolution of 1 h. A comparison of time series shows good agreement between
the PWV measurements retrieved from KUMODeS, GPS and the LA between 20 and 22 December 2016.
On the other hand, some differences between them appeared after the heavy rainfall of 22 December.
Although further investigation is required to evaluate the performance of KUMODeS, the preliminary resultof the comparison implies the consistency and potential of KUMODeS measurements.

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*G07-4-06
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Solar radiation pressure acceleration acting on geodetic satellites: precise
orbit determination vs surface materials* Akihisa Hattori , Toshimichi Otsubo
Hitotsubashi University, Tokyo, Japan
Satellite orbits are subjected to various non-gravitational forces and solar radiation pressure has been oneof the major error sources in orbit determination. Solar radiation pressure acting on a satellite depends on
how sunlight illuminates its surface and is reflected there. The cannonball model is widely applied forspherical geodetic satellites. In this model, the scale factor of the actual acceleration in comparison with an
ideal spherical black body case is expressed by a solar radiation pressure coefficient C_R.
This study attempts to relate the behavior of the C_R solutions derived from precise orbit determination
with the optical properties of the satellites' surface.
We use the geodetic analysis software “c5++" (Otsubo, 2016) to estimate the solar radiation pressure
coefficients C_R of the six geodetic satellites: Ajisai LAGEOS-1, LAGEOS-2, LARES, Starlette and Stella.
Satellite laser ranging data for the past 20 years are analyzed where the C_R coefficients are estimated per
30 days.
It is clearly seen that the estimated C_R values for Ajisai, 1.041 on average, are smaller than those of othersatellites, ranging from 1.075 to 1.164. This is explained by the fact that the surface of Ajisai is largely
covered by mirrors where the surfaces of the other satellites are covered by a metallic body and cornercube reflectors.
In addition, this study deals with time variation of solar radiation pressure. When the optical properties ofthe satellite's surface were completely spherical symmetry, the C_R value would be constant. Sengoku(1995) predicted that the annual variation should dominate for Ajisai. However, our C_R solutions of Ajisai
from precise orbit determination show a semi-annual periodic variation much larger than the predicted
annual variation. We attribute the reason to a 5-cm-height metallic ring attached to one of the pole and thedetailed material distributions both of which were not considered in the previous study.

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*G07-5-01
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

The VLBI Global Observing System and its link to GGOS
* Axel Nothnagel 1) , Dirk Behrend 2) , Hayo Hase 3) , Arthur Niell 4) , Bill Petrachenko 5) , Gino Tuccari 6)
University of Bonn, Bonn, Germany 1) , NVI Inc., Greenbelt MD, USA 2) , BKG/AGGO, Wettzell/La Plata,
Germany/Argentina 3) , Haystack Observatory, Westford MA, USA 4) , Dominion Radio Observatory,
Penticton, Canada 5) , IRA/INAF, Noto, Italy 6)
The International VLBI Service for Geodesy and Astrometry (IVS) and its infrastructure constitutes one of
the fundamental components of GGOS for two main reasons: VLBI is unique in its ability to determine
UT1-UTC and the Earth's rotation axis in space (precession/nutation), and it is one of the two techniques todefine the scale of the terrestrial reference frame. The latter quantity is tightly connected to the IVS
observing network with its precise station coordinates and velocity components. Starting about five years
ago, the IVS began implementing the new VGOS concept (VLBI Global Observing System) of fast slewing
telescopes enabling a better sampling of the atmosphere and its refraction effects. Experience has beengathered from the on-going developmental sessions, and some preliminary results are available from thesemeasurements. On the other side, the legacy network is still contributing results with very good long term
stability. The observational data and the results of the IVS Analysis Centers are kept on openly accessible
servers and, thus, form an indispensable contribution to the GGOS project.

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*G07-5-02
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

VGOS development for Ishioka 13-m antenna* Takahiro Wakasugi , Michiko Umei , Tomoo Toyoda , Masayoshi Ishimoto , Ryoji Kawabata , Basara
Miyahara
Geospatial Information Authority of Japan, Tsukuba, JapanThe Geospatial Information Authority of Japan (GSI) constructed a new VLBI facilities in Ishioka. It is
designed for the next-generation VLBI system called VGOS, which is promoted by the International VLBI
Service for Geodesy and Astrometry (IVS) in order to meet the requirements of Global Geodetic Observing
System (GGOS). In addition to the VGOS facilities, Ishioka has GNSS Continuously Operating Reference
Stations and a gravity measurement facility in order to contribute to GGOS as a core observatory.
Since February 2015, the Ishioka 13-m antenna observed legacy S/X sessions with Tsukuba 32-m to obtainaccurate positions of the new site. Then, Ishioka has started the international observations dedicated for
Earth rotation measurement taking over the role of Tsukuba 32-m from the beginning of 2017. In parallelwith these legacy observations, we have carried out several broadband observations compatible with VGOS
frequency setup. From August to September 2016, we installed a new signal chain including QRFH
(Quadruple-ridged flared horn), up-down converters, and high speed digital samplers at Ishioka in order toparticipate in VGOS Trial sessions which were broadband observations coordinated by IVS. Several
experimental broadband observations with Kashima 34-m of NICT and Hobart 12-m of AuScope were also
performed, and the compatibility of equipment between Ishioka and other overseas stations was confirmed.
We report on the recent development of VGOS equipment and results of the legacy and broadband
sessions for Ishioka.

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*G07-5-03
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Broadband VLBI System GALA-V* Mamoru SEKIDO 1) , Kazuhiro TAKEFUJI 1) , Hideki UJIHARA 1) , Tetsuro KONDO 1) , Masanori
TSUTSUMI 1) , Yuka MIYAUCHI 1) , Eiji KAWAI 1) , Hiroshi TAKIGUCHI 2) , Ryuichi ICHIKAWA 2) ,Yasuhiro KOYAMA 2) , Kennichi WATABE 3) , Tomonari SUZUYAMA 3) , Ryoji KAWABATA 4) , Yoshihiro
FUKUZAKI 4) , Masayoshi ISHIMOTO 4) , Takahiro WAKASUGI 4) , Jun'ichi KOMURO 2) , Kenjiro TERADA
2), Kunitaka NAMBA 2) , Rumi TAKAHASHI 2) , Tetsuro AOKI 2)
National Institute of Information and Communications Technology, Kashima Space Technology Center,
Kashima, Japan 1) , National Institute of Information and Communications Technology, Headquarter,
Koganei, Japan 2) , National Institute of Advanced Industrial Science and Technology, National Metrology
Institute of Japan, Tsukuba, Japan 3) , The Geospatial Information Authority of Japan, Tsukuba, Japan 4)
We have developed a broadband VLBI system named GALA-V, which is compatible with the VGOS (VLBI
Global Observing System) specification. The development contains broadband receiver system, dataacquisition system, and up to data processing software for precision delay determination. This systemdemonstrated sub-pico second precision VLBI delay measurement by one second of observation between
Japanese domestic broadband VLBI stations: Ishioka 13m and Kashima 34m. We conducted a series ofbroadband VLBI experiments between two small telescopes installed at NICT(Tokyo) and NMIJ(Tsukuba)
for measurement of clock difference between UTC(NICT) and UTC(NMIJ). Analysis results of theseexperiments proved that broadband VLBI system enables pico-second precision observation even withsmall diameter radio telescopes. Weighted RMS of post-fit residual delay were around ten and a few picoseconds on 1.6m-2.4m antenna pair. The experiment results suggest that delay precision was improved to a
sufficient level by broadband system, and the error of geodetic/clock analysis is dominated by atmosphericdelay uncertainty.

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*G07-5-04
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Strategies to improve precision, accuracy, and latency of current and future
VLBI Intensive sessions* Niko Kareinen , Thomas Hobiger , Ruediger Haas , Grzegorz Klopotek
Chalmers University of Technology, Gothenburg, Sweden
The International VLBI Service for Geodesy and Astrometry (IVS) observing
programs currently include 1-hour long VLBI sessions normally observed on
one (IVS-INT1, IVS-INT2) or three baselines (IVS-INT3). These sessions are
known as the Intensive (INT) sessions and their purpose is to provide daily
UT1-UTC estimates. However, the short observation duration, the limited numberof participating telescopes, and the timeliness requirements make operation andanalysis of the INTs a challenging task. We carried out different studies that
try to help solving some of the drawbacks of these single-baseline VLBI sessions.
In doing so, various analysis strategies and the impact of auxiliary anda priori data were evaluated by re-analysing more than one decade of Intensive
sessions observed on the Kokee-Wettzell baseline in fully automated and consistentmanner. We find that the largest variability in the obtained UT1-UTC
accuracy is related to the availability of high-quality a priori Earth Orientation
Parameters. Concerning operational INT processing, one currently faces the
problem that the observed VLBI group delays contain ambiguities which need
to be resolved. This is usually performed in a semi-automated mode. Therefore,
we implemented a fully automated robust ambiguity estimation method basedon the L1-norm, which increased the successfully resolved sessions by at least
5 %. Another question which we addressed is related to the upcoming VGOS
networks and the way how those can deliver ultra-rapid UTC-UTC products.
Based on current INT networks and through extensive simulations we investigated
optimal locations for tag-along stations which enable flexible scheduling of
three-station network sessions which can provide UT1-UTC with high accuracy.
The results from our investigations are important for the transition from thecurrent VLBI to operational VGOS and pave the way for future high quality
UT1-UTC products.

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*G07-5-05
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Error budget analysis in Geodetic VLBI* Minghui XU 1) , James A. Anderson 2) , Harald Schuh 2) , Guangli Wang 1)
Shanghai Astronomical Observatory, Chinese Academy of Sciences, 200030 Shanghai, China 1) , Helmholtz
Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg 14473 Potsdam, Germany
2)

Source structure effects have remained an error source in geodetic VLBI for many decades, both because
their impacts on geodetic VLBI have been underestimated, and because it was difficult to image suchamounts of radio sources regularly. In this report, the magnitudes of structure effects and their influence on
measurement noise will be discussed using closure delays, closure phases, source images derived from thegeodetic visibility data, and the delay residuals of individual observables after VLBI data analysis. The error
budget of structure effects, measurement noise, and all other error sources due to incomplete modeling in
geodetic VLBI will be studied. This will greatly help us to have a good insight for the forthcoming VGOS.

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*G07-P-01
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Status of the ESA Earth Explorer missions
Mark Drinkwater , Pierluigi Silvestrin , Roger Haagmans , Michael Rast , * Michael Kern
European Space Agency
With the recent successes of ESA's Earth Observation Programmes, through the realization of highly
successful Earth Explorers, the launch of the first in the series of operational Sentinel satellites for
Copernicus, the development of sophisticated meteorological satellites, and with the rapidly increasing
power of technologies for data processing, analysis and dissemination, Europe has entered a new era forthe development and exploitation of Earth-observing satellites. An important part of these ESA Programmes
are its science-driven Earth Explorer missions which are distinguished by unique scientific objectives,
focused on some of today's most important urgent scientific concerns in order to respond to a broad range
of demands, from the challenges of understanding climate change to supporting a multitude of humanactivities on Earth and measuring their impact on the natural environment.
As of today, four out of the seven approved Earth Explorer missions have been launched: GOCE (2009),
SMOS (2009), CryoSat (2010), and Swarm (2013). The last three are successfully operating while GOCE
reentered the atmosphere in 2013 as a successful conclusion to its extended mission. These satellites eachcarry fundamentally new instrument technologies and the data that they are reporting are yielding
fundamentally new insights into different aspects of the Earth system. Four other Explorer missions: ADMAeolus, EarthCARE, Biomass and FLEX are in varying stages of development and are planned to belaunched in the coming years.
This presentation will place the Earth Explorers in the context of ESA's Earth Observation Programmes,
and will provide an overview of their respective scientific objectives and observational capabilities,
together with some of the highlights of the Explorer missions in operation or main characteristics of themissions being currently built. Further, it will outline the expected next steps in the programme in the near
future.

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*G07-P-02
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

The ISO Geodetic Registry and Related Standards
Michael Craymer 1) , * Larry Hothem 2)
Canadian Geodetic Survey, Natural Resources Canada, Ottawa, Canada 1) , U.S. Geological Survey, Reston,
VA, U.S.A. 2)
The International Standards Organization Technical Committee 211 (ISO/TC 211) on Geographic
Information/Geomatics has taken responsibility for establishing the ISO Geodetic Registry, a registry ofinternational geodetic reference systems and transformations. Such a registry is needed primarily by GIS
software to define the various reference frames and transformations they use. The data contained in theregistry are the parameters defining geodetic reference systems and adopted transformations between
them and need to be validated by official sources. The ISO Geodetic Registry has been defined inaccordance with the ISO International Standard (IS) 19127. This standard defines the data elements
required, as well as the rules for its maintenance, in compliance with IS 19135 (procedures for registrationof items) and IS 19111 (describing the elements necessary to fully define reference systems). As specified
in IS 19135, the ISO Geodetic Registry consists of an online information system or database with a userinterface and web services for access, a Registry Manager hosting the Registry and taking care of its daily
operations, and a Control Body that approves the content of the Registry. The Norwegian Mapping
Authority is serving as the initial Registry Manager and has funded and hosted the registry management
software. The Control Body consists of geodetic experts nominated by the TC 211 member and liaisonorganizations with its chair and vice-chair nominated by the IAG. The ISO Geodetic Registry was madepublically available earlier this year, populated with an initial set of global and regional reference frames
and their associated transformations. Further population of the Registry continues and geodetic agencies
are encouraged to submit their own reference frames and transformations. We describe the parameters
required to be entered for such reference frames and transformations and provide the status of revisions of
the supporting standards IS 19111 and IS 19127.

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*G07-P-03
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

New design and facilities for the International Database for Absolute Gravity
Measurements (AGrav): A support for the Establishment of a new Global
Absolute Gravity Reference System* Hartmut Wziontek 1) , Reinhard Falk 1) , Sylvain Bonvalot 2) , Axel Ruelke 1)
BKG Federal Agency for Cartography and Geodesy, Frankfurt/Main and Leipzig, Germany 1) , BGIInternational Gravimetric Bureau / GET, Toulouse, France 2)
After about 10 years of successful joint operation by BGI and BKG, the International Database for Absolute
Gravity Measurements "AGrav" was under a major revision. The outdated user interface was replaced by a
responsive, high level web application framework based on Python and built on top of Pyramid.
Functionality was added, like interactive time series plots or a report generator and the interactive mapbased station overview was updated completely, comprising now clustering and the classification of
stations. Furthermore, the database backend was migrated to PostgreSQL for better support of theapplication framework and long-term availability.
As comparisons of absolute gravimeters (AG) become essential to realize a precise and uniform gravity
standard, the database was extended to document the results on international and regional level, including
those performed at monitoring stations equipped with SGs. By this it will be possible to link different AGs
and to trace their equivalence back to the key comparisons under the auspices of International Committee
for Weights and Measures (CIPM) as the best metrological realization of the absolute gravity standard. In
this way the new AGrav database accommodates the demands of the new Global Absolute Gravity
Reference System as recommended by the IAG Resolution No. 2 adopted in Prague 2015.
The new database will be presented with focus on the new user interface and new functionality, calling all
institutions involved in absolute gravimetry to participate and contribute with their information to built up amost complete picture of high precision absolute gravimetry and improve its visibility. A Digital Object
Identifier (DOI) will be provided by BGI to contributors to give a better traceability and facilitate thereferencing of their gravity
surveys.
BGI mirror site : http://bgi.obs-mip.fr/data-products/Gravity-Databases/Absolute-Gravity-data/
BKG mirror site: http://agrav.bkg.bund.de/Powered by TCPDF (www.tcpdf.org)

*G07-P-04
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

IGFS geoportal development for gravity, geoid, GGM and DEM data
* Georgios S. Vergos 1) , Vassilios N. Grigoriadis 1) , Riccardo Barzaghi 2) , Daniela Carrion 2) , Sylvain
Bonvalot 3) , Franz Barthelmes 4) , Mirko Reguzzoni 2) , Hartmut Wziontek 5) , Kevin M. Kelly 6)
IGFS CB, GravLab, Department of Geodesy and Surveying, Aristotle University of Thessaloniki,
Thessaloniki, GR-54124, Greece 1) , IGFS,ISG / DICA, Politecnico di Milano, Milano, Italy 2) , BGI, GET /Observatoire Midi-Pyrenees, Toulouse, France 3) , ICGEM, GFZ, Potsdam, Germany 4) , IGETS, BGI / BKG,Frankfurt/Leipzig, Germany 5) , IDEMS / Esri, Redlands CA, USA 6)
The International Gravity Field Service (IGFS) Central Bureau (CB) has recently been established at
DGS/AUTH and one of its main activities has been the promotion of IAG gravity-field related services alongwith the development of a new, user-friendly website. One critical issue that needs to be incorporated by
IGFS is to answer user needs in terms of providing reliable feedback as to what kind and what type ofgravity-field related data one can retrieve from IGFS. With that in mind, IGFS has developed a dedicatedgravity-field related geoportal with the sole purpose of organizing a modern, user-friendly and coherent onestop point where the interested user can visualize the current data availability within BGI, ICGEM, ISG, and
IDEMS. The developed geoportal is incorporated as an IGFS application within the dedicated IGFS
application server using open-source solutions (GeoServer, OpenLayers, PHP, PostgreSQL) and the GSSH
coastline for the presentation of a basic cartographic background. The geoportal itself is not intended toprovide the data themselves, but it rather serves as a one-stop point for showing data availability anddirecting to the respective IAG service for data retrieval. In this work the main steps taken for setting up
the server are outlined along with some examples of the available data and information that the user can
retrieve.

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*G07-P-05
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

IGFS metadata for gravity and geoid. Structure, build-up and application
module* Georgios S. Vergos 1) , Vassilios N. Grigoriadis 1) , Riccardo Barzaghi 2) , Daniela Carrion 2)
GravLab, Department of Geodesy and Surveying, Aristotle University of Thessaloniki, Thessaloniki,
GR-54124, Greece 1) , DICA, Politecnico di Milano, Milano, Italy 2)
Gravity field related products have been the focus of almost all geosciences in the sense that they provide
realistic representation of the physical properties of system Earth. The rigorous documentation andarchiving of gravity field related data, either irregularly distributed and on a grid, has become mandatory inorder to ensure coherent and unambiguous utilization by users and archiving in related data management
servers and services. Given the above, the International Gravity Field Service (IGFS) has taken steps inorder to generate metadata for gravity field and geoid related data so that fragmentation of databases atnational and international level as well as user needs can be addressed. To that respect, the general
structure of the gravity and geoid metadata has been generated, describing all necessary fields that the
metadata should have, while an online PHP-based web application has been developed and became
available as an IGSF product to assist users to generate metadata for their gravity-related information. In
this work we describe the main characteristics of the metadata structure and give details on the developed
web application. Finally, the dedicated IGFS application server, igfsapps.topo.auth.gr, is described anddetails on the incorporation of the gravity and geoid metadata application as an online IGFS service areprovided.

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*G07-P-06
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

The Data Base of the International Geodynamics and Earth Tide Service(IGETS)
Christian Voigt 1) , Christoph Foerste 1) , * Hartmut Wziontek 2) , David Crossley 3) , Bruno Meurers 4) ,Vojtech Palinkas 5) , Jacques Hinderer 6) , Jean-Paul Boy 6) , Jean-Pierre Barriot 7) , Heping Sun 8)
GFZ German Research Centre for Geosciences, Potsdam, Germany 1) , BKG Federal Agency for
Cartography and Geodesy, Leipzig, Germany 2) , Department of Earth and Atmospheric Sciences, St. Louis
University, St. Louis, MO, USA, 3) , Department of Meteorology and Geophysics, University of Vienna,
Vienna, Austria 4) , Geodetic Observatory Pecny, Ondrejov, Czech Republic 5) , EOST-IPGS (UMR 7516
CNRS/Universite de Strasbourg), Strasbourg, France 6) , Geodesy Observatory of Tahiti, University ofFrench Polynesia, Faa'a, Tahiti, France 7) , Institute of Geodesy and Geophysics, Chinese Academy of
Sciences, Wuhan, China 8)
The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by IAG. IGETS
continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to support geodetic andgeophysical research activities using superconducting gravimeter data in an international network. IGETS
provides time series to monitor temporal variations of the Earth's gravity field and surface deformation bylong term records from ground gravimeters, tiltmeters, strainmeters and other geodynamic sensors. IGETS
also continues the activities of the International Center for Earth Tides (ICET) in collecting, archiving anddistributing Earth tide records of various geodynamic sensors.
The IGETS data base is hosted by GFZ and is accessible via http://igets.gfz-potsdam.de to the geodetic andgeodynamics community as well as to all other interested data producers and users. At present, records
from superconducting gravimeters at 34 stations worldwide are available. Level 1 products are raw gravity
and local air pressure records with 1 minute sample rate. As a new feature, records with 1 or 2 seconds
samples are already provided for a few stations. Level 2 products consist of gravity and air pressure data
corrected for instrumental perturbations and ready for tidal analysis, which are derived from Level 1
datasets and computed by the University of French Polynesia. Residual time series after geophysicalcorrections considered as Level 3 products are derived from Level 2 datasets and computed by EOST.
A major benefit of IGETS is the provision of digital object identifiers (DOI) for the data sets of every station.
This ensures a long term availability and an increased visibility as part of an international network but also
a proper citation. As IGETS is aiming to present all kind of long-term geodynamic time series, interested
station operators are cordially invited to contribute with their data sets and, in return, benefit from being
part of the IAG service.

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*G07-P-07
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Effects of tidal perturbation on the geopotential for application of precise
clock comparison to long-distance leveling: Case study of Japan as coastal
areas* Yuki Kuroishi
The University of Tokyo, Tokyo, Japan
Recent engineering advancement of precise comparison of optical clocks at a great distance, targeting toan accuracy equivalent to 1 cm in height difference, sheds new light on accurate geodetic leveling overlong distances. Based on the theory of relativity, the rate difference between the clocks reflects thegeopotential difference between the clock locations. Deriving the geopotential difference from the clock
rate difference, however, requires removal of significant perturbation on the geopotential associated with
time-variable tides, for example.
Supposing the application of chronometric leveling to coastal regions such as Japanese islands, weconcern about the perturbation due not only to earth tides (ET) but to ocean tidal loading (OTL). Here, we
evaluate the magnitudes of differential perturbation (DP) due to both ET and OTL separately over different
distances ranging from a few tens to a thousand of kilometers. The results show that over a distance of 50
km the temporal changes in combined DP due to ET and OTL can reach the magnitude of 1 cm in terms ofequivalent height difference (EHD). Over a distance of 600 km OTL can produce DP with a peak-to-peakamplitude of 1 cm EHD, and over a distance of 1000 km even root-mean-square amplitudes of OTLinduced DP reach about 2 cm EHD. Therefore, future geodetic application of precise clock comparison to
constraining a nationwide height datum over long distances must unavoidably take into consideration theremoval of perturbation due not only to ET but to OTL.

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*G07-P-08
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Activities of the Asia-Oceania VLBI Group for Geodesy and Astrometry(AOV)
Ryoji Kawabata 1) , Takahiro Wakasugi 1) , * Michiko Umei 1) , Jim Lovell 2)
Geospatial Information Authority of Japan, Tsukuba, Japan 1) , University of Tasmania, Hobart, Australia 2)
The Asia-Oceania VLBI Group for Geodesy and Astrometry (AOV) was established in 2014 as a subgroup of
the International VLBI Service for Geodesy and Astrometry (IVS) in order to foster regional collaboration of
VLBI. AOV coordinates six regional sessions in a year on regular basis by sharing resources of scheduler,
stations, and correlators. AOV members are also enhancing their close collaboration by sharing informationof recent activities in several face-to-face meetings. Successful broadband VLBI experiments withtelescopes in Australia and Japan in August 2016 marked the start of VGOS in this region under thecollaboration of AOV. We talk on the recent activities of the AOV.

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*G07-P-09
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Geodetic Observations in Mizusawa VLBI Observatory* Yoshiaki Tamura 1) , Takaaki Jike 1) , Seiji Manabe 2)
Mizusawa VLBI Observatory, National Astronomical Observatory of Japan 1) , National Astronomical
Observatory of Japan 2)
Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, is
operating many geodetic observation systems such VLBI, GNSS and gravimeters.
For the VLBI observation, we commenced constructing VERA (VLBI Exploration ofRadio Astrometry) in 2000. VERA consists of four VLBI stations and each station has
a 20m antenna. We started regular geodetic VLBI observations with VERA in 2004.
One of VERA stations joins in IVST2 and AOV networks at present. For the GNSS
observations, we are operating GPS observations at VERA stations. Also, we areoperating an IGS station and a GESS (Galileo Experimental Sensor Station) in the
Mizusawa campus in cooperation with GFZ Potsdam. For the gravity observation, we
had been operating gravity change observation with a superconducting gravimeter at
Esashi Earth Tides Station for the year 1988-2008, and have been operating similar
observation at Mizusawa since 2009 until now. In the Mizusawa campus, all of thesefacilities are located within 250m area and collocated observations are performed.
We introduce those geodetic observations systems in Mizusawa VLBI Observatory.
Besides we introduce several observation results including those at the Tohoku
Earthquake in 2011 obtained with the different techniques.

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*G07-P-10
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Development of Wideband Antennas* Hideki UJIHARA , Kazuhiro TAKEFUJI , Mamoru SEKIDO , Ryuichi ICHIKAWA
National Institute of Information and Communications Technology
Wideband antennas for VLBI were developed and reported in this poster.
Wideband feeds and OMTs were newly developed to upgrade Kashima 34m antenna and small portable
VLBI stations named MARBLE of NICT.
Our project, named Gala-V, uses 3.2-14.4GHz with NINJA feeds and 6.5-15GHz with IGUANA-H feeds.
Wideband geodetic observation, methanol masers observations of 6.7 GHz and 12.2 GHz in same time andother various wideband radio astronomical observations are capable now with these antennas in Japan.

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*G07-P-11
IAG Symposium / IAG05. IAG Joint / G07. Global Geodetic Observing System (GGOS) and Earth monitoring services

Contribution for international geodetic frame of SLR observation at the
Shimosato Hydrographic Observatory* Hiroko Fukura 1) , Yusuke Yokota 2)
Shimosato Hydrographic Observatory, Japan Coast Guard, Wakayama, Japan 1) , Hydrographic andOceanographic Department, Japan Coast Guard, Tokyo, Japan 2)
The Hydrographic and Oceanographic Department of the Japan Coast Guard (JHOD) has been carrying out
the Satellite Laser Ranging (SLR) observation at the Shimosato Hydrographic Observatory (SHO) since1982. For 35 years, the SLR observation at the SHO contributed to a construction and a development of theInternational Terrestrial Reference Frame (ITRF), and also made a major contribution to an establishmentof a world geodetic system as a national geodetic system in Japan in April 2002. After the major renovation
between 2007 and 2009, the Shimosato station observed a crustal movement of the 2011 Tohoku-oki
earthquake and continuously contributed to a global geodesy. The ranging precision (normal point RMS)
maintains high accuracy of 1 - 2 cm.
In this presentation, we review a history of the SLR observation at the SHO. Our continuous SLR
observation is important for a discussion to develop the future GGOS.
Acknowledgements: We acknowledge supports from NAO, JAXA, NICT, ILRS, and many associations
around the world. We thank the senior staffs in the Shimosato Hydrographic Observatory for their efforts
for maintenance and operation of SLR continuous observation.

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*J01-1-01
Joint Symposium / J01. Monitoring of the cryosphere

Seismic Tremors and their Relation to Cryosphere Dynamics in April 2015
around the Lutzow-Holm Bay, East Antarctica* Masaki Kanao
National Institute of Polar Research, Tokyo, Japan
Characteristics and statistics of seismic tremors occurring during April 2015 were investigated by using
short-period and broadband seismographs deployed at Syowa Station (SYO), in the Lutzow-Holm Bay(LHB), East Antarctica. In order to examine a relationship between surface environments in particularcryosphere variation, the MODIS satellite images were utilized for comparison with the detected tremor
events. Since a large volume of sea-ice was discharged during the April, together with several large icebergs
passed through from the west to the east at northern edge of the fast sea-ice of LHB, it was expected todetect seismic tremors involving surrounding cryospehre dynamics. During the one month, a total numberof 49 tremor events including short duratiing ice shocks were identified. Majority of the events (N=39) had
their duration times more than 15 minutes, which were divided into tremors and ice shocks by theexperience definition at SYO. Cryospheric sources as recorded by seismic tremors were classified into
several origins (collision, calving, crevassing, crashing, etc.); "crevassing events" along the large cracks
inside the fast sea-ice in LHB (04 April), "discharge events" of fast sea-ice from the Bay (07 April), "collision
events" between iceberg and the edge of fast sea-ice (14 April), "crashing movement" between
fragmentation of fast sea-ice and packed sea-ice (18 April), and the other origins. In particular, strong
amplitude tremors with harmonic overtones were assumed to be occurred independently from whether
condition, because these overtone tremors were identified at less stormy days by comparison with
infrasound data at SYO.

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*J01-1-02
Joint Symposium / J01. Monitoring of the cryosphere

Repetitive cryoseismicity at the Fimbulisen Ice Shelf, East Antarctica* Myrto Pirli 1) , Sebastian Hainzl 2) , Andreas Koehler 3) , Johannes Schweitzer 4)
Skjetten, Norway 1) , GFZ German Research Centre for Geosciences, Potsdam, Germany 2) , University ofOslo, Oslo, Norway 3) , NORSAR, Kjeller, Norway 4)
A source region of repetitive cryoseismic activity has been identified at the Fimbulisen ice shelf, inDronning Maud Land, East Antarctica. The specific area is located at the outlet of the Jutulstraumen
glacier, near the Kupol Moskovskij ice rise. Although the activity is mostly expressed through events ofsmall magnitude, they are large enough to be recorded by the permanent seismic stations in the region(SNAA, TROLL, Watzmann-array), within an observation distance range between 210 and 310 km. The useof waveform cross-correlation detectors and Hidden Markov Model classifiers has provided a uniquedataset extending over 13 years, from 2003 to 2016. Phases of low seismicity rates are alternating withintense activity intervals that exhibit a strong tidal modulation that is expressed in terms of event
occurrence times, their geographic distribution and amplitude variation. The observed correlation follows
both the neap-spring and the semi-diurnal ocean-tide cycle. These temporal characteristics of the observed
cryoseismicity are approached through rate and state seismicity models with the prospects of constraining
the physical mechanisms that trigger this activity and enabling the identification of the corresponding
dynamic processes at work at this particular region of the Fimbulisen ice shelf.

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*J01-1-03
Joint Symposium / J01. Monitoring of the cryosphere

Seismology reveals ice sheet basal conditions* Genti Toyokuni 1) , Hiroshi Takenaka 2) , Ryota Takagi 1) , Masaki Kanao 3) , Seiji Tsuboi 4) , Yoko Tono 5) ,Dean Childs 6) , Dapeng Zhao 1)
Tohoku University, Sendai, Japan 1) , Okayama University, Okayama, Japan 2) , NIPR, Tachikawa, Japan 3) ,JAMSTEC, Yokohama, Japan 4) , MEXT, Tokyo, Japan 5) , IRIS/PASSCAL Instrument Center, Socorro, NM,
USA 6)
Basal conditions of the Greenland Ice Sheet (GrIS) are a key research topic in climate change studies. The
recent construction of a seismic network provides a new opportunity for direct, real-time, and continuous
GrIS monitoring. Here we use ambient noise surface wave data from seismic stations all over Greenland fora 4.5-year period to detect seismic velocity changes beneath the inter-station lines. We observe clear
seasonal/long-term velocity changes for many station pairs, and propose a plausible mechanism for thevelocity changes. The dominant factors causing these changes might be pressurization of both the GrIS andunderlying crust by seasonal/long-term snow accumulation, and depressurization by ice thinning due to
GrIS flow and ice mass loss. However, heterogeneity in GrIS basal conditions might impose strong
regionalities on the results. An interesting feature is that, even at adjacent station pairs in the inland GrIS,
both velocity decrease and increase can be caused by snow accumulations. The former pair might belocated on a thawed bed that decreases velocity by increased meltwater due to pressure melting, whereas
the latter pair might be located on a frozen bed that increases velocity by compaction of ice and bedrock.
The results suggest that surface waves are very sensitive to the GrIS basal conditions, and further
observations will contribute to a more direct and quantitative estimation of water balance in the Arctic
region.

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*J01-1-05
Joint Symposium / J01. Monitoring of the cryosphere

Advances in Design and Deployment of Seismic Arrays for Polar Regions* Audrey Huerta 1) , J. Paul Winberry 1) , Bruce Beaudoin 2) , Paul Carpenter 2) , Doug Wiens 4) , Andrew
Nyblade 3) , Rick Aster 7) , Sridhar Anandakrishnan 3) , Jason Hebert 2) , Philip Chung 2) , Kent Anderson 2) ,Susan Bilek 5) , Terry Wilson 6)
Central Washington University, Ellensburg, WA USA 1) , IRIS PASSCAL Instrument Center, Socorro, NM
USA 2) , The Pennsylvania State University, State College, PA, USA 3) , Washington University in St. Louis,
St. Louis, MO, USA 4) , New Mexico Institute of Mining and Technology, Socorro, NM USA 5) , The Ohio
State University, Columbus, OH USA 6) , Colorado State University, Fort Collins, CO, USA 7)
Efforts since the 2007-2008 International Polar Years have focused on enhancing the design anddeployment of seismic arrays for polar regions; including enhancements in power systems, seismometers,
digitizers, and deployment logistics. These advances have resulted in seismic systems that are polar-rated,
are light and small, have low power usage, deploy quickly, and thus, seismic arrays can incorporate larger
numbers of seismometers.
Polar regions have been particularly challenging for seismic studies. Seismic systems must be designed towithstand cold/wet conditions, high-latitude solar limitations, extreme winds, as well as operate in remotelocations with limited maintenance. In addition, the expense associated with accessing these remotelocations drives the design towards minimal installation time and logistical load (i.e., size and weight), while
maximizing ease-of-use in the field, in data handling, and in telemetry compatibility.
Here we review the advances made in the polar seismic arrays through the past 10 years, and the range ofscientific discoveries that have resulted, focusing on the long-term science project, POLENET, and therecently funded Major Research Instrumentation project, GEOICE. Advances in system design include lowpower consumption, optimizing solar systems, and advanced power/battery systems that optimize battery
capacity and operational limits. The scientific projects include ice dynamics, ice shelf stability, hydrology,
tectonic histories, and basic solid earth structure.

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*J01-2-01
Joint Symposium / J01. Monitoring of the cryosphere

Inter-annual modulation of seasonal glacial velocity changes in the Eastern
Karakorum detected by ALOS-1/2 data
* Muhammad Usman , Masato Furuya
Space Geodesy Research Laboratory, Department of Earth and Planetary Sciences, Hokkaido University,
N10W8, Kita-ku, Sapporo 060-0810, JAPAN
Whereas the ice sheets all over the world are receding, the glaciers in Karakoram are either stagnant oradvancing, which is known as ‘Karakoram anomaly'. The surging dynamics and mass balance have been
extensively studied in this area. However, in the Eastern Karakorum Range, the spatial and temporalchanges in glacial velocity have been so far poorly understood. We have analyzed nearly all the available
ALOS-1/2 data in this area and have examined the inter-annual modulation of five glaciers. The glacierswith size >30km, i.e. Siachen, Baltoro and Eastern tributary of Kundos, are mostly showing a considerable
velocity change in their various parts, accompanying clear seasonal changes both in ALOS-1/2 data.
However, this change mostly depends upon the individual glacier and is variable in space and time. On theother hand, the smaller glaciers (<30km), i.e. Singkhu, Gasherbrum and Western tributary of Kundos
glaciers, are showing a slowdown in ALOS-2 data. Analysis of the local air surface temperature data at fiveobservatories indicates that during the same season, the temperature trend in the study area is uneven andprobably varies significantly between different glaciers. It can result in localized warming/cooling that canaffect the availability of melt-water for an individual glacier. The excess surface melt-water at eachindividual glacier may undergo a variety of en/sub-glacial hydraulic and hydrological processes that are
further different at each glacier. Thus, it will result in a complex velocity behavior in this region.

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*J01-2-02
Joint Symposium / J01. Monitoring of the cryosphere

The influence of the Antarctic lithosphere on glacial isostatic adjustment
modelling* Jorg Ebbing 1) , Folker Pappa 1) , Valentina Barletta 2) , Rene Forsberg 2) , Fausto Ferraccioli 3) , Bas Blank, Wouter v.d. Wal 4) , Michael Kern 5)
Kiel University, Kiel, Germany 1) , DTU Space, Copenhagen, Denmark 2) , British Antarctic Survey,
Cambridge, UK 3) , TU Delft, Delft, The Netherlands 4) , ESA-ESTEC, Noordwijk, The Netherlands 5)
4)

In the ESA Support to Science Element GOCE+Antarctica, we study the influence of the lithosphericstructure on estimates of GIA. From recent geophysical, especially seismological, studies new insights on
the deep structure of the Antarctic continents are available. However, the seismological models differ inresolution and do not provide a consistent image of the lithosphere. This is critical in analysing the
feedback between the lithosphere and glacial loading or unloading.
To reduce such ambiguities, we combine the latest seismological models with gravity gradient data derived
from the GOCE satellite mission and the recent ESA Polar Gap airborne survey. The gradients are inparticular sensitive to the geometry and density variations of the main lithospheric layers, i.e. ice andsediment thickness, the Moho depth and the temperature and composition of the upper mantle. Initial
results indicate that differences exist in the mode of compensation for West and East Antarctica related todifferent mantle properties.
The impact of an improved lithospheric model on GIA modelling is estimated by testing the sensitivity to
the new temperature and density distribution and by comparing 1D and 3D viscosity models, especially inareas of low viscosity such as in the rapidly thinning Amundsen Sea sector of the West Antarctic Ice Sheet.

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*J01-2-03
Joint Symposium / J01. Monitoring of the cryosphere

Geodetic studies of GIA and ice sheet changes by JARE
* Yoichi Fukuda 1) , Yuichi Aoyama 2) , Koichiro Doi 2) , Hideaki Hayakawa 2) , Jun'ichi Okuno 2) , Jun
Nishijima 3) , Takahito Kazama 1) , Keiko Yamamoto 4) , Toshihiro Higashi 5) , Kazuo Shibuya 2)
Kyoto University, Kyoto, Japan 1) , National Institute of Polar Research, Tokyo, Japan 2) , Kyushu University,
Fukuoka, Japan 3) , National Astronomical Observatory, Tokyo, Japan 4) , TeraGrav LLC, Kyoto, Japan 5)
The Antarctic ice sheet, which relates to the global climate changes through the sea level rise and ocean
circulation, is an essential element of the Earth system for predicting the future environment changes. Thus
many studies of the ice sheet changes have been conducted by means of in-situ geodetic observations,satellite observations such as satellite gravimetry and satellite altimetry as well. For these studies, one of
the largest uncertainties is the effects of GIA, which, on the other hand, includes valuable information
about the rheological properties of the solid Earth, because GIA is the rheological response of the solid
Earth to the ice mass loading. The observational studies of the GIA effects should also contribute toinvestigate the inner structure of the Earth.
In view of these points, JARE (Japanese Antarctic Research Expedition) have been conducting absolutegravity measurements, GNSS and other geodetic observations at Syowa station and surrounding areas in
East Antarctica. In particular, repeated absolute gravity measurements and continuous GNSS observations
at Syowa station have been conducted since 1995, and these observation have revealed the temporalvariations in both gravity and GNSS measurements due to the GIA. JARE also succeeded the absolutegravity measurement at Langhovde during 2011/2012 austral summer, which was the first outdoor
measurement by JARE. Subsequently, JARE performed the outdoor absolute gravity measurement at
Selungen, the central parts of the Sor Rondane Mts., during 2013 austral summer.
In this paper, related to the studies of GIA and ice sheet changes, we report the geodetic observations so
far made by JARE, and the future plans as well.

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*J01-2-04
Joint Symposium / J01. Monitoring of the cryosphere

Using geodetic data to constrain contemporary GIA signals in Scandinavia
and North America* K. Simon , R.E.M. Riva
Delft University of Technology
The present-day glacial isostatic adjustment (GIA) signal in two major former glaciation centres,
Scandinavia and North America, is constrained in a semi-empirical model by joint inversion of GPSmeasured land deformation rates and GRACE-measured gravity changes. Both the GPS and GRACE
datasets are corrected a priori for the effect of hydrological loading using the PCR-GLOBWB hydrology
model, a correction which can, at least at local scales, significantly impact the fit of model predictions to theobservational data. In the Scandinavian region, the GRACE trend is also corrected for present-day ice masschanges using IceSat data for the glacierized regions of Svalbard and the Russian Arctic. The observational
data are combined with a suite of forward GIA model predictions which allow for variation in both ice sheet
history and Earth model characteristics, with the best-fit posterior model simultaneously minimizing themisfit between both types of constraint. When only GPS data are incorporated into the prior model a good
fit is obtained (X2 < 1). The result is similar when only GRACE data are used as constraint, and the best
overall fit is obtained when both datasets are inverted. Within formerly glaciated regions, the method
provides a realistic prediction of the uncertainty associated with the GIA process at a level that is typically~1 order of magnitude smaller than the uncertainty associated with forward GIA models. For example, forvertical uplift rates, predicted GIA uncertainties range from ~0.2-1 mm/yr, with the largest rates present in
the former load centres of the northern Gulf of Bothnia and Hudson Bay. The GIA predictions can be usedin sea-level studies to better constrain the magnitude and uncertainty of the GIA contribution to regional
sea-level budgets. Also assessed is the sensitivity of the model predictions to variations in ice sheet andEarth model combinations, and the ability of the method to resolve preferred values for these parameters.

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*J01-2-05
Joint Symposium / J01. Monitoring of the cryosphere5000 Year Advance and Retreat Models for West Antarctica and a
Geodetically Based Solution for Mantle Viscosity and More Recent andAccelerated Cryospheric Loss
* Erik Ivins 1) , Helene Seroussi 1) , Lambert Caron 1) , Surendra Adhikari 1) , Eric Larour 1) , Douglas Wiens 2), Andrew Lloyd 2) , Mirko Scheinert 3)
Jet Propulsion Lab, California Institute of Technology, Pasadena, USA 1) , Washington University, SaintLouis, USA 2) , University of Dresden, Dresden, Germany 3)
We model the present-day time-dependent bedrock motion of Antarctica driven by deep Earth elastic andviscous-gravitational response to continent-wide glacial mass changes. During the past two decades ice
mass balance assessment has been achieved using space-based imaging and surface mass balance (SMB)
modelling, altimetry and SMB, and with GRACE time-varying gravity. Crustal uplift trends are only recently
emerging as a reliable source of constraint from data employed in the POLENET Project using Global
Positioning System (GPS) geodesy. Two other observations have also emerged in the last decade: seismic
imaging on the upper mantle and transition zone, at various levels of resolution, and rough maps of thebasal hydrology that reveal channels and lake activity to be rather pervasive in many part of west
Antarctica. The latter two advances in our knowledge were poorly integrated into models of mantle and ice
history, the two main features that control predictions of glacial isostatic adjustment (GIA) in West
Antarctica. Numerous models have emerged using the seismic imaging of the shallow upper mantle tocompute GIA with laterally varying viscosity. Here we present new results of a traditionally radially layered
model with updated ice history and seismically informed upper mantle viscosity structure and relatively
free lower mantle viscosity.

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*J01-3-01
Joint Symposium / J01. Monitoring of the cryosphereHigh resolution gradient fingerprint mapping and its impact on urban
planning.
Eric Larour , * Erik Ivins , Surendra Adhikari
Jet Propulsion Laboratory
Local sea level rise is a measure of several competing processes, such as the contribution of melting icefrom polar ice sheets, short-term processes related to ocean and atmospheric circulation, vertical landmotion, viscoelastic adjustment of the mantle and crust and intense storm flooding. Of all thesecomponents, polar ice sheets will contribute most in the near to long-term future. It is therefore paramountto understand how sensitive
local sea level is to spatio-temporally variable patterns of ice thickness in glaciated areas around the world.
Here, we propose a new tool to assess this sensitivity based on gradient fingerprint mapping (GFM). Thismethod quantifies exactly the derivative dS/dH, where S is local sea level and H ice thickness around theworld. This derivative can be used to compute local projections of sea level using the following approach: S= dS/dH * DH + deltaS, where dS/dH is the gradient fingerprint (as it relates to ice) and DH any projectedchange in ice thickness (be it from observations extrapolated in time, or semi-empirical approaches, ormodel-based projections). deltaS encompasses other time variable components (assumed of a lower order)
described above. Using high-resolution GFM,
urban planners can assess which glaciated areas around the world will be of relevance to sea level change
at their specific location, and how to instantly transfer projections of polar ice sheet evolution into localized
sea-level change projections, along with associated uncertainties.
This work was performed at the California Institute of Technology's Jet Propulsion Laboratory under acontract with the National Aeronautics and Space Administration's Cryosphere Science Program.

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*J01-3-02
Joint Symposium / J01. Monitoring of the cryosphere

Sea level rise from the Greenland and Antarctica ice sheet melt fromcombined CryoSat and GRACE inversion* Rene Forsberg , Sabastian Simonsen , Valentina Barletta
DTU Space, Lyngby, Denmark
The combination of space-based remote sensing data, especially gravity field changes from GRACE andelevation changes from CryoSat, may yield time series of Greenland and Antarctica mass balance with both
high temporal and spatial resolution, highlighting the varying individual mass loss behaviour of major
glaciers systems, while still keeping a “correct" overall ice sheet wide mass loss. Although GIA-related
errors continue to be large in Antarctica, the temporal changes in mass balance are well determined, andshow significant acceleration both over the Antarctic Peninsula and the Pine Island/Thwaites glaciersystems. For Greenland the large yearly melt event of 2012 followed by extraordinary cool summers havemeant that the Greenland ice sheet mass loss have been slightly decreasing during the CryoSat period
2010-16, with large variations between individual glaciers and ice streams.
In the presentation we outline change results from CryoSat and GRACE 2010-2016, for both Greenlandand Antarctica, using models of firn compaction and density as auxillary data. We estimate an overall massbalance of Greenland around -265 GT/yr and for Antarctica -145 GT/yr, representing nearly a doubling of
Antarctica mass loss since 2002, while Greenland show only relatively small overall accelerations, withlarge regional melt region variations. From the ice sheet melt data, we find a current global sea level risecomponent of 1.1 mm/yr, or about 1/3 of the currently observed global sea level rise. Sea level rise fromthe melting ice sheets is far from constant across the globe due to associated gravity field and loadingchanges, and we show estimates of the current regional “fingerprinting" of the sea level rise signal.

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*J01-3-03
Joint Symposium / J01. Monitoring of the cryosphereA 25-year Arctic Sea-level Record (1991-2016) and first look at Arctic Sea
Level Budget Closure* Ole Andersen 1) , Stine K Rose 1) , Marcello Passaro 2) , Jerome Benveniste 3)
DTU Space 1) , TUM Munich 2) , ESA Esrin 3)
A new initiative within the ESA Sea Level Climate Change initiative (SL-cci) framework to improve theArctic sea level record has been initiated as a combined effort to reprocess and retrack past altimetry tocreate a 25-year combined sea level record for sea level research studies. One of the objectives is toretracked ERS-2 dataset for the high latitudes based on the ALES retracking algorithm through adapting the
ALES retracker for retracking of specular surfaces (leads). Secondly a reprocessing using tailored editing to
Arctic Conditions will be carried out also focusing on the merging of the multi-mission data. Finally aneffort is to combine physical and empirical retracked sea surface height information to derive anexperimental spatio-temporal enhanced sea level product for high latitude. The first results in analysing
Arctic Sea level variations on annual inter-annual scales for the 1992-2015 from a preliminar version ofthis dataset is presented. By including the GRACE water storage estimates and NOAA halo- and thermosteric sea level variatios since 2002 a preliminary attempt to close the Arctic Sea level budget is presented
here. Closing the Arctic sea level budget is by no mean trivial as both steric data and satellite altimetry isboth sparse temporally and limited geographically.

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*J01-3-05
Joint Symposium / J01. Monitoring of the cryosphere

Glacier surge mechanism of Steele Glacier in Yukon, Canada: the2011-2016 surging episode* Takahiro Abe , Masato Furuya , Daiki Sakakibara
Hokkaido University, Sapporo, Japan
Glacier surge is a periodical orders-of magnitude speed-up event during a short active phase,accompanying terminus advance and ice thickness changes. Near the border of Alaska and Yukon, Canada,
there are numerous surge-type glaciers, and their behaviors has received a good deal of scientificattentions. To date, the dynamics have been examined at some surge-type glaciers, but there remain somequestions about the generation mechanism.
High-quality images of recent satellites have allowed us to capture the evolutions of surging episodes withhigh temporal resolution. Steele Glacier in the southwest Yukon is one of the recently activated surge-type
glaciers after the quiescence of ~50 years. It experienced the last surge in 1965-1967, and the peak speed
was about 24 m/d in early summer 1966 (Stanley, 1969). However, the details of the surging evolution
remain unclear. Here we examined the spatial and temporal changes in ice speed, ice thickness andmoraines associated with the recent event for the first time in ~50 years.
We used ALOS/PALSAR, Landsat-7, Landsat-8, and Sentienl-1A images to derive the ice speed evolution
between 2007 and 2016. Although we have no data in late 2011-early 2013 due to the data availability,
RADARSAT-2-based velocity data (Waechter, 2013) showed the latest surge initiated in 2011, and theSentinel-1A-based velocity data showed it terminated in fall 2016. The observed maximum speed was
greater than 20 m/d in early summer 2015, whereas the quiescent speed was ~0.4 m/d between 2007 and2011. The rapid acceleration changed the ice thickness, which is revealed by Terra/ASTER DEMs. In
2006-2011, the ice thickened above the confluence. In 2013-2016, the ice thickened in the middle anddownstream region, while it thinned above the confluence.
Based on the ice thickness changes and the moraine movements, the surge started at the confluence of
Hodgson and Steele Glaciers. We will discuss the surge mechanism based on the diverse datasets.

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*J01-P-01
Joint Symposium / J01. Monitoring of the cryosphereClassification of ice tremor recorded at Syowa Station in Antarctica* Yuya Tanaka 1) , Yoshihiro Hiramatsu 1) , Yoshiaki Ishihara 2) , Masaki Kanao 3)
Kanazawa University, Ishikawa, Japan 1) , ISAS/JAXA, Kanagawa, Japan 2) , NIPR, Tokyo, Japan 3)
Tectonic earthquakes and tremors related to ice (ice tremor) have been observed by seismic stations in
Antarctica. Ice tremors are the tremors which are originates in some ice motion (Kanao et al., 2012).
Purposes of this study are to classify ice tremors and to reveal the spatio-temporal variation in the
distribution of ice tremors.
We use the waveform data recorded by seismometer at coastal stations. The analysis period is from January
to December in 2014. We define here an ice tremor as the tremor of which P-waves and S-waves are notclear and the duration is longer than five minutes.
We find the total of 148 ice tremors in 2014. The monthly number of the ice tremors correlates well withthe monthly mean temperature from April to December. We classify the ice tremors into three types basedon a temporal variation in their spectrum features. Type A is the ice tremor which shows that the duration
is long (about ten thousands seconds) and the amplitude is small over the waveform. Type B is that ofwhich dominant frequency changes irregularly over the waveform. Type C is that of which dominantfrequency continuously decreases and the overtone is recognized. The hypocenters of 47 ice tremors are
determined in this study. There are 26 ice tremors, six in the coastal area, six on the sea area and 14 on theland area, within ~ 150 km from the stations.
In summer, both the seismic and microbaroms amplitudes are large and the shape of the waveform of type
A is excited by sea wave. In winter, the amplitude of microbaroms is large, while that of the ice tremor is
not recorded well because of growing coastal ice (Grob et al, 2011). The hypocenters of type C are locatedon the sea area ~ 150 km away from Syowa station. Eckstaller et al. (2006) and MacAyeal et al. (2008)
reported ice tremors related to iceberg and the spectral feature of them are similar to that of type C.
Therefore, we suggest that the source of the type C is related to the iceberg motion.

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*J01-P-02
Joint Symposium / J01. Monitoring of the cryosphere

GROUND DEFORMATION MAPPING BY ALOS1/2 INSAR: CASE STUDIESAT HERSCHEL ISLAND, CANADA, AND BATAGAIKA CRATER, SIBERIA* Kazuki Yanagiya , Masato Furuya
The University of Hokkaido, Hokkaido, Japan
The permafrost area covers about 1/4 of the northern hemisphere and its thawing can lead to grounddeformation. That ground deformation has been studied as a serious problem in the Arctic Ocean coastal
area such as Russia for a long time, because the deformation causes damage to architectures at these areas.
However, there have been no quantitative observation data, and the spatial and temporal distributions have
hardly been investigated. On the other hand, by the recently global warming influence, the importance oforganic carbon stored in permafrost is pointed out. Although the release of methane gas is confirmed insome thermokarst lakes, it is very difficult to observe the permafrost in a wide area by field study. Instead, it
is technically possible to monitor the subsidence and uplift of the ground over the permafrost area, which
could potentially make a significant contribution to the monitoring thawing process of permafrost.
In this study, we attempted to detect ground deformation signal in permafrost area by remote sensing using
interferometric synthetic aperture radar (InSAR). Using the data of two SAR satellites ALOS and ALOS2
launched by JAXA, we observed recent ground deformation from 2007 to 2016. Focusing on the slump
terrain with relatively fast fluctuation velocity as the observation target, we detected ground subsidence in
Herschel Island in Canada and Batagaika Crater in Russia. In Herschel Island, we observed the subsidence
and coastal erosion in recent years by ALOS2 which has not been repoted. At the Btagaika Crater, however,
it is not yet certain if the detected signals really indicate subsidence, because the employed digital
elevation models seem to have biases.

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*J01-P-03
Joint Symposium / J01. Monitoring of the cryosphere

Temperature dependent seismic-frequency attenuation in ice andpermafrost* Seth Saltiel 1) 2) , Brian Bonner 2) , Shan Dou 2) , Jonathan Ajo-Franklin 2)
UC Berkeley, Berkeley, CA, USA 1) , Lawrence Berkeley National Lab, Berkeley, CA, USA 2)
There is an increasing interest in cryoseismic waves and their ability to monitor seismogenic processes andenvironmental conditions in the cryosphere [Podolskiy and Walter 2016]. However, laboratory work tounderstand and interpret this information is lacking, especially near the melting point and at seismicfrequencies. For example, seismic attenuation in ice and permafrost is very sensitive to temperature,especially close to the melting point, providing the opportunity to obtain temperature profiles from seismic
data, given controlled experimental attenuation databases. Peters et al. [2012] estimated englacial
temperature from a seismic survey based on resonance measurements, > 100 Hz, on ice cores [Kuroiwa
1964], showing good agreement with other measured and modeled temperature profiles in the area. This
technique could be improved with seismic-frequency laboratory measurements. In saline permafrost, 1
MHz P-wave attenuation was measured to increase dramatically near the eutectic temperature, suggesting awave-induced phase change attenuation mechanism [Dou et al., 2016]. Broadband measurements andcomparison to crystallization kinetics could confirm this hypothesis. We have adapted a seismic-frequency(0.1 - 100 Hz) sub-resonance apparatus [Saltiel et al., 2017] to measure shear modulus and attenuation offrozen materials under controlled temperature conditions. These measurements can be directly applied toongoing efforts to use active and passive seismic surveys to measure englacial temperature profiles andmonitor permafrost thaw. We are also pursuing laboratory experiments to contribute to our understanding
and interpretation of seismic data of glacier bed sliding frictional behavior, and ice tensile/shear fracturing
to constrain calving and crevassing rates. New experimental facilities make the systematic exploration of
the seismic properties of frozen materials possible, which will increase the accuracy and utility ofcryoseismology datasets.

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*J02-1-01
Joint Symposium / J02. Recent large and destructive earthquakes

Complex seismicity and hypocenter distribution of the 2016 Kumamoto
earthquakes, Kyushu, Japan, and their relation to the stress field and crustal
structure* Hiroshi Shimizu , Group for urgent joint seismic observation of the 2016 Kumamoto earthquakes
Institute of Seismology and Volcanology, Kyushu University, Shimabara, Japan
Large earthquakes of M6.5 and M7.3 occurred in April, 2016, in the Kumamoto prefecture, Kyushu, Japan.
An urgent joint seismic observation by several universities and institutes in Japan was conducted in order
to investigate the detailed feature of the seismic activity.
The hypocenter of the M6.5 earthquake of April 14 locates beneath the Hinagu fault zone. While thehypocenter of the M7.3 earthquake of April 16 locates about 5km WNW of the M6.5, and beneath the
Futagawa fault zone. The seismic activity was distributed along both the Futagawa and Hinagu fault zones,
and the induced earthquakes were activated along the Beppu-Shimabara graben. However, detailed
hypocenter distribution and the focal mechanism solutions indicate that the strike of the M6.5 fault is
oblique to the trace of Hinagu fault, and that the initial rupture of the M7.3 occurred at off-fault of the
Futagawa fault. In addition, the almost aftershocks did not occur at the fault plane on which the main
rupture of M7.3 took place.
In this region, the high background seismicity had been observed, and M5.0 earthquake occurred in 2000.
Inelastic strain distribution estimated by seismic moment tensor data implies that the source region
corresponds to the relatively large strain area, which suggests the large inelastic strain created stressconcentration. Although the N-S minimum principal stress is dominated in this region, the maximum andmoderate principal stresses are spatially alternated. The complex fault system and seismicity could be
attributed to such a uniaxial extension of deviatoric stress field.
Seismic tomography and magnetotelluric analysis show that the low velocity, moderate to high Vp/Vs ratio
and conductive region exists below the large earthquakes. In addition to the stress concentration, the fluid
supply from the lower crust probably trigger the large earthquakes and high-level seismicity.

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*J02-1-02
Joint Symposium / J02. Recent large and destructive earthquakes

Detailed crustal deformation and fault ruptures of the 2016 Kumamoto
Earthquake revealed by ALOS-2 SAR data
* Tomokazu Kobayashi , Hiroshi Yarai , Yu Morishita , Satoshi Kawamoto , Satoshi Fujiwara , Takayuki
Nakano
GSI of Japan, Tsukuba, Japan
We report ground displacement associated with the 2016 Kumamoto Earthquake obtained by ALOS-2 SAR
data. For the SAR analyses, we applied InSAR and pixel offset methods, which has successfully provided a
3D displacement field showing the widely- and locally-distributed deformation. The obtained displacement
field shows clear displacement boundaries linearly along the Futagawa, the Hinagu, and the Idenokuchi
faults across which the sign of displacement component turns to be opposite, suggesting that the fault
ruptures reached the ground surface or subsurface. The known fault trace of the Futagawa fault terminates
at the western edge of Aso caldera, but the displacement discontinuity clearly extends into the caldera witha position slightly shifting northward. Our fault model suggests that the main rupture occurred on the
Futagawa fault with a right-lateral motion including a slight normal fault motion. The rupture on the
Futagawa fault extends into the Aso caldera with slightly shifting the position northward. Of note, the fault
plane oppositely dips toward southeast. It may be a conjugate fault against the main fault. For the
Idenokuchi fault, a normal fault motion is dominant at the depth of around 5 km. The Idenokuchi faults
runs near the Futagawa fault in parallel, and they have different slip components separately. It maybe
suggest a slip partitioning, which supports the idea proposed by Toda et al. (2016). In the western side of
the source region, the slip on the Hinagu fault, in which the Mj6.5 and Mj6.4 foreshocks occurred with apure right-lateral motion, is also deeply involved with the main shock.
Acknowledgements: ALOS-2 data were provided from the Earthquake Working Group under a cooperative
research contract with JAXA (Japan Aerospace Exploration Agency). The ownership of ALOS-2 data
belongs to JAXA.

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*J02-1-03
Joint Symposium / J02. Recent large and destructive earthquakes

Ground motion simulation during the 2016 Kumamoto earthquake
mainshock in near-fault area and Aso caldera* Kimiyuki Asano , Tomotaka Iwata
Disaster Prevention Research Institute, Kyoto Universiy, Uji, Kyoto, Japan
We studied the strong ground motions caused by the heterogeneous rupture process during the mainshockof the 2016 Kumamoto earthquake sequence (Mj7.3). The source rupture process was analyzed using
strong motion data, assuming a fault geometry along the Hinagu and Futagawa faults in accordance withthe surface ruptures. We assigned point sources densely with an interval of 0.2 km on the assumed fault
planes in order to reproduce appropriately near-fault ground motions, and estimated spatiotemporal slip at
control points discretized with an interval of 1.8 km on the fault planes by the multiple time-window linear
waveform inversion method (e.g., Hartzell and Heaton, 1983). The rupture started at a northwest-dipping
fault plane along the Hinagu fault with almost pure right-lateral strike-slip, and continuously propagatedacross the junction of the Hinagu and Futagawa faults. Then, it propagated northeastward along the
Futagawa fault, and stopped to rupture in the western part of the Aso caldera. The significant slip with 3-5
m including normal-slip component were observed on the Futagawa fault, and shallowest part has slip
ranging from 1 to 2 m, which is consistent with surface rupture distribution. Strong ground motion time
histories including significant coseismic displacement along the fault-parallel direction observed at twonear-fault stations (Mashiki and Nishihara) were reproduced well by this source model. Significant faultnormal displacement with continuous cracks observed in the Aso valley area could be explained as lateralground movement induced by the strong forward directivity pulse generated associated with the rupture on
the Futagawa fault. We also conducted a 3D ground motion simulations up to 1 Hz using the 3D velocity
structure model JIVSM (Koketsu et al., 2012) and the finite difference method to see the effect of thesource rupture process including source directivity effects on the spatial variation in strong ground motions
during this event.

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*J02-1-04
Joint Symposium / J02. Recent large and destructive earthquakes

Simultaneous estimation of the dip angles and slip distribution on the two
active faults of the 2016 Kumamoto earthquake through a weak non-linear
inversion of InSAR data based on ABIC
* Yukitoshi Fukahata , Manabu Hashimoto
Kyoto University, Kyoto, JapanAt the 2016 Kumamoto earthquake, surface ruptures were observed not only along the Futagawa fault,
where main ruptures occurred, but also along the Hinagu fault. To estimate the slip distribution on thesefaults, we extend a method of non-linear inversion analysis (Fukahata and Wright 2008) to a two-faults
system. With the method of Fukahata and Wright (2008) we can simultaneously determine the optimal dip
angle of a fault and the slip distribution on it, based on Akaike's Bayesian Information Criterion (ABIC) by
regarding the dip angle as an hyperparameter. By inverting the InSAR data with the developed method, we
obtain the dip angles of the Futagawa and Hinagu faults as 61º ± 6º and 74º ± 12º, respectively. The slip on
the Futagawa fault is mainly strike slip. The largest slip on it is over 5 m around the center of the model
fault (130.9º in longitude) with a significant normal slip component. The slip on the Futagawa fault quickly
decreases to zero beyond the intersection with the Hinagu fault. On the other hand, the slip has a local
peak just inside Aso caldera, which would be a cause of severe damage in this area. A relatively larger
reverse fault slip component on a deeper part around the intersection with Aso caldera suggests thatsomething complicated happened there. The slip on the Hinagu fault is almost a pure strike slip with a peakof about 2.4 m. The developed method is useful in clarifying the slip distribution, when a complicatedrupture like the Kumamoto earthquake happens in a remote area.

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*J02-1-05
Joint Symposium / J02. Recent large and destructive earthquakes

Postseismic deformation of 2016 Kumamoto earthquake by the dense GNSS
continuous observation* Shigeru Nakao 1) , Takeshi Matsushima 2) , Takao Tabei 3) , Makoto Okubo 3) , Tadashi Yamashina 3) ,Takahiro Ohkura 4) , Takuya Nishimura 4) , Takuo Shibutani 4) , Masahiro Teraishi 4) , Takeo Ito 5) , Takeshi
Sagiya 5) , Kenjiro Matsuhiro 5) , Teruyuki Kato 6) , Jun'ichi Fukuda 6) , Atsushi Watanabe 6) , Yusaku Ohta 7) ,Satoshi Miura 7) , Tomotsugu Demachi 7) , Hiroaki Takahashi 8) , Mako Ohzono 8) , Teruhiro Yamaguchi 8)
Kagoshima University, Kagoshima, Japan 1) , Kyushu University, Fukuoka, Japan 2) , Kochi University,
Kochi, Japan 3) , Kyoto University, kyoto, Japan 4) , Nagoya University, Nagoya, Japan 5) , The University ofTokyo, Tokyo, Japan 6) , Tohoku University, Sendai, Japan 7) , Hokkaido Universiy, Sapporo, Japan 8)
The 2016 Kumamoto earthquake (M7.1) occurred on April 16 following the M6.5 earthquake on April 14,
2016. The maximum intensity 7 was observed in Mashiki-machi two times. These earthquakes occurred in
the two active faults zone, Hinagu fault zone and Futagawa fault zone. After the occurrence earthquake
activity enlarged to east from the aftershock area of the 2016 Kumamoto earthquake. Earthquake activity
become high in northern region of Aso volcano and central part of Ohita prefecture. Our group started
settlement of the continuous GNSS observation site in aftershock area of main shock, around Aso volcano
and central Ohita prefecture in order to observe postseismic deformation and relationship between seismic
activity and crustal deformation.
Twenty-one GNSS sites have been set up by April 28. There are nine sites in aftershock area, four sites ineast area to Aso volcano, four sites in the central Ohita prefecture and three sites in southern part ofHinagu fault zone. Bernese GNSS Software Ver. 5.2 is used for GNSS data analysis of our newly sites
together with GEONET and JMA GNSS sites in volcanoes (Aso, Kujyu and Garan-dake) in Kyushu for theperiod from April 15. We used CODE precise ephemerides and CODE Earth rotation parameters. The
coordinates of the GNSS sites are estimated with respect to ITRF2008.
North-east displacement at the sites of western side of Hinagu fault and south-west displacement at the siteof eastern side of Hinagu fault are observed. Postseismic deformation continues in January, 2017. After slip
is assumed the cause of observed postseismic deformation. Fault parameters of two faults (Futagawa fault
and Hinagu fault) are estimated. Fault slip on Hinagu fault is larger than that Futagawa fault. Width of two
faults is 40 km and dip is 89 and 57 degree. It seems that after slip fault extend to the mantle. Long timeobservation of postseismic deformation is needed to separate deformation caused by after slip andresponse of viscoelasticity.

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*J02-2-01
Joint Symposium / J02. Recent large and destructive earthquakes

Comparison of macroseismic studies of two similar megathrust earthquakes
in Ecuador* Juan-Carlos Singaucho 1) , Celine Beauval 2)
Instituto Geofisico - Escuela Politecnica Nacional (IG-EPN), Quito, Ecuador 1) , Institut des Sciences de la
Terre (ISTerre), Grenoble, France 2)
The 2016 Muisne earthquake (7.8 Mw) in Ecuador was one of the most damaging events in the last 50
years in the country. This event caused 663 fatalities and total collapse of several structures in theepicentral zone. Comparing this earthquake with the megathrust event of 1942, 7.8 Mw, the main
characteristics of the rupture process are recognized; however, distribution of damages are very different.
In this paper a comparison of the intensities of the two mentioned events with intensity attenuation
equations and ground motion to intensity conversion equations (GMICEs) is performed. A revision of theoriginal evaluation of the 1942 earthquake is included. This comparison indicates that the seismic
intensities for the 1942 event might be overestimated which could affect the general shape of the maximum
intensity map. Finally, shake maps for the mainshock and two biggest aftershocks are generated using
strong motion signals of the National Accelerometric Network. The latest, to observe amplification patterns
due to site effects.

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*J02-2-02
Joint Symposium / J02. Recent large and destructive earthquakes

The 2016 Mw 7.8 Pedernales, Ecuador earthquake: aftershock sequence
analysis using a minimum 1D velocity model
Sergio Leon-Rios 1) , Ana Luiza Martins 1) , Amaya Fuenzalida-Velasco 1) , Lidong Bie 1) , Tom Garth 1) ,Pablo Gonzalez 1) , James Holt 1) , * Andreas Rietbrock 1) , Benjamin Edwards 1) , Marc Regnier 2) , Diego
Mercerat 3) , Michel Pernoud 3) , Matthieu Perrault 4) , Javier Santo 4) , Alexandra Alvarado 4) , Susan Beck 5), Anne Meltzer 6)
Department of Earth, Ocean and Ecology. School of Environmental Sciences. University of Liverpool.
Liverpool, United Kingdom 1) , Geoazur, Universite Nice, IRD, CNRS, OCA. Nice, France 2) , CEREMA,
CNRS. Nice, France 3) , Instituto Geofisico de la Escuela Politecnica Nacional. Quito, Ecuador 4) ,Department of Geosciences, University of Arizona. Tucson, Arizona, United States 5) , Department of Earthand Environmental Sciences, Lehigh University. Bethlehem, Pennsylvania, United States 6)
On the 16th April 2016, a Mw 7.8 mega-thrust earthquake occurred in northern Ecuador, close to the cityof Pedernales. The event ruptured an area of 120 x 60 km and was preceded by a Mw 4.8 foreshock,located only ~15 km south of the epicentre, and registered 10 minutes before the main event.
A few weeks after the main event a large array of instruments was deployed by a collaborative project
between the Geophysical Institute of Ecuador (IGEPN), IRIS (USA), Geoazur (France) and the University ofLiverpool (UK). This dense seismic network, with more than 70 stations, includes broadband, short period,
strong motion and OBS instruments and is currently recording the aftershock activity of the main event.
Using data recorded both on the permanent and the recently deployed network we manually picked -with
SDX- and located -with SDX and NonLinLoc- 250+ events corresponding to the aftershock sequence. P and
S arrival times were used to obtain a minimum 1D velocity model. After relocate the seismicity we analysed
the spatial distribution and its relation with the co-seismic slip and with previous models of inter-seismic
coupling. It is possible to identify two lineations in the aftershock activity located to the north and south of
the rupture. Moreover, the geodetic slip model shows that the boundaries of the maximum coseismic slip
coincides with the observed lineaments in the aftershocks and with the rupture area of a previous Mw 7.8
event in 1942. This suggests that the features to the north and south may impose a barrier to rupture
propagation, creating different segments in the subduction zone beneath Ecuador.
Previous activity has presented a northward-propagating series of ruptures greater than Mw 7 spaced
approximately 20 years apart. An open question is therefore whether the present event is the start of afurther series of large magnitude events in northern Ecuador, and whether slow slip events/creep in thesouth have fully accommodated the strain due to subduction.

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*J02-2-03
Joint Symposium / J02. Recent large and destructive earthquakes

The 2015 Nepal earthquake: Evidence for a horizontal underthrusting ofIndia beneath the Himalaya* Qi Wang 1) , Xuejun Qiao 2)
China University of Geoscience, Wuhan 1) , Institute of Seismology, China Earthquake Administration 2)
The 2016 Gorkha Nepal earthquake (Mw=7.9) is a fresh and bitter reminder of seismic potential induced
by underthrusting the India subcontinent beneath the Himalaya and thus provide a rare opportunity toilluminate puzzles regarding the continental subduction and seismicity, for which we knew little as yet.
Himalayan earthquakes are assumed to suddenly release elastic strain energy built up on the basal
decollement, a mega-thrust fault along which the Indian plate is descending. However their growth toachieve greatness is impeded usually by complex structures on the megathrust. Here, by analysis of surface
displacements observed mostly in southern Tibet with GPS geodesy, we show that coseismic slip of > 1 m
in 2016 has propagated northward for 130-160 km at the base of the Himalaya, extending substantially into
below southern Tibet. Our modeling reveals a shallowly-dipping plate interface that runs over a mid-crustal
ramp fault assumed below the topographic front of the high Himalaya and stretches almost horizontally
15-25 km above a deep seismic reflector imaged beneath southern Tibet ( known as the Main Himalayan
Thrust), therefore distinguishing a mid-crustal shear zone of Indian upper crust in between which underlies
a tapered accretionary wedge. Our finding sheds insight into two puzzling features in the Himalaya: why
mid-crustal seismicity is absent for the continental subduction, and convergent deformation is primarily
localized at its frontal thrust. In addition, the planar surface of the megathrust and its seismogenic downdip
width of at least 200 km highlight a potential for generating giant earthquakes ( Mw~9 ) . We conclude thatany model adopting a mid-crustal ramp- decollement geometry as the plate interface for India
underthrusting beneath the Himalaya and Tibet should be modified.

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*J02-2-04
Joint Symposium / J02. Recent large and destructive earthquakes

Is the 2013 Lushan earthquake (Mw=6.6) an independent event or a strong
aftershock of the 2008 Wenchuan, China mainshock (Mw=7.9)?
* Shoubiao Zhu
Institute of Crustal Dynamics, China Earthquake Administration,Beijing, China
Following the 2008 Wenchuan earthquake (Mw=7.9), the 2013 Lushan strong shock (Mw=6.6) occurredagain on the Longmen Shan thrust fault. Ever since the earthquake occurred, it has been a topic of hot
debate on whether it is a strong aftershock of the 2008 Wenchuan earthquake or a new independent one.
To this purpose, we investigated the seismogenic fault for the Lushan earthquake, and found that it issituated on the same fault system as that for the Wenchuan earthquake, and the Lushan shock ruptured oneof the barriers which were left unbroken in the 2008 Wenchuan earthquake. In addition, we analyzed thestatistical properties of the Wenchuan-Lushan earthquake sequence (WLES) using three establishedempirical laws on aftershocks. The modelling results showed that the WLES, in which the Lushan event isregarded as one of aftershocks of the Wenchuan mainshock, well satisfied three accepted statistical laws,
namely the Gutenberg-Richter relation, modified Omori-Utsu law and Bath's law. At the same time, we
observed that the weak and ductile materials between the hypocenters of the Wenchuan and Lushan
shocks resulted in seismic gap in between, and the strong materials in the source region and special curved
geometry of seismogenic fault for the Lushan event may be responsible for the approximately 5-year delayof the occurrence. In particular, the focal mechanism of the Lushan event, like most of the other strong
aftershocks of the Wenchuan mainshock, is nearly thrust-type fault, suggesting the Lushan earthquake,
together with other strong aftershocks, is controlled by the same stress environment. Most of all, we noticed
that the Lushan event was triggered by the 2008 Wenhcuan main shock. Taken together, it is reasonable toinfer that the Lushan event is a strong aftershock of the Wenchuan earthquake. Meanwhile, we propose in
the paper that it is an important criterion for identification of aftershocks by means of judging whether they
are triggered by the main shock.

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*J02-2-05
Joint Symposium / J02. Recent large and destructive earthquakes

Coseismic deformation associated with the 2001 Ms 8.1 Kunlun earthquake
from GPS and its tectonic implications* Kaihua Ding 1) , Qi Wang 1) , Jeffrey Freymueller 2) , Ping He 1) , Shuiping Li 1) , Yunguo Chen 1) , Yangmao
Wen 3) , Caijun Xu 3) , Shaomin Yang 4) , Xuejun Qiao 4)
University of Geosciences, Wuhan, China 1) , University of Alaska, Fairbanks, USA 2) , Wuhan University,
Wuhan, China 3) , Institute of Seismology, China Earthquake Administration, Wuhan, China 4)
We conducted several GPS surveys of triangulation network in the vicinity of surface rupture caused by the2001 Kunlun Ms 8.1 earthquake, to deduce its coseismic deformation. Since we first carried out the nearfiled survey in 2015, we have collected GPS data at 33 triangulation network sites, which are spreadingalong the surface rupture and centered in the Kusai Lake, Kokoxili, China. Due to the availability of thesenear-filed observations, we provided an updated set of GPS coseismic displacements, after removing theinterseismic and postseismic deformation. The GPS-derived coseismic displacement filed shows that the
maximum coseismic displacement is 2.412m at a site with the closest distance of ~2km to the surface
rupture.
Constrained by the GPS coseismic displacements, we used a variable slip model to further invert for thecoseismic slip distribution associated with this event. The GPS-derived result is in consistent with previous
studies from field measurements, high-resolution satellite images and InSAR. The largest slip occurred on
the Kusai Lake segment with two obvious asperities on the whole. As a result of the existence of near-fieldobservations, we estimated a more detailed slip pattern of these two asperities, one with smaller slip of
4~6m extending to a deeper depth of ~20 km and the other with larger slip of 5~8 m to ~10 km depth. At
the eastern end of the 426-km-long rupture, the GPS data show evidence for small (<2 m) but non-zero slip,
in a section of the fault where the earlier InSAR data did not show any slip. Based on our preliminary
results, we can get that slip is penetrating coseismically much deeper than the typically assumed depth of
the seismogenic layer. In order to verify this, we are conducting more experiments.

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*J02-3-01
Joint Symposium / J02. Recent large and destructive earthquakes

Shattering a plate boundary: Complex multi-fault rupture during the 2016
Mw 7.8 Kaikoura earthquake, New Zealand* Ian Hamling 1) , Sigrun Hreinsdottir 1) , Stephen Bannister 1) , Eric Fielding 2) , Bill Fry 1) , Caroline Holden, Ana Kaiser 1) , Nicola Litchfield 1) , Christof Mueller 1) , Laura Wallace 1) 3) , Tim Wright 4)
GNS Science, Lower Hutt, New Zealand 1) , Jet Propulsion Laboratory, California Institute of Technology,
Pasadena, CA, USA 2) , University of Texas Institute for Geophysics (UTIG), Austin, Texas, USA 3) ,University of Leeds, Leeds, UK 4)
1)

On 14th November 2016, the northeastern South Island of New Zealand was struck by a major Mw 7.8
earthquake. The earthquake was the most powerful experienced in the region in more than 150 years.
Shaking felt across the whole of New Zealand with widespread damage across much of the northern South
Island and in New Zealand's capital city, Wellington. The earthquake straddled two distinct seismotectonic
domains, breaking multiple faults in the predominantly strike-slip Marlborough Fault System and thecontractional North Canterbury fault zones. Aftershocks continue to follow a broad NE-SW trend proximal
to the Humps and Hundalee faults in the North Cantebury fault zone before stepping north, approximately
following the Jordan Thrust and Kekerengu faults. Field observations, in conjunction with InSAR, GPS, andseismology reveal this to be one of the most complex earthquakes ever recorded. The rupture propagatednorthward for more than 170 km along both mapped and unmapped faults, before continuing offshore at its
northeastern extent. The earthquake also generated a tsunami which was detected at four tide gauges along
the east coast of the both the North and South Islands. Simple travel time inversion places the source of thetsunami in the coastal area ranging from just south of Kaikoura northwards to Cape Campbell. Geodetic
and field observations reveal surface ruptures along at least 12 major crustal faults, extensive uplift alongmuch of the coastline and widespread anelastic deformation including the ~8 m uplift of a fault-boundedblock. While most of the deformation can be explained by crustal faulting alone, global moment tensors
show a larger thrust component suggesting that the southern end of the Hikurangi may have also slipped.
This complex earthquake defies many conventional assumptions about the degree to which earthquake
ruptures are controlled by fault segmentation, and should motivate re-thinking of these issues in seismic
hazard models.

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*J02-3-02
Joint Symposium / J02. Recent large and destructive earthquakes

Surface Ruptures that could have been caused by aftershocks of the 2016
Kaikoura earthquake* Sidao Ni
Instite of Geodesy and Geophysics, Chinese Academy of Sciences
Surface ruptures provide essential information for identification of causative faults, inferring earthquake
source parameter scaling laws and estimation of recurrence and magnitude of future earthquakes.
However, some surface ruptures are not necessarily generated coseismically by the mainshock, and instead
could be caused by aftershocks. Surface ruptures on more than 10 faults have been observed after the2016 M7.8 Kaikoura earthquake, making it one of the most complex events involving of multiple faults. In
order to investigate whether some of the surface breaks are caused by aftershocks, we relocated the two
M6.5 aftershocks and a few ~M6 aftershocks and determine their centroid depth as well as moment
tensors. Rupture directivity of some of the aftershocks are also studied with a recently developed method of
measuring the difference between centroid and hypocenter location. Preliminary results suggest that somesurface ruptures could be caused by aftershocks. Accordingly, the surface breaks and ground deformation
caused by the aftershocks should be taken into account when modeling rupture processes of themainshock with geodetic or geological observations.

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*J02-3-03
Joint Symposium / J02. Recent large and destructive earthquakes

Crustal deformation of the 2016 Kaikoura earthquake, New Zealand,
revealed by ALOS-2* Yu Morishita , Tomokazu Kobayashi , Satoshi Fujiwara , Hiroshi Yarai
Geospatial Information Authority of Japan, Tsukuba, JapanThe 2016 Kaikoura earthquake, New Zealand, occurred on 13 November 2016. We revealed the details ofcrustal deformation associated with the earthquake by ALOS-2 SAR data applying InSAR, a Pixel Offset
method, and decomposition of these displacement data into vertical and horizontal components. Very large
and extensive displacement was mainly detected around the Kekerengu Fault, the Jordan Thrust, theHundalee Fault, and the Humps Fault Zone (e.g., more than 9 m uplift and horizontal shift around theKekerengu Fault). We also constructed rectangular fault models with a uniform slip distribution using the
3D displacement data. The constructed fault models indicate that complicated fault motion occurred along
both known active faults and also along unmapped faults. In addition to the large displacements, numerous
linear discontinuities in the differential phase of InSAR images which may represent surface ruptures ofseveral centimeters or larger were observed. These small-displacement linear surface ruptures may havebeen triggered by the main large fault slips.

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*J02-3-04
Joint Symposium / J02. Recent large and destructive earthquakes

Complex rupture of the 2016 Kaikoura earthquake, New Zealand* Simone Cesca 1) , Joachim Saul 1) , Yong Zang 2) , Rongjiang Wang 1) , Sebastian Hainzl 1) , Vasiliki
Mouslopoulou 1) , Onno Oncken 1) , Torsten Dahm 1)
GFZ German Research Centre for Geosciences, Potsdam, Germany 1) , Peking University, Beijing, China 2)
The M7.8 Kaikoura earthquake struck New Zealand on November 13, 2016 at 11:02:58, followed by asignificant aftershock sequence. This was the largest event instrumentally recorded in the region. It took
place in a complex tectonic environment, controlled by the subduction of the Pacific plate offshore the East
coast of New Zealand and the Alpine transform fault. The seismic waveforms footprint indicates a complex
rupture process. The seismic moment tensor computed by GEOFON shows a strong non-double-couple
term, as also depicted by other global moment tensor catalogues, suggesting the complex rupture of one or
multiple faults. Similarly, the hypocentral distribution of aftershocks appears distributed and clusters along
lineaments with different orientations. The surface expression of rupture processes confirms the activationof mutiple faults with different orientations either during the main shock or the early postseismic phase.
Finally, the surface deformation is characterized by a distributed uplift, but includes smaller scale
anomalies, such as localized coseismic extrusion of more than 5 meters. We perform a broad seismologicalanalysis, combining regional and teleseismic seismic data, to determine the rupture process of the main
shock and tens of aftershocks. The main shock is analysed by combining InSAR, GPS and seismic data toresolve the slip distribution on a finite fault, both revealing strong rupture directivity and slip heterogeneity
along the rupture area. The aftershock are investigated through a full waveform regional moment tensor
inversion, revealing a combination of different rupture styles, including thrust, strike-slip and very shallow
near vertical faulting, characteristic of different spatial clusters. Combining this information with thekinematic source analysis of the main shock, we propose a multiple rupture process for the Kaikoura
earthquake rupture process.

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*J02-3-05
Joint Symposium / J02. Recent large and destructive earthquakes

Seafloor displacement of the 13 November 2016 New Zealand earthquake
estimated from tsunami waveforms and GPS data
* Aditya Gusman 1) , Kenji Satake 1) , Endra Gunawan 2)
The University of Tokyo, Tokyo, Japan 1) , Bandung Institute of Technology, Bandung, Indonesia 2)
A large earthquake (Mw 7.8) occurred on 13 November 2016 at 11:02:56 UTC in North Canterbury, New
Zealand. The earthquake initiated at 42.6925 S, 173.0221 E, and depth of 15 km beneath South Island. The
earthquake has an oblique faulting mechanism and produced surface ruptures from multiple active faults.
The aftershock area is 150 km long and 40 km wide and a part of it is located offshore. A large tsunami
amplitude of 2.5 m was recorded at Kaikoura tide gauge and 5 cm to 50 cm were recorded at seven othertide gauges. The Kaikora tide gauge record also indicated a vertical uplift of 0.9 m. The vertical uplifts at
KAIK and CMBL GPS stations which are located near the coast and within the source area are 0.4 and 1 m,
respectively.
In this study, we used tsunami waveforms at four tide gauges (Castle point, Wellington, Kaikoura, andChristchurch) and the uplift data to estimate the seafloor displacement. We distributed 72 (18 x 4) B-spline
function unit sources with spatial distance of 10 km. The resolution test show that the dataset can resolve
well the displacement with 20 km of spatial variation anywhere in the offshore but the displacement with
10 km spatial variation can be resolved around the Kaikoura station.
The earthquake produced two distinct uplift regions within the aftershock area. The first region is locatedimmediately northeast of Kaikoura and the second region is centered at approximately 70 km northeast of
Kaikoura. Both seafloor uplift regions are peaked at about 1 m, and the uplift tends to become graduallysmaller from the shoreline toward offshore. We interpreted that this displacement is generated by the
combination of multiple active faults and an underlying thrust fault ruptures. Tsunami simulation produced
tsunami amplitudes of more than 0.5 m along 200 km coastline and the maximum tsunami amplitude is 3
m. The tsunami propagation model shows that oscillation of water body occurred locally near the coastline
within the tsunami source area.

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*J02-4-01
Joint Symposium / J02. Recent large and destructive earthquakes

Postseismic deformation following the 2016 Mw 7.8 Kaikoura earthquake,
New Zealand.
* Sigrun Hreinsdottir 1) , Ian Hamling 1) , Susan Ellis 1) , Laura Wallace 1) 2) , Paul Denys 3) , Neville Palmer 1), Lara Bland 1) , Phaedra Upton 1) , Charles Williams 1) , Elisabetta D'Anastasio 1)
GNS Science, Lower Hutt, New Zealand 1) , The University of Texas at Austin, Austin, USA 2) , University ofOtago, Dunedin, New Zealand 3)
The November 14 2016 Mw 7.8 Kaikoura earthquake in New Zealand ruptured at least 12 major crustal
faults and caused widespread damage across the northern South Island. In response to the earthquake
several new continuous and semi continuous GPS stations were installed in the region to augment the
GeoNet CGPS network. In addition, InSAR data acquired by ALOS-2 and Sentinel-1A/B, which are
acquired every 6-12 days, are used to measure post-seismic deformation across the region.
We will present the first few months of the postseismic deformation following the Kaikoura earthquake. The
most rapid early postseismic deformation is observed in the region of Cape Campbell, coinciding with alarge cluster of aftershocks, with about 24 cm NE motion and 26 cm uplift observed at CGPS site CMBL by
the end of 2016. Sites NW of Cape Campbell have a similar NE trend and uplift with decreasing rate NWfrom the Needles fault. Coastal sites, south of the Clarence fault move in a more easterly direction, with thesite KAIK moving 8.5 cm ESE and insignificant vertical change.
A simple postseismic deformation model based on the best-fit coseismic fault planes and assuming a 30-kmthick elastic layer overlying a Maxwell viscoelastic mantle is able to broadly reproduce the direction of
postseismic deflections from north to south, but predicts maximum displacements too far inland. Adding in
the dipping Pacific plate slab as an elastic body reduces the magnitude of postseismic displacement in themodel but does not change directions or the location of maximum displacements significantly. We also
undertake time-dependent inversions of the afterslip, solving for slip on the crustal faults that ruptured in
the earthquake, as well as the underlying subduction interface. The best-fit postseismic models haveafterslip on the crustal faults that ruptured in the earthquake, as well as on the subduction interface
beneath the northern South Island, in addition to a component of mantle relaxation.

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*J02-4-02
Joint Symposium / J02. Recent large and destructive earthquakes

Intraslab rupture triggering megathrust rupture co-seismically in the
December 17, 2016 Solomon Islands Mw 7.9 earthquake* Thorne Lay 1) , Lingling Ye 2) , Charles Ammon 3) , Hiroo Kanamori 2)
University of California Santa Cruz, Santa Cruz, USA 1) , California Institute of Technology, Pasadena, USA
2), The Pennsylvania State University, University Park, USA 3)
The December 17, 2016 Solomon Islands earthquake (Mw 7.9) initiated near 103 km deep in the
subducting Solomon Sea slab near the junction of the Solomon Islands and New Britain trenches. Most
aftershocks are located near the Solomon Islands plate boundary megathrust west of Bougainville, whereprevious large interplate thrust faulting earthquakes occurred in 1995 (Mw 7.7) and 1971 (Mw 8.0).
Teleseismic body wave modeling and aftershock relocations indicate that the initial 30 s of the 2016
rupture occurred over depths of 90 to 120 km on an intraslab fault dipping ~30 deg to the southwest,
almost perpendicular to the dipping slab interface. The next 50 s of rupture took place at depths of 32 to 47
km in the deeper (Domain C) portion of the overlying megathrust fault dipping ~35 deg to the northeast.
High susceptibility to triggering in the region accounts for this compound rupture of two separate fault
planes.

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*J02-4-03
Joint Symposium / J02. Recent large and destructive earthquakes

Anatomy of the source zones of large earthquakes in Japan* Dapeng Zhao , Zhouchuan Huang , Xin Liu
Tohoku University, Sendai, Japan
We use high-resolution seismic tomography to study the detailed 3-D structure in the source zones of large
earthquakes in Japan to clarify their causal mechanisms. To image the Tohoku megathrust zone, wecollected a large number of arrival-time data of suboceanic events (M 3.5-6.0) in the Tohoku forearc under
the Pacific Ocean. The suboceanic events are relocated precisely using local arrival times of P and S waves
and sP depth phase, and many outer-rise events near the Japan Trench were located by a portable OBS
network. Then we inverted the arrival-time data to determine tomographic images of the megathrust zone
beneath the Tohoku forearc. The obtained Vp and Vs images are similar to each other, and they show
significant velocity variations in the megathrust zone. The 2011 Tohoku megathrust earthquake (Mw 9.0)
and its major foreshocks and aftershocks (M > 6.0) occurred in high-velocity (high-V) areas of themegathrust zone, which may represent rigid asperities where the subducting Pacific plate and theoverriding Okhotsk plate were strongly coupled. A prominent high-V area with large coseismic slip extends
from the Tohoku mainshock hypocenter to the Japan Trench, which may represent the mainshock asperity.
We also determined detailed tomographic images in the source zone of the 2011 Iwaki crustal earthquake(M 7.0) and the Fukushima nuclear power plant (FNPP) area. Prominent low-velocity and high Poisson's
ratio zones are revealed beneath the Iwaki source area and the FNPP, which may reflect fluids released
from the dehydration of the subducting Pacific slab. Our results suggest that the Iwaki earthquake wastriggered by the ascending fluids from the Pacific slab dehydration and the stress variation induced by the2011 Tohoku mainshock. The similar structures beneath the Iwaki source area and the FNPP suggest thatthe security of the FNPP site should be strengthened to withstand potential large earthquakes in the future.

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*J02-4-04
Joint Symposium / J02. Recent large and destructive earthquakes

From Sumatra 2004 to Today, through Tohoku-Oki 2011: what we learn
about Tsunami detection by ionospheric sounding.
* Giovanni Occhipinti 1) , Lucie Rolland 2) , Julian Eisenbeis 1) , Shingo Watada 3) , Pierdavide Coisson 1) ,Jonathan Makela 4) , Philippe Lognonné 1) , Hélène Hebert 5)
Institut de Physique du Globe de Paris, Paris, France 1) , Géoazur - Université Nice Sophia Antipolis,
Valbonne, France 2) , Earthquake Research Institute, University of Tokyo, Tokyo, Japan 3) , University of
Illinois, Urbana, IL, United States 4) , Commissariat Energie Atomique, Arpajon, France 5)
The tsunamigenic Tohoku earthquake (2011) strongly affirms, after the 26 December 2004, the necessity toopen new paradigms in oceanic monitoring. Detection of ionospheric anomalies following the Sumatra
event demonstrated that ionosphere is sensitive to earthquake and tsunami propagation: ground andoceanic vertical displacement induces acoustic-gravity waves propagating within the neutral atmosphereand detectable in the ionosphere. Observations supported by modelling proved that tsunamigenic
ionospheric anomalies are deterministic and reproducible. Tsunami signature in the ionosphere isroutinely detected and we show here perturbations of total electron content (TEC) measured by GPS andfollowing tsunamigenic eartquakes from 2004 to 2011, nominally, Sumatra (26 December, 2004 and 12
September, 2007), Chile (14 November, 2007), Samoa (29 September, 2009) and the Tohoku-Oki (11 Mars,
2011). Additionally, new exciting measurements in the far-field were performed by Airglow measurement in
Hawaii, showing IGWs induced by the Tohoku tsunami in the Pacific Ocean, as well as by two new recent
tsunamis: the Queen Charlotte (27 October, 2013, Mw 7,7) and Chili (16 September, 2015, Mw 8.2). The
detection of those two new events strongly confirms the potential interest and perspective of the tsunami
monitoring by airglow camera, ground-located or potentially onboard on satellite. Observations close to theepicenter, performed by GPS networks located in Sumatra, Chile and Japan, highlight the first TEC
perturbation observed within the first 10min after the seismic rupture. This perturbation contains
informations about the ground displacement, as well as the consequent sea surface displacement resulting
in the tsunami. In this talk we present all this new observations in the ionosphere and we discuss, under
the light of modelling, the potential role of ionospheric sounding in the oceanic monitoring and future
tsunami warning system.
Works presented here @ www.ipgp.fr/~ninto

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*J02-4-05
Joint Symposium / J02. Recent large and destructive earthquakes

Linking Oceanic Tsunamis and Geodetic Gravity Changes of Large
Earthquakes
Yuning Fu 1) , * Y. Tony Song 2) , Richard Gross 2)
Department of Geology, Bowling Green State University, Bowling Green, Ohio, USA 1) , NASA Jet
Propulsion Laboratory 2)
Large earthquakes at subduction zones usually generate tsunamis and coseismic gravity changes. These
two independent oceanic and geodetic signatures of earthquakes can be observed individually by modern
geophysical observational networks. The Gravity Recovery and Climate Experiment (GRACE) twin-satellites
can detect gravity changes induced by large earthquakes, while altimetry satellites and Deep-Ocean
Assessment and Reporting of Tsunamis (DART) buoys can observe resultant tsunamis. In this study, we
introduce a method to connect the oceanic tsunami measurements with the geodetic gravity observations,and apply it to the 2004 Sumatra Mw 9.2 earthquake, the 2010 Maule Mw 8.8 earthquake and the 2011
Tohoku Mw 9.0 Earthquake. Our results indicate consistent agreement between these two independentmeasurements. Since seafloor displacement is still the largest puzzle in assessing tsunami hazards and its
formation mechanism, our study demonstrates a new approach to utilizing these two kinds ofmeasurements for better understanding of large earthquakes and tsunami

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*J02-4-06
Joint Symposium / J02. Recent large and destructive earthquakes

Postseismic gravity changes caused by viscoelastic relaxation after recent
great earthquakes since 2004
* Shin-Chan Han 1) , Jeanne Sauber 2) , Fred Pollitz 3)
University of Newcastle 1) , NASA Goddard Space Flight Center 2) , US Geological Survey 3)
GRACE detected regional-scale coseismic and postseismic gravity changes after recent great earthquakes,
including 2004 Sumatra-Andaman, 2005 Nias, 2006/2007 Kuril, 2007 Bengkulu, 2009 Samoa-Toga, 2010
Maule, 2011 Tohoku-Oki, 2012 Wharton Basin (Indian Ocean), and 2013 Okhotsk earthquakes. Those
earthquakes caused abrupt changes in the Earth's gravity field and triggered gradual postseismic
adjustment expected to continue for years to decades by viscoelastic relaxation. Significant postseismic
gravity changes were recorded in GRACE by not only megathrust ruptures (as large as Mw9.2), but also
earthquakes (as small as Mw8.1) with very different mechanisms, such as strike-slip earthquakes andnormal faulting events. The cumulative postseismic gravity changes can be even larger than the coseismicchanges depending on the rupture mechanism and the Earth's rheological structure around the region. For
example, the results from the GRACE Level-2 data found that the combined coseismic gravimetric signal
from Mw8.3 Kuril thrust and Mw8.1 normal faulting events (doublet) was too small to be distinguished by
GRACE, but it produced substantial postseismic gravity change, indicating the prominent influence ofviscous asthenosphere underlying the thin elastic lithosphere in the Kuril trench. The similar results werealso found after the 2009 Samoa-Tonga earthquake doublet. We have an opportunity to examine the Earth's
deformations from various types of earthquakes at time-scales from months to decades comprehensively
using nearly 15 years of continuous gravity measurements from GRACE and to be extended for anotherdecade or longer by GRACE-FO. In this presentation, we review the GRACE observations of gravity
changes from those earthquakes and provide the numerical modelling results of gravity change
predominantly by viscoelastic relaxation. We will show the regional variability in the rheological structures
along different plate boundaries.

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*J02-P-01
Joint Symposium / J02. Recent large and destructive earthquakes

Fault source model for the 2016 Kumamoto earthquake sequence based on
ALOS-2/PALSAR-2 pixel-offset data: evidence for dynamic slip partitioning* Yuji Himematsu , Masato Furuya
Hokkaido University
Series of earthquakes including three Mw > 6 earthquakes occurred in Kumamoto prefecture in the middleof the Kyushu island, Japan. In order to reveal the associated crustal deformation signals, we applied offset
tracking technique to ALOS-2/PALSAR-2 data covering three Mw > 6 earthquakes and derived the 3D
displacements around the epicenters. We could identify three NE–SW trending displacement
discontinuities in the 3D displacements that were consistent with the surface location of Futagawa andHinagu fault system. We set three-segment fault model whose positions matched the displacement
discontinuities, and estimated the slip distributions on each segment from the observed pixel-offset data.
Whereas right-lateral slip was dominant in the shallower depth of the larger segments, normal fault slip was
more significant at a greater depth of the other segment. The inferred configuration and slip distribution ofeach segment suggest that slip partitioning under oblique extension stress regime took place during the2016 Kumamoto earthquake sequence. Moreover, given the consistent focal mechanisms derived fromboth the slip distribution model and seismology, the significant non-double couple components in the focal
mechanism of the main shock are due to simultaneous ruptures of both strike-slip and normal faulting at
the distinct segments.

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*J02-P-02
Joint Symposium / J02. Recent large and destructive earthquakes

Crustal deformation of the 2016 Kumamoto earthquake sequence (1) Foreshocks * Tomokazu Kobayashi , Satoshi Kawamoto , Yohei Hiyama
GSI of Japan, Tsukuba, Japan
We will show the crustal deformation and the fault models obtained from SAR (ALOS-2) and Kinematic-GPS
observations for the 2016 Kumamoto earthquake foreshocks that occurred on Apr. 14th and 15th, 2016
with a Japan Meteorological Agency (JMA) magnitude (Mj) of 6.5 and 6.4, respectively.
SAR: By applying conventional InSAR and MAI techniques, ground displacements have been successfully
mapped. The most concentrated crustal deformation is located on the western side of the Hinagu fault
zone. A locally distributed displacement which appears along the strike of the Futagawa fault can be
identified in and around Mashiki town, suggesting that a different local fault slip also contributed toward
foreshocks. Distributed slip models show right-lateral fault motion on a plane dipping west by 80 deg for
the Hinagu fault and normal fault motion on a plane dipping south by 70 deg for the local fault beneath
Mashiki town. The slip in the north significantly extends down to around 10 km depth, while in the south
the slip is concentrated near the ground surface, perhaps corresponding to the Mj 6.5 and the Mj 6.4
events, respectively.
Kinematic-GPS: InSAR data cannot further separate the individual crustal deformation due to its temporal
resolution. In this context, we processed Kinematic-GPS data and successfully exploited the individual
coseismic displcaements for the two events. The constructed fault models show that the Mj6.5 event islocated around the junction of the Futagawa fault and the Hinagu fault, while the Mj6.4 is located in thesouth of the Mj6.5 event. This analysis result demonstrates that Kinematic-GPS data can contribute toderive the individual source properties for the two events that occurred temporarily close to each otherwithin a day.
Acknowledgements: ALOS-2 data were provided from the Earthquake Working Group under a cooperative
research contract with JAXA (Japan Aerospace Exploration Agency). The ownership of ALOS-2 data
belongs to JAXA.

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*J02-P-03
Joint Symposium / J02. Recent large and destructive earthquakes

Crustal deformation of the 2016 Kumamoto earthquake sequence (2) Mainshock * Hiroshi Yarai , Tomokazu Kobayashi , Yu Morishita , Satoshi Fujiwara
Geospatial Information Authority of Japan
Coseismic deformation derived from the 2016 Kumamoto Earthquake sequence was observed by GNSS
stations of the permanent GNSS Earth Observation Network system (GEONET) and ALOS-2/PALSAR-2
SAR analysis. We will introduce the crustal deformation and estimated fault model of the Kumamoto
earthquake mainshock that occured on Apr. 16th, 2016 with a Japan Meteorological Agency (JMA)
magnitude (Mj) of 7.3.
Clear coseismic displacements due to the Kumamoto earthquake were observed by GEONET. NE
displacement of 75 cm and subsidence of 20 cm was detected at the Kumamoto observation station, which
is located on the north side of the Futagawa fault. On the south side of the fault, SW displacement of 97 cm
and uplift of 28 cm was detected at the Choyo stations.
We have also successfully detected distributed ground displacements for the Kumamoto Earthquake by
applying a SAR interferometry, MAI and Pixel Offset analysis of ALOS-2 data. The obtained displacement
field shows clear displacement boundaries linearly along the Futagawa, the Hinagu, and the Denokuchi
faults across which the sign of displacement component turns to be opposite, suggesting that the fault
ruptures occurred there.
We invert the InSAR results with GNSS data to construct a fault model of the earthquake. Our fault modelfor the main shock suggests that the main rupture occurred on the Futagawa fault with a right-lateralmotion including a slight normal fault motion. Due to the normal faulting movement, the northern side of
the active fault subsides with approximately 2 m. The rupture on the Futagawa fault extends into the Aso
caldera with slightly shifting the position northward. Of note, the fault plane oppositely dips toward
southeast. It may be a conjugate fault against the mainly-slipped fault.
Acknowledgements.
The PALSAR-2 data obtained by the ALOS-2 were provided by the Japan Aerospace Exploration Agency(JAXA) through the Agreement between GSI and JAXA. The ownership of PALSAR-2 data belongs to JAXA.

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*J02-P-04
Joint Symposium / J02. Recent large and destructive earthquakes

Crustal deformation of the 2016 Kumamoto earthquake sequence (3) - Small
displacement linear surface ruptures detected by ALOS-2 SAR * Satoshi Fujiwara , Hiroshi Yarai , Tomokazu Kobayashi , Yu Morishita , Takayuki Nakano , Basara
Miyahara , Hiroyuki Nakai , Yuji Miura , Haruka Ueshiba , Yasuaki Kakiage , Hiroshi Une
GSI of Japan, Tsukuba, Japan
We constructed and analyzed the ground surface displacement associated with the 2016 Kumamoto
earthquake sequence using satellite radar interferometry images of the Advanced Land Observing Satellite
2. The radar interferogram generally shows elastic deformation caused by the main earthquakes but manyother linear discontinuities showing displacement are also found. Approximately 230 lineaments are
identified, some of which coincide with the positions of known active faults, such as the main earthquake
faults belonging to the Futagawa and Hinagu fault zones and other minor faults; however, there are much
fewer known active faults than lineaments. In each area, the lineaments have a similar direction anddisplacement to each other, therefore, they can be divided into several groups based on location and major
features. Since the direction of the lineaments coincides with that of known active faults or their conjugate
faults, the cause of the lineaments must be related to the tectonic stress field of this region. The lineaments
are classified into the following two categories: (1) main earthquake faults and their branched sub-faults;and (2) secondary faults that are not directly related to the main earthquake but whose slip was probably
triggered by the main earthquake or aftershocks.

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*J02-P-05
Joint Symposium / J02. Recent large and destructive earthquakes

Relationship between subsurface structure and large-scale fissures in thenorthwestern region in Aso valley caused by the 2016 Kumamoto
earthquake* Issei Doi 1) , Toshitaka Kamai 1) , Satoshi Goto 2) , Ryokei Azuma 3) , Takahiro Ohkura 4) , Hidehiko Murao 5), Kenji Mima 6)
Disaster Prevention Research Institute, Kyoto University, Uji, Japan 1) , Integrated Graduate School of
Medicine, Engineering, and Agricultural Sciences, Yamanashi University, Kofu, Japan 2) , Faculty ofEngineering, Osaka Institute of Technology, Osaka, Japan 3) , Graduate School of Science, Kyoto University,
Kyoto, Japan 4) , Murao Chiken, Toyama, Japan 5) , Ohta Geo Research.Co.,Ltd., Nishinomiya, Japan 6)
In accompanied with the 2016 Kumamoto earthquake, fissures with the length and the height a few
hundred meters and two meters, respectively, emerged in Aso valley (inside the Aso caldera). In this area,
the top layer consists of sediments in the caldera lake created by Aso-4 eruption with the thickness a few
tens of meters. InSAR and seismic data show that the region with the size of 1-4 square meter moved 1-2 m
northward horizontally during strong motion of the mainshock (Fujiwara et al., 2016; Doi et al., 2016). We
investigated the mechanism of the movement of these regions by estimating subsurface structure beneath
this area.
Two station spatial auto-correlation (2ST-SPAC) method (Hayashi and Craig, 2016) was applied to estimate
subsurface structure using ambient noises. We succeeded to estimate the S-wave velocity structure to thedepth of 130 m in and around the regions with fissures. In the regions where large scale fissures weredeveloped, a layer with S-wave velocity less than 150 m/s lay from the surface to the depth of 60 m,
followed by two layers with 250 m/s and 300 m/s at depths of 60-90 m and 90-130 m, respectively. This
low-velocity layer was considered to represent soft sediments in the caldera lake due to Aso-4 eruption andconsistent with the nearby boring profile. Two relatively higher layers might correspond to lava layers after
Aso-4 eruption. Moreover, the S-wave velocity at the top surface to the depth of 5 m was so slow as 80 m/s.
We continue to estimate the distribution of the soft sediments and lava structure beneath them, to elucidate
how fissures were generated in this area.

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*J02-P-06
Joint Symposium / J02. Recent large and destructive earthquakes

New Guidelines for the Seismic Forecast Information after Big Earthquakes
in Japan* Noriko Kamaya , Kiyoshi Takeda , Tetsuo Hashimoto
Japan Meteorological Agency, Tokyo, Japan
A big earthquake of M6.5 occurred at 21:26 on 14 April, 2016 (JST) in Kumamoto Prefecture. That was the
beginning of “The 2016 Kumamoto Earthquake". Japan Meteorological Agency (JMA) issued information
about aftershock probability after 18 hours of this earthquake. However, after 28 hours of the M6.5
earthquake, a bigger earthquake of M7.3 occurred in the same region and triggered distant earthquakes.
The seismically active area was finally spread up to about 150km long. As this seismic activity was revealed
that it was not a simple mainshock - aftershock patterns, JMA stopped issuance of the following information
about aftershock probability. With lessons learned from this, seismologists and JMA discussed under aframework of the Headquarters of Earthquake Research Promotion (HERP), and new guidelines were
published in August 2016. The points of the guidelines are followings.
(1)JMA calls attention to strong motion which is similar level to the first big earthquake for about one week
after big earthquakes.
(2)If there were prior cases of foreshock - mainshock - aftershock series or earthquakes with similar
magnitude which occurred in the short term near the big earthquakes, JMA calls attention to such cases.
(3)If active faults and assumed source regions of big thrust-type subduction-zone earthquakes existed near
the big earthquakes, JMA explains the characteristics and calls attention to them.
(4)After one week, if the active seismic activity continues, JMA issues aftershock probability. The
probability is shown by magnification ratio which compares to the probability just after the biggest
earthquake and before the big earthquakes.
(5)JMA uses a word “earthquake" instead of “aftershock" when JMA calls to attention to strong motion by
aftershocks, because the word of “aftershock" gave some impression to people that bigger earthquakes
would not occur.
We will introduce new Japanese policy and actual examples about Seismic Forecast Information after big
earthquakes.

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*J02-P-07
Joint Symposium / J02. Recent large and destructive earthquakes

Characterized Source Model of 2016 Meinong Earthquake, Taiwan, Inferredby the Empirical Green's Function Method* Yin-Tung Yen 1) , Yi-Ying Wen 2) , Ming-Che Hsieh 1)
Sinotech Engineering Consultants, Inc., Taipei, Taiwan 1) , Department of Earth and Environmental
Sciences, National Chung Cheng University, Minhsiung, Taiwan 2)
We investigate the source characteristics of the 2016 (ML6.6) Meinong earthquake, which strongly struck
the southwest Taiwan on 2016/02/06 03:57:26 (local time), by strong motion simulation with the
Empirical Green's Function Method (EGFM).This event induced a noticeable amount of building damage
reported due to the strong ground motion, especially two high-rise buildings collapsed in Tainan City andcaused totally 117 deaths and more than 500 casualties. Several source models of the 2016 Meinong
earthquake inverted by strong motion, teleseismic and GPS data were proposed from various studies. Mostof them show two asperities on the east –west trending fault plane. In this study, we focus on thecharacterized source model (CSM), which includes one or more rectangular Strong Motion Generation
Areas (SMGAs) on a presumed fault plane. The CSM can be derived by implementing EGFM using smallevent records as the empirical Green's functions. An optimal CSM will be derived by fitting the synthetics
to the observed waveforms. The CSMs can be utilized conveniently for inputs of a source model to predict
strong ground motions for earthquake scenarios in addressing the seismic hazard. Thus, validation of CSM
for a specific earthquake will benefit the reliability of predicting source model. For a seismically active
region like Taiwan, it is important to perform ground-motion-simulation cases for moderate-to-large events
to obtain an empirical relationship for addressing CSMs. Then, shaking maps from strong motion
simulations for specific fault scenarios can be useful for seismic disaster preparation plan.

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*J02-P-08
Joint Symposium / J02. Recent large and destructive earthquakes

Slip Distribution of the 2015 Lefkada Earthquake and its Implications for
Fault Segmentation
Lidong Bie , Pablo Gonzalez , * Andreas Rietbrock
The University of Liverpool, Liverpool, UK
It is widely accepted that fault segmentation limits earthquake rupture propagations and therefore
earthquake size. While along-strike segmentation of continental strike-slip faults is well observed, direct
evidence for segmentation of off-shore strike-slip faults is rare. A comparison of rupture behaviors in
multiple earthquakes might help reveal the characteristics of fault segmentation. In this work, we study the2015 Lefkada earthquake, which ruptured a major active strike slip fault offshore Lefkada Island, Greece.
We report ground deformation mainly on the Lefkada Island measured by interferometric synthetic radar(InSAR), and infer a coseismic distributed slip model. To investigate how the fault location affects theinferred displacement based on our InSAR observations, we conduct a suite of inversions by taking various
fault location from different studies as a prior. The result of these test inversions suggests that the Lefkada
fault trace is located just offshore Lefkada Island. Our preferred model shows that the 2015 earthquake
main slip patches are confined to shallow depth (< 10 km), with a maximum slip of ~1.6 m. In comparison
to the 2003 earthquake, which mainly ruptured the northern part of the Lefkada fault, we suggest that the2015 earthquake closed the seismic gap, at least partially, left by the 2003 earthquake by rupturing theshallow part of the Lefkada fault. The spatial variation in slip distributions for the two earthquakes reveals
segmentation along strike, and possibly downdip of the Lefkada fault. A comparison of aftershock locations
and coseismic slip distribution shows that most aftershocks appear near the edge of main coseismic slip
patches.

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*J02-P-09
Joint Symposium / J02. Recent large and destructive earthquakes

Characterized source model for estimating strong ground motions during
2016 Tottori-ken Chubu Earthquake* Susumu Kurahashi 1) , Kojiro Irikura 1) , Ken Miyakoshi 2)
Aichi Institute of Technology, Aichi, Japan 1) , Geo-Research Institute, Osaka, Japan 2)
Strong ground motions from the 2016 Tottori-ken Chubu earthquake (Mw6.2) struck in Kurayoshi city,
Tottori prefecture, on Japan Sea side, on October 21, 2016. PGA of 1494 gal was observed at TTR005(Kurayoshi,epicentral distance: 6km) station. We estimated the characterized source model, which explain
broad-band strong motions, during this earthquake based on the results of the waveform inversion using
the strong motion data and the empirical Green's function method.
First, we analyzed the slip distribution during this earthquake using the multi-time window linear waveform
inversion method (Sekiguchi et al., 2000). Target frequency range is 0.1-1.0Hz. As a result, large slip area
was constructed round the hypocenter. Seismic moment of the estimated model is 2.0*10^18Nm.
Next, the characterized source model was constructed based on the slip distribution from the waveform
inversion. We extracted asperity from the slip distribution and high rate area (HRA) from the moment rate
distribution by the criterion of Somerville et al. (1999). The area and location of the asperity and the HRA
are estimated to be nearly the same.
Finally, we analyzed the SMGA model using the empirical Green's function method (Irikura, 1986). We
attempted to examine whether the strong ground motions at TTR005 located very near the fault plane are
simulated. Target frequency range is 0.3-10.0Hz. As a result, the location of the SMGA is nearly the same as
the estimated large slip area from the waveform inversion results. The scaling relationship SMGA area
versus seismic moment is consistent with on that of combined area of asperities versus seismic moment by
the previous study (Irikura and Miyake, 2001). The asperity, the HRA and the SMGA of this earthquake arecollocated with nearly the same area.

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*J02-P-10
Joint Symposium / J02. Recent large and destructive earthquakes

Changes of S-wave velocity and polarization anisotropy associated with the2011 Tohoku Earthquake detected by the observation of the seismic
ACROSS signals* Takahiro Kunitomo 1) 2) , Yasuhiro Asai 1) , Hiroshi Ishii 1)
Tono Research Institute of Earthquake Science, Mizunami, Gifu, Japan 1) , Nagoya University, Nagoya,
Aichi, Japan 2)
We analyzed the seismic ACROSS ( Accurately Controlled, Routinely Operated , Signal System ) signals
using the data of the borehole observation network of Tono Research Institute Earthquake Science (TRIES)
and detected clearly changes of S-wave velocity and polarization anisotropy associated with the 2011 off
the Pacific coast of Tohoku Earthquake (March 11, 2011 Mw 9.0, hereinafter called Tohoku Earthquake) in
Tono area of epicentral distance approximately 600km, located in the southwest Japan. Seismometers andstrain meters or stress meters at the borehole stations are installed in the Toki granite at a depth of 110m 1030m, whose direct distance from the seismic ACROSS transmitter (the Toki station) to seismometers are
210m - 8.5km. We estimated daily changes of the direct S-wave travel times by the cross spectrum method
for two years from April, 2010 to March, 2012. Coseismic travel time delays of the direct S-waves
associated with the Tohoku Earthquake were 0.3 - 7.3ms, and the detailed processes to gradually recover tothe original travel times over a year were observed. Coseismic decreases in S-wave apparent velocity were
0.2 - 0.6%, and decreases of the velocity observed by stations in the southeastern direction from thetransmitter were remarkable. At these stations, changes of the S-wave polarization anisotropy that the SHwave velocities were decreased considerably in comparison with the SV-wave were observed. The crust in
this area was elongated in direction of NE-SW to NNE-SSW with the change in the order of 10e-6 strain or
10kPa associated with the Tohoku Earthquake. As a result, the S-wave velocity decreased due to the
opening of cracks in the rock. Vertical (high angle) cracks in the WNW - ESE and NW - SE direction wereopened, so that the SH-wave propagated in NE direction was considerably delayed in comparison with the
SV-wave.

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*J02-P-11
Joint Symposium / J02. Recent large and destructive earthquakes

A coupled model of stress-driven frictional afterslip and viscoelastic
relaxation following the 2011 Tohoku-oki earthquake* Junichi Fukuda 1) , Kaj Johnson 2)
The University of Tokyo, Tokyo, Japan 1) , Indiana University, Bloomington, Indiana, USA 2)
Postseismic deformation following the 2011 Mw9.0 Tohoku-oki earthquake has been captured by both onland GNSS and seafloor GPS/Acoustic networks. Previous studies have shown that the observed
postseismic displacements can be reproduced as a sum of contributions from viscoelastic relaxation of
coseismic stress changes in the upper mantle and afterslip on the plate interface surrounding the coseismic
rupture. In most previous studies, viscoelastic relaxation and afterslip were modeled separately andafterslip was estimated kinematically. In this study, we develop a three-dimensional coupled model of stressdriven frictional afterslip and viscoelastic stress relaxation in order to investigate the frictional properties
on the plate interface, upper mantle rheology, and the relative contributions of the viscoelastic relaxation
and afterslip to the overall postseismic deformation following the 2011 Tohoku-oki earthquake.
We assume that afterslip is governed by a rate-strengthening friction law that is characterized with a friction
parameter (a-b)*sigma. Viscoelastic relaxation of the upper mantle is modeled with a biviscous Burgers
rheology that is characterized with the steady-state and transient viscosities. We calculate the evolution ofafterslip and viscoelastic relaxation using an assumed coseismic slip model as the initial condition.
We examine the effects of the friction parameters, mantle viscosities, elastic thickness of the slab and upper
plate, and coseismic slip distribution on the model prediction and explore the range of the parameters thatcan fit the observed postseismic displacements. We also examine if afterslip overlaps regions that ruptured
seismically during M6.3-7.2 earthquakes from 2003 to 2010. We find that significant overlap between
afterslip and the historical M6.3-7.2 coseismic rupture areas are required to fit the horizontal
displacements.

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*J02-P-12
Joint Symposium / J02. Recent large and destructive earthquakes

Tidal triggering of earthquakes after the 2011 Tohoku earthquake* Sachiko Tanaka
National Research Institute for Earth Science and Disaster Resilience
I investigated correlations between tides and earthquakes off the Pacific coast of eastern Japan for about
five years after the 2011 Tohoku earthquake (Mw 9.1). A previous study has shown a high correlation in thenorthern part of the focal area of the Tohoku earthquake, where the mainshock rupture initiated, in about
ten years prior to the Tohoku earthquake (Tanaka, 2012). The data I used are the Global Centroid Moment
Tensor (CMT) solutions of shallow earthquakes (H < 70 km) with Mw 5.0 or larger for the period from 1976
to 2015. For each event, I calculated tidal shear stresses on the fault plane (Tanaka et al., 2002), andassigned a tidal phase angle at the time of occurrence. Based on the distribution of tidal phase angles, I
tested whether they concentrate near some particular angle or not by using the Schuster's test (Schuster,1897). In this test, the result is evaluated by p-value, which represents the significance level to reject thenull hypothesis that the earthquakes occur randomly irrespective of tidal phase angle. After the Tohoku
earthquake, no significant correlation was found in the area where a high correlation was found before the
Tohoku earthquake. The p-values in this area are larger than 10% in the period of about five years after the
Tohoku earthquake. On the other hand, small p-values were observed on the northwest side of the large
slip area of the Tohoku mainshock. A small p-value of 2.8% was obtained in the area near the coast, wherelarge postseismic afterslip has been identified by geodetic measurements (Sun et al., 2014; Iinuma et al.,2016). In this region, no significant correlation was found for about 35 years prior to the Tohoku
earthquake. The p-value was smallest (1.6%) just after the Tohoku earthquake, and gradually increased withtime. This behavior seems to be correlated with time evolution of afterslip which shows rapid decay overtime (Ozawa et al., 2012).

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*J02-P-13
Joint Symposium / J02. Recent large and destructive earthquakes

The ISC Event Bibliography: an update* Domenico Di Giacomo , Elizabeth Ball , Dmitry StorchakInternational Seismological Centre, Thatcham, UK
Researches studying specific earthquakes and/or seismic events in general are often required to do time
consuming searches in order to retrieve the literature concerning the events of their interest. To facilitate
this task, in 2012 the International Seismological Centre (ISC) launched a new service, the ISC Event
Bibliography (Di Giacomo et al., 2014), that allows users to do interactive searches(www.isc.ac.uk/event_bibliography/bibsearch.php) of scientific articles based on event parameters and,optionally, publication metrics (e.g., journal, author, year of publication etc.). The journals included in our
database are not limited to seismology but bring together a variety of geoscience fields (e.g., engineering
seismology, geodesy and remote sensing, tectonophysics, monitoring research, tsunami, geology,
geochemistry, hydrogeology, atmospheric sciences, etc.) making this service useful also in multidisciplinary
studies. Usually papers dealing with large data set are not included (e.g., papers describing a seismic
catalogue). Some of the most notable earthquakes are the subject of several hundreds of articles publishedover a period of few years. Currently the ISC Event Bibliography includes over 18,000 individual
publications from about 500 titles related to over 15,000 events that occurred in last 100+ years. The
bibliographic records in the Event Bibliography start beginning of last century, and it is updated as new
publications become available, and with this contribution we intend to show the usefulness of the ISC
Event Bibliography considering recent large events.

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*J02-P-14
Joint Symposium / J02. Recent large and destructive earthquakes

The seismotectonic implications of source models of M-7 class earthquakes
before ad after the 2011 Tohoku-Oki Earthquake using offshore tsunami
records* Tatsuya Kubota , Ryota Hino , Yusaku Ohta , Syuichi Suzuki
Tohoku University, Sendai, Japan
Some major (M ~7) earthquakes occurred in and around the rupture area of the 2011 Tohoku-Oki
Earthquake. In this study, we investigated their source models using offshore tsunami records anddiscussed their relationships with the mainshock, which will give us new implications for subduction zone
tectonics.
On March 9, 2011, Mw 7.2 and 6.6 interplate earthquakes preceded the mainshock at ~ 30 km northeast
from the mainshock epicenter. The rupture area of the Mw 7.2 event was complementary to its postseismic
slip area and to the epicenters of smaller seismicity before the mainshock. After the Mw 6.6 event, one of
the aftershocks of the Mw 7.2, seismicity abruptly expanded to the area next to the mainshock epicenter.
This migration of seismicity after the Mw 7.2 earthquake suggests the occurrence of the cascading
propagation of the major earthquakes and aseismic slip towards the mainshock epicenter, which was likely
to trigger the mainshock.
After the mainshock, some intraslab earthquakes occurred near the Japan Trench, associated with the slab
bending stress perturbed by the 2011 mainshock. Based on a finite fault modeling of the intraslab doublet
earthquake on Dec. 12, 2012, the shallow normal-faulting sub-event (Mw 7.2) extends down to ~ 35 – 40
km whereas the top of the deep thrust-faulting sub-event (Mw 7.2) was estimated at ~ 45 – 50 km,
indicating an obvious deepening of the intraslab seismicity after the mainshock. The change is interpreted
as the results of static stress change and of reduction of shear strength in the slab. Meanwhile, an intraslab
strike-slip earthquake (Mw 7.0) in 2011 beneath the landward slope of the Japan Trench happened within
the shallow portion of the slab under the downdip extensional field and its fault did not expand below thestress neutral depth estimated by the pre-2011 seismicity. This suggests that the enhancement of thedowndip tensional stress after the mainshock was not large as compared to the near-trench area.

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*J03-1-01
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Pre-, Co-, and Post-seismic deformation of the 2016 Oct 21th M 6.6 Central
Tottori earthquake* Takuya Nishimura , Manabu Hashimoto , Yoshinobu Hoso , Hiromu Sakaue , Yuji Ito
Kyoto University, Kyoto, Japan
There is a zone of active microseismicity along the Japan Sea coast in the San'in region, southwest Japan.
Some large earthquakes including the 1943 M7.2 Tottori and the 2000 M7.3 western Tottori earthquakes
also occurred in this seismic zone. Nishimura et al.(2014) showed a zone of high strain rate observed by
GNSS almost overlapped the seismic zone and proposed to call it “the San'in shear zone".
We constructed 13 continuous GNSS stations in late 2014 so as to clarify a detailed distribution of the
San'in shear zone. These stations constitute three linear arrays across the shear zone. An M 6.6 earthquake
hit central Tottori prefecture on October 21, 2016. Our GNSS network, as well as GEONET revealed adetailed pattern of crustal deformation before, during, and after the earthquake. We report the deformation
observed by GNSS and InSAR.
Deformation in the San'in shear zone is characterized by right-lateral shear movements. The 20-km-wideshear zone extends in an east-west direction and accommodates 5 mm/yr of shear movements. The M6.6
earthquake occurred in the shear zone.
Coseismic displacement was observed at our GNSS stations. The largest horizontal displacement is 9 cm
toward east-southeast and the largest vertical one is subsidence of 4 cm. We estimate parameters of arectangular fault model using the observed displacement. The estimated parameters suggest a vertical fault
oriented NWN-SES with left-lateral strike slip, which is concordant with aftershock distribution. The
estimated moment magnitude is ~6.2. SAR interferograms of ALOS-2 show a clear quadratic pattern ofsurface coseismic displacement.
Postseismic displacement at GNSS stations reached 2 cm as of end of December, 2016. Although a spatial
pattern of postseismic displacement is similar to that of the coseismic displacement, observed postseismic
displacement is concentrated near the source fault. It suggests shallow afterslip along the coseismic fault.

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*J03-1-02
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Postseismic deformation following the 1995 Kobe earthquake detected by
space geodesy* Manabu Hashimoto 1) , Takuya Nishimura 1) , Taku Ozawa 3) , Hiroshi Munekane 2) , Mikio Tobita 4)
DPRI, Kyoto University, Uji, Japan 1) , Geospatial Information Authority, Tsukuba, Japan 2) , National
Research Institute for Earth Sciences and Disaster Resilience, Tsukuba, Japan 3) , Japan Aerospace
Exploration Agency, Tsukuba, Japan 4)
A Mw 6.8 earthquake hit the city of Kobe, southwest Japan, and its surrounding area on January 17, 1995.
The source faults, trending in the NE-SW direction, are estimated beneath the foothill of the Rokko
Mountains, but it has a dominant right lateral strike slip components. The Rokko Mountains may have been
built by the motion of active faults, but coseismic uplift may not be enough. There fore postseismic
deformation might contribute to the building of the Rokko Mountains.
In order to study the postseismic deformation, we collected all available space geodetic data during about
20 years, including ERS-1/2, Envisat, JERS-1, ALOS/PALSAR and ALOS-2/PALSAR-2 images andcontinuous GPS data, and reanalyzed. Especially, temporal continuous GPS observation made by the
Geographical Survey Institute, Japan in and around the Kobe area is important. We recalculated
coordinates of these continuous GPS stations with recent PPP procedure using reanalyzed orbits andclocks of satellites.
Time series analysis of JERS-1 images revealed line-of-sight (LOS) decrease of the Rokko Mountains.
PSInSAR results of ALOS/PALSAR also revealed slight uplift north of the Rokko Mountains. Theseobservations suggest that the Rokko Mountains might have uplifted during the postseismic period.
LOS increase in a wedge shaped region between two active faults in the vicinity of the NE terminus of thesource fault of the Kobe earthquake, which indicates that the subsidence between these two faults
continued up to 2010. Continuous GPS observation during the first two years of the postseismic periodshows north-south extension with right lateral motion between these two faults.
These observations suggest that the Rokko Mountains may have uplift till 2010. On the other hand, active
faults near the NE terminus continued to slip with the formation of graben-like structure, due tocoseismically loaded stress.

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*J03-1-03
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Slow Slip Events in Cascadia: Observation and Hazard Analysis Derived
from Sentinel-1 InSAR* Howard Zebker , Yujie Zheng
Stanford University, Stanford, CA
Slow slip events (SSEs), also known as silent earthquakes or episodic tremor and slip (ETS), areearthquakes unfolding in slow motion. Energy release over a long time causes seismic waves with suchlong periods that the motion is imperceptible to all but the most sensitive instruments, and with little shortperiod shaking. The total moment released in an SSE may be quite large, and stress transfer from the event
may either increase or relax elastically stored strain. It is important to understand the nature and impact ofthese often regularly-repeating and predictable events, and whether they are adding to hazard potential orameliorating it.
Here we report on our efforts to help assess the earthquake hazard along the Cascadia region of the Pacificnorthwest and determine, from spaceborne InSAR data, if SSE events are affecting the earthquake risk. We
produce spatially dense crustal deformation observations that, when used with the existing GPS andseismic data, can localize and assess the size of slow displacements. Our goal is to measure SSE crustal
displacements in Cascadia, using InSAR with finer and more comprehensive coverage than the existing
GPS network, to solve for both a model of the slip at depth and the potential for a large and destructive
earthquake.
The challenge of InSAR over Cascadia is that the dense forest cover leads to significant InSAR
decorrelation. We use persistent scatterer (PS) point identification, interpolation of the sparse phase field,
inverse solutions optimized for transient detection, and separation of the secular and transient signals,
which may allow for a superior assessment of the hazard potential of a massive earthquake in the Pacificnorthwest. This work is, to our knowledge, the first implementation of the type of hazard analysis fromcrustal deformation that has been shown in Hawaii and Mexico to an environment where nearly all of thesurface is hidden beneath a very thick vegetation canopy.

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*J03-1-04
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Hidden Earthquake Potential in Plate Boundary Transition Zones* Kevin Furlong , Matthew Herman
Penn State University, University Park PA
Plate boundaries can exhibit abrupt changes in their tectonic deformation at triple junctions and otherplate boundary transitions. At such locations, the superposition of two crustal deformational regimes may
combine to generate displacement signals that do not reflect the actual earthquake cycle strain
accumulation in the region. Two examples of this effect are in the vicinity of the Mendocino triple junction(MTJ) along the west coast of North America, and at the southern end of the Hikurangi subduction zone,
New Zealand. In the region immediately north of the MTJ, the observed signal (GPS) of crustal
displacements is intermediate between Pacific and Juan de Fuca (JdF) motions. With distance north, thesignal rotates to become more aligned with JdF - NAm displacements - the motions expected along acoupled subduction interface. The deviation of that subduction interface signal near the MTJ has beenpreviously interpreted to reflect clock-wise rotation of a coastal, crustal block and/or reduced coupling at
the southern Cascadia margin. The geologic record is consistent with the signal reflecting the combined
effects of northward crustal shortening (on geologic time scales) associated with the MTJ Crustal Conveyor
overprinted onto the subduction earthquake cycle signal. At the Hikurangi to Alpine Fault transition in New
Zealand plate interactions switch from subduction to oblique translation along the Alpine fault system.
Here the signal recorded by GPS shows a reduction in plate motion-directed displacements, which has
been interpreted to reflect reduced coupling. This signal records both the subduction interface coupling
related to the megathrust earthquake cycle, and the shear deformation produced by the extensive rightlateral shear of the Marlborough Fault system. The relevance of this effect is seen in the recent (November2016) Kaikoura earthquake, which ruptured the megathrust interface and produced strike slip
displacements on upper-plate crustal faults.

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*J03-1-05
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Interseismic Strain Partitioning in Nankai Subduction Zone, Southwest
Japan: Block Movement and Internal Deformation of the Forearc Sliver* Takao Tabei 1) , Masahiko Shiomi 1) , Takeo Ito 2) , Makoto Okubo 1)
Kochi University, Kochi, Japan 1) , Nagoya University, Nagoya, Japan 2)
We study interseismic strain partitioning in the Nankai subduction zone, southwest Japan (SWJ). Obliquesubduction of the Philippine Sea plate (PHS) and strong coupling on the plate interface have deformed theoverriding SWJ arc in two ways: interseismic crustal shortening in the direction of PHS convergence andlong-term lateral block movement of the forearc sliver along the Median Tectonic Line (MTL) that is the arcparallel strike-slip fault dividing the forearc from the rest of SWJ. Slip deficit on the MTL fault plane may
disturb local deformation filed.
Basic data used in this study are GPS displacement rates obtained from the nationwide continuous
network. We incorporate the rates from dense campaign measurements along two traverse lines across the
MTL to improve spatial resolution around it. Furthermore we add seafloor displacement rates near the
Nankai Trough to better estimate plate coupling far offshore. PHS interface and MTL fault plane are
reproduced by many triangular elements to a depth of 50 km and 15 km, respectively. We introduce
Markov Chain Monte Carlo method to simultaneously estimate slip deficit distribution on the PHS interface
and MTL fault plane, together with the Euler vector of the forearc block motion relative to SWJ.
The slip deficit rate on the PHS interface is the strongest (> 50 mm/yr) at the depth of 15-25 km, which
nearly overlaps with the main rupture zone at the last megathrust event in 1946. While the slip deficit rates
decrease steeply toward the deeper portion, they are still large enough in a shallower zone near the trough.
Rate of the forearc block motion is 5-7 mm/yr relative to SWJ but locking of the MTL fault plane is not
uniform from east to west. The block motion across the MTL and partial locking of its boundary fault plane
have caused a small-scale shear deformation zone in the SWJ arc.

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*J03-2-01
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Postseismic Deformation Following the 2002 Mw7.9 Denali Fault
Earthquake* Jeffrey Freymueller 1) , Hugh Harper 1) , Yan Hu 2)
University of Alaska Fairbanks, Fairbanks, USA 1) , University of Science and Technology of China, Hefei,
China 2)
An Mw7.9 strike slip earthquake struck on November 3, 2002, in central Alaska, rupturing ~325 km of the
Denali fault and two other faults. The earthquake caused a strong postseismic transient that continues tohave a substantial effect today. Distinguishing between different mechanisms of postseismic deformation(e.g., afterslip, viscoelastic relaxation) remains a challenging problem for many earthquakes. Early studies
done in the first few years after the Denali event demonstrated that the observed postseismic response
could not be explained by a single mechanism, but estimates of the contributions of afterslip andviscoelastic relaxation were plagued by tradeoffs between unknown parameters. As a result, thepostseismic models determined using the first few years of data did not predict the future observations
well.
We use a homogeneously reprocessed time series of GPS data from before and after the earthquake toreassess the postseismic deformation using as much as 15 years of data after the event. We analyze thevariations in the time series themselves to identify subsets of the data in space and time for which a single
postseismic mechanism is dominant. We also assess tradeoffs between the imprecisely known “steady"deformation and the postseismic transient. We compute the postseismic deformation using finite element
models including realistic 3D elastic and viscoelastic structures, and constrain models based on theobservations. One complexity is that the afterslip distribution, in practice, generally needs to be estimatedempirically, although we experiment with models that base the afterslip distribution on the coseismic stresschanges (which are uncertain due to incomplete knowledge of the coseismic slip). Coseismic andpostseismic models are self-consistent, using the same earth structure, which eliminates an inconsistency
in the previous studies.

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*J03-2-02
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Estimation of spatiotemporal distribution of interplate slip after the 2003
Tokachi-oki earthquake incorporating viscoelastic relaxation* Yuji ITOH 1) , Takuya NISHIMURA 2)
Graduate School of Science, Kyoto University 1) , Disaster Prevention Research Institute, Kyoto University 2)
The 2003 Mw 8.0 Tokachi-oki earthquake is an interplate earthquake along the Kurile trench. Its
postseismic deformation has been observed by GNSS [e.g., Miyazaki et al. 2004]. Estimation of
spatiotemporal afterslip is a key to clarify the healing process after large earthquake. Because thepostseismic deformation should be caused by both viscoelastic relaxation and afterslip, it is important toincorporate both effects for the modeling. In this study, we estimated a spatiotemporal interplate slip forabout 7.5 years following the 2003 event as well as the coseismic slip of the 2003 and M 6-7 class
earthquakes simultaneously. We included a viscoelastic response of interplate slip in the estimation of theslip.
For the data analysis, we corrected the effect of the 1993 Hokkaido-Nansei- oki earthquake for theobserved GNSS data in Hokkaido by using the model of Ueda et al. [2003]. The secular velocity before the2003 event was estimated from the corrected data and removed from the postseismic data. And then, we
removed a seasonal variation and displacements of the M6-7 events in the postseismic period. Finally, we
down-sampled the residual time series with an interval of 1-6 months. We used about 7.5 years long GNSS
data until the 2011 Tohoku-oki earthquake.
For the modeling of postseismic deformation, we constructed a model consisting of the coseismic slip ofthe 2003 and the following M6-7 class events, interplate slip including afterslip following these events andviscoelastic relaxation. We assumed the two-layers viscoelastic structure estimated by Itoh and Nishimura[2016] to estimate interplate slip distribution.
A preliminary result shows large postseismic slip occurred in the up-dip and down-dip extensions of thecoseismic slip region and implies an interplate coupling had not been recovered to that before the 2003
event at the time of the 2011 event.

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*J03-2-03
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Reconciling short and long term observations of megathrust cycles at
subduction zones* Rob Govers 1) 1) 1) , Kevin Furlong 2) 2) 2)
Utrecht University, Netherlands 1) , The Pennsylvania State University, U.S.A. 2)
Regional models of the earthquake cycle have become increasingly sophisticated tools to understand theseismological and geodetic observations. They capture critical physical processes like (partial) locking of
the plate interface, the detailed co-seismic slip, poro-elastic and mantle relaxation and afterslip. Emerging
from both the observations and the models is that similar physical processes are active at different margins,
and that part of the observed complexity is controlled by them being in different stages of the earthquake
cycle. We use geodynamic models to isolate the geodetic and geological signature of these physicalprocesses over many mega-thrust cycles. Co-seismic and subsequent slip on the subduction interface are
dynamically (and consistently) driven. Our setup allows us to incorporate earthquake history, to access thesensitivity of the (short-term) seismological and geodetic signals to mechanical properties of the overriding
plate/slab system, and to predict (longer-term) geological imprints. We find that the mega-thrusts induce
significant tensile stresses in the overriding plate near the down-dip end of the co-seismic fault. Down-dip
afterslip reduces these tensile stresses, and observed aftershocks agree with fast slip during a short period
here. Transient tectonic uplift and subsidence of the overriding plate results from flexure/buckling.
Permanent deformation of the overriding plate accumulates slowly inboard of the locked plate contact in
response to long-term compression. We discuss the potential of thrust faults in the overriding plate for
producing transient uplift/terraces. We review pre-, co- and post-seismic observations and conclude that
our models capture the principal aspects of megathrust cycles that are shared by many margins, includingthat in Chile, in Alaska-Aleutians, Sumatra-Andaman, and in the Japan Trench margin.

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*J03-2-04
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Heterogeneous interseismic coupling along the Peruvian subduction zone
and rigid motion of the Peruvian Sliver* Juan Carlos Villegas-Lanza 1) , Mohamed Chlieh 2) , Olivier Cavalie 2) , Hernando Tavera 1) , Patrice Baby 2), Jose Chire 3) , Jean-Mathieu Nocquet 2)
Instituto Geofisico del Peru, Lima, Peru 1) , Geoazur, Universite de Nice Sophia-Antipolis, IRD, OCA, CNRS,
Valbonne, France 2) , Instituto Geografico Nacional, Lima, Peru 3)
Over 100 survey and continuous GPS measurements acquired in Peru between 2008 and 2013 provide
new insights into the present-day crustal deformation of the Peruvian margin. The GPS velocity field
together with information of compiled active faults reveal the rigid motion of the Peruvian Forearc Sliver
extending from the trench to the boundary between the Western and Eastern Cordilleras, moving
southeastward at a rate of 4-5 mm/yr relative to the stable South America. GPS data also reveal that
tectonics in the Cordillera Oriental is dominated by 2-4 mm/yr of crustal shortening accommodated along
the sub-Andean fold and thrust belt. In a local Peruvian Sliver reference frame the residual GPS velocity
field reflects important lateral variations of the GPS gradients which attest for along-strike heterogeneous
pattern of interseismic coupling along the megathrust. Heterogeneous interseismic coupling models
indicate shallow and relatively weak coupling in northern Peru, deep and highly locked asperities
distributed along the central and southern Peru coasts. These coupling patterns are consistent with pastmoderate tsunami-earthquakes in northern Peru and with the rupture areas of large and great megathrustearthquakes in central and southern Peru suggesting that seismic asperities might be persistent features ofthe subduction megathrust. Creeping segments correlate with the location of rupture limits of great pastearthquakes and with the location of ridges and fracture zones supporting their role as seismic barriers to
rupture propagation. In Central of Peru, where the great 1746 Mw~9.0 Lima-Callao occurred, the current
interseismic moment deficit would suggest a recurrence time of at least 305 +- 40 yrs to reproduce asimilar event. The occurrence of the 1940-2007 sequence of Mw~8.0 earthquakes may increase thisrecurrence time only by 30%.

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*J03-2-05
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Crustal deformation and surface kinematics after the 2010 earthquakes in
Latin America* Laura Sanchez , Hermann Drewes
Deutsches Geodaetisches Forschungsinstitut, Technische Universitaet Muenchen, Germany
A continuous crustal deformation model for Latin America and the Caribbean inferred from GNSS
measurements gained after the strong earthquakes occurred in 2010 in Chile and Mexico is presented. Thismodel is based on a multi-year velocity solution for a network of 456 continuously operating GNSS stations
covering a five years period. The deformation model is computed from the discrete station velocities using
the least square collocation (LSC) approach with empirically determined covariance functions. While theeffects of the Baja California earthquake can be considered as local, the effects of the Maule earthquake
changed the surface kinematics of a large area (between the latitudes 30S-45S from the Pacific to the
Atlantic coasts). Before the Maule earthquake, the strain rate field in this area showed a strong west-east
compression with maximum rates of about 0.40 micro-strain/a. In accordance, the deformation vectors
were roughly parallel to the plate subduction direction and their magnitudes decreased with the distancefrom the subduction front. After the earthquake, the largest compression (0.25 micro-strain/a) occurs
between the latitudes 37S and 40S with a N30E direction. The maximum extensional strain rate (0.20 to0.35 micro-strain/a) is observed in the Sub-Andean zone in the Patagonia south of latitude 40S. The
extensional axes rotate from a N30E direction in the central Araucania zone to a westerly direction of
N72W in the western part of Patagonia. In the northern region of parallel 35S, the extension is also
directed to the Maule zone (S45W) but with quite small rates. This complex kinematics causes a large
counter clockwise deformation pattern rotating around a point south of the epicentre (35.9S, 72.7W). The
magnitude of the deformation vectors varies from 1 mm/a close to the rotation point up to 22 mm/a nearthe 2010 earthquake epicentre. The direction of the largest deformation vectors points to the epicentre.

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*J03-3-01
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Modeling lithospheric tectonics with space geodesy: the problem oftimescales* Mian Liu 1)
University of Missouri, Columbia, USA 1) , The Computational Geodynamics Lab, Beijing, China 2)
Space-based geodesy has provided unprecedented details of crustal kinematics that have been widely usedin models of lithospheric dynamics, but the results are sometimes unsatisfactory and confusing. The
problem arises from the timescale-dependent lithospheric rheology. Space-based geodetic measurements,
usually over a few years, take snapshots of the deforming crust that is often dominated by transient elastic
or viscoelastic strain. The tectonic evolution of lithosphere, however, only leaves permanent (plastic) strain
in geological records. Thus using space-based geodetic measurements in long-term lithospheric dynamic
models requires consideration of all elastic, viscous, and plastic strains. I will illustrate this challenge in ourstudies of tectonic evolution in western US, the Andes, and the Tibetan Plateau. In the southwestern US,
crustal kinematics delineated by the GPS measurements differs significantly from that reconstructed fromthe geological records, leading to different estimates of the driving forces. Our numerical model shows that
the GPS data is dominated by the transient viscoelastic shear strain across the Pacific-North American
plate boundary zone. The geological strain in the past few million years, on the other hand, reflects mainly
the extensional strain driven by gravitational collapse of the Basin and Range Province. Across the Andean
orogenic belt, the GPS-measured crustal shortening is largely elastic and tends to be restored by repeatedtrench earthquakes, whereas permanent strain accumulates in the subandes where the plastic strength ofthe crust is lower than that of the plate interface. Across the Himalayan-Tibetan orogen, deformation by the
indentation of the Indian plate is largely limited to the Tibetan Plateau, whereas gravitational potential
energy is chiefly responsible for the widespread crustal deformation measured by GPS in much of central
and eastern Asia.

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*J03-3-02
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Anisotropic horizontal thermal contraction of young oceanic lithosphereinferred from stress release by oceanic intraplate earthquakes* Ryohei Sasajima , Takeo Ito
Nagoya University, Nagoya, Japan
1. Introduction
Oceanic lithosphere experiences thermal contraction, which is up to 3 % in volume, due to cooling after it
is generated at oceanic ridges. Thermal stress due to thermal contraction is the main cause of oceanic
intraplate earthquakes (OCEQs). One unresolved problem regarding this phenomenon is how freely theoceanic lithsphere contracts in horizontal directions due to thermal contraction. In other words, how is theboundary condition of the oceanic lithosphere? This is important for estimating driving/resistive forces ofmantle convection through force equilibrium of lithosphere, and clarifying the cause of orthogonal ridgetransform fault systems. Thus, this study attempted to estimate the horizontal thermal contraction rates ofthe oceanic lithosphere by analyzing stress release due to observed OCEQs.
2. MethodFirst, we analyzing each component of stress release due to observed OCEQs in world oceanic lithospherein 1964-2015. We found strong anisotropy of stress release in young oceanic lithosphere (5-15Ma) that
extensional stress release dominates in the ridge-parallel component and compressional stress release
dominates in the spreading-directional component. Next, we conducted a numerical simulation of thermal
stress evolution of the oceanic lithosphere in order to investigate how large anisotropy of thermal
contraction can explain the observed anisotropic stress release.
3. Results and Discussion
By comparing the observed and modeled brittle stress release rates, we found that ridge-parallel
contraction rates of young oceanic lithosphere are only 0-30 % of spreading-directional contraction rates; itmeans strong anisotropic horizontal thermal contraction. This smallness of ridge-parallel contraction
produces extensional thermal stress in the ridge-parallel component, which may play a role of weakening oflong transform faults by reducing normal stress on the transform faults.

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*J03-3-03
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

GPS observation of Biot's slow wave in the Earth's crust triggered by
Hurricane Sandy's storm surge* Geoffrey Blewitt 1) 2) , Jinhai Zhang 3) 4) , William E. Holt 4) , Zhenxing Yao 3)
Nevada Geodetic Lab., Nevada Bureau of Mines & Geology, University of Nevada, Reno, U.S.A. 1) ,Department of Physics, University of Nevada, Reno, U.S.A. 2) , Key Laboratory of Earth and Planetary
Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China 3) , Departmentof Geosciences, Stony Brook University, Stony Brook, New York, U.S.A. 4)
A phenomenon predicted by *Biot (1956) is an ultra-slow (subsonic) wave in a poroelastic medium withhigh permeability, in which the fluid and surrounding matrix oscillate with opposite phase. Although thereis evidence for Biot's slow wave in specially constructed laboratory settings, its direct observation in nature
has remained elusive owing to rapid attenuation and a lack of natural low frequency (~0.1 mHz) excitation
sources. Our routine determination of thousands of GPS positions around the globe with centimeter
accuracy every 5 minutes presents the opportunity to search for poroelastic phenomena in the relevant
bandwidth between seismic and tidal frequencies. Here we show, using 5-minute GPS data observed innortheast USA around the landfall of Hurricane Sandy of October 29-30, 2012, evidence of a highlyattenuated wave propagating in the Earth's crust over hundreds of km inland at ~65 m/s with ~12 cm
amplitude. Such a phenomenon is consistent with Biot's slow wave being triggered by the associated 4-m
storm surge, then propagating in a highly permeable crust with abundant fluid-saturated interconnectedcracks. The ability to observe such waves opens a new window on Earth's poroelastic structure, withprospects to better understand connections between hydrology, seismology, geodesy and tectonics.
*Biot, M.A. (1956), Theory of propagation of elastic waves in a fluid-saturated porous solid, 1. Lowfrequency range. Journal of the Acoustical Society of America, 28, 168-178.

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*J03-3-04
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Performance of 3-D Surface Displacement Measurement from Sub-pixel
Correlation of Optical Imagery and InSAR: a Multi-Sensor Approach* Dewan Mohammad Enamul Haque 1) , Yasser Magsoudi Mehrani 2) , ASM Maksud Kamal 1)
Department of Disaster Science and Management, University of Dhaka, Dhaka, Bangladesh 1) , Faculty ofGeodesy and Geomatics Engineering, K.N.Toosi University of Technology,Tehran, Iran 2)
The main objective of this research is to calculate the three-dimensional (3-D) surface displacement fields
using optical image sub-pixel correlation and interferometric synthetic aperture radar (InSAR) technique toinvestigate the events: Gorkha (2015), Kashmir (2005), and Duzce (1999). To help reach the goal, imagery
from multiple sensors e.g. ASTER, SPOT, Sentinel, ERS and ENVISAT were employed. Earthquake surface
displacement in the satellite line of sight (LOS) direction is measured by InSAR analysis and the opticalimage sub-pixel correlation technique provided the horizontal surface displacement components. The
vertical component of surface displacement was derived from these horizontal and LOS components. The
performance of this 3-D surface displacement measurement approach was validated by field and GPS
measurements.

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*J03-3-05
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Lithosphere dynamics and earthquake simulation: implication for seismic
hazard analysis* Alik Ismail-Zadeh 1) 2) , Alexander Soloviev 2) , Vladimir Sokolov 3)
Institute of Applied Geosciences, Karlsruhe Institute of Technology, Karlsruhe, Germany 1) , Institute ofEarthquake Prediction Theory and Mathematical Geophysics, Russian Academy of Sciences, Moscow,
Russia 2) , National Center for Earthquakes and Volcanoes, Saudi Geological Survey, Jeddah, Kingdom of
Saudi Arabia 3)
Understanding of lithosphere dynamics, tectonic stress localization, earthquake occurrences, and seismic
hazards has significantly advanced during the last decades. Modeling of lithosphere dynamics andearthquake simulations coupled with a seismic hazard analysis can provide a better assessment of potential
ground shaking due to earthquakes. We employ a model of lithospheric block-and-fault dynamics
constrained by geological, geophysical, and geodetic observations to simulate earthquakes in a seismicprone region. This model allows for studying the influence of fault network properties and regional
movements on seismic patterns. The model's performance is analyzed in terms of reproduction of basic
features of the observed seismicity such as the frequency-magnitude relationship, clustering ofearthquakes, fault slip rates, and earthquake mechanisms. We present results of our studies related tomodeling of lithosphere dynamics in the Caucasian and Tibet-Himalayan regions. We use then thesimulated large seismic events together with observations (recorded and historic earthquakes) for
probabilistic seismic hazard assessment, and discuss how hazard assessment can be improved.

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*J03-P-02
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

Analysis of Detailed Crustal Strains due to the Dense GNSS Array in the
Tokai Region, Central Japan* Teruyuki Kato 1) , Hiromu Sakaue 2) , Takuya Nishimura 3) , Ryoya Ikuta 4) , Yasushi Harada 5)
Earthquake Research Institute, the University of Tokyo, Tokyo, Japan 1) , Graduate School of Science, Kyoto
University, Kyoto, Japan 2) , Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan 3) ,Institute of Geosciences, Faculty of Science, Shizuoka University, Shizuoka, Japan 4) , School of Marine
Science and Technology, Tokai University, Shizuoka, Japan 5)
The Tokai region is an area of scientific interest where the Philippine Sea plate subducts from the easternend of the Suruga-Nankai Trough in the south of the Japanese Islands, and is expected to generate a large
interplate earthquake in the near future. Recent investigations suggest that the largest possible earthquake
in this region could be M9 class earthquake, and is called as the Nankai Trough earthquake. Moreover, thearea has experienced long-term slow slip events (SSE) during 2000-2005 and since around 2013. The
Japanese University Consortium for GNSS Research (JUNCO) established a dense GNSS array in theregion and started observation in around 2004 for monitoring the crustal deformation. The array is anaugmentation of the GEONET, the nationwide GNSS array established by the Geospatial Information
Authority of Japan (GSI). The network consists of more than 50 GNSS sites and is denser with 5-10km
baseline lengths, compared with the 20km spacing of GEONET.
The data taken by the network has been used to monitor the strain accumulation in the area as well as toinvestigate slip evolution of the long-term SSE. This study shows temporal change of strains for theobserved 12 years up until 2016. Results show strong disturbances from nearby large earthquakes of the2009 August Suruga Bay earthquake (Mw6.3), and the 2011 Off Tohoku earthquake (Mw9.1). In particular,
the Suruga Bay earthquake affected the area with significantly complicated strain pattern, suggesting
importance of dense GNSS array introduced in this study. We are now archiving the obtained data together
with ancillary data for making the data available more publicly for further researches in the area.

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*J03-P-03
Joint Symposium / J03. Deformation of the lithosphere: Integrating seismology and ge
odesy through modelling

The topography of the lithosphere-asthenosphere boundary beneath the
Korean Peninsula from S receiver functions* Sang-Hyun Lee 1) , Junkee Rhie 1) , Tae-seob Kang 2) , Seongryong Kim 1) , Hyun Jae Yoo 2) , Won Sang Lee
3), Yongcheol Park 3)
Seoul National University, Seoul, Korea 1) , Pukyong National University, Busan, Korea 2) , Korea Polar
Research Institute, Incheon, Korea 3)
The topography of the lithosphere-asthenosphere boundary (LAB) beneath the Korean Peninsula wasdetermined using teleseismic S-receiver functions, obtained from the seismographs in Korea from 2005 to
2012. The receiver functions were migrated from the delayed time to the corresponding conversion points(CCP) of S-to-p phases using the IASP91 model and stacked with the common conversion points in circularbin. The LAB beneath the Korean Peninsula was determined at a depth range of 60 - 100 km from the CCP
stacked receiver functions. The LAB depth is deep at the north and getting shallow to the south with a rapidchange along the tectonic boundary between the Gyeonggi Massif and the Okcheon Fold Belt. This shallow
LAB, considering the Precambrian bedrock of the Korean Peninsula, implies the lithosphere thinningaccompanied by the coeval subduction of the paleo-Pacific plate since the Jurassic. The northwardsubduction of the oceanic plate from the southeast in the Jurassic could result in the northward dipping of
the LAB depth beneath the Korean Peninsula. The structure in the uppermost mantle reflects the complex
tectonic history surrounding the Korean Peninsula. Therefore, the LAB topography reveled in this study
would contribute to understand the tectonic history of the Korean Peninsula.

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*J04-1-01
Joint Symposium / J04. Geohazard early warning systems

ShakeAlert@taiwan* Yih-Min Wu 1) 2) , Ming Yang 1) , TC Huang 2)
National Taiwan University, Taipei, Taiwan 1) , Academia Sinica, Taipei, Taiwan 2)
The Earthquake Early Warning System (EEWS) based on the low-cost P-Alert seismic network in Taiwan
has proved indispensable by a few earthquake events since 2010. This dense network can produce detailed
shaking maps and identify direction of source rupture in almost real-time. Equip with real-time acceleration
data and the time-dependent attenuation relationship of peak ground acceleration (PGA), our system,
ShakeAlert@taiwan, can compute predicted PGA immediately before the observed PGA arrive. Thisadvantage can provide sufficient time for hazard assessment and emergency response, comparing to theconventional shaking map. The performance of ShakeAlert@taiwan was tested against historical moderateto-large inland earthquake (ML > 5.5) events. Take 2016/02/5 Meinong, Taiwan earthquake as an example,
it converge to stable result and produce shaking map within 16 seconds after the earthquake occurred. The
processing time for possible maximum PGA, taking into account the PGA saturation, can be reduced to 8
seconds. In comparison with traditional methods, ShakeAlert@taiwan can quickly identify possible damage
region and provide the valuable warning information for hazard mitigation.

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*J04-1-02
Joint Symposium / J04. Geohazard early warning systems

Challenges for implementing Earthquake Early Warning: A Case Study in
Nicaragua
Frederick Massin 1) , * John Francis Clinton 1) , Maren Boese 1) , Carlo Virgilio Cauzzi 1) , Wilfried Strauch 2)
Swiss Seismological Service (SED) ETH, Zurich, Switzerland 1) , Instituto Nicaraguense de Estudios
Territoriales (INETER), Managua, Nicaragua 2)
Earthquake early warning (EEW) systems aim at providing fast and accurate estimates of event parameters
or local ground shaking over wide ranges of source dimensions and epicentral distances. Numerous
approaches, in a variety of tectonic settings, are already operational and warnings publicly available insome regions.
The Swiss Seismological Service (SED) has integrated EEW solutions into the SeisComP3 (SC3)professional earthquake monitoring software. VS(SC3) provides fast magnitude estimates for network-based
point-source origins using conventional triggering and phases association techniques, while FinDer(SC3)matches the evolving patterns of ground motion to track on-going rupture extent, and hence can provide
accurate ground motion predictions for finite fault ruptures. SC3 is widely used, including in Central
America, and at INETER in Nicaragua.
SED and INETER started a joint project to assess the feasibility of EEW in Nicaragua and Central America
and to set up a prototype EEW system. We test VS(SC3) and FinDer(SC3) softwares at INETER since 2016.
We report on the successes and challenges of operating an EEW system where seismicity is high, but
infrastructure is fragile and the design and operation of a seismic network is challenging (in Nicaragua, on
average 50% of all stations do not work effectively for EEW). Broad seismic data exchanges in Central
America provides real time data at INETER from stations operated by neighboured countries. We compare
the observed performance of EEW in Nicaragua with an ideal setting, featuring optimized network
geometry and latency. Without a reliable network, it is impossible to guarantee EEW with a minimum
number of missed and false alarms. Implementation of EEW under these conditions can lead to loss ofconfidence in the system by end-users. We make proposals to improve the Nicaraguan and the Joint
Central American Seismic Networks for EEW.
The project is funded by the Swiss Development Agency and supported by Nicaragua.

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*J04-1-03
Joint Symposium / J04. Geohazard early warning systems

Reducing Digitiser Latency for Earthquake Early Warning: New Strategies
for Seismic Hardware* Clare Sweeney , Neil Watkiss
Guralp Systems Ltd, Reading, United Kingdom
The latency between earthquake origin and issuing an alert is one metric used to assess the performance ofEarthquake Early Warning Systems. Total latency accumulates from many sources (e.g. P-wave propagation,
digitization, transmission, receiver processing, triggering, event declaration). Data delivery latency is thetime taken for digitization, packetisation, transmission and receipt of data. The two main contributors todata delivery delays are data packetization (Brown et al., 2011) and digitisation.
Data packetisation: SEEDlink protocol is commonly used, however, packet size is fixed to 512-byte
miniSEED records; each with a 64-byte header. SEEDlink can cause typical large data transmission
latencies of >0.7 s at typical sampling rates. We propose a new ultra-low-latency protocol, GDI, an efficientand flexible method of exchanging data between seismic stations and data centers in large networks.
Instead of fixed-length packets, GDI dispatches data sample-by-sample as acquired by the data-logger. A
self-adaptive scheme assesses available bandwidth and judges the smallest packet size needed for the
fastest transmission. A light 4-byte header maximizes efficiency for small packet sizes.
Digitisation: Most current seismic data-loggers implement acausal (linear phase FIR) filters; but thesecannot be computed in true real-time and give spurious precursors to seismic wave onsets (e.g. Scherbaum& Bouin, 1997). Acausal filtering typically contributes >0.3 s to data delivery delays. Causal (minimum
phase) FIR filters are typically non-standard in seismic data-loggers, yet, the improved latency and sharper
onset determination mean that causal filters offer significant advantages for EEWS, reducing digitization
delays to 20–60 ms (at sample rates of 100–250 sps).
Using a twofold strategy of causal filtering combined with a rapid data transmission protocol, such as GDI,
we show significantly reduced data delivery latencies to 40–60 ms (at typical sample rates).

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*J04-1-04
Joint Symposium / J04. Geohazard early warning systems

A new methodology for Earthquake Early Warning (EEW) by a high-dense
seismic network deployed at interstation distance of less than 5 km
* KENJI KANJO
Takamisawa Cybernetics Co.ltd.,Tokyo,Japan
Many of current EEW systems issue estimated intensity distribution maps according to empiricalattenuation relationships which require information of source parameters and focal distance. These
information are determined based on point source model which is not applicable for finite source model oflarge earthquakes. EEW is essential for the source area of inland earthquakes where heavy damages are
expected. In most cases, EEW is issued lately in the source area which described as “a blind zone".
Seismic networks, in case of Japan, are deployed for the determination of hypocenter at about 20-30 km
interstation distance. That span delays the detection of P-wave arrivals by about 3-4 s. In this study, we
present a new methodology for EEW which used peak ground acceleration (PGA) estimated from P wave,
taking advantage of the differential velocity (i,e., ~1.73) and the amplitude ratio (i,e., ~1/5) of P and S-waves.
The efficiency of this method suggests the distribution of a high-dense seismic network of 5 km interstation
distance, considering a span distance less than that of velocity of P-wave (i,e., 6 km/s). The slowness
analysis of P waves tells information of the rupture starting point and its depth. Firstly, peak groundacceleration (PGA) on free surface is estimated from maximum P-wave amplitude in one-second time step
until the arrival of S-wave at the first detected station, and then adjusted to that on the engineering base
(PGAE) by eliminating the site effect. Secondly, we estimate PGAE on far site from a relevant attenuation
relationship and adjusted to PGA considering site amplification. Finally, we issue real-time intensity map inevery second time step till the declining of PGA. The described method is useful to improve EEW system
and also to perform disaster estimation immediately after the occurrence of large event, in order to avoid
data extrapolation and the time consuming waveform inversion analysis.

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*J04-2-01
Joint Symposium / J04. Geohazard early warning systems

Magnitude scaling relationships from the first 3s of P-wave arrivals in
Mainland of China* Jindong Song 1) 2) , Dongwang Tao 1) 2) , Shanyou Li 1) 2) , Qiang Ma 1) 2) , Haiying Yu 1) 2)
Institute of Engineering Mechanics, China Earthquake Administration, Harbin, China 1) , Key Laboratory of
Earthquake Engineering and Engineering Vibration, Harbin, China 2)
One of the critical technologies of earthquake early warning is determining the size of an earthquake fromthe first few seconds after the P-wave arrivals. We derive empirical magnitude scaling relationships formainland of China using a dataset of 214 past earthquakes and 2511 vertical waveforms recorded inmainland of China by China Strong Motion Networks Center (CSMNC) between 2007 and 2015. The
events range in magnitude from 4.0 to 8.0. We use the predominant period (tau-c) and the peak
displacement amplitude (Pd) measured from the first 3 seconds of P-wave arrivals to determine periodmagnitude and amplitude-magnitude scaling relationships respectively. The average error in magnitude
estimates is 0.3 magnitude units for events with magnitudes ranging from 4.0 to 6.5, and 0.5 magnitudeunits for events with magnitudes greater than 6.5. we observe the saturation effect for magnitudes greaterthan 6.5, especially in amplitude-magnitude scaling relationships. In cases of the Ms 8.0 Wenchuan
earthquake and the Ms 7.0 Lushan earthquake, such warnings would be available within 10s of the origin
time of a large earthquake. Our magnitude scaling relationships may be useful for developing anearthquake early warning system in mainland of China.

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*J04-2-02
Joint Symposium / J04. Geohazard early warning systems

A Fast Algorithm for Earthquake Early Warning Systems Based on the
Energy release of P Waves in the Interval tS-tP
Armando Cuellar 1) , * Gerardo Suarez 2) , Juan Manuel Espinosa-Aranda 1)
Centro de Investigacion y Registro Sismico (CIRES) 1) , Instituto de Geofisica, UNAM 2)
The Mexican earthquake alert system (SASMEX), operating since 1991, is in a unique situation because
seismic waves that potentially damage Mexico City take approximately one minute to reach the soft soils of
the city. Today, the system covers the entire Mexican subduction zone. As a result, cities close to theseismic zones were added to the system and alerted also of impending earthquakes. In those cases, theprocessing time of the original algorithm is relatively long, as it is based on the energy released in twice theS-P interval. We present another algorithm, which measures the maximum seismic energy released and thecumulative energy growth in the S-P period. The algorithm detects the P wave and measures the energy
growth, which is in turn calibrated to magnitude and decides whether a magnitude threshold is exceeded.
The algorithm stops when the S wave arrival is detected. Seismic field sensors need to be near the
epicenter and at least two nearby instruments should confirm the potential alert. A regression model basedon records from 144 subduction earthquakes 4.7>Mw<8.1 calibrated the magnitude estimator M(tS-tP).
The magnitude is determined with a family of linear equations, which relate it to the sum of squared
accelerations and the maximum acceleration. The algorithm was tested on a subset of 97 earthquakes. The
threshold to activate the early warning system is magnitude M(tS-tP) >5.8. Out of 97 events, 93 werecorrectly classified with a magnitude larger than 5.8, demonstrating the robustness of the method. The
south Napa earthquake (Mw6) is an excellent example where strong motion data was recorded nearby. The
application of the tS-tP algorithm to the 24 August 2014, Napa earthquake shows that in this hypotheticalscenario, the tS-tP algorithm would give a warning time of 10 seconds to the city of Berkeley. In
comparison, the ShakeAlert algorithm provided a warning time of only 5 s.

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*J04-2-03
Joint Symposium / J04. Geohazard early warning systems

Seismogeodesy for Rapid Earthquake Magnitude Estimation* Dara Goldberg 1) , Yehuda Bock 1) , Diego Melgar 2)
University of California, San Diego, La Jolla, California, United States of America 1) , University ofCalifornia, Berkeley, Berkeley, California, United States of America 2)
Earthquake magnitude is a concise metric that provides invaluable information about the destructive
potential of a seismic event. Rapid magnitude estimation for earthquake and tsunami early warning relies
on near-field seismic and geodetic instruments. However, seismic instruments experience well-documented
complications at long periods, which hinders accurate and timely estimates of ground displacement. As
such, the relation between ground motions measured with strong-motion accelerometers (broadband
seismometers clip in the near field of large earthquakes) and magnitude saturates, leading tounderestimation of earthquake magnitude. However, ground motions measured with GNSS do scale withmagnitude without saturation [Crowell et al., 2013; Melgar et al., 2015]. Therefore, we supplement highfrequency strong-motion accelerations with Global Navigation Satellite System (GNSS) long-period
displacement observations to better inform rapid response. We refine magnitude scaling relations using
peak ground displacement (PGD) by adding a large GNSS dataset of earthquakes in Japan. We demonstratethat seismogeodesy, the optimal combination of GNSS and seismic instrumentation, improves thesensitivity of displacement time series compared to GNSS alone. This not only means that ground motion
can be detected at farther stations, but also that smaller seismic arrivals (i.e. P-waves) become visible in thedisplacement time series. P-wave amplitude (Pd) has been examined as an early indicator of earthquake
magnitude. Relations between Pd and magnitude using seismic-only instruments also appear to suffer fromsaturation, while seismogeodetic data has been demonstrated to eliminate saturation [Meier et al., 2016,
Crowell et al., 2013]. We create seismogeodetic displacements by combining the GNSS dataset withJapanese KiK-net and K-net accelerometer data to explore the potential of seismogeodesy for magnitudescaling using P-wave amplitude with several seconds of data.

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*J04-2-04
Joint Symposium / J04. Geohazard early warning systems

Determination of warning earthquake magnitude from the initial P-wave
recordings based on half periods and characteristic periods* Dongwang Tao 1) 2) , Qiang Ma 1) 2) , Jindong Song 1) 2) , Haiying Yu 1) 2) , Jiang Wang 1) 2) , Shanyou Li 1) 2)
Institute of Engineering Mechanics, China Earthquake Administration, Harbin, China 1) , Key Laboratory of
Earthquake Engineering and Engineering Vibration, Harbin, China 2)
The determination of earthquake magnitude from the first several seconds of P-waves is fundamental inearthquake early warning (EEW) systems. There exist kinds of method to estimate the magnitude ofongoing earthquake, including peak displacements, characteristic periods and predominant periods. In thispaper, the half period of the P-wave is implemented to determine the warning earthquake magnitude.
Different seismic events in different regions of strong motion records is used to study the differences in thehalf periods of the first P waves. This paper discusses the characteristics at the beginning of waveforms in
the Wenchuan mainshock and aftershock events and determines the correlation between the motion ofmoderately strong earthquakes in the early half cycle parameters and the earthquake magnitude. The effectof attenuation relations studied in the P wave seismic phase to S-wave phase time range, peak
displacement with the time window length increases the variation characteristics, and different magnitude
between peak displacement curve regularity is also investigated. Characteristics of cycle parameters in the
P-waves for the records in the same time azimuth angle with the variation of the time window is also studies
similarly. According to the research results, it is shown that there is a difference in the initial rupture of theearthquake with different sizes. In addition, this paper also discusses the relationship between the initial
moving half period, the characteristic period and the source scale.

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*J04-3-01
Joint Symposium / J04. Geohazard early warning systems

Testing of GMPEs for absolute velocity response spectra for earthquake
early warning of long-period ground motion intensity in Japan* Yadab P. Dhakal , Wataru Suzuki , Takashi Kunugi , Shin Aoi
National Research Institute for Earth Science and Disaster Resilience
We constructed ground motion prediction equations (GMPEs) for absolute velocity response spectra(AVRS) at periods between 1 s and 10 s with an objective of rapid prediction of long-period ground motion
intensities recently proposed by Japan Meteorological Agency (JMA) for earthquake early warning (EEW)(Dhakal et al. 2015). The GMPEs require JMA magnitude and hypocentral distance as basic input
parameters and the values are corrected for site conditions a priory defined. The JMA magnitude, that is anamplitude-based magnitude, is estimated faster than moment magnitude. The success of predictions for
future events depends on whether the future events are sufficiently similar to the trained events in the
GMPE models in terms of location, magnitude, and individuality of the events. The GMPEs used data fromevents having Mw >= 6.5 and recorded by K-NET and KiK-net until 2012. In this paper, we discuss
performance of the GMPEs for recent large earthquakes that occurred in Japan after the construction of the
GMPEs. We found that the GMPEs performed satisfactorily in the region of high intensities but performed
relatively poorly at distances beyond about 200 km in the case of the 2016, Mw 7.1 Kumamoto earthquake.
We found that the event errors associated with the Kumamoto earthquake are quite larger than those forthe events employed in the GMPEs. It is found that a part of the errors is from a bias due to an uneven
azimuthal coverage of the data at long distances. For other large events that occurred in off the Pacific
Coast of Japan (e.g., 2016 Nov 22, 05:59 JST, Mw 7.0, east off Fukushima Prefecture earthquake; 2015 Feb
17, 08:06 JST, Mw 6.7, far east off Sanriku earthquake), we found that the results are satisfactory.
References
Dhakal YP, Suzuki W, Kunugi T, Aoi S, 2015, Ground motion prediction equations for absolute velocity
response spectra (1-10 s) in Japan for earthquake early warning, Journal of Japan Association for
Earthquake Engineering 15(6), 91:111.

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*J04-3-02
Joint Symposium / J04. Geohazard early warning systems

Real-time prediction of ground shaking without source information: Dataassimilation and simulation of seismic wave propagation for Earthquake
Early Warning* Mitsuyuki Hoshiba , Masashi Ogiso
Meteorological Research Institute, JMA, Tsukuba, Japan
Many of the present Earthquake Early Warning (EEW) systems quickly determine the hypocenter andmagnitude, and then predict strength of ground motions. The Mw 9.0 Tohoku earthquake, however,revealed some technical issues with such methods: under-prediction at large distances due to the large
extent of the fault rupture, and over-prediction because the system was confused by multiple aftershocks
that occurred simultaneously. To address these issues, we have proposed a new concept for EEW (Hoshiba
and Aoki, 2015, BSSA), in which the present wavefield is estimated precisely in real time by applying data
assimilation, and then the future wavefield is predicted by simulation of seismic wave propagation.
Information on the hypocenter and magnitude is not required. We call it “numerical shake prediction" by
analogy to “numerical weather prediction" in meteorology.
In many methods of the present EEW systems, the strength of ground motions (PGA, PGV, seismic
intensity) are predicted using the hypocentral distance and magnitude based on a ground motion
prediction equation, which usually leads the prediction of concentric distribution. However, actual groundshaking is not always concentric, even when site amplification is corrected. The strength of shaking may bemuch different among earthquakes even when their hypocentral distances and magnitudes are almost thesame. For some cases, PGA differs more than 10 times, which leads to imprecise prediction in EEW.
In numerical shake prediction, because future is predicted from the present condition, it is possible toaddress the issue of the non-concentric distribution. Once the heterogeneous distribution is actuallyobserved in ongoing wavefield, future distribution is predicted accordingly to be non-concentric. We will
indicate examples of M 6 crustal earthquakes occurred at central Japan, and the 2016 Kumamoto
earthquake (Mw 7.0), during which M 6 class earthquake was remotely triggered apart from 70 km from theepicenter.

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*J04-3-03
Joint Symposium / J04. Geohazard early warning systems

Real-Time Ground Motion Prediction based on Radiative Energy Transfer
using Front-Site Waveform Information and Data Assimilation for the
Application to Regional Earthquake Early Warning* Mike Lindner 1) 2) , Masato Motosaka 2)
Karlsruhe Institute of Technology, Karlsruhe, Germany 1) , Tohoku University, IRIDeS, Sendai, Japan 2)
In-time warning of strong ground motion for citizens in affected areas is one of the primary objectives ofEarthquake Early Warning. To satisfy this requirement, continuous front-site observation and quick
analyzing algorithm to ensure enough warning time are indispensable. Existing network systems depend on
fast source parameter estimation while on-site methods try to predict ground motion from an observation ata target site. Latter systems are currently the fastest approach for highly vulnerable sites, but they lack on
quality in prediction. This study uses the radiative transfer theory based on ray scattering, to model a realtime numerical ground motion map for the region of Miyagi. The authors use a two-layered model torepresent processes in geological structures by simulating the energy transfer in the bedrock as a functionof scattering. The processes on the surface layer are then modeled as a function of local amplification andthe bedrock information. Prediction is done for a circular area with an observation site as the central point.
The predictive model uses band-passed filtered acceleration information from surface stations, projected
onto the bedrock layer, by using a scalar transfer function. An energy impulse, which is a function of the
PGA for a time length $dt$ is then used to simulate the distribution of energy within the area. Surface
intensity is estimated by multiplying the bedrock model with the surface amplification. This process isrepeated in steps of $dt$ second and can be done almost instantaneously. Furthermore, by using otherobservation sites within the prediction radius, evaluation and correction of the predictive field are achieved
using data assimilation. The developed system allows it to model an interpolated wave-field behind, and a
predicted wave-field in front of the wave-front, thus providing ground motion information around recordingsites. The authors currently work on the extension of the proposed method into a network.

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*J04-3-04
Joint Symposium / J04. Geohazard early warning systems

Propagation of local undamped motion (PLUM) method and its
improvement using P-phase discrimination for more rapid earthquake early
warning based on wavefield-estimation approaches* Yuki Kodera
Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan
Earthquake early warning methodologies based on wavefield estimation have been recently proposed by
Hoshiba (2013) and Hosiba and Aoki (2015) to address technical challenges that come from point-sourcemodel approaches such as underprediction of strong motion when large earthquakes (M>~8) occur andoverprediction when multiple earthquakes simultaneously happen. The propagation of local undamped
motion (PLUM) method is a simple wavefield-estimation algorithm derived from the method proposed by
Hoshiba (2013). The PLUM method predicts strong motion at a target site by taking the maximum among
real-time seismic intensities (Kunugi et al., 2013) observed at seismometers within 30km of the target site.
A simulation of the PLUM method for the 2011 off the Pacific coast of Tohoku Earthquake (Mw 9.0) (theTohoku-oki earthquake) showed that the PLUM method predicted accurate seismic intensities in the Kanto
region, where the EEW system of the Japan Meteorological Agency (JMA) underpredicted strong motion.
The PLUM method, however, has room for improvement in rapid warning issuance since its prediction
process rely only on strong motion by S phase and do not utilize P-phase information available before the Sphase arrival. We introduced a simple P-phase discriminator that uses V/H (ratio of vertical to horizontal
components of acceleration) and modified the prediction process of the PLUM method. The modified
method first conducts on-site prediction of S-phase strong motion for seismometers assumed to beobserving P phase. After that, the modified method predicts strong motion for target sites in the same way
as the original method. We applied the modified method to the Tohoku-oki earthquake and the Mj 6.5 andMj 7.3 earthquakes in the 2016 Kumamoto earthquake sequence. Results showed that the modified method
provided longer warning times by 5 s in the Tohoku-oki earthquake and 1 s in the Mj 6.5 and Mj 7.3
earthquakes, compared with the original method.

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*J04-3-05
Joint Symposium / J04. Geohazard early warning systems

Recent advances in tsunami warning and earthquake early warning of theJapan Meteorological Agency after the 2011 Great Tohoku Earthquake andTsunami* Satoshi HARADA
Japan Meteorological Agency, Tokyo, JapanThe Japan Meteorological Agency (JMA) is the sole organization to issue warnings on natural hazards inJapan. JMA started its operation of tsunami warnings in 1949 and since then JMA has improved its
warnings in accuracy and swiftness. And JMA started the service of earthquake early warning (EEW)
provision to the public in 2007. For the 2011 Great Tohoku Earthquake and Tsunami (Mw9.0), JMA issued
Major Tsunami Warnings, the highest category of JMA's tsunami warning, in three minutes, and issued
EEWs 8.6 seconds after the earthquake detection. These warnings were promptly disseminated to the
public via various ways such as TV, radio and mobile phones. On the other hand, this event also posedseveral issues to be improved on JMA's warning systems, and JMA took various measures based on thelessons learned from this event. Major countermeasures for tsunami warnings are, 1) introduction ofqualitative expression of tsunami height estimation like "Huge", which will be used when JMA issues
tsunami warnings based on pre-assumed maximum magnitude because the earthquake is too large toestimate the magnitude appropriately within around three minutes, and 2) utilization of ocean bottompressure gauges in updating tsunami warnings. Regarding EEW, as the countermeasure for the difficulty in
hypocenter and magnitude estimation when multiple events occur simultaneously, JMA introduced theIntegrated Particle Filter (IPF) method in 2016, which is expected to greatly improve the ability to separate
individual events from simultaneously occurred multiple earthquakes. JMA also plans to introduce the new
method, i.e., the propagation of local undamped motion (PLUM) method, into EEW in the near future which
addresses the issue of under-prediction for massive earthquakes with large rupture zones. This method
adopts the technique of sequential prediction of seismic intensity by assimilating expanding ground tremor
observations into forecasting.

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*J04-4-01
Joint Symposium / J04. Geohazard early warning systems

Geo-hazard early warning systems: A UNESCO perspective
Jair Torres 1) , Margherita Fanchiotti 1) , * John Clinton 2)
UNESCO, Paris, France 1) , Swiss Federal Institute of Technology (ETH), Zurich, Switzerland 2)
The Sendai Framework recognises the need to "substantially increase the availability of, and access, tomulti-hazard early warning systems and disaster risk information and assessments to the people by 2030".
UNESCO strongly believes in the benefits of individual, cluster and multi-hazard early warning systems tobetter address the specificities of each hazard in an integrated manner. While considerable progress has
been made in the field of early warning, these systems continue to be less developed for geo-hazards andsignificant challenges remain in advancing their development for specific hazards, particularly for suddenonset hazards such as earthquakes. Furthermore, there is a need for better collaboration among and acrosscommunities of scientists, practitioners and policy-makers worldwide. As the only UN agency with amandate in Earth Sciences, UNESCO is actively engaged in promoting cooperation, knowledge exchange
and capacity building on geo-hazard early warning across the globe. By operating at the interface between
science, education, culture and communication, UNESCO is best placed to facilitate the establishment ofthese systems. UNESCO recently launched the International Platform on Earthquake Early Warning
Systems, to assess the state of the art in earthquake early warning globally and foster dialogue for capacity
building and policy making around these systems. In line with this mandate, UNESCO is organising an
International Conference on Earthquake Early Warning Systems in October 2017. UNESCO also promotes
landslide early warning through the International Consortium on Landslides and has produced a study on
mobile early warning systems for volcanic eruptions. Finally, UNESCO leads the Intergovernmental
Oceanographic Commission, which coordinates the establishment of tsunami early warning systems
worldwide. Thanks to its key role in promoting early warning systems, UNESCO is part of the International
Network on Multi-Hazard Early Warning Systems.

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*J04-4-02
Joint Symposium / J04. Geohazard early warning systems

Real-Time Tsunami Inundation Forecast System using NIED S-net* Shin Aoi , Naotaka Yamamoto , Wataru Suzuki , Kenji Hirata , Hiromitsu Nakamura , Takashi Kunugi ,Tomohiro Kubo
NIED, Tsukuba, JapanOne of the lessons learned from the 2011 Tohoku earthquake is the importance of offshore observations.
JMA issued the initial tsunami warning three minutes after the 2011 Tohoku earthquake, however,estimated tsunami heights were underestimated. Although the estimated tsunami heights were raised about
half an hours after the earthquake occurrences, the power failures prevented the residence from receiving
updated tsunami information. It consequently caused enormous fatalities and significant damages to theeastern Pacific coast of Japan, indicating the importance to deliver prompt and accurate forecast ofearthquake and tsunami to the onshore residences. The Japanese government decided to construct the
Seafloor Observation Network for Earthquakes and Tsunamis along the Japan Trench (S-net), which isoperated by National Research Institute for Earth Science and Disaster Resilience (NIED). NIED S-net is
expected to provide additional lead time for earthquake and tsunami early warning. We develop a new
realtime tsunami inundation forecast system using NIED S-net. In our system, several appropriate tsunami
scenarios that can explain offshore tsunami observations are quickly selected by using multiple indicesfrom the Tsunami Scenario Bank (TSB), which contains offshore tsunami pre-calculated waveforms, coastal
tsunami heights, inundation depth maps, and others. One of the key features of our system is that tsunami
inundations are estimated explicitly without any source information, which may contain large estimation
error. Many calculations are performed in advance to investigate the sensitivities of the source models tocoastal tsunami heights and inundation depth along the Pacific coast of Chiba prefecture in the Kanto
region. We evaluate and improve our system through the demonstration experiments with local
governments. We also validate the performance of the system for the simulated data as well as the observed
data of the 2016 Fukushima-oki earthquake.

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*J04-4-03
Joint Symposium / J04. Geohazard early warning systems

New Insights on Tsunami Genesis and Energy Source* Y. Tony Song 1) , Soomon Yim 2) , Ali Mohtat 2)
NASA Jet Propulsion Laboratory 1) , Oregon State University 2)
Conventional tsunami theories suggest that earthquakes with significant vertical motions are more likely togenerate tsunamis. In tsunami models, the vertical seafloor elevation is directly transferred to the seasurface as the only initial condition. However, evidence from the 2011 Tohoku earthquake indicatesotherwise; the vertical seafloor uplift was only 3 - 5 meters, too small to account for the resultant tsunami.
Surprisingly, the horizontal displacement was undeniably larger than anyone's expectation; about 60
meters at the frontal wedge of the fault plate, the largest slip ever recorded by in-situ instruments. The
question is whether the horizontal motion of seafloor slopes had enhanced the tsunami to become as
destructive as observed. In this study, we provide proof: (1) Combining various measurements from the2011 Tohoku event, we show that the earthquake transferred a total energy of 3.1e+15 joule to the ocean,in which the potential energy (PE) due to the vertical seafloor elevation (including seafloor
uplift/subsidence plus the contribution from the horizontal displacement) was less than a half, while thekinetic energy (KE) due to the horizontal displacement velocity of the continental slope contributed amajority portion; (2) Using two modern state-of-the-art wave flumes and a three-dimensional tsunami
model, we have reproduced the source energy and tsunamis consistent with observations, including the2004 Sumatra event. Based on the unified source energy formulation, we offer a competing theory to
explain why some earthquakes generate destructive tsunamis, while others do not.

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*J04-4-04
Joint Symposium / J04. Geohazard early warning systems

Synthesis of Offshore Tsunami Records and Inundation Including Seismic
Waves and Tsunami: Anticipated Nankai Trough Earthquakes, Southwest,
Japan* Tatsuhiko Saito 1) , Toshitaka Baba 2) , Shunsuke Takemura 1) , Eiichi Fukuyama 1)
National Research Institute for Earth Science and Disaster Resilience 1) , Tokushima University, Tokushima,
Japan 2)
New tsunami observation networks such as DONET and S-net are designed for the observation inside
earthquake focal area. When analyzing the tsunami recorded inside the focal area, seismic waves andtsunami appear at the same time. Theories that describe both seismic waves and tsunami are necessary.
Saito and Tsushima (2016) proposed a method for synthesizing ocean-bottom pressure records consideringboth seismic waves and tsunami, but their method is not applicable to sea-surface displacement records.
Recent observation enables us to observe tsunami by sea-surface displacement by using GPS buoys. Inazu
et al. (2016) showed that real-time tsunami source estimation is possible if if we utilize high-precision, realtime GPS height observations equipped with cargo ships and tankers. This study shows a method thatsynthesizes tsunami records of sea-bottom pressure change and sea-surface displacement including
seismic waves and tsunami. As examples of huge earthquake, the scenarios of anticipated Nankai-Troughhuge earthquakes proposed by Hok et al. (2011) are used. By using their rupture scenarios as seismic
sources in seismic-wave propagation simulations, we calculated spatial and temporal variation of the seasurface displacement without considering gravity (e.g., Takemura et al. 2015). Then, we included thecontribution of gravity by numerically solving tsunami equations and also simulated the inundation withhigh-resolution topography data using JAGRUS (Baba et al. 2015). Seismic waves and tsunami
simultaneously appeared in both ocean-bottom pressure change and sea-surface displacement during theearthquake rupture, which would make tsunami analyses difficult. The seismic-wave contribution to seabottom pressure records is greater than to the sea-surface displacement. The data sets created in this study
would be useful for practical tests of tsunami-prediction algorithms using offshore tsunami records,
especially including the records inside the focal area.

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*J04-4-05
Joint Symposium / J04. Geohazard early warning systems

Rapid estimation of tsunami source location based on Tsunami Centroid
Location (TCL) using NIED oceanfloor observation networks* Naotaka YAMAMOTO , Takeshi NAKAMURA , Shin AOI , Wataru SUZUKI , Narumi TAKAHASHINational Research Institute for Earth Science and Disaster Resilience, Tsukuba, Ibaraki, Japan
A rapid method of estimating tsunami source locations using real-time ocean-bottom hydrostatic pressure
data from a dense offshore observation network has been proposed (Yamamoto et al., GRL, 2016). In thismethod, we calculate a characteristic location representing the real-time tsunami disturbance calledtsunami centroid location (TCL), which is the centroid location of the maximum absolute amplitude of thereal-time ocean-bottom hydrostatic pressure changes. The TCL could approximate the tsunami source
centroid location, which is the weighted center of the absolute values of the initial sea surface heightdisplacements and presents the approximate tsunami source location. In this presentation, we report
whether the TCL can approximate the centroid location of the tsunami source by examining various nearfield synthetic tsunami scenarios and several observed micro tsunamis from NIED oceanfloor observation
networks; Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET) and the Seafloor
Observation Network for Earthquakes and Tsunamis (S-net). In addition, we propose the method of realtime forecast for the arriving time on the target coastline using the TCL in order to issue the lead-time forcitizens on the coasts.

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*J04-5-01
Joint Symposium / J04. Geohazard early warning systems

Tsunami data assimilation including effects of coseismic deformation for realtime tsunami forecasting using pressure gauges* Takuto Maeda
Earthquake Research Institute, the University of Tokyo, Tokyo, Japan
Recent developments of dense networks of ocean-bottom pressure gauges are expected to bring us highly
reliable, fast warnings of tsunami attacks. Among wide variety of proposed methods for tsunami forecasting,data assimilation (DA) approach provides a successive estimation of tsunami wavefield rather thanestimates of seismic source fault slip or initial sea height, which is suitable for real-time monitoring. The
ocean bottom pressure gauge records, however, contain an offset due to coseismic deformation beneaththe sensor. Here I propose a new method on the tsunami DA with separation of the coseismic deformation
to estimate the true tsunami height.
In the original DA method, the pressure gauge data are directly assimilated to the shallow-water equation.
The tsunami height at a step away is forecasted by numerical simulation, and the residual between
forecasted and observed tsunami heights at the station location is used to assimilate the surrounding
tsunami wavefield by the optimum interpolation kernel. Since the data assimilation uses the tsunami height
estimated by pressure gauges, the assimilated tsunami wavefield should be contaminated by the coseismic
deformation.
In the proposed method, we estimate the coseismic deformation in addition to the tsunami height. It isshown that the coseismic deformation can be approximately expressed as a solution of an inhomogeneous
Laplace equation having pressure height as a source term. This equation is numerically solved for
estimation of coseismic deformation term. A numerical experiment for this method with a real stationlayout was performed. By applying the proposed method to hypothetical observations, it correctly
separated the coseismic deformation. It is noteworthy that the initial tsunami rise-up at very early time dueto the coseismic deformation was clearly detected by this separation, which could be useful for shortening
the necessary time for forecasting tsunami.

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*J04-5-02
Joint Symposium / J04. Geohazard early warning systems

A fast tsunami data assimilation approach on the 2012 Haida Gwaii
earthquake: based on the employment of Green's function* Yuchen Wang , Kenji Satake , Takuto Maeda
Earthquake Research Institute, University of Tokyo, Tokyo, Japan
Tsunami data assimilation has been proposed for tsunami hazard warning. It estimates the tsunami wave
field by assimilating tsunami data observed offshore into a numerical simulation, without calculating initial
sea surface height at the source. The Optimum Interpolation (OI) method is widely adopted in assimilating
observed data. However, the traditional data assimilation approach requires quite large calculating time,
because the forecasted waveforms are still calculated with tsunami propagation model for the entire region.
In this study, we present a new approach based on the employment of Green's function to improve thespeed of data assimilation for tsunami warning. For the OI method, if the residual between observed andcalculated tsunami height is not zero, there will be an assimilation response around the station. We
consider the occurrence and linear propagation of such tsunami-height response as the ‘Green's function'of a station. Then the forecasted tsunami wave field can be calculated as the superposition of the Green's
functions corresponding to different stations. Similarly, the observed tsunami data is repeatedly assimilated
during the time window, and more Green's functions are superposed to the forecasted waveforms at Points
of Interest (PoI).
This approach greatly reduces the time cost for tsunami warning because it no longer needs to run thetsunami propagation model, as long as the Green's functions are calculated in advance. It requires
additional computer memory space for pre-calculated Green's function, but it does not have a significant
impact on computational efficiency for regional-scale tsunami data assimilation. We apply our method tosynthetic and real-time tsunami of the 2012 Haida Gwaii earthquake. The comparison with traditional data
assimilation method reveals that this approach could achieve an equivalent high accuracy while saving
much time for valid tsunami warning.

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*J04-5-03
Joint Symposium / J04. Geohazard early warning systems

Evaluating the efficiency of a tsunami warning system to recover a tsunami
source based on the r-solution method* Tatyana Voronina 1) 2) , Alex Romanenko 2) , Artem Loskutov 3)
Institute of Computational Mathematics and Mathematical Geophysics of SB RAS 1) , State University
Novosibirsk Russia 2) , Institute of Marine Geology and Geophysics, FEB RAS Yuzhno-Sakhalinsk, Russia 3)
The mega thrust earthquakes quite often result in large tsunamis that may inflict a severe loss and pain to
the population of the coastal communities. The development of the Tsunami Warning Systems is likely be
the most constructive way in the mitigation of the destructive effect of potential tsunamis. To accurately
forecast the inundation and run up in the near-field coast, where a warning should be issued in no morethan 20 minutes, it is necessary to gain the insight into a tsunami source at the early stages of tsunami
propagation. We offer a method for recovering a tsunami source and taking into account a particulararrangement of the monitoring system with respect to a tsunami source area and the sea bottom
topography, we have developed the inversion method where the inverse problem operator was regularized
by the least square inversion using the truncated Singular Value Decomposition approach. This method isbased on the inversion of remote measurements of the water-level data without a priori information on asource but on their general spatial localization. Analyzing the singular spectra of a matrix obtained bynumerical calculations one can estimate the subsequent inversion by a certain observational system thatwill allow offering a more effective disposition for the tsunami wave recorders by precomputations. The
results obtained allow revealing the way to improve the inversion by selecting the most informative set ofavailable recording stations. To avoid potential instability of the numerical solution, the r-solution method
is used. This method seems to be attractive in view of computations since the main efforts are required for
calculating the matrix to be obtained. In this study, we apply the approach proposed to evaluating theefficiency of a tsunami warning system to recover areal tsunami sources for the event of 6 February, 2013near the Solomon Islands and for the event of 16, September, 2015 (Illapel, Chile).

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*J04-5-04
Joint Symposium / J04. Geohazard early warning systems

Improvement of tsunami-forecasting method based on tsunami inversion:
small-size and large-amplitude tsunamis* Hiroaki Tsushima
Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, JapanFor more accurate forecasting of small-size and large-amplitude tsunamis, I improve the tFISH algorithm,
which is a tsunami forecasting method based on offshore tsunami-waveform inversion for initial sea-surface
height distribution. In the tFISH, initial sea-surface height distribution is expressed by a linear
superposition of elementary tsunami sources each of which size is about 20 km. The size is small enough toresolve tsunami sources of moderate to large interplate earthquakes, but tsunamis that affect coastal
communities are sometimes generated by a spatially small-size event such as a 2016 Nov. Mw 6.9
intraplate normal-faulting earthquake, occurring off Fukushima prefecture, northeastern Japan, andresulting in the 1.4-m-height tsunami at a coastal tide gauge. Because the source is comparable or smaller
than that of an elemental source in the tFISH, the tFISH may not resolve the source and decrease accuracyof tsunami forecasting. To solve the problem, this study proposes a two-steps inversion. At the first step, theconventional tFISH inversion is performed. Then, we go to the second-step inversion when the following
criterion is satisfied: the estimated source is expressed by extremely small number of elemental sources(e.g., one source only), meaning that the source may be unresolved image of the true source. At the second
step, we perform tsunami inversion with elemental sources whose sizes are much smaller than the original.
The elemental sources are distributed to sea area where tsunami source is imaged in the first-stepinversion. Finally, we decide whether the second-step solution is chosen as the final solution using thefollowing criterion: the comparison between observed tsunami waveforms and the calculations in the
inversion shows the better agreement than in the first-step inversion. Numerical test assuming the 2016 offFukushima earthquake shows the good performance of the new approach to avoid the unresolved tsunami
source image.

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*J04-5-05
Joint Symposium / J04. Geohazard early warning systems

Near-field tsunami forecasting from offshore pressure data in association
with the earthquake early warning
Akiko Horiuchi 1) , Ryota Hino 1) , * Yusaku Ohta 1) , Hiroaki Tsushima 2)
Graduate School of Science, Tohoku University, Sendai, Japan 1) , Meteorological Research Institute,
Tsukuba, Japan 2)
Effective mitigation of tsunami disasters requires tsunami forecasts that are made in real time and theprovision of timely evacuation warnings to affected communities. Tsushima et al. (2014) developed
tFISH/RAPiD, which is the initial sea surface height distribution estimated from rapidly acquired GNSS
data provides robust finite source size information that is incorporated into an offshore tsunami data
inversion for reliable tsunami predictions along the near-field coast. In contrast, it is slightly difficult toobtain the reliable initial sea surface height distribution for M7 class earthquakes in the offshore region by
RAPiD because of the difficulty of the accurate estimation of small coseismic displacement field comparedwith more large events.
Based on these backgrounds, we have developed an alternative algorithm that improves near-filed tsunami
forecasting based on offshore tsunami data after an earthquake by incorporating earthquake early warning(EEW) data. Basic scheme is the same with the tFISH/RAPiD, we estimate the initial sea surface height
distribution using the EEW data. We assumed that the single rectangular fault deduced from the scaling law
between the earthquake magnitude and the fault dimension.
We retrospectively applied tFISH/EEW to the 2011 Sanriku-Oki earthquake (March 9, 2011, Mw 7.2) basedon the actual ocean bottom pressure (OBP) record and EEW information. The predicted results
immediately after the earthquake (~2 to 3 min) the arrival times and wave heights of the first tsunami wave
along the near-field coast could be predicted more accurately than the estimation based only on offshore
tsunami data. After more time, the estimated initial sea surface distribution by the tFISH/EEW had
continuously changed, and it was similar to that based on offshore tsunami data alone.
We will discuss more detail characteristic and its ability of the tFISH/EEW algorithm based on the various
case studies.

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*J04-5-06
Joint Symposium / J04. Geohazard early warning systems

Airborne observations with a nadir-pointing radar altimeter for a greattsunami detection* Tomoyuki Hirobe 1) , Niwa Yoshihiro 1) , Takahiro Endoh 1) , Daisuke Inazu 2) , Takero Yoshida 1) , Hidee
Tatehata 1) , Akitsugu Nadai 3) , Takuji Waseda 1) , Toshiyuki Hibiya 1)
The University of Tokyo, Tokyo, Japan 1) , Tokyo University of Marine Science and Technology, Tokyo,
Japan 2) , National Institute of Information and Communications Technology, Tokyo, Japan 3)
Most tsunami forecasting systems rely on the predicted magnitude and epicenter of an earthquake. Thissystem sometimes underestimates the tsunami, especially when the magnitude of associated earthquake islarge and the tremor continues for a long time. Recent study reveals that satellite radar altimeters arecapable of detecting tsunami (e.g., J. Gower, 2007), however real-time detection is still difficult due to thelow frequency of sampling possessed by satellite systems. In this study, we suggest to detect tsunami
directly by airborne radar altimeters.
We performed nadir pointing observations using Frequency Modulated Continuous Wave (FMCW) radar,which is attached to the bottom of an airplane body. The radar observation procedure is basically similar tothe present satellite radar altimeter. However, in airborne observation, airplane altitude is changing by a
few meters at any time during the flight. Thus, a precise prediction of airplane positions by Global
Navigation Satellite System (GNSS) is also important. We estimated the position and altitude by a baseline
kinematic analysis. We then estimated the averaged sea surface height (SSH) by the radar altimeter
observation and the GNSS analysis result.
We conducted airborne observations once in June 2016, and twice in December 2016. To check the
precision of SSH measurements, the flight days and paths were decided according to the satellite SSH
altimeter Jason-2 and Jason-3 schedules so as to compare with their SSH data. After correcting the geoid
and tidal changes, we confirmed that our observation error is less than 10 cm in average, which is sufficient
to capture large tsunamis offshore. In the future, we expect to form a dense observation network by using
multiple commercial airplanes equipped with the same radar altimeter, which enables real-time tsunami
detections.

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*J04-6-01
Joint Symposium / J04. Geohazard early warning systems

Developing a Rapid Tsunami Response System: Application to SouthAmerica Region* Bruno Adriano , Shunichi Koshimura
Tohoku Univesity, Sendai, Japan
Using high-performance computing and spatial information science, an advanced method of tsunami
inundation forecasting and mapping can be developed to enhance real-time disaster response.
Given the maximum tsunami height and flow depth distribution, we perform quantitative estimation of
exposed population using global population data, and the numbers of potential death by applying tsunami
fragility curve. The prototype system under development is focused on South American region. In the trial
operation, we verify the capability of the method as a new tsunami response system for three major tsunamiprone cities, Tumaco in the southern pacific coast of Colombia, Lima in the central coast of Peru, andIquique in the northern coast of Chile. The bathymetry and topography data for the target cities were
provided under the SATREPS project frameworks between Japan and the respective countries.
The tsunami simulation is based on the TUNAMI code developed by Tohoku University, Japan. The nested
grid system for the bathymetry and topography data varies from 27 arc-second to 10 m resolution for theregional propagation and local inundation modeling, respectively. The global population data is taken form
LandScan 2011 model. The mapping result and web publication are constructed using open-software,
Generic Mapping Tools and Python Programing Language, respectively. The preliminary tests of the
proposed system show promising result. The average total computational time for all regions isapproximately 35 minutes.

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*J04-6-02
Joint Symposium / J04. Geohazard early warning systems

The Operational Result for GEONET Real-time Analysis System for Rapid
Finite Fault Modeling* Naofumi Takamatsu 1) , Satoshi Kawamoto 1) , Yohei Hiyama 1) , Satoshi Abe 1) , Yusaku Ohta 2) , Takuya
Nishimura 3)
Geospatial Information Authority of Japan, Tsukuba, Japan 1) , Research Center for Prediction ofEarthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Sendai, Japan 2) ,Disaster Prevention Research Institute, Kyoto University, Uji, Japan 3)
Geospatial Information Authority of Japan (GSI) has been continuously operating the REGARD (Real-time
GEONET Analysis system for Rapid Deformation monitoring; for more detail see Kawamoto et al., 2017 inthis symposium), which estimates earthquake fault model in real-time from 1-Hz GNSS observation, since2015. REGARD has successfully observed the co-seismic displacements and estimated the finite fault
model for some earthquakes of ~M7 since it ran.
Mainshock (M7.3) and two foreshock (M6.5 and M6.4, respectively) hit inland area of western Japan in the2016 Kumamoto earthquake. The co-seismic displacements of about 100cm at most were observed from
1-Hz kinematic positioning, which was consistent with the result of GEONET F3 solution. REGARD system
calculated that Mw of the mainshock is 6.85 in 58 seconds from event origin time. The final fault model of
REGARD was estimated along the Futagawa fault zone within 6 minutes. This result is consistent with theevaluation by the Headquarters for Earthquake Research Promotion, which reports that the Kumamoto
earthquake is considered to be mainly due to the activity of the Futagawa fault zone.
REGARD was able to detect the crustal deformation for other two earthquakes: one occurred at Tottori
prefecture, western part of Japan, on 21th October 2016 (M6.6) and the other occurred off the Pacific coastof Tohoku region on 22th November 2016 (M7.4). However, the estimated finite fault model was slightly
longer than the post-processed rectangular fault model by GSI for the case of Tottori, which led theoverestimation of Mw, and the solution converted to the conjugate fault for the Tohoku because signal-tonoise ratio of GNSS kinematic positioning results were relatively small compared with the mainshock of
Kumamoto earthquake. Further studies are needed to enhance the fault model estimation process for M6-7
class earthquakes, e.g. prepare more accurate initial condition and/or set multiple initial condition.

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*J04-6-03
Joint Symposium / J04. Geohazard early warning systems

Real-time multi-GNSS precise point positioning for earthquake and tsunami
early warning over Asia-Pacific regions* Jianghui Geng , Shaoming Xin , Xiaotao Li , Jiang Guo , Xingyu Chen
Wuhan University, Wuhan, China
Real-time GNSS precise point positioning (PPP) is capable of measuring centimeter-level positions epoch
by epoch at a single station, and is thus treasured in earthquake and tsunami early warning where static
displacements in the near field are critical to rapidly and reliably determining the magnitude of destructive
events. However, most operational real-time PPP systems at present rely on only GPS data. The deficiencyof such systems is that the high reliability and availability of precise displacements cannot be maintained
continuously in real time, which is however a crucial requirement for disaster resistance and response.
Multi-GNSS, including GLONASS, BeiDou, Galileo and QZSS other than only GPS, can be a solution to thisproblem because much more satellites per epoch (e.g. 30-40) will be available. In this case, positioning
failure due to data loss or blunders can be minimized, and on the other hand, positioning initializations canbe accelerated to a great extent since the satellite geometry for each epoch will be enhanced enormously.
This in turn will improve greatly the success rate of ambiguity fixing which, critically, plays as an indicativeand guarantee of successful achievement of centimeter-level ground displacements. We established a
prototype real-time multi-GNSS PPP service based on Australian national network which can collect andstream high-rate data from all five navigation systems above. We estimated high-rate satellite clock
corrections and enabled undifferenced ambiguity fixing for multi-GNSS, which therefore ensures highavailability and reliability of precise displacement estimates in contrast to GPS-only systems. We will report
the preliminary performance of this service and analyze its potential to earthquake and tsunami early
warning.

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*J04-6-04
Joint Symposium / J04. Geohazard early warning systems

Real-Time Detection of Tsunami Ionospheric Disturbances with Stand-Alone
GNSS Receivers* Giorgio Savastano 1) 2) , Attila Komjathy 2) , Olga Verkhoglyadova 2) , Yong Wei 3) 4) , Augusto Mazzoni 1) ,Mattia Crespi 1)
Department of Civil, Building and Environmental Engineering, University of Rome, La Sapienza, Rome,
Italy 1) , Ionospheric and Atmospheric Remote Sensing Group, Jet Propulsion Laboratory, California
Institute of Technology, Pasadena, California, USA 2) , Pacific Marine Environmental Laboratory, National
Oceanic & Atmospheric Administration (NOAA), Seattle, WA, USA 3) , Joint Institute for the Study ofAtmosphere and Ocean (JISAO), University of Washington, Seattle, WA, USA 4)
Tsunamis can produce gravity waves that propagate up to the ionosphere generating disturbed electron
densities in the E and F regions. These ionospheric disturbances are studied in detail using ionospheric
total electron content (TEC) measurements collected by continuously operating ground-based receivers
from the Global Navigation Satellite Systems (GNSS). Here, we present results using a new approach, also
known as VARION (Variometric Approach for Real-Time Ionosphere Observation), and for the first time, weestimate slant TEC (sTEC) variations in a real-time scenario from GPS, Galileo, GLONASS and BeiDou
constellations. Specifically, we study the 2016 New Zealand tsunami event using 1-Hz real-time data
recorded from several GNSS receivers with multi-constellation tracking capabilities located in the Pacificregion. We compare estimates of sTEC variations obtained using GPS, Galileo, GLONASS and BeiDou
constellations. We observe sTEC perturbations with amplitudes up to 0.8 TEC units that correlate well intime and space with the propagating tsunami waves. The efficiency of the real-time sTEC estimation using
the VARION algorithm has been demonstrated for the 2012 Haida Gwaii tsunami event. We conclude thatthe integration of different satellite constellations is a crucial step forward to increasing the reliability ofreal-time tsunami detection systems using ground-based GNSS receivers as an augmentation to existingtsunami early warning systems.

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*J04-6-05
Joint Symposium / J04. Geohazard early warning systems

Inversion of tsunami and sea level uplift from GNSS-TEC: toward a
breakthrough for tsunami monitoring systems?
* Philippe Lognonne 1) 2) , Virgile Rakoto 1) 2) , Khaled Khelfi 1) 2) 6) , Lucie Rolland 3) , Elvira Astafyeva 1) 2) ,Pierdavide Coisson 1) , Giovanni Occhipinti 1) 2) , Carene Larmat 4) , Dimitri Komatitsch 5)
Institut de Physique du Globe de Paris-Sorbonne Paris Cite, Paris, F 1) , Universite Paris Diderot, Paris F 2) ,GeoAzur-Observatoire de la Cote d'Azur, Valbonne, F 3) , Los Alamos National Laboratory, NM, USA 4) ,Laboratory of Mechanics and Acoustics, Marseille, F 5) , Centre de recherche en astronomie, astrophysiqueet geophysique, Alger, Algerie 6)
Ionospheric signals associated to atmospheric gravity waves generated by near and far field tsunamis are
now routinely detected as well as acoustic waves generated by near-source ocean or solid earth uplift.
Complete modeling of these signals can be done especially with solid/ocean/atmosphere coupled normalmode summation which allows to model the tsunami amplitude not only in the ocean layer, but also in theatmosphere and ionosphere. This captures all the coupling and most of the physics of the propagation,
including effects due to atmospheric local time, oceanic bathymetry and atmospheric wave attenuation.
We show here that 1D waveform inversions of the ionospheric signals model the tsunami sea levels
variations with very high accuracy. These inversions based on tsunami normal-mode summations model
the sea level vertical displacement close to the ionospheric piercing point of the GPS receiver-satellite pairand can therefore be compared to DART data. Inversions were therefore made for several tsunamis (2012
Haida Gwai, 2006 Kuril, 2011 Tohoku), in either far or near field. Statistics demonstrate the error of theinversion to be less than 10% of the peak-to-peak amplitude of the tsunami. These first results open
important perspectives for densifying global tsunami monitoring systems, by offering tsunami heightmeasurement in any fixed location equipped with a dual GPS system or even from mobile platforms, suchas boats and aircrafts.
Recent modeling shows in addition that the acoustic pulse generated by large earthquakes not only reaches
the ionosphere above the quake in less than 8-10 minutes, but provides a direct measurement of thevertical amplitude as well as the projection of the Earth or ocean affected surface.
These advances in the ionospheric inversions and the further developments of GNSS constellations willcomplement the existing surface seismic, geodetic and ocean systems and will likely improve future
regional and global tsunami warning systems.

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*J04-6-06
Joint Symposium / J04. Geohazard early warning systems

Possibility of real-time volcanic plume monitoring using GNSS phaseresidual and SNR data
* Yusaku Ohta 1) , Masato Iguchi 2)
RCPEVE, Graduate School of Science, Tohoku University 1) , DPRI, Kyoto University 2)
A volcanic explosion is one of the largest energy release phenomena on earth. The ash fall can seriously
affect human activity. Thus, the monitoring and prediction of ash fall is very important. Unfortunately,
visible light cameras cannot be used to observe eruptions that occur at night and/or when skies are cloudy.
Several researchers have investigated the applicability of meteorological radar to the monitoring of thespatiotemporal distribution of eruption clouds, including the ash. Global Navigation Satellite System(GNSS) data provide a useful alternative to meteorological radar for detecting volcanic plumes (e.g. Ohta
and Iguchi, 2015).
Recently, the GSI and Tohoku University have developed a nationwide (>1200 sites) real-time crustal
deformation monitoring system (REGARD), based on kinematic GNSS analysis, to determine the coseismic
fault model of large earthquakes. We will discuss the possibility of the real-time volcanic plume monitoring
using GNSS phase residual and SNR data based on the REGARD system.

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*J04-7-02
Joint Symposium / J04. Geohazard early warning systems

Dynamic of aquifer compaction: Insight from continental-scale Sentinel-1
InSAR survey* Mahmud Haghshenas Haghighi , Mahdi Motagh
GFZ German Research Centre for Geosciences
Overextraction of groundwater for decades has caused high rates of land subsidence in many plain aquifersof Iran. Geodetic measurements have been used in the past to study this problem in some of the majorbasins in Iran. Among them, Interferometric Synthetic Aperture RADAR (InSAR) has proven a powerful tool
to obtain a regional overview of the extent and rate of displacement in a large scale. However, because theavailability of regular SAR data acquisition was limited in the past, these studies are limited to some major
plain aquifers.
After the launch of Sentinel-1, it is now possible to acquire SAR data regularly with large spatial coverage
all over the world, providing the opportunity to produce displacement maps in continental scales. The
purpose of this paper is to analyze elastic and inelastic deformation behavior of developed groundwaterbasins using large-scale Sentinel-1 InSAR. Using more than two years of data available in the archive of
Sentinel-1 cyclic elastic deformations and continuous inelastic deformations induced by groundwater
withdrawal are separated and the ratio between them is estimated for several aquifers. Moreover, the ratio
between vertical and horizontal displacement is evaluated by decomposition of displacement maps derived
from different look angles. Our results exhibit significant inelastic deformation behavior in major aquifers ofIran, which makes groundwater remediation measures a challenging task for depleted aquifers.

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*J04-P-01
Joint Symposium / J04. Geohazard early warning systems

Real-Time Seismological Monitoring System in Northern Sakhalin* Igor V. Matveev , Vera V. Bykova , Alexander G. Mikhin , Ruben E. Tatevossian
Institute of the physics of the Earth RAS, Moscow, Russia
Oil and gas are intensively exploited off-shore the Northern Sakhalin. Taking into account high level ofseismic activity in the region and ecological risk of the corresponding infrastructure, permanentseismological monitoring is required. All the instrumentation and the monitoring system in a whole aredesigned in the Institute of the Physics of the Earth, RAS (Moscow, Russia). The final goal is to develop
early-warning system to mitigate ecological risk. The system consists of 12 seismic stations, each equippedwith three-component broadband velocimeter (T = 0.03 – 120 s) and accelerometer. The stations arespaced at about 20-30 km. Data is transferred to Khabarovsk, where the headquarter controlling all
exploitation and transportation is situated. Data are automatically processed there in real time. The phasepicking is based on the STA/LTA algorithm. For tuning the algorithm of phase-picking, records areprocessed manually, in parallel. The system operates since September 2015. It is planned as a part of multicomponent ecological early-warning monitoring system. Many hundreds of earthquakes are alreadyparameterized and included in the catalogue. Strong-motion records are also obtained including records offelt earthquakes (intensity 4-5 MSK64 scale). Thus the system provides not only information for seismicity
monitoring but also for engineering and future designing in the region.

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*J04-P-02
Joint Symposium / J04. Geohazard early warning systems

An Earthworm based Earthquake Early Warning System with Integrated
GMPEs and IPEs for Southwest Iberian Peninsula* Jose Antonio Jara , Nuria Romeu , Xavier Goula , Yolanda Colom , Antoni Roca
Cartographic and Geological Institute of Catalonia, Barcelona, Spain
The South Iberian Peninsula is located near a complex plate boundary between Eurasia and Africa. Several
very large earthquakes have occurred, especially offshore Cape San Vicente and in the Gulf of Cadiz. The
largest one, the 1755 Mw 8.5 Lisbon earthquake, was associated with a destructive tsunami causing morethan 60,000 casualties and significant damage in the SW Iberian Peninsula and NW Morocco (Buforn et al.
1998; Baptista et al. 2003; Gutscher et al. 2006; Grandin et al. 2007).
This study presents the development and results of a prototype of an Earthquake Early Warning System(EEWS) (Kanamori, 2005) in front of potentially destructive earthquakes occurring in Southwest Iberian
Peninsula (Pazos et al., 2015), within the framework of the Alertes-Rim Spanish project. The existence ofpotential targets and recent events as 1962 Mw 6.2 and 1969 Mw 7.8, make this region suitable for the
implementation of an EEWS.
This EEWS, based on the Earthworm (USGS) tools, was implemented to automatically produce location
scenarios, with an optimized location and estimated magnitude that minimize the warning time (Romeu etal., 2016). Furthermore, the most suitable ground motion and intensity prediction equations, for this region,
have been selected and integrated into the EEWS to provide potential damages scenarios.
Once the setup stage was over, the prototype was put into operation early 2015. Comparing to Instituto
Geografico Nacional (IGN) catalog, hypocentral locations and magnitudes assessment are fairly good. Leadtimes obtained are on the order of tens of seconds for the majority of targets, which is long enough tomitigate damage for a big area of the southern coasts of Portugal and Spain, demonstrating the possibilityof a regional, reliable and effective EEWS in the region.

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*J04-P-03
Joint Symposium / J04. Geohazard early warning systems

Numerical shake prediction incorporating heterogeneous structure: the2016 Kumamoto Earthquake* Masashi Ogiso 1) , Mitsuyuki Hoshiba 1) , Azusa Shito 2) , Satoshi Matsumoto 2)
Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan 1) , Institute of Seismology
and Volcanology, Kyushu University 2)
Needless to say, heterogeneous structure, especially attenuation structure is important for ground motion
prediction. In the new concept of real time ground motion prediction, called “Numerical Shake
Prediction" proposed by Hoshiba and Aoki (2015), prediction of ground motion prediction is done by theestimation of current wavefield using data assimilation and simulation of wave propagation successively.
We expected that the simulation with heterogeneous structure would improve the precision of groundmotion prediction in the numerical shake prediction scheme. In this study, first we estimated theheterogeneous attenuation structure of the western part of Japan, then we evaluated the effect of thestructure through the case of the 2016 Kumamoto Earthquake sequence.
To estimate intrinsic and scattering attenuation structure simultaneously, we conducted Multiple Lapse
Time Window Analysis for the seismic stations distributed in the western part of Japan. Derived attenuation
structure shows strong intrinsic and scattering attenuation around active faults and volcanoes in the
Kyushu area. We derived tentative 2D velocity structure using the distribution of average apparent velocityof each station used in the MLTWA.
We conducted real time ground motion prediction simulation based on the numerical shake prediction
scheme with heterogeneous structure for the Kumamoto Earthquake. In the case of 10 s ahead prediction,
RMS of intensity prediction residuals improved by 15 % compared with the case of homogeneous structure.
The rate of improvement became high in the 20 s ahead prediction. These fact shows the importance ofconsidering the heterogeneous structure for the longer lead time.
Acknowledgment
We used waveforms observed by K-NET/KiK-net/Hi-net operated by NIED, the seismic network of Kyoto
Univ., Kyushu Univ. and JMA. This study was supported by the Joint Usage/Research Center program ofEarthquake Research Institute, the University of Tokyo.

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*J04-P-04
Joint Symposium / J04. Geohazard early warning systems

Waveform matching for the ocean bottom pressure data toward real-timetsunami forecast* Wataru Suzuki , Shin Aoi , Naotaka Yamamoto
National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Ibaraki, Japan
Large-scale and dense ocean bottom observation networks have been maintained by NIED for regions
along the Japan Trench (S-net) and along the Nankai Trough (DONET). To take an advantage of the ocean
bottom observation network, we are developing a real-time tsunami forecast system including inundation
for the Pacific coast of Chiba prefecture, using the real-time ocean bottom pressure data observed by S-net(Aoi et al., 2017). In this system, the several tsunami scenarios that reasonably explain the observed ocean
bottom pressure data are selected according to the multi-index method (Yamamoto et al., 2016) from thepre-calculated database. The forecast information is generated from the coastal tsunami height andinundation information related to the selected tsunami scenarios. To advance the robustness of forecast
and warning, it is better to implement several different approaches for real-time tsunami detection andforecast. In this study, therefore, we examine the matching for the time series of the ocean bottom pressurechange at each station for selecting the tsunami scenarios that well explain the observation well using thesimulated data for 150 S-net stations. When we use L1 and L2 norms to evaluate the fitness between theobserved and scenario pressure data, the scenarios that give the smallest L1 and L2 norms do not provide
the sufficient forecast result in the point that they underestimate the coastal tsunami height as well as theocean bottom pressure data. This is probably because L1 and L2 norms are sensitive in the slightdifference of phase information. Therefore, we pose the condition for the selected scenarios that the
number of the stations where the maximum absolute amplitude of scenario is equal or greater than theobserved one exceeds a criterion value before the evaluation according to L1 and L2 norms. This condition
makes the waveform matching between the observed and scenario data better and the forecast result moresatisfactory.

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*J04-P-05
Joint Symposium / J04. Geohazard early warning systems

Development of semi-real-time tsunami calculation system for ocean-bottompressure gauge stations in southwestern and northeastern Japan* Takeshi Nakamura , Narumi Takahashi , Wataru Suzuki , Naotaka Yamamoto
National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan
Ocean-bottom pressure gauge data are useful for detecting tsunami signals at suboceanic earthquakes andrapidly issuing warnings to coastal areas. We developed a semi-real-time calculation system that measurespressure perturbations at pressure gauge networks installed in offshore areas of southwestern andnortheastern Japan (called DONET and S-net, respectively) in order to identify tsunami signals. The system
automatically calculates geodetic deformations and tsunami propagation immediately after getting seismic
source information on hypocenter, magnitude, and mechanism. The calculation area and grid size arecategorized into four different areas and sizes, respectively, from the epicentral location of an earthquake toconduct an efficient calculation from the source to the networks. The calculation results for transoceanic
tsunamis in a 7.5 arc-minute grid can be available in approximately 35 s after getting source information to
output waveform data by executing the optimized parallel calculation code on our computer server. System
operations began in July 2015 and have been applied to tsunamigenic earthquakes in the Pacific Ocean.
The system is effective in identifying tsunami signals and automatically predicting tsunami propagation in
offshore areas, which may be useful for further data analyses on tsunami propagation.

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*J04-P-06
Joint Symposium / J04. Geohazard early warning systems

Sea level observations in the coasts of the Mexican Pacific of the tsunami
caused by the 2011 Tohoku Earthquake* Octavio Gomez-Ramos 1) , Jorge Zavala-Hidalgo 2) , Angel Ruiz-Angulo 2) , Felipe Hernandez-Maguey 1) ,Miriam Zarza-Alvarado 1) , Jose Santiago-Santiago 1) , Valente Gutierrez-Quijada 1)
Geophysics Institute, National Autonomous University of Mexico 1) , Center for Atmospheric Sciences,
National Autonomous University of Mexico 2)
The 2011 Tohoku earthquake (Mw 9.0) generated a powerful tsunami that traveled across the Pacific
Ocean, reaching the western pacific on the American coastlines several hours after the initial shock. This
event was registered in the 9 tide gauge stations that the Servicio Mareografico Nacional (Instituto deGeofisica, UNAM) had operating at the moment in the coasts of the Mexican Pacific: La Paz, Acapulco,
Mazatlan, Huatulco, Puerto Vallarta, Salina Cruz, Lazaro Cardenas, Puerto Madero and Zihuatanejo. The
data show that the first station to register the event was Puerto Vallarta at 19:10 UTC, 13 hours and 24
minutes after the earthquake, and the last station to register the perturbation was Puerto Chiapas at 22:06
UTC, 2 hours and 56 minutes later. The highest registered peak range was 3.22 meters in the station of
Zihuatanejo, with a dominant period of the oscillations between 17 and 21 minutes, and a height above thetidal forecast of 1.38 meters. The data also show that in Acapulco the highest peak range was not reachedduring the first wave, it happened three and a half hours later, similar to what has happened with otherremote tsunamis such as that generated by the 2014 Iquique earthquake. Thus, far-field tsunamis represent
a hazard to our Mexican towns along the coastlines. The observations also suggest that some locations areprone to amplify the waves and could be initially neglected by small resolution forecast resulting fromnumerical simulations. Therefore, implementing regional forecast systems for remote tsunami events aresuggested to alert and act on time against those remote events.

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*J04-P-07
Joint Symposium / J04. Geohazard early warning systems

Decay Properties of Bay Oscillations Induced by the Tsunami of NankaiTrough Earthquake* Yusuke Oishi 1) 2) 3) , Takashi Furumura 2) , Fumihiko Imamura 3) , Kei Yamashita 3) , Daisuke Sugawara 4)
Fujitsu Laboratories LTD., Kawasaki, Japan 1) , The University of Tokyo, Tokyo, Japan 2) , Tohoku University,
Sendai, Japan 3) , Museum of Natural and Environmental History, Shizuoka, Japan 4)
In order to better understand the duration of tsunamis caused by large earthquakes, we investigate
resonance responses of bays and their decay properties based on tsunami simulations for the Nankaitrough earthquake.
It has been reported that tsunami-induced oscillations in bays continue for a very long time, up to several
tens of hours. For example, the tsunami warning of the 2011 Tohoku-Oki earthquake (Mw9.0) could not becanceled for two days after the earthquake. A good estimation of when tsunamis are settled is required for
operations such as rescue, marine traffic, and coastal factories.
In this study, we examined the tsunami durations in bays based on the simulations for the eleven Nankaitrough earthquake source models provided by the Central Disaster Prevention Council (CDPC) of Japan.
We focused on the tsunami properties in bays around the Tokyo bay, i.e., the Tokyo, Sagami and Suruga
bays. The result of spectral analysis of the simulated waveforms confirmed that these bays have the same
peak periodic component of period of 〜70 min for the four of the eleven CDPC sources and T = 〜80 min
for the other seven sources. For all the eleven sources, a large component of T = 〜110 min appears only in
the Tokyo bay, implying that the component is the result of the resonance oscillation of the Tokyo bay.
We then investigated the decay time constant of each periodic component to understand the duration of
the tsunamis that last in the bays. When the peak spectral period of T = 〜70 min is generated in Tokyobay, the average decay time constant is 〜600 min for both components of T = 〜70 and 〜110 min. On theother hand, when the peak spectral period of T = 〜80 min appears, the component of T = 〜110 min has alonger decay time constant of 〜800 min and that of the component of T = 〜80 min is 〜600 min. These
results suggest that the decay property of each spectral component is not independent but interacts witheach other.

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*J04-P-08
Joint Symposium / J04. Geohazard early warning systems

Real-time correction of tsunami site effect by frequency-dependent tsunamiamplification factor* Hiroaki Tsushima
Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, JapanFor tsunami early warning, I developed frequency-dependent tsunami-amplification factor and used it todesign a recursive digital filter that can be applicable for real-time correction of tsunami site response. In
this study, I assumed that a tsunami waveform at an observing point could be modeled by convolution ofsource, path and site effects in time domain. Under this assumption, spectral ratio between offshore andthe nearby coast can be regarded as site response (i.e. frequency-dependent amplification factor). If theamplification factor can be prepared before tsunamigenic earthquakes, its temporal convolution to offshore
tsunami waveform provides tsunami prediction at coast in real time.
In this study, tsunami waveforms calculated by tsunami numerical simulations were used to develop
frequency-dependent tsunami-amplification factor. Firstly, I performed numerical tsunami simulations
based on nonlinear shallow-water theory from many tsuanmigenic earthquake scenarios by varying theseismic magnitudes and locations. The resultant tsunami waveforms at offshore and the nearby coastal
observing points were then used in spectral-ratio analysis. An average of the resulted spectral ratios fromthe tsunamigenic-earthquake scenarios is regarded as frequency-dependent amplification factor. Finally,
the estimated amplification factor is used in design of a recursive digital filter that can be applicable in time
domain.
The above procedure is applied to Miyako bay at the Pacific coast of northeastern Japan. The averaged
tsunami-height spectral ratio (i.e. amplification factor) between the location at the center of the bay and theoutside show a peak at wave-period of ~20 min. A recursive digital filter based on the estimatedamplification factor shows good performance in real-time correction of tsunami-height amplification due tothe site effect.
This study is supported by Japan Society for the Promotion of Science (JSPS) KAKENHI grant 15K16309.

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*J04-P-09
Joint Symposium / J04. Geohazard early warning systems

Revisiting the 1985 M8.1 Michoacan earthquake: Tsunami simulations andsynthetic GPS data to test rapid response* Angel Ruiz-Angulo 1) , Diego Melgar 2) , Carlos Mendoza 3)
Centro de Ciencias de la Atmosfera, UNAM, Mexico City, Mexico 1) , UC Berkeley, California, USA 2) ,Centro de Geociencias, UNAM, Juriquilla, Mexico 3)
The 1985 Michoacan earthquake was a catastrophic event for Mexico. In terms of lives it had a toll of
10,000-20,000 casualties and the total economic cost was more than 5 billion dollars. The earthquake
generated a local tsunami, which at the time did not generate much attention since most of the damage
from the event was due to strong shaking in Mexico City. However, the extent of the tsunami wassignificant in the coast of Michoacan. In the industrial port city of Lazaro Cardenas, wave heights reached
up to 2.5 m, with inundation distances of about 500 m. A segment of railroad of 1.5 km was destroyed andseveral fishing boats were reported missing. In Zihuatanejo, the impact was very similar and several beachfront restaurants were washed away. In spite of this, at that time, in 1985, urbanization and development of
the coastline was still somewhat sparse. However, much has changed in the intervening 30 years. We argue
that the impacts from a repeat of an event such as this one would be much more significant today. The
current population along the Mexican Pacific coastline has increased considerably and infrastructure hasdeveloped as well. Many locations have already suffered from flooding events during hurricanes andtropical storms, suggesting a rather high risk in case of a tsunami.
We use a published finite fault inversion for the earthquake and its largest aftershock as the initialcondition of tsunami simulations and study the impacts along the coastline. Furthermore we generate
synthetic high-rate GPS data for stations that exist today and show that the magnitude and extent of theearthquake could have been known within the first 60s of the event origin time. We show that rapid
tsunami models that rely on these fast earthquake source products can provide useful forecasts of tsunami
intensity in the first minutes after a large event.

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*J04-P-10
Joint Symposium / J04. Geohazard early warning systems

REGARD: GNSS-based rapid finite fault modeling system* Satoshi Kawamoto 1) , Yohei Hiyama 1) , Satoshi Abe 1) , Naofumi Takamatsu 1) , Yusaku Ohta 2) , Takuya
Nishimura 3) , Masaru Todoriki 4)
Geospatial Information Authority of Japan 1) , Graduate School of Science, Tohoku University 2) , Disaster
Prevention Research Institute Kyoto University 3) , Fujitsu Laboratories LTD. 4)
We present a newly developed real-time GNSS system REGARD (the Real-time GEONET Analysis system
for Rapid Deformation monitoring), which estimates single rectangular fault and slip distribution models
within 3 minutes. The new system is part of the GNSS Earth Observation Network (GEONET) operated by
Geospatial Information Authority of Japan, and it was developed in collaboration with Graduate School of
Science, Tohoku University.
The REGARD system consists of real-time GNSS positioning, automatic detection of coseismic
displacements by seismic events, and quasi real-time finite fault model inversion. The real-time data fromthe GEONET stations are processed by the RTKLIB (Takasu, 2013) and GSILIB (GSI, 2015) softwares.
Then, the displacement time-series are monitored by RAPiD algorithm (Ohta et al., 2012) to detect
earthquake events. If an early earthquake warning with M > 7 is issued and/or the displacement more than
10 cm occurred at neighboring 3 stations, the finite fault models are estimated from the coseismic
displacement field.
The performance of the automatic inversions of the finite fault models is examined by using real raw GNSS
data of the past large earthquakes: the 2003 Tokachi-oki earthquake (moment magnitude (Mw) 8.3), the2011 Tohoku earthquake (Mw 9.0), and the 2011 off Ibaraki earthquake (Mw 7.7). A simulated 1707 Hoeitype Nankai Trough earthquake (Mw 8.7) is also tested. The Mw estimates with high variance reductions >90 % were derived for all the earthquakes within 3 minutes. It is noteworthy that the Mw 8.83 wasestimated for the 2011 Tohoku earthquake by 3 minutes without saturations. The performance assessmentof REGARD confirmed that the real-time GNSS analysis is very powerful to estimate reliable Mw for large
earthquakes with M > 8 rapidly.

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*J04-P-11
Joint Symposium / J04. Geohazard early warning systems

Accuracy of a continuous/on-demand GPS/Acoustic seafloor positioning
using a slackly moored buoy in the Kuroshio region* Misae Imano 1) , Motoyuki Kido 2) , Yusaku Ohta 3) , Narumi Takahashi 4) 5) , Tatsuya Fukuda 5) , Hiroshi
Ochi 5) , Chie Honsho 2) , Ryota Hino 3)
Graduate school of Science, Tohoku University, Miyagi, Japan 1) , IRiDES, Tohoku University, Miyagi, Japan
2), RCPEV, Tohoku University, Miyagi, Japan 3) , NIED, Ibaraki, Japan 4) , JAMSTEC, Kanagawa, Japan 5)
For the real-time detection of seafloor crustal movement associated with large earthquakes in a subduction
zone, we have developed a continuous and on-demand GPS/Acoustic (GPS/A) seafloor positioning systemusing a slackly moored buoy, and tested the system over a year in Kumano-nada, Nankai Trough. In thesystem, the mooring cable length was designed to be 1.5 times the water depth (~3 km) for safety reasons
against the strong Kuroshio current. The moored buoy usually drifts by wind and current within a circle of~4-km radius around the array, which consists of six transponders forming a ~3 km triangle on the seafloor.
Apart from the array center, large systematic error (> 1 m) arises in the positioning because of significant
error propagation of the observation data (e.g. the buoy position, travel time) due to uncertainty of arraygeometry. To reduce the error, we redetermined the array geometry with 20-30 cm accuracy using newalgorithm applied to campaign data. Using the revised array geometry, we compare final accuracies with
automatic processed data on the buoy (realtime PPP and traveltime detection) and post-processed data(with precise almanac and manual waveform readout) for further improvement in the automatic algorithm.
The former accuracy was 0.7/0.9 m in EW/NS component. In this presentation, we introduce the latteraccuracy comparing the former one. Then, for further reduction of these error especially in the automatic
procedure, we introduce our effort in the presentation to (1) determine again the array geometry using a
new set of intense campaign data, (2) carefully evaluate the precision in real-time PPP using a precise
moving table, (3) refine the traveltime detection algorithm against reflection from the surface.

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*J05-1-01
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Southern Costa Rica and the Next Decade: A Spatial and Temporal
Opportunity for an International Subduction Zone Observatory* Marino Protti , Cyril Muller
Costa Rica Volcanological and Seismological Observatory, Heredia, Costa Rica
A locked segment of the Middle America Subduction Zone surrounding Osa peninsula in southern Costa
Rica has experienced large (Mw=7.2-7.4) earthquakes in 1856, 1904, 1941 and 1983. With an average
recurrence interval of roughly 40 years and 34 years since the last rupture, the timing is right to instrument
and record data of unrivalled importance before, during and after the next megathrust earthquake in thisregion.
The subducting young and anomalous (rejuvenated and thickened) lithosphere there, leads to shallow
subduction. As a consequence, the plate interface beneath Osa peninsula lies 4 to 8 km beneath land
where it is easily accessible for inland drilling. Furthermore, since the trench is only 20-30 km from the SW
coastline of Osa peninsula, submarine cables with seafloor instrumentation, power and data transmission
could be deployed and tight to borehole instrumentation, at a much lower cost than in other subduction
zones.
The Costa Rica Volcanological and Seismological Observatory at Universidad Nacional (OVSICORI-UNA) istaking advantage of this great geographical and temporal opportunity to build and operate a dense
geodynamic control network to record a wealth of data of unrivalled importance before, during and after
the next megathrust earthquake in this region. With the growing interest for international subduction zone
observatories, we invite the scientific community to joint efforts to fully capture the geophysical processes
occurring in this subduction zone.

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*J05-1-02
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Spatio-temporal variation of the postseismic deformation of the 2011 off the
Pacific coast of Tohoku Earthquake (M9.0) detected by means of terrestrial
and seafloor observations* Takeshi Iinuma 1) , Yusaku Ohta 2) , Satoshi Miura 2) , Jun Muto 2) , Fumiaki Tomita 2) , Motoyuki Kido 2) ,Ryota Hino 2)
Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan 1) , Tohoku University, Sendai,
Japan 2)
Clear postseismic deformations are still being detected in terrestrial and seafloor geodetic observations on
and around the Japanese Islands. Recently, Tomita et al. [2017, in Review] reported displacement rates at
seafloor stations that were newly installed in 2012. We estimated displacement rates at the GNSS
continuous stations at the Geospatial Information Authority of Japan and Tohoku University during theperiod from September 2012 to May 2016 (Period B). The same period in which Tomita et al. [2017]
estimated displacement rates at the seafloor stations. Taking a trench-normal profile that runs through themain rupture area of the Tohoku Earthquake, in the forearc region, the trench-normal displacement rates
during Period B were as large as one fourth of those during the period from April to December 2011
(Period A). In contrast, the differences between the vertical components in Periods A and B are very clear.
The large local subsidence around the Ou Backbone Range observed in Period A had almost vanished in
Period B, while the uplift rates in Period B were more than half those in Period A. The low viscosity beneath
the Ou Backbone Range hypothesized by Muto et al. [2016] to account for the large local subsidence, also
accounts for the rapid decay of local deformation. Because the inland rheological heterogeneity strongly
affects the vertical displacement rate field, we estimated the distribution of interplate coupling andpostseismic slip based only on horizontal displacement rates and applying Sun et al. [2014]'s model to
exclude the effects of viscoelastic relaxation. Preliminary results indicate that postseismic slip occurred at
the shallow plate interface off the Fukushima and Ibaraki Prefectures and at the deep portion beneath the
Pacific coast of the Iwate Prefecture during Period B, the same as Period A. Estimated back-slip in the main
rupture area of the 2011 Tohoku Earthquake indicates interplate coupling at the area has alreadyrecovered.

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*J05-1-03
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Stress field around fault zones of the 2016 Kumamoto earthquake sequence(Mj7.3) inferred from moment tensor data from 1996 to 2016
* Satoshi Matsumoto 1) , Yusuke Yamashita 2) , Manami Nakamoto 3) , Masahiro Miyazaki 2) , Shin-ichi Sakai, Yoshihisa Iio 2) , Kazuhiko Goto 5) , Tomomi Okada 6) , Mako Ohzono 7) , Toshiko Terakawa 8) , Masahiro
Kosuga 9) , Masayuki Yoshimi 10) , Youichi Asano 11)
Kyushu University, Shimabara, Japan 1) , Kyoto University, Uji, Japan 2) , National Institute of Polar
Research, Tokyo, Japan 3) , University of Tokyo, Tokyo, Japan 4) , Kagoshima University, Kagoshima, Japan5), Tohoku University, Sendai, Japan 6) , Hokkaido University, Sapporo, Japan 7) , Nagoya University,
Nagoya, Japan 8) , Hirosaki University, Hirosaki, Japan 9) , National Institute of Advanced Industrial Scienceand Technology, Tsukuba, Japan 10) , National Research Institute for Earth Science and Disaster Resilience,
Tsukuba, Japan 11)
4)

The 2016 Kumamoto earthquake sequence started from 14 April 2016 in Kumamoto prefecture, middle
part of Kyushu Island, Japan and involved the largest event with magnitude of 7.3 occurred on 16 April
2016. Events over M 6 also occurred before and after the mainshock. High background seismic activity
observed in this area before the earthquake occurrence. Inelastic strain distribution in the area estimatedby seismic moment tensor data implies that the major events of the sequence occurred “around" large
strain region. This suggests that the large inelastic strain created stress concentration. In this study weanalyzed the seismic moment tensor data before and after the occurrence of the sequence and estimatedstress field in the hypocentral area. As general tendency, dominated minimum principal stress (sigma 3) inthe N-S direction obtained and the maximum principal stress takes value close to the moderate one. The
stress field reveals spatial heterogeneous feature, which varies from southern to northern part of the area.
We found that the stress field around the fault zone is consistent with co-seismic fault behavior of theearthquake sequence and decreasing maximum horizontal stress. The results shows that complex coseismic rupture and the seismic activity associated with the sequence could be attributed to the uniaxial
extension of deviatoric stress field.

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*J05-1-04
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Effects of Postseismic Stress Redistribution of the 2011 Tohoku Earthquake
on Fault Activities* Yan Hu 1) , Roland Burgmann 2) , Naoki Uchida 3) , Brent Delbridge 2) , Kelin Wang 4)
University of Science and Technology of China 1) , University of California Berkeley 2) , Tohoku University 3), Geological Survey of Canada 4)
The postseismic deformation and seismicity following the 2011 Mw9.0 Tohoku-Oki earthquake have beenrecorded at unprecedented spatial-temporal resolution. Taking advantage of these observations, we haverefined our published three-dimensional (3D) viscoelastic finite element models to study the evolution of
the stress field following the 2011 earthquake. The model incorporates the first-order 3D structural
heterogeneity in NE Japan which includes the subduction of the Pacific and Philippine Sea plates, and thelaterally-heterogeneous and depth-layered rheological structure of the upper mantle. We assume that theupper mantle is characterized by a bi-viscous Burgers rheology. Our preferred model well reproduces thefirst-order pattern of the five-year GPS observations of the postseismic crustal deformation in bothhorizontal and vertical directions. We calculate postseismic Coulomb stress perturbations (CSP) on
published known crustal faults as well as over nodal planes of earthquakes from focal mechanism data.
Overall, thrust faults tend to undergo stress decrease after the 2011 earthquake while normal and strikeslip faults tend to undergo stress increase. After the 2011 mainshock, events in the forearc and near the
rupture region of the subducting slab underwent generally CSP decrease, while the events downdip of the2011 rupture experienced generally CSP increase. The outer rise of the Pacific plate underwent CSP
increase.

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*J05-1-05
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Modeling deformation processes of the island arc crust and mantle during
the postseismic period of the Tohoku-oki earthquake* Bunichiro Shibazaki 1) , Satoshi Miura 2) , Akemi Noda 3) , Takeshi Iinuma 4) , Takumi Matsumoto 3)
International Institute of Seismology and Earthquake Engineering, BRI, Tsukuba, Japan 1) , Tohoku
University, Sendai, Japan 2) , National Research Institute for Earth Science and Disaster Resilience,
Tsukuba, Japan 3) , Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan 4)This paper investigates postseismic viscoelastic deformation in the island arc crust and mantle andpostseismic slip of the Tohoku-oki earthquake considering the heterogeneous rheological structure. We
first calculated the effective viscosity distribution of the Japanese island arc crust and upper mantle. Then,
we calculated the viscoelastic deformation of the Japan island arc during the postseismic period of the
Tohoku-oki earthquake considering the coseismic slip distribution obtained by our inversion analysis using
a finite element method. After removing the viscoelastic deformation from the observed displacement data,
we performed inversion analysis to obtain postseismic slip distribution. For calculation of the effective
viscosity distribution of the Japanese island arc crust and upper mantle, we first considered the thermal
structure obtained by dense geothermal observations from Hi-net boreholes (Matsumoto, 2007) and by
Tanaka et al. (2004). The model could not reproduce well a postseismic strain anomaly (decreases in areal
strain) along the volcanic front after the 2011 Tohoku-oki earthquake, which was found by Miura et al.
(2014). Therefore, we considered local low viscosity region beneath volcanoes. In this case, a postseismicstrain anomaly (decreases in areal strain) along the volcanic front can be reproduced. We also obtained
postseismic slip by the inversion analysis. The results indicate large postseismic slip occurred below the
deeper part of the coseismic slip region. We test several viscoelastic structures and report a model which
explains well the postseismic deformation in the inland region of northeastern Japan.

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*J05-1-06
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Frictional strength of plate interfaces inferred from numerical simulations ofstress fields for oceanic plates: Application to the North American-Pacificplate interface off northeast Japan* Akemi Noda 1) , Mitsuhiro Matsu'ura 2)
National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan 1) , Institute of
Statistical Mathematics, Tokyo, Japan 2)
Steady plate subduction along a curved interface brings about stress changes at constant rates in thesurrounding lithosphere (Fukahata and Matsu'ura, 2016). So, in subduction zones, not only frictional
resistance at plate interfaces but also steady plate subduction causes tectonic stress fields. The stress field
caused by frictional resistance is basically compressive, but that caused by steady plate subduction isbasically tensile in a seismogenic depth-range. Comparing these stress patterns with the actual tectonic
stress fields, we can obtain information about the absolute frictional strength of plate interfaces on thesame idea as Terakawa and Matsu'ura (2009).
In northeast Japan, the Pacific plate is descending beneath the North American plate. Before the 2011
Tohoku-oki earthquake, the focal mechanisms of seismic events at and around the plate interface were
thrust-fault type (e.g., Asano et al., 2011), indicating that the compressive stress field due to frictional
resistance was dominant there. The drastic increase of normal-fault type events after the Tohoku-oki
earthquake could be interpreted as the change in stress regime from compression to tension. In this study,
we estimate the lower limit of frictional strength at the plate interface through the 2-D numericalsimulations of stress fields for descending oceanic plates. The advantages of oceanic plates are, it passes
through the plate-to-plate interaction zone within a limited time (1-2Ma), and its rheological property ismuch simpler than the overriding plate (Matsu'ura et al., 2017 JpGU-AGU Joint Meeting). The results ofnumerical simulations show that the tensile stress in the upper part of the oceanic lithosphere reaches 200
MPa at the depth-range of 10-20km. We will show the downdip variation of frictional strength to reproduce
the pre-seismic compressive stress field at and around the plate interface.

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*J05-2-01
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

A unified representation of Earth's quasi-dynamic deformation processes* Sylvain Barbot
Earth Observatory of Singapore
The last three decades have witnessed an explosion of studies on fault processes, from kinematic modelingof geodetic data to dynamic modeling of fault rheology. These studies were made possible by fundamental
solutions that describe the stress and displacements caused by slip on a fault. In contrast, direct imaging of
the kinematics of off-fault deformation is still impractical, and the dynamic modeling of anelastic
deformation still relies on computationally intensive numerical methods (e.g., Barbot & Fialko, 2010). Here,
we describe a novel approach that allows us to resolve distributed processes in kinematic inversions ofgeodetic data and to incorporate off-fault processes in numerical models of earthquake cycles. We quantify
analytically the displacement and stress incurred by distributed anelastic strain in finite shear zones(Barbot, Moore & Lambert, BSSA, 2017). We use these elementary solutions to simultaneously invert forslip on faults and distributed strain in the surrounding rocks. We apply this new technique to study
postseismic relaxation following the 2016 Mw 7.0 Kumamoto, Japan earthquake (Moore et al., 2017). We
directly image the spatial distribution of effective transient viscosity in the Kyushu lower crust, revealing
the systematic variations associated with the volcanic arc and plutonic bodies. Our formulation also allows
the dynamic simulation of earthquake cycles with distributed deformation using the integral method, anapproach more accurate and many orders of magnitude faster than classic finite-element techniques. We
simulate earthquakes cycles within the lithosphere-asthenosphere system using rate-and-state friction andthe power-law flow of olivine (Lambert & Barbot, 2017), revealing the prevalence of viscoelastic flow in theearly stage of postseismic relaxation. Our approach will be instrumental in building comprehensive
physical models of stress evolution at plate boundaries.

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*J05-2-02
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Rheological Structure Beneath Java Island after the 2006 Java Tsunami
Earthquake Based on GPS Data
* Endra Gunawan 1) , Irwan Meilano 1) , Hasanuddin Z. Abidin 1) 2) , N. Rahma Hanifa 1) , Rio Raharja 1) ,Susilo Susilo 1) 2) , Joni Efendi 1) 2)
Bandung Institute of Technology, Bandung, Indonesia 1) , Geospatial Information Agency, Cibinong,Indonesia 2)
We determine postseismic deformation associated with the 2006 Java tsunami earthquake using Global
Positioning System (GPS) data located in Java Island. By using an analytical approach of logarithmic andexponential functions, we find decay time in the order of hundred days after the mainshock as observed byeight years data after the mainshock. This result suggests that decay time for magnitude 7 class tsunami
earthquake is longer than a general megathrust earthquake event for similar magnitude. In our postseismic
deformation analysis, we investigate the contribution of aftersip and viscoelastic relaxation of the 2006
earthquake. We also calculate the effect of using different coseismic fault to the viscoelastic relaxation. By
simultaneously calculate viscoelastic relaxation and afterslip, our result of best-fit rheological modelcomprises a 60 km elastic layer thickness with a viscosity of 2.0 x 1e17 Pa·s in the asthenosphere. We alsofind that afterslip contribute of more than two-thirds (~80%) of horizontal displacements in the GPS data, inwhich asesimic slip occurred at deeper part of the coseismic rupture.

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*J05-2-03
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Afterslip and Viscoelastic Relaxation Model Following The 2010 Mentawai
Earthquake Deduced from Postseismic Surface Deformation* Mohammad Yuzariyadi 1) , Irwan Meilano 2) , Endra Gunawan 2) , Kosuke Heki 1)
Space Geodesy Laboratory, Hokkaido University 1) , Graduate Research on Earthquake and Active Tectonic(GREAT) Institut Teknologi Bandung 2)
Sumatra, Indonesia, is an island of high tectonic activity due to the northeastward subduction of the IndoAustralia beneath the Eurasian Plates at a rate of ~60 mm/year. This plate convergence causes high seismic
activity in the region, and the M7.8 Mentawai earthquake on October 25th, 2010 is just one of those. We
study its postseismic viscous relaxation in the upper mantle using geodetic data along the Sumatra
subduction zone. Previous studies found that both afterslip and viscoelastic relaxation are responsible forthe observed postseismic deformation (e.g. Gunawan et al., 2014). The two mechanisms have different
temporal and spatial domains (Wang, 2007). Afterslip occurred up- and down-dip segments of thecoseismic fault rupture and generated a crustal deformation in short to medium periods (e.g. Hsu et al.,
2002; Freed, 2007). On the other hand, viscoelastic relaxation dominates the deformation over the larger
area and the longer period (e.g. Wang et al., 2001; Pollitz et al., 2006).
The analysis in our previous study of the first two years of postseismic surface deformations revealed thatafterslip contributed significantly to the postseismic deformation. We first modeled the deformation by theviscoelastic relaxation and isolated the afterslip contribution by subtracting the model from the data. Thenwe estimated the afterslip distribution on the plate interface. According to Ardika (2015), afterslip causedby the 2007 Mentawai earthquake can be modeled using a logarithmic function and continued for about ahalf year after the mainshock.
Keywords: Earthquake cycle, Postseismic deformation, Viscoelastic Relaxation, Afterslip

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*J05-2-04
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Reciprocal relationship between seismically estimated slip rates andgeodetically estimated slip-deficit rates at plate interfaces: Physicalinterpretation and logical consequence* Mitsuhiro Matsu'ura 1) , Shunichi Nomura 2) , Yoshihiko Ogata 1) , Naoki Uchida 3)
Institute of Statistical Mathematics, Tokyo, Japan 1) , Tokyo Institute of Technology, Tokyo, Japan 2) ,Tohoku University, Sendai, Japan 3)
Repeating earthquakes, the sequence of stress accumulation and release at isolated small asperities on aplate interface, can be regarded as a renewal process in statistics. From such a point of view, we modeled asequence of repeating earthquakes and developed an objective Bayesian method to estimate the spacetime distribution of interplate slip rates from the recurrence intervals of repeating earthquakes. Appling thismethod to the complete data set of repeating earthquakes in northeast Japan for 18 years before the 2011
Tohoku-oki earthquake, we revealed spatiotemporal variations of interplate slip rates (Nomura et al, GJI
208, 2017). For a seismically calm period (1996-2000), we compared the average slip-rate distribution
estimated from repeating earthquake data with the average slip-deficit-rate distribution estimated from GPS
array data (Hashimoto et al., GJI 189, 2012), and found good reciprocal relationship between their spatial
patterns. What we can estimate from repeating earthquake data is the background slip rates for small
asperities. On the other hand, what we can estimate from GPS array data is the slip-deficit rates ofunderlying large asperities. So, the sum of the slip rate and the slip-deficit rates should be equal to a plateconvergence rate, but the actually estimated slip rates are a bit small to satisfy the above postulation. Thismay be responsible for the empirical relation between recurrence intervals and magnitudes of repeating
earthquakes (Nadeau & Johnson, BSSA 88, 1998), which scales the amplitude of slip rates. If we use atheoretical relation instead of the empirical one, the above postulation, which suggests a hierarchic
structure of asperities, is well satisfied.

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*J05-2-05
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Characteristics of spatiotemporal variation of hypocenters and the diversityof waveforms of deep low-frequency earthquakes in northeastern Japan* Masahiro Kosuga
Hirosaki University, Hirosaki, Japan
We have investigated the characteristics of spatiotemporal variation of hypocenters of deep low-frequency(DLF) earthquakes in northeastern Japan using the earthquake catalog of the Japan Meteorological Agency,
and relocated hypocenters by the hypoDD method. DLF earthquakes are believed to occur by anothermechanism than the fault motion because they occur below the depth of brittle/ductile transition. However,
the mechanism is still unknown. Thus the comparative study of spatiotemporal variation of hypocenters
and waveform characteristics among many source areas is important to clarify the source process of DLF
earthquakes.
We found that the thickness of the seismogenic layer of DLF earthquake varies in space at distances of
100–250 km. We also found that the areas with nearly constant seismicity have a spacing of 100–150 km.
These values are several times larger than the spacing of hot fingers that correlate well with areas of lowvelocity anomalies in the Tohoku district. No clear temporal change of seismicity of DLF earthquakes wasfound after the 2011 Tohoku-Oki earthquake, which suggests a small change in the stress at the source
depths of DLF earthquakes.
We next examined the diversity of waveforms of DLF earthquakes by grouping the events using waveform
cross-correlation. In a time window just after S-wave, closely located earthquakes tend to form a single
group, which suggest the similarity of focal mechanisms among the grouped events. However, the values ofcross-correlation are much lower than those of ordinary high-frequency events. This suggests that the focal
mechanisms and/or source process of DLF earthquakes are different from event to event. In time windowsof later phases, the correlation take lower values and the grouped events were not colocated. Thus the later
phases have less information of source mechanism than S-wave, which should be considered for the source
study by waveform modeling.

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*J05-3-01
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Spatial heterogeneity of crustal stress* Yoshihisa Iio
DPRI, Kyoto University,Uji,Japan
It has long been believed that crustal stress is highly heterogeneous in space. Direct stress measurements
in boreholes show that directions of the maximum compressional stress axis change in location, from aborehole site to another, or even within a same borehole. These measurements imply that crustal stress isfractal. Heterogeneous slip distributions and hypocentral distributions are explained by heterogeneousstress fields. Stress inversion studies of focal mechanisms reveal that estimated stress field changes inspace and also in time. Recently, it is reported that directions of the maximum compressional stress axischange before and after large earthquakes. These phenomena are usually explained by small magnitudes ofdifferential stress (maximum minus minimum compressional stress) in focal regions However, theestimated magnitudes are too small compared with those estimated from frictional experiments, thus analternative explanation is that they reflect heterogeneous stress field. They assume that crustal stress ishighly heterogeneous and acts on each fault in a direction to which the fault easily slips. Namely, faults of adifferent orientation are subjected under different stress field. When slips of large earthquakes generatestress changes, only faults that are favorable for those stress changes can be triggered by the stresschanges, and an apparent stress field could be estimated by stress inversions using only those triggered
earthquake data.
In this study, we will try to reveal that crustal stress is regarded as uniform in a km scale from stressinversion analyses of focal mechanism, different from the usual idea of a fractal-like stress field. We analyze
precise focal mechanisms and do a simple simulation of crustal stress considering heterogeneous
structures.

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*J05-3-02
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Fault rocks and paleostress fields in the San-in shear zone, western Japan* Hideto Uchida , Hideki Mukoyoshi
Shimane University, Shimane, Japan
Recent geodetic study revealed that the strain rate in the San-in Region is actually high and this active
region of deformation is called ‘the San-in shear zone'. The San-in shear zone almost overlaps with the
San-in seismic zone and the some inland earthquakes (the 2000 Western Tottori earthquake and the 2016
Central Tottori earthquake) occurred in the San-in shear zone. To understand the crustal deformation in theshear zone, the Crustal Dynamics project has planned very high-density seismic observation ofseismograph in 1000 point around aftershock area of the 2000 Western Tottori earthquake. On the other
hand, it is important for us to reveal the distribution and characters of fault rocks around aftershock area
and compare paleostress field in the past with that in the present day.
Recent geologic study around aftershock area of the 2000 Western Tottori earthquake revealed that the
distribution of faults around aftershock area was concordant with the aftershock distribution and explained
the relation between the geometry of the source fault and inactive fault.
In this study, We estimated paleostress fields formed inactive fault in granitic rocks around aftershock areaby the Hough-transform-based stress tensor inversion method (Yamaji et al., 2006; Sato and Yamaji, 2006).
First, I estimated paleostress fields of each faults having fault gouge or cataclasite as characters of fault
rocks. As the result, two stress tensors were detected with strike-slip faulting regimes from faults having
fault gouge. One is consistent with the present stress field in SW Japan. On the other hand, three stresstensors were detected with reverse and normal faulting regimes from faults having cataclasite.
With respect to different paleostress fields, fault system around aftershock area was formed by stress fields
with reverse and normal faulting regimes in the past seismogenic zone and by stress fields with strike-slip
faulting regimes in shallow depth with low confining pressure.

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*J05-3-03
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Three-dimensional seismic velocity structure beneath the northern South
Island, New Zealand from dense seismic observation* Tomomi Okada 1) , Yoshihisa Iio 2) , Satoshi Matsumoto 3) , Stephen Bannister 4) , Shiro Ohmi 2) , Masumi
Yamada 2) , Shintaro Horiuchi 1) , Tsutomu Miura 2) , Tadashi Sato 1) , Jarg Pettinga 5) , Francesca Ghisetti 6) ,Richard Sibson 7)
Tohoku University, Japan 1) , Kyoto University, Japan 2) , Kyushu University, Japan 3) , GNS Science, New
Zealand 4) , Univerisity of Canterbury, New Zealand 5) , Terra Geologica, New Zealand 6) , University ofOtago, New Zealand 7)
The northern South Island of New Zealand straddles the plate boundary between the Australian and PacificPlates and is a transition zone between the Hikurangi subduction margin and a continental transform
system, with the Alpine Fault as its principal component. The Alpine Fault separates two distinct tectonic
provinces. To the SE lies the Marlborough system of dextral strike-slip faults (MA faults), while to the NW
lies an area of active compressional inversion where inherited normal faults are reactivated predominantly
as steep reverse faults (e.g. Buller-Nelson area - BN faults). In this study, we image the seismic velocity
structure beneath the shallow seismogenic zone for both the eastern MA faults and the western BN faults.
A temporary dense seismic observation network was deployed in the northern and central parts of theSouth Island, New Zealand. We use data from these temporary stations (51 stations), acquired from March2011 to April 2015, together with data recorded by the New Zealand GeoNet network (22 stations). For the
analysis we also include data from the aftershocks of the 2016 Kaikoura earthquake, recorded by GeoNet.
Total number of located earthquakes is 5389. We employed the Double-Difference Tomography Method torelocate hypocenters and estimate the seismic velocity structure. The results from the seismic tomography
show low-Vp, Vs and a high Vp/Vs zone beneath the epicenters in the NW South Island. The high Vp/Vs
area seems to be continuously distributed from the upper surface of the subducted crust to the bottom of
the shallow seismic active area in BN faults. We also see seismic low-velocity area in and beneath the
hypocenter and the focal area of the 2016 M7.8 Kaikoura earthquake. These observations suggest that fluid
from the subducting plate weakens the crust and promotes the occurrence of earthquakes in this area.

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*J05-3-04
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

3d distribution of fluids and their origins in a seismogenic zone, Northern
Miyagi, NE Japan
Zenshiro Saito 1) , * yasuo Ogawa 1) , Masahiro Ichiki 2) , Hideyuki Satoh 3)
Tokyo Institute of Technology, Tokyo, Japan 1) , Tohoku University, Sendai, Japan 2) , AIST, Geological
Survey of Japan, Tsukuba, Japan 3)
Northern Miyagi is a seismically active region located in one of the strain concentration zones in NE Japan.
This area experienced three large earthquakes, in 1900 (M7.0), 1962 (M6.5) and 2003 (M6.2). The 2003
earthquake was well studied and its focal mechanism and aftershock distribution support that theearthquake was a high angle reversed fault, which is a reactivation of an originally normal fault, created in
the Miocene during the Japan opening. Geologically, the area is mostly simply covered with thick sedimentand is surrounded by granitic rocks of Kitakami Mountains to the east and to the north. The objectives ofthis study are to image the geofluid in three dimensions using magnetotellurics (MT) and to relate them toearthquake activities in the region.
We used MT data at 67 sites in total, covering 50km x 50km area. 39 sites are new and 32 sites are fromthe compilations of the previous three MT profiles in the area (Nagao, 1997; Mitsuhata et al, 2001; Sato etal., 2005). The previous profile data were inverted assuming the structure is quasi-two-dimensional, but wehave found strong three-dimensionality in the dataset. We inverted the data using 3d inversion code,
WS3dMTINV (Siripunvaraporn and Egbert, 2009). The model showed three deep conductors around the
focal depths of the three large earthquakes. This suggests that high pore pressure fluid is episodicallyexpelled from the reservoir to induce earthquakes in a less permeable zone..
Current high seismicity is seen at the outer rim of the deep conductors. The northernmost conductor at1962 earthquake has a deeper extension to northwest toward Kurikoma volcano. However the conductors
at 1990 and 2003 earthquakes have no deeper extensions. The former conductor at 1962 earthquake
implies fluid supplied from the volcanoes. In contrast, the latter conductors at 1990 and 2003 earthquakes
imply fluids trapped in sediment at the rim of the Miocene rift.

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*J05-3-05
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

A new temperature proxy on faults during earthquake by using maturity ofcarbonaceous materials: Kinetic effect on the maturation* Shunya Kaneki , Tetsuro Hirono
The University of Osaka, Osaka, Japan
Quantitative estimation of frictional heat produced in the fault zone (i.e., maximum temperature) is one of
the keys to estimate the slip behaviors of earthquakes. Irreversible thermal maturation reaction ofcarbonaceous materials, which is very sensitive to maximum temperature, is reported to be a great
indicator for frictional heat recorded in fault rocks. In fact, such maturation process could be strongly
affected not only by maximum temperature but also by heating rate. However, previous studies haveconducted under the heating rate of ~1 degree per second, which is markedly lower than that during
earthquake slip (several tens to several hundreds of degrees per second). Here we performed new heating
experiments at two different heating rates (~1 and ~100 degrees per second) by using carbonaceous
material sampless retrieved from an ancient plate-subduction fault. We then carried out IR and Raman
spectroscopic analyses and py-GC/MS analysis to characterize the degree of the maturation. The samples
after high heating rate of 100 degrees per second showed relatively low maturation than those after 1
degree per second-heated samples. Thus, heating rate is one of the important factors to estimate themaximum temperature recorded in the faults, and our results could indicate that previous researches
underestimate the temperature.

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*J05-4-01
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

GPS VELOCITY FIELD IN THE NORTHWESTERN CORNER OF SOUTH
AMERICA* Hector Mora-Paez 1) , James Kellogg 2) , Jeff Freymueller 3) , Dave Mencin 4) , Rui Fernandes da Silva 5) ,Leonardo Cardona-Piedrahita 1) , Sindy Lizarazo 1) , Leidy Giraldo 1) , Fredy Diaz-Mila 1)
Colombian Geological Survey, Space Geodesy Research Group, Bogota, Colombia 1) , University of South
Carolina, Columbia SC, USA 2) , University of Alaska, Fairbanks, USA 3) , University of Colorado, Boulder,
USA 4) , University of Interior Beira, Portugal 5)
Global Positioning System (GPS) data from southern Central America and northwestern South America
collected at GPS permanent stations during the last ten years reveal wide plate margin deformation along a
1400 km length of the North Andes. Associated with the oblique subduction of the Nazca plate at the
Colombia-Ecuador trench is the “escape" of the North Andes block (NAB). This work presents anddiscusses a new horizontal velocity field for northwestern South America derived from CORS (Continuously
Operating Reference Stations) GPS observations of geodetic networks located in Colombia, Panama andEcuador. In Colombia, the GeoRed network is a dedicated GNSS network for geodynamic studies installedby the Colombian Geological Survey through the Space Geodesy Research Group that currently consists of
100 stations. In this work, we use data from GeoRed permanent stations with a minimum of 2.5 years ofobservations. Using GPS velocity vectors for 53 permanent stations, we have estimated a new regional
geodetic velocity field. We used an updated model for the present-day angular velocity of the SouthAmerican plate (SEGAL model) based on a much denser network of CORS velocity solutions (Fernandes etal., in prep.). We combined our velocity field with the published results of Nocquet et al. (2014), to provide
a more complete picture of velocities across the entire North Andes block. Nocquet et al. (2014) used alarge number of sites in Ecuador, with only a few sites in Colombia, so the two data sets are highly
complementary. They defined the stable South American plate using a different set of sites than used in the
SEGAL model, so we used the four overlapping sites between the two data sets, all located in northern
Ecuador or southern Colombia, to compute the offset between the two South America frames. We thenestimate the motion of the North Andes block using a subset of these sites, and investigate tectonic motions
relative to the North Andes block.

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*J05-4-02
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Taiwan vertical velocity field from precise leveling observations, 2000-2015* Kwo-Hwa Chen 1) , Kuo-En Ching 2)
National Taipei University, New Taipei City, Taiwan 1) , National Cheng Kung University, Tainan, Taiwan 2)
The active Taiwan mountain belt is located at the plate convergence boundary between the Eurasian plate
and the Philippine Sea plate. Therefore, a high accuracy vertical velocity field is very important tounderstand the on-going mountain building mechanism and the earthquake potential of reverse faults. The
precise leveling is always the best way to obtain the high accuracy vertical velocity field until now eventhough it has the limitation of high field surveying cost. In this study, five precise leveling measurements
during 2000-2015 from a whole-island leveling network including 2137 benchmarks were used to infer ahigh accuracy vertical velocity field in Taiwan. First, the systematic errors of the leveling observations listed
in the specification of first-order leveling were corrected. Second, the leveling network adjustment of which
was minimum constrained to the orthometric height of K999 benchmark was estimated to obtain theorthometric height of the benchmarks distributed in the main roads of Taiwan. The slope-dependent errorsof the leveling observations were also analyzed in this study. By means of the coordinate time series
analyses and the accommodations of the effects of coseismic displacements, the vertical velocity of eachbenchmark was estimated by Least-squares Estimation (LSE), respectively. Finally, a GNSS-derived surface
vertical velocity field in Taiwan, 2000-2015, was used for the comparisons to examine the performance ofthe leveling-derived one in this study.

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*J05-4-03
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Observation of aseismic crustal deformation in Taiwan by analysis of InSAR
and GPS data
* Kotaro Tsukahara , Youichiro Takada
Hokkaido University, Sapporo, Japan
In this study, we report aseismic crustal deformation detected by InSAR images and GPS data insouthwestern Taiwan where is characterized by high convergence rate and very low seismicity. GPS
observation network has been well established there, which is preferable to correct noisy interferograms.
We use SAR data of L-band satellites (ALOS and ALOS-2) to obtain coherent images even for dense forests.
After removing long wave-length noise and height dependent term from interferograms using the GPS
velocity field (Tsai et al, 2015) and DEM, we stacked the corrected interferograms for further noise
reduction. Using these images, we derived the quasi-vertical and quasi-east velocity fields. We found very
rapid uplift in the area stretching about 25 km in the N-S direction with about 5 km E-W width. The uplift
rate increases from south to the north, and it shows step-wise change in the eastern flank. Ching et al,(2016) reported up to 20 mm/yr uplift rate detected by leveling survey passing through the southern part of
the uplift area. The quasi-uplift rate obtained by InSAR at the southern part is consistent with those given
by leveling survey. On the other hand, the maximum uplift rate detected by InSAR reaches up to 45 mm per
year at the northern part, twice as large as the rate along the levelling route. Judging from very low
seismicity in this region, the severe crustal deformation we detected with InSAR is aseismic.
The 2-D distribution of whole uplift rate seems impossible to explain only by fault motion, and mud diapir
should be another important factor. We found a sharp displacement discontinuity in the coseismic
interferogram of the Meinong earthquake (M6.4), which implies that the aseismic uplift is mainly driven by
the mud diapir, but the shallow active fault works as a pre-existing weakness.

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*J05-4-04
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Rapid crustal deformation in SW Taiwan caused by the interaction between
active faults and reactivated mud diapirs* Kuo-En Ching 1) , Yuan-Hsi Lee 2) , Ruey-Juin Rau 1) , Ming Yang 1) , Yi-Jhen Hung 1) , Song-Chuen Chen 3) ,Lingho Chung 2) , Jei-Ching Hung 4) , Chien-Liang Chen 3)
National Cheng Kung University, Taiwan 1) , National Chung Cheng University, Taiwan 2) , Central
Geological Survey, Taiwan 3) , Taiwan High Speed Rail Corporation, Taiwan 4)
The geodetic data from 2002 to 2016 and 17 ALOS SAR images between 2007 and 2011 were collected inthis study to understand the rapid surface deformation in SW Taiwan. The geodetic data comprise 35 dualfrequency and 9 single-frequency continuous GPS stations, 65 campaign-mode GPS stations between 2002
and 2015 and 10 precise leveling routes between 2010 and 2016. All surface velocities are relative to theChinese continental margin. From north to south, three regions (HLVRs) with extremely high line-of-sightvelocity of larger than 40 mm/yr were identified in SW Taiwan. Two of them (middle and southern HLVRs)
are located within the central gap between two NE-SW-striking faults, which are the Lungchun fault (LCNF)
to the west and the Chishan fault (CSNF) to the east. An uplift rate of ~80 mm/yr is detected at the middle
HLVR. At the middle HLVR, a shortening rate of ~47 mm/yr and a left-lateral rate of ~6 mm/yr are shown
across the LCNF, while an extension rate of ~32 mm/yr, and a right-lateral rate of ~11 mm/yr are
represented across the CHNF. For the region south of the southern HLVR, a shortening rate of ~2 mm/yr
and a right-lateral rate of ~10 mm/yr are shown across the LCNF, while a shortening rate of ~3 mm/yr, anda left-lateral rate of ~1 mm/yr are presented across the CHNF. Therefore, the middle HLVR is moving
toward NE while the southern HLVR is moving toward SW. After comparing with the locations of mud
diapirs and the seismic reflection profiles in SW Taiwan, we proposed that these three isolated HLVRs are
the ongoing active inland mud diapirs. The overpressured sediments and fluid are squeezed and pushed
upward due to the tectonic compression. Because these inland mud diapirs are bounded by the active
faults, the materials are also extruded toward the free boundaries along the channel constructed by thesefaults.

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*J05-4-05
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Performance of VADASE single-frequency GPS solutions in the 2016 M 6.5
Meinong, Taiwan, earthquake* Ruey-Juin Rau 1) , Choon-Muar Ker 1) , Giorgio Savastano 2) , Mattia Crespi 2)
National Cheng Kung University, Tainan, Taiwan 1) , University of Rome “La Sapienza", Rome, Italy 2)
The 6 February 2016 MW 6.5 Meinong earthquake produced widespread strong shaking with 30-85 cm/s
Peak Ground Velocity (PGV) in the 30-km-away Tainan city, where we installed eight 1-Hz single-frequency(SF) and one dual-frequency (DF) GPS stations about 4 month before the earthquake. The observed PGVs
are significantly higher than the near-fault ground motion collected from moderate-sized earthquakes
occurred worldwide and caused about 10 buildings collapsed and 117 death in the Tainan city. We
processed the 1-Hz SF GPS data with both VADASE (Variometric Approach for Displacement Analysis
Standalone Engine) and RTK positioning approaches. VADASE developed by the Sapienza University
utilizes the broadcast orbits and the time differences of the high-rate carrier phase observations to acquire
the receiver motions at centimeters accuracy level. The RTKLIB software (Tomoji Takasu) was used for RTK
solutions which requires reference stations. The comparisons between VADASE and RTK solutions for all
the 1-Hz SF GPS stations are in general consistent. We also compare the VADASE 1-Hz SF GPS solutions
with the nearby 40 m away DF GPS stations. The differences between these two are about 3 mm/s and 5mm/s for H and V component, respectively. Based on the seismological observations, the Meinong event
has a strong directivity effect with the seismic waves propagating mainly toward the west to where our GPS
stations are located. This effect can be clearly seen in most of the 1-Hz SF GPS solutions indicating 25-40
cm/s, EW-PGV, in contrast to 7-20 cm/s, NS-PGV. Two stations however, show significant large NS-PGV of
32-40 cm/s in comparison with the EW-PGV of 5-11 cm/s. These two stations are located near the E-Wtrending Hsinhua fault, where the fault may act as a structural barrier which caused fault-normal motions
observed. The use of the VADASE approach in the 1-Hz SF GPS for the 2016 Meinong earthquake clearly
demonstrates the feasibility of SF GPS Seismology.

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*J05-5-01
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Early recurrence of an M6 intraplate earthquake (5.8 years) observed innorthern Kanto region, Japan, after the 2011 Tohoku-oki earthquake* Yo Fukushima 1) , Shinji Toda 1) , Satoshi Miura 2)
International Research Institute of Disaster Science, Tohoku University 1) , Graduate School of Science,
Tohoku University 2)
The March 2011 Mw9.0 Tohoku-oki earthquake caused significant stress changes in the eastern half ofHonshu Island, resulting in the excitation of widespread seismic activity. In northern Kanto region, swarmlike normal faulting activities were induced. One of such events was an M6 event on 19 March 2011
(hereafter called event A).
Approximately 5.8 years later on 28 December 2016, another M6 normal fault earthquake occurred(hereafter called event B). The epicenter of this event determined by the Japan Meteorological Agency islocated a few kilometers away from that of the event A.
Performing InSAR processing using Japanese ALOS and ALOS-2 satellite data, it was found that thecoseismic displacements for the two events were remarkably similar when the interferograms obtainedusing data acquired from the same direction were compared. Specifically, the locations of displacement
discontinuity lines directing NW-SE, which should correspond to surface rupture, were almost identical,
and the displacement patters were also similar, suggesting that the same fault ruptured.
The slightly larger displacement for the event A (maximum displacement discontinuity of ~45cm comparedto ~30cm for the event B) indicates that this event was associated with larger slip on the fault at least close
to the ground. A preliminary inversion for the event B found a dip angle of 42 degrees with fault slip
confined in the upper-most 5km in the crust.
Two questions arise from our result: 1) How can only the upper part of the seismogenic layer (within 5km)
rupture? 2) How can an M~6 earthquake re-rupture with such an extremely short time interval of 5.8 years?
Two hypotheses can be proposed for the latter question: either a rapid loading of the fault occurred after
the event A, possibly associated with the postseismic deformation due to the 2011 Tohoku-oki earthquake,or the stress level on the fault remained high after the event A, enabling further slip on the fault without
significant loading.

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*J05-5-02
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Crustal deformation process in Mid-Niigata as observed by dense GPS
network before and after the 2011 Tohoku-oki earthquake* Angela Meneses-Gutierrez 1) , Takeshi Sagiya 2) , Shutaro Sekine 3)
Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan 1) , Disaster Mitigation
Research Center, Nagoya University, Nagoya, Japan 2) , Association for the Development of Earthquake
Prediction, Tokyo, Japan 3)
The Niigata-Kobe Tectonic Zone (NKTZ) is a deformation zone along the east coast of Japan Sea, withlocalized E-W contraction (Sagiya et al. 2000). Meneses-Gutierrez and Sagiya (2016) studied strain rate
distributions based on GPS data from GEONET in central Japan before and after the Tohoku-oki
earthquake and found persistent localized contraction (4-10x10-8/yr), in northern NKTZ, showing that theconcentrated contraction is mainly inelastic in the form of aseismic fault slip. However, complete scalecharacterization of the deformation source was not possible due to limited spatial resolution of the GPSdata.
In 2010, the Association for the Development of Earthquake Prediction in collaboration with Nagoya
University, constructed 20 continuous GPS sites in Mid-Niigata. Analysis of this network with GEONET
allows a better description of the deformation source in the area. We evaluate the Mid-Niigata response
during the preseismic (2008-2011) and postseismic period (2013-2016) of the Tohoku-oki earthquake. We
calculate horizontal strain rate distributions from the displacement rate data using Shen et al.'s method(1996), with a 15km distance decay constant. Then, we decompose the E-W strain rate with respect to its
wavelength following Meneses-Gutierrez and Sagiya (2016). We found persistent localized contraction in
the short wavelength component within 40 km before and after the quake. However, differences in theamplitude and horizontal location of the localized deformation suggested that elastic heterogeneities of thecrust, acting in different sense before and after the event, might affect the deformation. We modeled thedeformation in the preseismic and postseismic period considering an aseismic fault and an elastic
heterogeneity as the source of deformation. We found that a fault cutting the whole crust at an angle of30-40º with a slip rate >10mm/yr and an elastic heterogeneity with horizontal width of 60km located above
the fault can explain the deformation.

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*J05-5-03
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Crustal deformation in and around the Atotsugawa fault before and after the
Tohoku-Oki earthquake* Tomomi Inamatsu 1) , Youichiro Takada 1) , Takeshi Sagiya 2) , Takuya Nishimura 3)
Hokkaido University, Sapporo, Japan 1) , Nagoya University, Nagoya, Japan 2) , Kyoto University, Kyoto,
Japan 3)
The 2011 Tohoku-Oki earthquake (Mw9.0) provides us the first opportunity to examine the responses ofstrain accumulation zones and active faults to megathrust earthquakes with dense permanent GPS network.
In this presentation, we report the differences and/or similarities between pre, co, and post seismic crustal
deformation of the earthquake using GPS data in and around the Atotsugawa fault, located at the central
part of Niigata-Kobe Tectonic Zone (Sagiya et al., 2000).
We used daily coordinates obtained from the GPS stations operated by university group in addition to
GEONET. For the pre- and post-seismic period, we estimated the velocity fields by removing annual andsemi-annual components. For the co-seismic displacement, we calculated 5 days average of the coordinates
before and after the earthquake, respectively, and subtracted each other. From the velocities anddisplacements, we calculated the strain rates following the method of Shen et al. (1996).
Spatial pattern of the co-seismic strain, which is the elastic response, is completely different from the preand post seismic strain rates pattern. Therefore we conclude that the pre and post seismic strain
concentration, similar to each other, is mainly caused by the inelastic straining (e.g. viscous flow) which isessentially driven by the absolute stress. The absolute stress accumulated over a long time scale is farlarger than the stress change by one earthquake, which explains the similarity between pre and post
seismic strain rates.
Looking in detail, the sense of pre- and post-seismic strain rates reverse in the south of the Hida mountain
range and to the east of Mt. Ontake. Both regions are known as thermally active areas and many small
earthquakes have been occurring frequently. Therefore, the change in the strain rates in these regions
might be related to the volcanic activities.

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*J05-5-04
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

The role of the lower crust in crustal deformation of the Japan island arc* Takeshi Sagiya , Angela Meneses-Gutierrez , Xuelei Zhang , Yumi Shimoyama , Kouki Kumagai
Nagoya University, Nagoya, Japan
In the Japanese island arc, interplate locking along the subduction interface of the Pacific plate and thePhilippine Sea plate has been considered as the main source of the crustal deformation. On the other hand,detailed analysis of crustal deformation before and after the 2011 Tohoku-oki earthquake has revealed
existence of persistent deformation associated with the Niigata-Kobe Tectonic Zone, a major inland
deformation zone (Meneses-Gutierrez and Sagiya, 2016), which is independent of the mechanicalinteraction at the subduction interface. This observation suggests that activity of inland deformation zones
is driven by regional tectonic stress that has been built up over a geological time scale. In addition, a
special structure that promotes localized deformation must exist in the lower crust associated with active
deformation in the upper crust. Such an idea is supported by a numerical simulation study, in which shear
localization occurs in the lower crust beneath an inland active fault even with a slow fault slip rate such as
1 mm/year. The nonlinear rheology is considered to be the most important cause of the shear localization(Zhang and Sagiya, submitted). Thus it is expected that localized deformation in the lower crust is pertinent
to each active fault. Once such a structure is created in the lower crust, it in turn controls the deformationof the upper crust. Such an idea is supported by the fact that crustal deformation pattern around active
faults is well explained by an elastic dislocation model with a locking depth of ~15km. Around the Atera
fault and the Gofukuji fault, major left-lateral strike slip faults, observations with dense GNSS network showthat the lower crustal shear localization beneath the active fault traces continue even during significant
perturbation due to the 2011 Tohoku-oki earthquake (e.g. Kumagai et al., 2017). The idea also provides aphysical basis for the block modeling of inland areas.

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*J05-5-05
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Importance of fault rheology around brittle-plastic transition in long-term
slip rate of major faults* Hiroyuki Noda
Kyoto University, Kyoto, Japan
A ductile shear zone underlies a seismogenic part of a major fault, and its rheology may significantly affectthe long-term slip rate. I have conducted numerical simulations of earthquake sequences on a major fault
penetrating a crustal plate under a constant far-field stress tau_pl, using a rate- and state-dependent frictionto-flow fault constitutive law. In this law, shear resistance is approximately given by a rate- and statedependent friction law in a shallow brittle part of the fault, and by power-law creep in a deep fully plastic
part. The rate-dependency of the shear resistance takes the maximum value in a transitional regime
between them. Note that the peak in the rate-dependency does not necessarily correspond with peak shear
resistance. If we assume excess pore pressure at depth which limits the effective normal stress at a certain
value, then a Christmas-tree-like strength profile does not exist, but a remarkable peak in the ratedependency still appears in the transitional regime. In present simulations, the fault hosts repeating
earthquakes in the brittle part, and slips by a long-term speed V_pl on average which depends on tau_pl.
The relation between tau_pl and V_pl is very well explained by a power law which is similar to what
unstable steady-state solutions with uniform slip rates V_ss follow. It should be noted that V_pl is larger
than V_ss for the same tau_pl approximately by a factor of 2 due to heterogeneous distribution of shear
stress. Since the relation between tau_pl and V_ss is given by spatial average of the rate-dependency, thetransitional regime having the prominent peak in the rate-dependency most significantly contributes to theamount of stress perturbation required to change the long-term slip rate of the fault.

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*J05-5-06
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Seismicity and Geothermal activities in the Upemba Rift Basin (SE of the DR
Congo)* Kadima Kabongo , Kipata Mwabanua
The University of Lubumbashi, Lubumbashi, DR Congo
The Upemba Rift Basin (URB) in the Southeastern area of the DR Congo is one of the nascent southwesternbranch of the East African Rift System (EARS). Classically, the EARS had been subdivided in two developed
branches : eastern and western branch. But, recent studies and observations led to the definition of two
additionnal nascent branches, a Southeastern and a Southwestern.
The first develops in the Mozambic rift channel and the second includes the Okavango basin in Botswana,
the Luano, Lukusashi, Lwangwa rift valleys in Zambia and the Mweru and Upemba rifts in DR Congo.
Among them, the URB is the less knwon and poorly documented. It is oriented NE-SW and fill by the Karooand recent glacio-fluvio-lacustrine sediments.
Gravity and structural evidence as long as seismicity and geothermal activities confirm the rifting ascentprocessus. The surface tracing, poorly controlled by gravity due to the reduced number of measurement
points, is transverse to a sub-meridian gravity accident between 26 and 27 East meridians.
Last twenty years seismic events recorded are generally of magnitude Mb about 4.2 showing the seismicity
axis parallel to the NE-SW trend of the structural look of the recent rift basins. Major earthquakes focal
mechanism solutions are consistent with the NW-SE crustal extension.
Numerous thermal springs had been recognized around the URB and the first, now defunct, geothermal
power plant in Africa built in 1953 in the Upemba valley. Its geothermal system is still active (recent
exploitation indicates hot spring of about 85.0 ~ 87.2 celcius degree, 60 Tons/hour outflow). A recent
Natural Source Audio Magnetotelluric profile below the thermal spring indicates the presence of an highresistivity dyke body (up to 10000 ohm-m2 resistivity). This particular area requires a more scientificinvestigation.

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*J05-P-01
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Investigation of remote earthquake triggering after the 2011 M9.0 Tohokuoki earthquake* Anca Opris 1) 2) , Bogdan Enescu 2) , Yuji Yagi 1)
University of Tsukuba, Tsukuba, Japan 1) , Kyoto University, Kyoto, Japan 2)
After the occurrence of the 2011 M9.0 Tohoku-oki earthquake, increased seismicity has been observed
over the Japanese Islands due to increased static and/or dynamic stresses (e.g., Toda et al., 2011;
Miyazawa, 2011). Miyazawa (2011) showed that a dynamically-triggered earthquake front propagated along
Japan following the Tohoku-oki earthquake.
In this study, we investigated the triggering mechanism and remote activation in more detail. We first
analyzed Hi-net (NIED) continuous waveform data to identify remote activation in the first minutes after theoccurrence of the Tohoku-oki mainshock. We located events that are not listed in the JMA catalogue, withmagnitudes from 1.2 to 3.4, which correspond to the arrival of Tohoku-oki surface waves in areas like Aichi,
Hyogo and Tokushima prefectures, as well as Kyushu, at about 1350 km from the Tohoku-oki epicenter.
To determine the dominant triggering surface-wave phases, we analysed low-frequency waveform
displacements at locations where remote triggering has been observed. The occurrence time for some of
the analysed triggered events in Kyushu correlates well with the arrival of large surface-wave displacementson the transverse component, suggesting that the Love-waves, rather than the Rayleigh-waves, may haveplayed the main role in triggered these remote earthquakes. The associated dynamic stresses are large,
with values of ~150 kPa in southernmost Kyushu. These observations imply that induced sharing motion
may have been responsible for the triggering of some of the detected remote events.
We also looked at the JMA earthquake catalog to observe the duration of increased seismic activity in areasof remote earthquake triggering. We found a clear increase in seismicity that lasted from a few days toabout two weeks, depending on the activated area. The geothermal/volcanic areas in Kyushu show thelongest and most clear seismicity activation.

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*J05-P-02
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Simulation of postseismic deformation caused by the 2011 Tohoku-Oki
earthquake* Hisashi Suito
Geospatial Information Authority of Japan, Tsukuba, JapanWe are developing a 3-D viscoelastic model using the FEM to understand the postseismic deformation that
followed the 2011 Tohoku-Oki earthquake. The question of which elements of the viscoelastic media affectthe surface deformation is of particular importance. We first examined the individual effects of two different
viscoelastic media, the mantle wedge and the oceanic mantle, which produce almost opposite deformation
patterns. The mantle wedge controls eastward motion, uplift of the Pacific coast and offshore regions, andextension across a broad area. In contrast, the oceanic mantle controls dominantly offshore westward
motion, subsidence across a broad area, minor uplift of the surrounding areas, and contraction offshore. We
then developed four different models to clarify which elements of the viscoelastic media affect the observed
surface deformation. The simplest model, with uniform viscosity for all viscoelastic media, could explain thehorizontal deformation but not the vertical deformation. The second model, with different viscosities for the
mantle wedge and the oceanic mantle, could explain the onshore observations but not those on theseafloor. The third model, which includes a thin weak layer beneath the slab, could essentially explain thenear-field onshore and seafloor observations but could not explain the far-field data. The final depthdependent model was able to explain the far-field data as well as the near-field data. In these typicalmodels, it is of particular importance to consider the different viscosities between the mantle wedge andthe oceanic mantle, and to include a thin weak layer beneath the slab. Far-field data as well as near-fielddata are also important for constraining the viscoelastic structure. Clearly, viscoelastic relaxation alone
cannot explain the observed deformation. We are now developing a combined viscoelastic and afterslip
model.

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*J05-P-03
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Spatiotemporal distribution of locking and aseismic slips prior to the 2011
Tohoku-oki earthquake* Momo Tanaka 1) , Shoichi Yoshioka 2) , Yukiko Nishino 3)
Graduate School of Science, Kobe University, Kobe, Japan 1) , Research Center for Urban Safety andSecurity Kobe University, Kobe, Japan 2) , Panasonic Corporation, Kyushu Branch, Fukuoka, Japan 3)
We obtained the horizontal and vertical tectonic crustal deformation in the Tohoku district. We investigated
GNSS data for seven years just prior to the 2011 Tohoku-oki earthquake (M9.0). We set the average
displacement rate of three GNSS stations in Niigata prefecture as a reference. Chebyshev polynomials
enabled high-precision estimation of the tectonic crustal deformation. We determined an optimal order ofthe polynomials, by minimizing AIC. After correcting offsets caused by coseismic crustal deformation andantenna exchange in the time series, we fitted logarithmic curve to horizontal data to eliminate the effects
of postseismic crustal deformations of the following three large earthquakes: the 2003 Tokachi-Oki (M8.0),
the 2005 Miyagi-Oki (M7.2), and the 2008 Iwate-Miyagi nairiku earthquakes. Then, we obtained thetectonic crustal deformation, by subtracting common-mode errors and the annual and semi-annual periodic
signals from the time series. Then, we performed the inversion analyses for the tectonic crustal deformation
with a time interval of one year, and estimated spatiotemporal interplate locking and aseismic slip
distributions. We used the geometry model of the Pacific plate by Nakajima and Hasegawa (2006). We
employed an inversion analysis which includes the following three prior constraints: the spatial slip
distribution is smooth to some extent, slip directions are mostly oriented in the direction of plateconvergence, and the temporal change in locking and slip distributions was smooth to some extent(Yoshioka et al., 2015). The results of our inversion analyses revealed locking of approximately 9 cm/year
at the offshore of Miyagi prefecture during the period from 2004 to 2010, indicating strong interplate
coupling. We also found that locking was 2 cm/year at the middle of offshore Sanriku in 2004, and it
became gradually smaller and almost disappeared in 2010.

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*J05-P-04
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Source processes of the M6-class repeating earthquakes which occurred innorthern Ibaraki Prefecture, Japan, on 2011 and 2016
* Kazuhito Hikima
Tokyo Electric Power Company Holdings, Inc., Tokyo, Japan
An M 6.3 crustal earthquake occurred on December 28, 2016 in northern Ibaraki Prefecture, Japan. Since
just after the great 2011 Tohoku Earthquake M 9.0, a significant increase in the shallow normal fault typeseismicity has been observed around this area, and the M 6.1 earthquake had occurred on March 19, 2011.
The crustal deformations of the 2016 and the 2011 earthquakes, estimated by InSAR data, are almost
identical (GSI, 2017), which means that comparable size earthquakes have repeated in the interval of only
about 5.7 years. However, the resolution is insufficient to discuss precise source mechanics, so source
process inversion analyses using near field strong motion data are performed in this study.
The waveforms of the K-NET and KiK-net (NIED) were used in these inversion analyses. Basically, identicalstations were selected for the 2016's and 2011's events. The acceleration waveforms were filtered between
0.03 and 0.8 Hz, and were integrated to velocity waveforms for the inversion analyses. The source
processes were inverted by the multi time window method. The size of sub-faults for the inversion analyses
were set in 1 km.
The epicenter of the 2016's event is located at about 7 km south of the 2011's event. Though, it was
revealed that the rupture of the 2016's event propagated toward the north and its large slip area (asperity)
exists fairly near the asperity of the 2011's event. However, the strike and the dip of these events aredifferent and it suggests that the fault planes of the events are not identical. Furthermore, the estimated slip
distributions show that the asperities of two events scarcely overlap each other. According to these results,
it is deduced that the dominant slip areas of the 2016's and 2011's events are different. The inversion
analyses suggest a following conclusion: adjacent but alternate faults had been activated in the interval of
about 5.7 years.

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*J05-P-05
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Numerical Simulation of Plate Deformation and Stress in the Andaman
Subduction Zone
R Yadav 1) , * VM Tiwari 1)
CSIR – National Geophysical Research Institute, Hyderabad, India 1) , CSIR – National GeophysicalResearch Institute, Hyderabad, India 2)
The oblique subduction of Indo-Australian plate beneath the Eurasian plate in the Sumatra-Andamanregion is characterized by the complex deformation patters. In order to investigate surface deformation andstress patterns in the subducting and overriding plate, we have set up a three-dimensional (3D) numericalsimulation utilizing 3D density model, derived from the joint modelling of satellite free air anomalies andgeoid undulation. The boundary condition for the model is constrained from the plate velocities at the
subduction zone and material properties are derived from the seismic velocities and density model. The
simulation of stress, strain and velocities, using different rheologies (elastic and viscous) shows a goodcorrelation with the observed GPS velocity components and seismicity of the region.

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*J05-P-06
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

The 2016 M6.5 Pidie Jaya Earthquake, Aceh Province, Indonesia; WhichFault?
* N. Rahma Hanifa 1) , Irwan Meilano 1) , Masyhur Irsyam 1) , Agustan Agustan 2) , Daryono Daryono 3) ,Danny H. Natawidjaja 4) , Wahyu Triyoso 1) , Sri Widiyantoro 1) , Sri Hidayati 5) , Mohamad Ridwan 6) , Susilo
Susilo 7) , Endra Gunawan 1) , Amir H. Isa 6) , Supartoyo Supartoyo 5) , Andri C. Utomo 8) , Gayatri I.
Marliyani 9) , Bagoes D. Ramdhani 1) , Refi R. Ramadian 1) , Suchi Rahmadani 1) , Alwidya A. Safitri 1)
Bandung Institute of Technology, Bandung, Indonesia 1) , Agency for the Assessment and Application ofTechnology, Indonesia 2) , Indonesian Agency for Meteorological, Climatological and Geophysics,
Indonesia 3) , Indonesian Institute of Sciences, Indonesia 4) , Center for Volcanology and Geological Hazard
Mitigation, Indonesia 5) , Ministry of Public of Works and Housing, Indonesia 6) , Geospatial Information
Agency, Cibinong, Indonesia 7) , Indonesian National Board for Disaster Management, Indonesia 8) ,University Gajah Mada, Yogyakarta, Indonesia 9)
The 2016 M6.5 Pidie Jaya Earthquake, Aceh Province, Indonesia occur in the morning at 05. 03.36 local
time. The epicenter was first automatically estimated by BMKG inland at 5,19 N and 96,36 E, then updated
offshore 5,25 N dan 96,24 E, in the depth of 15 Km. The shaking was widely felt across Aceh Province, withintensity VII-VIII MMI, causing 106 casualties, 700 injuries, and 16.238 house damages (BNPB, 2017).
This earthquake occurred in place where no fault is mapped in the 2010 National Seismic Hazard Map ofIndonesia. The National Center for Earthquake Studies then conducted survey to mapped the source faultof the earthquake. We conducted field observation of surface ruptures and deploy temporary continuous
GPS measurement 3 days after the main shock. We analyze the fault location based on field observation
data, seismicity data, geomorphology data, and geodetic INSAR data. We present the preliminary result of
the fault source of the 2016 Pidie Jaya earthquake based on those data, which is updated in the New
National Seismic Hazard Map 2016.

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*J05-P-07
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Regional stress field inferred from focal mechanisms obtained by dense
seismic observation in the northern South Island, New Zealand* Tadashi Sato 1) , Tomomi Okada 1) , Yoshihisa Iio 2) , Satoshi Matsumoto 3) , Stephen Bannister 4) , Shiro
Ohmi 2) , Masumi Yamada 2) , Tsutomu Miura 2) , Jarg Pettinga 5) , Francesca Ghisetti 7) , Richard Sibson 6)
Tohoku University, Japan 1) , Kyoto University, Japan 2) , Kyushu University, Japan 3) , GNS Science, New
Zealand 4) , Univerisity of Canterbury, New Zealand 5) , University of Otago, New Zealand 6) , Terra
Geologica, New Zealand 7)
The northern South Island and the southernmost North Island of New Zealand lie in the transitional area of
subduction of the Pacific plate, with the Pacific plate subducting beneath the Australian plate obliquelyfrom the northeast. Due to the plate subduction, active seismicity in the northern South Island can be seen.
For example, a Mw 7.8 earthquake occurred in the Kaikoura region of northern South Island at 11:32 am(UT) on 14 November 2016. In this study, we obtained focal mechanisms of the micro- to moderate-sizedearthquakes in order to estimate the spatiotemporal variation of the crustal stress field, including the
Kaikoura earthquake.
We analyzed the data acquired by a dense seismic array (see also Okada et al, this meeting) which has beenrecording over 2 years from 1 April 2013 to April 2015. We determined focal mechanisms using the HASH
program (Hardebeck, 2002; 2003). During that time period, there have been two major seismic clusters;
the first, consisting of aftershocks of the 1990 Lake Tennyson earthquake, occurred in the center of thenorthern South Island, while the second, which consisted of aftershocks of the 2013 Cook Strait
earthquakes, occurred in the northeast of the northern South Island. For shallow earthquakes, strike-slip
type focal mechanisms seem to dominate. P axes were oriented to ~N120E, which is similar to that found inprevious studies (Reyners et al., 1997; Balfour et al., 2005; Sibson and Ghisetti, 2011; Townend et al.,2012) and which seems to be consistent with most of GEONET-CMTs of the aftershocks of the 2016
Kaikoura earthquake. T axis were oriented to NE-SW. For intermediate-deep earthquake, normal, strike-slip,
reverse faulting seems to be mixed. Most of the P axes were oriented to NE-SW, which is also consistent
with previous studies (Reyners et al., 1997; Townend et al., 2012).

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*J05-P-08
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Crustal stress and strain inversion of the Taiwan orogen using a mixed linearnonlinear Bayesian approach* Ray Y. Chuang
National Taiwan University, Taipei, Taiwan
The state of stress and strain in the crust is fundamental information for understanding bonging tectonic
status and processes. It is common to use seismic data for inverting stress state at depths and geodetic data
for estimating strain rates on the surface. However, it is arbitrary to determine spatial smoothing in regular
damped least-squares for stress and strain inversions. Therefore, we extend the common stress and strain
inversions into a mixed linear-nonlinear Bayesian framework, which provides objective way to estimate
regularization parameters. In this method, one can estimate principal stress orientations with 3D smoothingby using focal mechanism solutions. The smoothing and fault plane selections can be determined by theMarkov Chain Monte Carlo (MCMC) approach with the Metropolis algorithm. We show examples of stressand strain inversions for the Taiwan orogen and demonstrate how crustal stress changes after a large
seismic event. The results show that the stress state of Taiwan is mainly dominated by strike-slip andreverse faulting with normal faulting in the northern and northeastern Taiwan, which is consistent withother studies. The stress state changes after the 1999 Chi-Chi earthquake is consistent with postseismic
movement.

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*J05-P-09
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Afterslip and viscoelastic components observed in surface gravity change
after the 2011 Great Tohoku earthquake* Shuhei Okubo 1) , Xinlin Zhang 2) , Yoshiyuki Tanaka 1) , Yuichi Imanishi 1) , Satoshi Miura 3) , Sadato Ueki
, Hiromitsu Oshima 1) , Tokumitsu Maekawa 4) , Kazumi Okada 4) , Miwako Ando 1)
The University of Tokyo, Tokyo, Japan 1) , China Earthquake Administration, Wuhan, China 2) , Tohoku
University, Sendai, Japan 3) , Hokkaido University, Sapporo, Japan 4)
3)

The 2011 earthquake off the Pacific coast of Tohoku imposed significant stress change within the crust andmantle, which results in postseismic crustal deformation and gravity change. In this presentation, we show
gravity change on the ground of Tohoku, Hokkaido and Kanto areas during the period between May 2011
and July 2016.
The gravity changes measured with an FG5 absolute gravimeter showed rather monotonous decrease of
30-40 microgals during 2011-2014. Since the elevation changes in the same period are 10 to 20 cm, thegravity decrease can be well explained in terms of afterslip around the fault of the Tohoku earthquake.
Surprisingly, however, the gravity trend showed slow but steady increase of 10 microgals since 2014
although the uplifting is still going on in the same period.
Remembering that the gravity change is composed of contributions from elevation change and volumetricstrain change (density change), the gravity increase since 2014 is likely to reflect viscoelastic strain change
within the mantle. The result will be discussed in more detail based on viscoelastic modeling of a sphericalearth.

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*J05-P-10
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

The spatial distribution of the stress ratio in the aftershock area of the 2000
Western Tottori Earthquake* Takaki Iwata
Tokiwa University, Mito, JapanA statistical approach to estimate a spatial stress pattern from P-wave first motions has been developed. In
this approach, without the determination of focal mechanisms, the spatial pattern of stress tensor isevaluated under the two assumptions: (i) the orientation of a fault plane is distributed randomly anduniformly; and (ii) the slip orientation of faulting is parallel to the one in which the shear stress ismaximized. With the two assumptions and smoothness constraint on the spatial variation in the stresstensor, the best estimate of the spatial stress pattern to fit observed P-wave first motions is found in theframework of a Bayesian statistics.
This approach was applied to the dataset of P-wave first motions taken from the aftershocks of the 2000
Western Tottori Earthquake. From the dataset compiled by Kawanishi et al. [2009, JGR], the P-wave first
motions with which O-C time for the P-wave arrival is within 0.1 s and that for the S-wave arrival is within
0.2 s (if the S-wave arrival is picked) were selected. After this selection, 47,570 P-wave first motions for3592 events were remained and analyzed.
From the estimated stress tensor, the spatial pattern of the stress ratio R =(sigma_1-sigma_2)/(sigma_1-sigma_3) was calculated where sigma_1, sigma_2, and sigma_3 denote themaximum, intermediate, and minimum principal stress, respectively. In the southern part of the main fault
orientated NNW-SSE, the value of R along the western side of the fault is high while it is low along theeastern side. The Tottori earthquake has a left-lateral strike slip fault, and therefore we may assume thestress field after the mainshock is compressive and extensional along the western and eastern sides along
the southern part of the main fault, respectively. The spatial pattern of the stress ratio revealed in this study
is consistent with the assumed stress field.

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*J05-P-11
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Seismic velocity structure in the lower crust beneath the seismic belt in the
San-in district, Japan* Hiroo Tsuda , Yoshihisa Iio , Takuo Shibutani
Kyoto University, Kyoto, Japan
In the San-in district in southwest Japan, a linear distribution of epicenters is seen along the Japan Sea
coast. The linear distribution is called the seismic belt in the San-in district. Large earthquakes also
occurred in the seismic belt. What localizes the earthquakes in the San-in district far from the plateboundary? We thought that the model proposed by Iio et al. (2002, 2004) could answer the question. The
model is as follows. A part of the lower crust has low viscosity. The low viscous part is called ‘weak zone'.
The stress and strain in the upper crust are concentrated right above the weak zone, and earthquakes occur
there. To verify whether the weak zone exists in the lower crust beneath the seismic belt, we estimated theseismic velocity structure there by seismic travel time tomography.
We carried out the tomography with the program, FMTOMO (Rawlinson et al., 2006). FMTOMO
implements wavefront tracking, which can trace rays robustly. The area of the velocity model contains Sanin, Sanyo, Shikoku and a part of Kinki district. The depth of the model extends 0-81 km. We used travel
times picked by Japan Meteorological Agency (JMA) for earthquakes that occurred in the study area. In
addition, we used the travel times manually picked for earthquakes that occurred within the Philippine Sea
Slab, because seismic waves from the earthquakes to stations in the San-in district pass through the lower
crust beneath the San-in district. We expect that the data can improve the resolution in the lower crust.
The tomography revealed that the lower crust beneath the seismic belt has low velocity anomalies andmight have low viscosity, since velocities of rocks decrease with temperature and/or water content.
Therefore, the results of this study support the model proposed by Iio et al. (2002, 2004).
Acknowledgement: We used JMA's earthquake catalogs. We also used waveform data from permanent
stations of National Research Institute for Earth Science and Disaster Resilience.

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*J05-P-12
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Depth dependence of stress field investigated from microseismicity innorthwestern Kii Peninsula, southwestern Japan* Sumire Maeda 1) , Toru Matsuzawa 1) , Keisuke Yoshida 1) , Shinji Toda 1) , Hiroshi Katao 2)
Tohoku University, Sendai, Japan 1) , Kyoto University, Uji, Japan 2)
The heterogeneous structure of the upper crust is one of the important factors controlling the earthquake
occurrence. Therefore, understanding the influence of the heterogeneous structure of the upper crust on
seismic activity leads to elucidating the process of the inland earthquake occurrence. To understand theabove, we investigated the relationship between seismic activity and heterogeneous structureaccommodating faults and fluids. In order to investigate the relationship between heterogeneous structureand seismic activity, the best study area is a region with high seismic activity. Thus, we selected thenorthwestern Kii Peninsula as the study area because of its high seismicity.
In this study, we focused on the seismic activity of the upper crust, and we investigated focal mechanism
solutions of the microearthquakes and stress field in detail.
The focal mechanisms determined in this study are categorized into three groups and the predominant
depths for the respective groups are different: 1) N-S tensional normal-fault type events mainly occur in theshallower part, 2) E-W compressional reverse-fault type at middle depths, and 3) N-S tensional and E-W
compressional strike-slip-fault type in the deeper part. We carried out stress tensor inversions and theresults also indicate that the stress field varies with depth: the shallower part is characterized by the strikeslip-fault type stress field of with N-S tension and E-W compression while the deeper part is the reversefault type with E-W compression.
The complicated distributions of focal mechanisms and stress mentioned above can be explained bythermal stress caused by a heat source in the lower crust and vertical weak planes related to the geologicalstructure.

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*J05-P-13
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Tectonic Loading of the Atera Fault inferred from Dense GNSS Observation* Koki Kumagai 1) , Takeshi Sagiya 2) 1) , Nobuhisa Matta 3)
Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan 1) , Disaster Mitigation
Research Center, Nagoya University, Nagoya, Japan 2) , Graduate School of Education, Okayama University,
Okayama, Japan 3)
he Atera Fault is in the east of Gifu Prefecture is a major active fault in Japan. The fault is left-lateral strike
slip in the NW-SE direction, consistent with E-W compressional stress. The geological slip rate is
2~4mm/year. However, a hydraulic fracturing experiment and the GEONET F3 solution suggested the
Atera Fault undergoes right-lateral displacement (Yamashita et al. 2010). We study crustal deformation andstress filed of the Atera Fault by GNSS observation and numerical modeling. We install dense GNSS
network near the fault trace with an average interval of several kilometers in order to reveal detailed crustal
deformation pattern. Based on GNSS daily coordinate from is January 2014 to October 2016, we calculate
average horizontal velocity at each GNSS site. The velocity pattern is dominated by the postseismic
deformation of the 2011 Tohoku-oki earthquake and interplate coupling at the Nankai Trough. We correct
overall deformation pattern in order to extract displacements related the fault activity. After the correction,a left-lateral displacement pattern is identified. Comparison with the elastic dislocation model showed that
our observation is consistent with geological estimated fault slip rate (2~4mm/year) and the seismologic
layer thickness (~15km). We also evaluate the topographic perturbation on the crustal stress filed under alithostatic equilibrium. The calculation suggests that the topographic effect is significant at shallow depth(~5km) and greatly affects the crustal stress pattern. The calculated maximum compressional axis at thehydraulic fracturing site depth of 350m is in the N-S with a differential stress of 2~4 MPa. The results
demonstrate that the motion of the Atera Fault is left-lateral, consistent with the regional stress filed. It isalso suggested that tectonic loading of a crustal fault does not change even under elastic perturbation due
to postseismic deformation and interplate coupling.

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*J05-P-14
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Spatio-temporal variation in Coda Q in the northeastern part of Niigata-Kobe
Tectonic Zone in 2009-2014* Masanobu Dojo , Yoshihiro Hiramatsu
Kanazawa University, Kanazawa, Japan
We focus on a high strain rate zone called Niigata-Kobe Tectonic Zone (NKTZ) (Sagiya et al., 2000) tounderstand a stress accumulation process in seismogenic zone. Jin and Aki (2005) showed that low coda Q
at low frequency bands corresponded spatially to the high strain rate zone. Hiramatsu et al. (2013) andTsuji et al. (2014) suggested that the cause of the high strain rate zone was attributed to the highdeformation rate below the brittle-ductile transition zone in the crust in the central part of the NKTZ. This
study investigates details of the spatial distribution of coda Q in the northeastern part of the NKTZ. We
have analyzed 646 events from January 2009 to February 2011 (period I) and 2194 events from January
2012 to October 2014 (period II).
We compare the data between the periods I and II. We applied t tests to analyze these temporal variations
and recognize that the variations are not statistically significant. These facts imply that the temporalvariation in coda Q caused by the 2011 earthquake is not significant in this study area.
The spatial distributions of coda Q at the 2-4 and 4-8 Hz frequency bands for periods I and II are found tobe negatively correlated with the differential strain rate (Sagiya et al., 2000; Nishimura 2015, personalcommunication). Positive correlations are found between the perturbation of the S-wave velocity (Nakajima
and Hasegawa, 2007) at 25 km depth and coda Q at the low frequency bands, and between theperturbation of the S-wave velocity at 10 km depth and coda Q at the middle frequency bands for both theperiods in this study area. These facts imply that the spatial distributions of coda Q at the low and middle
frequency bands reflect mainly the heterogeneity of the lower crust and the upper crust, respectively. We
suggest that the deformation in the upper crust, as well as the ductile deformation in the lower crust, may
be a dominant cause of the high strain rate in the northeastern part of the NKTZ.

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*J05-P-15
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

The gravity anomalies analysis over the active reverse fault zones in Japan* Nayuta Matsumoto 1) , Yoshihiro Hiramatsu 2) , Akihiro Sawada 2) , Shinsuke Okada 3) , Ryo Honda 4) ,Toshiyuki Tanaka 4)
Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan 1) , Institute of
Science and Engineering, Kanazawa University, Kanazawa, Japan 2) , International Research Institute ofDisaster Science, Tohoku University, Sendai, Japan 3) , Tono Research Institute of Earthquake Science,
Mizunami, Japan 4)
Our object is to examine subsurface features of the reverse fault zones and defines their faulting type,dipping direction, continuity and segmentation through gravity anomalies .In this study, we analyze 43
reverse fault zones in northeast Japan and the northern part of southwest Japan among major active fault
zones selected by Headquarters for Earthquake Research Promotion.
We compiled the gravity data published by the Gravity Research Group in Southwest Japan (2001), theGeographical Survey Institute (2006), Yamamoto et al. (2011), Honda et al. (2012), and the Geological
Survey of Japan, AIST (2013) in this study. We apply terrain corrections with 10 m DEM (Sawada et al.
2015) under the assumed density of 2670 kg/m3 and a band-pass filtering, then remove linear trend. We
calculate the derivatives and structural parameters from a gravity gradient tensor, such as a first horizontal
derivatives (HD), a first vertical derivatives (VD), a normalized total horizontal derivative (TDX), a dip angle(β), and a dimensionality index (Di),At 21 fault zones, the subsurface structural boundaries are highlighted clearly along the faults with thederivatives. The structural boundaries are partly detected at 13 fault zones and not detected at 9 fault
zones. At these 9 fault zones, gravity anomalies do not highlight the fault structures but they show low
anomaly basins, which restrict surface traces of the active fault zones.
We divide the results into several groups according to their faulting types, such as reverse faults,
reactivated reverse faults in which a reverse fault structure is dominant, reactivated reverse faults in whicha normal fault structure is still dominant, and normal faults with gravity anomalies of a trough structure.
The Nagano basin east margin fault zone is newly formed reverse faults in the sedimentary basin in the
Quaternary. However, gravity anomalies detect a normal faulting. We suggest that gravity anomalies detect
the east margin of the trough.

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*J05-P-16
Joint Symposium / J05. Crustal dynamics: Multidisciplinary approach to seismogenesis

Influence of water on rheological properties of feldspar aggregates under the
lower crustal temperature and pressure* Masanori Kido 1) , Jun Muto 1) , Sanae Koizumi 2) , Hiroyuki Nagahama 1)
Tohoku University, Sendai, Japan 1) , Earthquake Research Institute, The University of Tokyo, Tokyo, Japan
2)

Fluids in deep part of the crust have an important role in deformation and seismicity of the crust. However,experimental data of crustal materials under the lower crustal conditions are insufficient. In this study, we
performed high temperature and high pressure deformation experiments to reveal rheological properties offeldspars under hydrous conditions. Axial compression tests on synthetic polycrystalline anorthite with 0.5
wt% of water were performed in a Griggs-type solid medium apparatus at temperature of 900 deg C andvarious confining pressures of 0.8-1.4 GPa. Times were changed to investigate the reduction of strength byvolume and grain boundary diffusion of water into samples. Water contents in samples were measured by
an FTIR method. As a result, strengths of wet anorthite tended to decrease with increasing time or strain
magnitude. It was suggested that anorthite samples were still not saturated with water in time range of thisstudy. Strengths of wet anorthite also decreased with increasing confining pressures. Differential stresses
were significantly lower than predicted values by previous flow laws for wet anorthite obtained by low
pressure experiments (<0.5 GPa). This implies that the effect of fugacity of water on strength in higher
pressure might be larger than those predicted by lower pressure experiments. Our experiments show thatthe strength of hydrous regions in the lower crust becomes lower than that predicted by previous studies.

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*J06-1-01
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Numerical experiments on estimation of frictional properties and slip
evolution on the Bungo Channel Long-term SSE fault with Ensemble Kalman
Filter* Kento Nishikiori , Kazuro Hirahara
Kyoto University, Kyoto, Japan
Long-term Slow Slip Events (LSSEs) occur on the plate interface beneath the source regions of theinterplate large earthquakes. The activity of SSEs possibly changes before large interplate earthquakes andSSEs may directly trigger them. Our final goal is to estimate slip evolution and frictional parameters with
Ensemble Kalman Filter (EnKF), one of data assimilation methods. In this paper, we execute numericalexperiments for the Bungo Channel LSSEs, southwest Japan, before analyzing the actual GNSS observationdata.
Our previous experiments for the Yaeyama SSEs in the Ryukyu region showed that, for well recovery ofparameters and slip evolution with EnKF, the conditions are: 1)SSEs have been observed more than once,2)The duration of SSEs is long, 3)SSEs are observed at observation points with enough density andcoverage. Hence, we target at the Bungo Channel LSSEs which have occurred several times with theduration of about 1 year.
We set a dipping fault in a homogeneous elastic half space and assume a rate-state friction law and theslowness law of state evolution. We set a circular velocity-weakening patch (radius R=40km) on the fault
plane with frictional parameters so that R/Rc=0.9 (Rc: critical nucleation radius). We generate synthetic
observed data by adding random numbers to the simulated surface displacement rates and performed
EnKF estimations of the frictional parameters A and L on the fault plane and B-A on the patch along withthe slip rates and the state variables.
The results show that if the duration of SSEs is sufficiently longer than the assimilation step, update ismoderately performed and calculation does not stop. As long as we use a simple model, we can estimate
the frictional parameters on the fault with considerable accuracy for the actual GNSS (GEONET)
distribution.
In our current model, frictional parameters are uniform on the SSE patch. We need to perform numericalexperiments with more complicated models.

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*J06-1-02
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)Long-term slow slip events in the Tokai region, central Japan, before 2000
* Tadafumi Ochi
Geological Survey of Japan, Tsukuba, Ibaraki, JapanThe Tokai region, central Japan, has been subjected to many large earthquakes due to the interplate
coupling. In order to monitor the crustal deformation in the interseismic period, many kinds of geodetic
observations have been conducted. The dense GNSS observation network, named GEONET in Japan since
the mid-1990s maintained by Geospatial Information Authority of Japan (GSI), revealed two long-term slow
slip events (LSSEs) in the region; one was from mid-2000 to mid-2005 (e.g. Suito and Ozawa, 2009), andthe other was from early 2013 and seems to be still ongoing (Ozawa et al., 2016). Ozawa et al. (2016)
mentioned that the center of the the ongoing event is near Lake Hamana, which is the south of the centerof the 2000-2005 event, and the released seismic moment of the ongoing event will be smaller than the sizeof the 2000-2005 event. Their result suggests that the LSSEs in the Tokai region are repeating phenomena
with variation in size and occurring place.
In order to reinforce the suggestion, I analyzed leveling data from 1981 to 1999 and length change data
between 1974 and 1992, which were also obtained by GSI . The network adjusted leveling data show
fluctuation in the vertical displacement rate at the inland benchmarks with respect to the benchmark at
Omaezaki cape, the nearest site from the trench and show that at least two LSSEs around 1987-1990 and
1983. Compared with 2000-2005 event, the 1987-1989 event is smaller and the 1983 event is the smallest.
The 1987-1990 event shows clearer difference in vertical the displacement pattern with respect to that of
the 2000-2005 event. It support the possibility of the variation in the occurring place. Although a simple
forward modeling using rectangular source fault for the 1987-1990 event show that the amount of released
seismic moment was about Mw 6.6, which was smaller than the 2000-2005 event done, the model cannot
explain the difference in displacement pattern and more sophisticated model is required.

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*J06-1-03
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Correlation between Coulomb Stress Rate Change Imparted by Two Slow
Slip Events and Seismic Rate Change in Lower Cook Inlet of the AlaskaAleutian Subduction Zone
Shanshan Li 1) , * Jeffrey Freymueller 1) , Jianjun Wang 2) , Natalia Ruppert 1)
University of Alaska Fairbanks, Fairbanks, USA 1) , Wuhan University, Wuhan, China 2)
We identified two long-term slow slip events (SSEs) in Lower Cook Inlet, southcentral Alaska(1995.0-2004.8 and 2009.85-2011.81) by inverting the GPS site velocities (Li et al. 2016). The earlier SSE(SSE1) lasted at least 9 years with Mw~7.8 and an average slip rate of ~82 mm/yr. The latter SSE (SSE2)
had almost the same area as the earlier one, which is within 40-60 km depth range, and a duration of ~2
years with Mw~7.2 and an average slip rate of ~91 mm/yr.
In order to see whether SSEs can trigger earthquakes outside the slow slipping area significantly andcontribute to the early earthquake warning, we resolved the Coulomb stress rate changes on receiver faults
in the crust and the slab using two different potential definitions for them. Our results showed that thesignificantly higher stress rate during SSE1 caused a significant decrease in the seismicity rate after SSE1
ended. However the area in the slab that experienced significant increasing stress rate change due to SSE1
slip did not show a clear pattern of decreasing seismic rate after SSE1 ends. No significant increasingstress rate change area influenced by SSE2 was identified in the crust. The area that experienced asignificant increase in stress rate in the slab due to SSE2 slip had a seismicity rate increase right after the
SSE2 started and seismic rate decrease after the SSE2 ended.
We also modeled the seismicity in potential triggering areas by using the rate/state stress transfer model(Dieterich, 1994). The observed seismicity can be well fitted with the increase in stress rate of the SSE1
period comparing with the one in the post-SSE1 period. But the stress rate due to slip from SSE2 was notlarge enough to explain the cumulative seismicity through time. Explaining the post-SSE2 seismicity ratechange requires some additional stress rate change such as an increasing slab pull stress rate after the SSE
started instead of a uniform slab pull stress rate over all time periods.

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*J06-1-04
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Insights into the Causal Relationship between Slow Slip Events and Tectonic
Tremors in Guerrero, Mexico* Carlos Villafuerte , Victor Cruz-Atienza
Instituto de Geofisica, UNAM, Mexico
Similar to other subduction zones, tectonic tremors (TT) and slow slip events (SSE) take place along thedeep segment of the plate interface in Guerrero. However, their interaction in this region is not as clear as
the Episodic Tremor and Slip observed in Cascadia and Japan. In this study we provide insights into suchinteraction analyzing the evolution of the deformation fields induced by the long-term 2006 SSE together
with independent new locations of TTs and low-frequency earthquakes (LFE). Unlike previous studies wefind that the SSE slip rate is the parameter that modulates the TT and LFE occurrence rate in the whole
tremor region. This means that the causal relationship between the SSE and the TT activity directly
depends on the stressing rate history of the locked asperities that is modulated by the SSE slip rate. We
have estimated that the frictional strength of the asperities radiating tremor downdip in the Sweet Spot isaround 32 kPa, which is ~2.2 times smaller than the corresponding value updip in the Transient Zone,
partly explaining the overwhelming tremor activity of the Sweet Spot despite that the slow slip there isalmost three times smaller. Based on the LFEs occurrence rate history during the inter-SSE period wedetermined that the short-term SSEs in Guerrero take place further downdip (about 35 km) than previously
estimated, with maximum slip of about 8 mm overlapping the Sweet Spot. This new model features acontinuum of slow slip extending across the entire tremor region of Guerrero.

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*J06-1-05
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

EFFECTS OF THE GEOMETRY OF THE MEXICAN SUBDUCTION ZONETECTONIC-INTERFACE ON THE STRESS TRANSFER DUE TO
INTERPLATE SLIP EVENTS.
* Miguel Angel Santoyo 1) , Vladimir Kostoglodov 2) , Carlos Mendoza 3)
Institute of Geophysics U. Michoacan, National Autonomous University of Mexico, Morelia, Mexico 1) ,Institute of Geophysics, National Autonomous University of Mexico, Mexico City, Mexico. 2) , Center ofGeosciences, National Autonomous University of Mexico, Queretaro, Mexico. 3)
We analyze in this work the effects of the tectonic interface geometry of the Mexican subduction zone on
the coulomb stress transfer produced by large interplate earthquakes and slow slip events, using a 3D
subducting slab model and explicit slip distributions. The interface geometry used here was previously
obtained based on seismicity depth profiles along the subduction zone. As a reference for the assessments,
we first obtained the stress change over extended fault planes; for slow slip events we considered threeplane segments with different dip angles and for earthquakes (M<8.0) we used a single extended fault
plane. Next we computed the stress transfer for the same slip distributions along the 3D interface. In allcases the interface surface was discretized by 2.0Km x 2.0Km segments, setting the observing points along
the same surface in a staggered-type grid, avoiding in this way possible singularities. Stress tensor changes
were computed for a 3D half-space, and analyzed using the Coulomb Failure Stress criterion. The stresschanges due to each subfault from each earthquake were computed on each grid segment of the interface
and resolved along its specific normal and slip directions. This computation procedure implied that for agiven earthquake, or slow slip event with a specific slip distribution, the coulomb stress change distribution
could vary depending on its relative location along the surface. Results are presented and compared for theplane segments and the 3D tectonic interface. The stress changes inside the main rupture patches showed
relative small variations between both assumptions; however, relatively larger variations could be foundoutside the main patches, especially where the interface presented bendings along the strike or dip
directions. Results suggest that the assumption of planar tectonic surfaces should be carefully explored forthis kind of analyses in this region

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*J06-1-06
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Laboratory observations of slow stick slip: implications for slow earthquakes
and the spectrum of fault slip behavior* Marco Maria Scuderi 1) , Elisa Tinti 2) , Cristiano Collettini 1)
La Sapienza University of Rome 1) , Istituto Nazionale di Geofisica e Vulcanologia (INGV) Rome 2)
Seismic and geodetic observations show that fault slip occurs via a spectrum of behaviors that include slow
earthquakes and tectonic tremor. These phenomena have been observed in a variety of tectonic
environments worldwide, however the underlying processes are poorly understood. Here we show resultsfrom lab experiments on simulated fault gouge. We used the double direct shear configuration and varied
the loading system stiffness (k) to produce the full spectrum of stick-slip behaviors, with durations ranging
from 10-3 to 1 second. We measured frictional rheology and elastic wave properties throughout the stickslip cycle for slow and fast events. At the end of the experiments we also collected the resulting fault zone
microstructure. When the loading stiffness is greater than the fault zone critical rheologic stiffness (kc) weobserve stable frictional sliding. For k≈kc we document emergent slow-slip events from steady shear. Whenkc>k we observe audible stick-slip. Stick slip stress drop and event duration vary systematically as afunction of the ratio k/kc. For both slow- and fast- slip events, P-wave velocity (Vp) begins to decrease prior
to the stress drop and the maximum slip velocity during failure coincides with the largest drop in Vp.
Microstructural observations show that with accumulated strain, deformation localizes along sharp shear
planes consisting of nanometric grains, which favor the development of frictional instabilities. Once thisfabric is established, fault fabric does not change significantly with slip velocity, and fault slip behaviour ismainly controlled by the interplay between fault rheological properties and the stiffness of the loading
system. As applied to tectonic faults, our results suggest that a single fault segment can experience a
spectrum of fault slip behaviour depending on the evolution of fault rock frictional properties and elastic
conditions of the loading system.

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*J06-2-01
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Completing the Seismic Cycle: Approaching 100% slip recovery along the
subduction megathrust beneath Nicoya Peninsula, Costa Rica
* Andrew Newman 1) , Christodoulos Kyriakopoulos 2) , Tiegan Hobbs 1)
Georgia Institute of Technology, Atlanta, Georgia, USA 1) , University of California Riverside, Riverside,
California, USA 2)
The seismogenic megathrust beneath the Nicoya Peninsula exhibits magnitude 7.5+ earthquakes
approximately every 50 years directly under land. Because of this, there have been numerous geophysicalstudies there including the Nicoya Seismic Cycle Observatory (NSCO) consisting of dense seismic and GPS
networks cooperatively operated by UC Santa Cruz, Georgia Tech, U. South Florida, and OVSICORI. As
detailed by a recent high-resolution 3D slab interface model by Kyriakopoulos et al. [JGR, 2015], themegathrust environment below Nicoya has strong along-strike transitions in oceanic crust origin andgeometries, including massive subducted seamounts, and a substantial crustal suture. Using GPS datacollected from campaign and continuous sites over the past two decades numerous studies have imaged
components of the seismic cycle, including late-interseismic coupling, frequent slow-slip events, coseismic
rupture of a moment magnitude 7.6 earthquake in 2012, and now several years of postseismic response.
We report on a reanalysis of all slip behavior measured through this time, using the 3D geometry andconsistent inversion methods to reveal a unified analysis of the full continuum of slip. We find that the lateinterseismic locking that was observed in the decade prior to the major earthquake, accurately reflects the
combination of episodic slow slip (contributing to weak to low-coupling zones), major coseismic rupture(contributing dominantly to the strongly locked patch), and afterslip (contributing to a combination ofstrongly locked zone transitioning to intermediately weak behavior). After accounting for all slip observed,
little energy is left for significant earthquake behavior, suggesting that the fault has indeed released nearly
its full potential, and likewise adding additional credence to the hypothesis that the megathrustenvironment is weak. Without the long-term and continuous geodetic observations made by the NSCO, thiswork would not have been possible.

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*J06-2-02
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Anomalous gravity changes observed during long-term slow slip events anda possible interpretation based on fluid flow
* Yoshiyuki Tanaka 1) , Yuichi Imanishi 1) , Shuhei Okubo 1) , Kazunari Nawa 2) , Yoshiaki Tamura 3) , Kenji
Yoshida 4)
Earthquake Research Institute, The University of Tokyo, Tokyo, Japan 1) , Institute of Geology andGeoinformation, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan 2) ,Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, Iwate, Japan 3) , Geodetic
Department, The Geospatial Information Authority of Japan, Tsukuba, Japan 4)
Slow-slip events (SSEs) have been observed in many plate boundary zones along the circum-Pacific seismic
belt. Previous studies have revealed that high-pressure fluids supplied from the subducted oceanic plate
can generate SSEs. However, the behavior of these fluids during an SSE has not been fully elucidated. In
this presentation, we discuss a possibility of fluid migrations along the plate interface on the basis ofspatiotemporal gravity changes observed by absolute and superconducting gravimeters during recent longterm SSEs in Japan, including those in the Tokai district, the Bungo Channel, and the Yaeyama Islands. The
limited spatiotemporal resolutions of the gravity data and uncertainties due to hydrological disturbances
preclude us from attributing the gravity changes to the SSEs uniquely. However, after removing theapparent effects due to vertical deformation of the observation sites, there still remain anomalous gravity
changes with the order of 1 microGal (10^-8 ms^-2) over the periods of the SSEs. A simple fluid flow modelthrough a fault fracture zone employing Darcy's law predicts gravity variation of 1 microGal/year for achange of 0.6 MPa (=0.1% of the lithostatic minus hydrostatic fluid pressure at a depth of 30 km) and apermeability value of 2 x 10^-11 m^2. The latter is a lower limit for which the rupture becomes slow,
obtained by a numerical simulation based on a poroelasticity theory (Yamashita, 2013). These results
indicate that the observed anomalous gravity changes can be associated with fluid pressure variations inthe slow slip areas. We will continue gravity observations, which is needed to exclude possibilities thathydrological disturbances coincidentally cause these anomalies.

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*J06-2-03
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Meaning and prospect for science of slow earthquakes* Kazushige Obara
Earthquake Research Institute, The University of Tokyo, Tokyo, Japan
Slow earthquake is a general term for low-speed fault slip phenomena compared to ordinary earthquake.
Slow earthquakes with wide range of characteristic times have been discovered since around the end of the20th century by densely distributed seismic and GNSS observation networks in Japan then detected inmany subduction zones along the circum-Pacific. During the last two decades we have recognized that theslow earthquakes were not special events at each region but common phenomena. Deep low frequency
tremor and short-term slow slip event (SSE) were independently discovered at Nankai and Cascadia
subduction zones, respectively, after that the coupling phenomena of episodic tremor and slip (ETS) weredetected in both regions. Deep very-low frequency (VLF) earthquake associated with ETS was firstly
detected in Nankai, after a while also detected in Cascadia. Based on recent marine temporal observation
at the western Nankai trough region, shallow tremor has been discovered in association with alreadyknown shallow VLF event like as deep ETS. Therefore, one of our next research targets is to find shallow
SSE which is expected to host shallow tremor and VLF. Detailed comparison between shallow and deep
slow earthquakes will bring new geological and physical constraints for the similar frictional property at thedifferent thermal and pressure regimes. In future, understanding activity mode, environment, andmechanism of slow earthquakes will contribute to development of Earth science in the following three
viewpoints. One is to reconstruct the new comparative subductology based on quantitative comparison
study of slow earthquakes at different subduction zones. Second is to reconstruct the approach ofearthquake science based on a unified understanding of slow deformations and fast slips. Third is tocontribute to advanced evaluation for the occurrence of megathrust earthquake based on understanding
mutual interaction between slow and huge earthquakes.

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*J06-2-04
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Emergence and disappearance of interplate repeating earthquakes after the2011 Tohoku-oki earthquake: transition between slow slip and earthquakes* Naoki Uchida 1) , Norishige Hatakeyama 1) 2) , Toru Matsuzawa 1) , Wataru Nakamura 3)
Tohoku University, Sendai, Japan 1) , Now at Mitsubishi Research Institute, Inc, Tokyo, Japan 2) , Japan
Meteorological Agency, Tokyo, Japan 3)
We investigated spatio-temporal changes in the interplate seismic activity following the 2011 Tohoku-oki
earthquake (M9.0) in the region where large postseismic slip was observed. We selected interplate
earthquakes by their focal mechanisms and conducted hypocenter relocation to examine the detailed
spatiotemporal distribution of interplate earthquakes. The results show that many interplate earthquakes,
including M~6 events, emerged immediately after the Tohoku-oki earthquake in areas where weakinterplate locking and very few interplate earthquakes had been observed before the Tohoku-oki earthquke.
The emergent earthquakes include repeating sequences, and the extremely long quiescence of small tomoderate earthquakes before the Tohoku-oki earthquake suggests that the source areas for the post-M9
M~6 events slipped aseismically during the quiescence. The repeaters' magnitudes decayed over time
following the Tohoku-oki earthquake and some sequences disappeared within a year. The emergence ofinterplate earthquakes suggests that regions where aseismic slip had been dominant, started to cause
seismic slip and the disappearance suggest the regions became aseismic again. Such behaviors can beinterpreted by conditional stability of faults that show instability when the fault loading rate inclease. We
consider coseismic increase of loading rate and subsequent decrease by the afterslip of the Tohoku-oki
earthquake caused the aseismic-seismic-aseismic transitions. This indicates that the conditaional stability
play an important role in the spatio-temporal distribution of earthquakes in interplate seismogenic zones.

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*J06-2-05
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Spatio-temporal distribution of earthquakes around the subducted seamountoff Ibaraki in response to the largest Mw7.8 aftershock of the 2011 Tohokuoki earthquake* Kimihiro Mochizuki 1) , Shinji Yoneshima 1) 2) , Tomoaki Yamada 1) , Masanao Shinohara 1)
The University of Tokyo, Tokyo, Japan 1) , Ishikawajima-Harima Heavy Industries Co., Ltd. 2)
M7 class earthquakes have repeatedly occurred ~100 km offshore of the Ibaraki prefecture at fairly
constant time interval of 20 years. It has been revealed that there exists a subducted seamount up-dip of
the source region of such repeating M7 earthquakes (Mochizuki et al., 2008). The region coincides with thesouthern limit of the fault region of the 2011 Tohoku-oki earthquake, where its largest aftershock with
Mw7.8 occurred 30 minutes after the main shock.
We collected one-year long seismic data using 31 ocean bottom seismometers around the subduction frontof the subducted seamount at a spatial interval of ~6 km from October, 2010, through September, 2011. In
the middle of the observation period, the 2011 Tohoku-oki earthquake and its largest aftershock occurred.
The epicenter of the largest after shock is located only ~30 km to the west (donw-dip) of the array, and its
rupture propagated up-dip toward the seamount. Recent studies on its rupture propagation (Honda et al.,2013; Kubo et al., 2013) revealed that the rupture stopped before the subducted seamount so that its
rupture occupies the area in subduction front of the seamount.
More than 20000 earthquakes around the OBS array were recorded. Visual identification and manual
picking of P and S arrivals through the records of ~30 stations are unrealistic. Therefore, we applied an
automatic picking method that we developed by referring to Grigoli et al. (2014). Having 3-D seismic
velocity structure around the region compiled by referring to the existing seismic profiles, we successfully
determined the hypocenter of each event by finding a grid point with the maximum semblance value in themodel volume.
The resulted distribution of the earthquakes shows two primary layers of seismicity. The upper layer may
represent distribution of small scale faults above the seamount. We found seismically quiet region in frontof the subducted seamount that appears consistent with the rupture area of the largest aftershock.

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*J06-2-06
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Seismic quiescence of deep very low frequency earthquakes from later 2014
in western Shikoku, Japan* Satoru Baba 1) , Akiko Takeo 1) , Aitaro Kato 1) , Takuto Maeda 1) , Kazushige Obara 1) , Takanori Matsuzawa
2)Earthquake Research Institute, The University of Tokyo, Tokyo, Japan 1) , National Research Institute for
Earth Science and Disaster Resilience, Tsukuba, Japan 2)
Deep very low frequency earthquakes (VLFEs) are frequently associated with episodic tremor and slip
(ETS) at the downdip region of the megathrust seismogenic zone along the subducting plate interface (Itoet al., 2007; 2009). As a member of slow earthquake family associated with slow slip, VLFE activity is
expected to be a proxy of interplate slipping. However, the time change of the deep VLFE seismicity has
not been investigated well compared to deep low frequency tremor (e.g., Obara et al., 2010). In this study,
we investigated long-term changes of the activity of deep VLFEs in western Shikoku where ETS and longterm slow slip event (SSE) frequently occurred.
We used continuous seismograms of 13 F-net broadband seismometers operated by National ResearchInstitute for Earth Science and Disaster Resilience (NIED) from 2nd April 2004 to 29th September 2016.
After applying the band-pass filter with a frequency range of 0.02—0.05 Hz, we adopted the matched-filter
technique (Shelly et al., 2007) in detecting VLFEs. The synthetic waveforms calculated by the wavenumber
integration method (Takeo, 1987) with the fault mechanisms obtained by Ide and Yabe (2014) at multiple
grid points in the Bungo channel and its neighboring inland region are used for templates. We defined thedetection threshold as eight times as large as the median absolute deviation (MAD) of the distribution.
We detected 700—1000 VLFEs at each grid point for 12 years. In inland region, the cumulative number ofdetected VLFEs increases steeply every half a year. This stepwise change is caused by ETS. In the Bungo
channel, the cumulative number of detected VLFEs increases gradually in 2010 and 2014 influenced bylong-term SSEs. Interestingly, the activity of deep VLFEs has been low since the latter half of the year 2014
in this region. The long-term SSEs in 2014 may influence the seismic quiescence of VLFEs.

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*J06-3-01
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Rapid Tremor Migration Induced by Pore Pressure Waves* Victor M. Cruz-Atienza 1) , Carlos Villafuerte 1) , Harsha Bhat 2)
Instituto de Geofisica, UNAM, Mexico 1) , Ecole Normale Superieur, Paris, France 2)
Observations in different subduction zones suggest that overpressured fluids close to the plate interface
may be linked to the origin of tectonic tremors (TT) and low frequency earthquakes (LFE). Fluids at nearlylithostatic pressures within the top few kilometers of the oceanic crust have been inferred in several
subduction zones, including the state of Guerrero, Mexico. The actual effect of fluid diffusion on fault zones
may strongly affect the seismicity rate by inducing transient changes in the effective fault-normal stresses.
These changes propagate slowly (i.e., ~50 meters per day or 0.002 km/h) during fluid-injection tests in theupper crust. However, when fluids are subject to nearly lithostatic pressures at depth (i.e., ~40 km), small
pore pressure gradients may induce large transient variations of the permeability that, under someconditions, produce solitary pressure waves propagating much faster across the fault zone. Recent TT
epicentral locations in Guerrero using the Tremor Energy and Polarization (TREP) method (Cruz-Atienza etal., JGR, 2015) show that sources of these events migrate with speeds ranging between 10 and 80 km/h
during slow slip events (SSE). Migration directions change with time, so they are first parallel to the slow
slip front as observed in other subduction zones. However, latter migration directions are different andconsistent with the pore pressure gradient induced by the slow slip, as predicted by our poroelastic
modeling of SSEs in Guerrero. A parametric study of the governing non-linear diffusion equation showsthat pore pressure waves propagate, under realistic conditions (as settled by experimental rock tests), withthe same speeds as those observed for the rapid tremor migrations (RTM) in Guerrero, Cascadia and Japan.
This result suggests that physical conditions surrounding the plate interface (such as pore pressure
gradients) are likely to produce pressure waves, and that these waves may be responsible for the RTM.

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*J06-3-02
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Comprehensive detection of low frequency tremor triggered by teleseismic
surface waves in northern Kii and western Shikoku, southwest Japan* Ryo Kurihara , Kazushige Obara , Akiko Takeo , Takuto Maeda
Earthquake Research Institute, The University of Tokyo, Tokyo, Japan
Deep low frequency tremor is sometimes triggered by surface waves from teleseismic events. Such tremor
is called as triggered tremor. In this study, we investigated finer spatiotemporal characteristics of triggered
tremor to reveal its activity. We applied matched filter technique to detect triggered tremor in northern Kii
and western Shikoku area in southwest Japan, where triggered tremor episodes were observed many times.
We used waveforms of low frequency earthquakes based on the JMA hypocenter catalog as templates oftremor. We analyzed NIED Hi-net waveform data for 67 teleseismic events with magnitude larger than 7.5
after Dec. 26, 2004.
As a result, triggered tremor episodes were observed at 9 and 15 teleseismic events in northern Kii and inwestern Shikoku, respectively. The activity area was limited in one spot in northern Kii. In western Shikoku,
two spots were activated by several teleseismic events, and either one of the two was by other events.
Along-dip migrations of triggered tremor were observed in both areas. Migration speed of triggered tremor
is about 10 km/h in northern Kii and about 40 km/h in western Shikoku. In northern Kii, the directions of
migrations are same in all cases. In western Shikoku, both up-dip and down-dip migrations were observed.
Although the estimated migration speed is much faster than that of episodic tremor and slip, about 10
km/day, tremor migration with similar speed to our result has been reported during non-triggered tremor inprevious studies. In northern Kii, migration speed of triggered tremor is similar to rapid tremor reversal andrapid tremor forward (Houston et al., 2011). In western Shikoku, migration of triggered tremor is similar to
rapid streak (Ghosh et al., 2010).
We considered models of the migrations of triggered tremor based on previously proposed models. The
fluid model (Ghosh et al., 2010) and tremor asperity model (Ando et al., 2012) may be reasonable for
migrations of triggered tremor.

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*J06-3-03
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Analyzing tectonic tremor and low-frequency earthquakes' activity inwestern Shikoku using automatic detection and location scheme* Natalia Poiata 1) , Jean-Pierre Vilotte 2) , Kazushige Obara 3) , Pascal Bernard 2)
National Institute for Earth Physics, Romania 1) , Institut de Physique du Globe de Paris, France 2) ,Earthquake Research Institute, University of Tokyo, Japan 3)
Slow earthquakes, spanning a wide range of duration and amplitude scales, unify a broad class of events
generating seismic signals that are significantly different from classical earthquakes. These events include
weak, long-duration and low-amplitude, nonstationary signals such as tectonic tremors, low-frequency
earthquakes and very-low frequency earthquakes. While the physical mechanism underlying the generationof slow earthquakes is not fully understood, they are considered to represent different manifestations of thesame process associated with fluid-enabled shear transients at brittle–ductile transition zones of active
faults. The ability to outline in fine detail the space-time pattern of slow earthquakes' energy release activity
and to clarify the relationship between its different components represents a key to understanding thephysics of underlying phenomena.
We present here an automatic scheme for detection and location of tectonic tremor and low-frequency
earthquakes based on the method of Poiata et al. (2016). The method is a computationally efficient arraytype detection and location scheme making use of multi-scale, frequency-selective coherence of signals'
statistical features recorded across the stations of seismic network. We demonstrate the efficiency of theautomatic scheme in detecting large number of low-frequency earthquakes during the energetic tectonic
tremor sequences in western Shikoku and providing the details about their space-time activity patterns (i.e.,
migration and tidal modulation). The obtained low-frequency earthquake catalogs are compared against theexisting tectonic tremor catalogs, as well as the catalog of low-frequency earthquakes provided by JMA. We
also discuss the potential capabilities of the developed system to provide a basis for continuous monitoring
and characterisation of tectonic tremor and low-frequency earthquakes' activity.

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*J06-3-04
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)Continuous S-wave signals following 2014 Mw 6.8 SSE in the Hikurangi
subduction margin offshore New Zealand* Yuriko Iwasaki 1) , Kimihiro Mochizuki 1) , Motoko Ishise 1) , Erin Todd 2) , Susan Schwartz 2) , Stuart
Henrys 3) , Martha Savage 4) , Anne Sheehan 5) , Yoshihiro Ito 6) , Laura Wallace 3) 7) , Spahr Webb 8) ,Tomoaki Yamada 1) , Masanao Shinohara 1)
The University of Tokyo, Tokyo, Japan 1) , The University of California Santa Cruz, Santa Cruz, California 2) ,GNS Science, Lower Hutt, New Zealand 3) , Victoria University of Wellington, Wellington, New Zealand 4) ,University of Colorado–Boulder, Boulder, USA 5) , Kyoto University, Kyoto, Japan 6) , University of Texas
Institute for Geophysics, Austin, USA 7) , Columbia University, Palisades, USA 8)
From May, 2014, for about a year, marine seismic and geodetic experiment was conducted at the Hikurangi
subduction margin. During this experiment, a Mw 6.8 SSE occurred from September through October,
2014, directly beneath the ocean bottom seismometer (OBS) network (Wallace et al., 2016). In this study,
we used continuous waveform data recorded by these OBSs, and applied an S-wave splitting analysis(Ando et al., 1983) and a polarization analysis for monitoring S-wave signals. These methods have beensuccessfully applied to waveform data from onshore seismic networks (Bostock and Christensen 2012;
Ishise and Nishida 2015).
As a result, we detected the continuous arrival of S-wave signals that appeared to have started in the later
half of the SSE. This continuous signal was identified as tremor and its source location was determined by
the envelope cross-correlation method (Todd et al., 2017, in prep). Our result, however, suggests that thesesignals occur continuously rather than as sporadic individual events, and that they last for more than two
weeks. Polarization directions change at the same time and remained stable through the two week duration.
Our analysis requires less OBSs than other methods for monitoring such S-wave signal, which may enable
us to detect as yet unidentified signals in the Hikurangi margin where seismic attenuation has been known
to be large. Distribution of the OBSs detecting such continuous signals suggests that they were generated
only around the subducted seamount adjacent to the slow slip area. This is consistent with the location ofindividual tremors identified with envelope cross-correlation methods (Todd et al., 2017, in prep). The slow
slip along the plate interface circumvented the subducted seamount (Wallace et al., 2016). By considering
our result with the slip distribution, we can put more constraints on relationship between frictional
properties along the plate interface and its topographic features.

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*J06-3-05
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Micro low-frequency tremor activity near Japan Trench* Satoshi Katakami 1) 2) , Yoshihiro Ito 2) , Kazuaki Ohta 2) , Ryota Hino 3) , Shuichi Suzuki 3) , Masanao
Shinohara 4)
Kyoto University, Kyoto, Japan 1) , Disaster Prevention Research Institute Kyoto University, Kyoto, Japan 2) ,Tohoku University, Miyagi, Japan 3) , The University of Tokyo, Tokyo, Japan 4)SSEs and low-frequency tremor have been observed near the trench by using ocean bottom observations,and these have been located in the updip portion of a coseismic slip area [Wallace et al., 2016; Yamashita
et al., 2015]. In addition, Ito et al. [2015] observed tremor sequences from the excitation of ambient noise
amplitude, accompanied with SSE in the source area of the Tohoku-Oki earthquake's mainshock. However,the signals observed within these sequences showed very weak amplitude and were observed at only one
station, nearest to the Japan Trench. Here, we report on our detection of micro low-frequency tectonic
tremor (mLFT) activity prior to the 2011 Tohoku-Oki earthquake near the Japan Trench by using modified
frequency scanning method (mFSM) as applied to ocean bottom seismometers (OBSs) at a single station.
The original frequency scanning method [Sit et al., 2012] proposed a tremor detection method of
calculating envelope waveform ratios through different bandpass filters of broadband data in the Cascadia
margin. We modified this analysis for short period OBS seismic data recorded at 17 OBSs deployed in anarea near the trench axis offshore Miyagi Prefecture, northeast Japan. Three bandpass filters of 2–4 Hz,
10–20 Hz, and 0.5–1.0 Hz, corresponding to the dominant frequency band of tremors, local earthquakes,
and ocean noise, respectively, were applied to the OBS records for a period between November 19, 2010
and March 9, 2011.
The results of applying the mFSM show three major tremor sequences, suggesting tremor activity in theshallowest part of the subduction zone. The sequences agree with the results of Ito et al [2015].
Furthermore, we successfully detected tremors at landward stations in the second sequence. We estimatedthe energy release from the envelope amplitude of two horizontal components filtered at 2-4Hz after
removing site effects. The energy estimates are in general very weak, compared with tremors typicallyobserved in other regions.

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*J06-3-06
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Rheologically controlled spatial separation of the megathrust seismogenic
zone and the zone of Episodic Tremor and Slip
* Kelin Wang 1) , Xiang Gao 2)
School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada 1) , Institute of
Oceanology, Chinese Academy of Sciences, Qingdao, China 2)
Episodic Tremor and Slip (ETS) is the most peculiar type of slow slip event. While slow slips of various
durations and magnitudes occur at all tectonic environments, ETS is the most abundant in subduction
zones of young and warm subducting slabs such as Cascadia, Nankai, and Mexico. Adding to the peculiarity
is a tendency to be confined to a narrow depth range around the tip of the mantle wedge. If the ETS zone isassumed to represent a transition from seismic to aseismic behavior, its spatial separation from theseismogenic zone makes it even more peculiar. Here we propose a thermo-rheological model to explain allthese peculiarities, especially the separation of the two zones. The model consists of the following key
components. (1) The dehydrating slab supplies ample fluids at shallow depths. (2) The tip portion of the
mantle wedge is fully serpentinized, and slab-derived fluids precipitates large amounts of silica further
updip. (3) Resultant permeability reduction around the wedge tip leads to locally very high pore-fluidpressure (Pf). (4) The seismogenic frictional behavior of the megathrust is terminated at a depth muchshallower than the wedge tip. (5) But the very high-Pf around the mantle wedge tip gives rise to another,
isolated friction zone responsible for ETS. (6) Separating the seismogenic and ETS zones is a segment ofsemi-frictional or viscous behavior that can produce long-term slow slip events. Using numericalcalculation, we show that warm slabs provide favorable conditions for components (1), (2), and (4), leading
to components (3), (5), and (6). We also show that under special geological circumstances, similar
conditions may occur and promote ETS-like phenomena even without a warm slab, such as in Hikurangi, oreven not in a subduction zone, such as along the San Andreas Fault. The new model reconciles a wide
range of seemingly disparate observations and defines a new framework for the study of slip behaviour andseismogenesis of major faults.

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*J06-4-01
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Renovated 3D image of Nankai accretionary wedge and shallow seismogenic
zone off Kumano through reprocessing of 3D seismic data
* Masataka Kinoshita 1) 2) , Kazuya Shiraishi 2) , Greg Moore 3) , Yasuhiro Yamada 2) , Gaku Kimura 4)
Earthquake Research Institute, Unv. Tokyo 1) , JAMSTEC 2) , Univ. Hawaii 3) , Tokyo University of Marine
Science and Technology 4)
For the next stage of the deep scientific drilling in Nankai Trough seismogenic zone off Kumano, it isessential to obtain precise structural image and depth estimation around the mega-splay and the plateboundary fault, as well as fine structures in accreted sediments around the drilling site. In 2006, three
dimensional multi-channel seismic data acquisition and processing were carried out. However, theobtained data could not necessarily resolve deep structures due to relatively short (4.5 km) streamers anddue to the strong Kuroshio current.
In order to obtain the clearer depth image for the next deep drilling target, we decided to reprocess a partof the 3D volume with today's advanced technology. First, preprocessing with recent technologies ofmultiple elimination and broadband processing was applied in order to clarify reflection signals. Second,
the pre-stack time migration for time domain imaging, the sophisticated velocity model building in depth
domain, and the pre-stack depth migration were carried out to obtain the fine depth image.
Improved images in the shallow accretionary wedge reveal dynamic deformation features (e.g. branching of
splay faults, thrusting of the lower Shikoku Basin formation, BSRs). Lower Shikoku Basin formation below
the forearc slope area show anomalously low Vp, consistent with estimation by Park et al. (2010 Geology).
Additional reflectors above decollements are identified in the formation.
Low Vp zone (<4km/s) spreads beneath the splay fault and above the top of oceanic crust, consistent with
Kamei et al. (2012).
3D geometry of the megasplay fault below the southeastern Kumano Basin indicates a bending downward
feature in its southeastern rim of reprocessed area. This bent area is overlain by an anomalously high-Vp
volume (>5 km/s). We also identify a couple of landward-dipping reflectors in this high-Vp region. Carefulinspection will modify or add these preliminary interpretations.

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*J06-4-02
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Evaluation of rock evolution process in seismogenic fault: Dynamic wave
propagation modeling to the digitalized fault rocks* Chandoeun Eng 1) , Tatsunori Ikeda 2) , Takeshi Tsuji 1) 2)
Earth Resources Engineering, Kyushu University, Fukuoka, Japan 1) , International Institute for CarbonNeutral Energy Research (I2CNER), Kyushu University, Fukuoka, Japan 2)
To understand the characteristics of the Nankai seismogenic fault in the plate convergent margins, we
calculated the P- and S-wave velocities (Vp and Vs) of digital rock models constructed from core samples ofan ancient plate boundary fault at Nobeoka in Kyushu, southwest Japan. We first constructed 3D digitalrock models from micro-CT images and identified their heterogeneous features (cracks or veins). We
replaced the cracks and veins with air, water, quartz, calcite, and other materials with different bulk andshear moduli. Using the Rotated Staggered Grid Finite-Difference Method, we performed dynamic wave
propagation simulation and quantified the effective Vp, Vs, and the ratio of Vp to Vs (Vp/Vs) of the 3D
digital rock models with different crack-filling minerals. Our results demonstrate that the water-saturated
cracks considerably decreased the seismic velocity and increased Vp/Vs. The Vp/Vs of the quartz-filledrock model was lower than that in the water-saturated case and calcite-filled rock model. By comparing theelastic properties derived from the digital rock models with the seismic velocities (e.g., Vp and Vp/Vs)
around the seismogenic fault estimated from field seismic data, we characterized the evolution of the deep
seismogenic fault. The high Vp/Vs and low Vp observed at the transition region from the aseismic toseismic regimes in the Nankai Trough are caused by open cracks (or fractures) while the low Vp/Vs andhigh Vp at the coseismic region suggests quartz-filled cracks. The results indicate that a great earthquake
could occur in the coseismic region partially due to slip velocity weakening of friction coefficient of quartz.
Key words: Digital rock, wave propagation simulation, fracture-filled materials, and earthquake fault

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*J06-4-03
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Down-dip variations in a subducting low-velocity zone linked to episodic
tremor and slip
* Aitaro Kato 1) , Mitsuhiro Toya 2) , Takuto Maeda 1) , Kazushige Obara 1) , Tetsuya Takeda 3) , Koshun
Yamaoka 4)
Earthquake Research Institute, the University of Tokyo 1) , Hanshin Consultants Co., Ltd. 2) , National
Research Institute for Earth Science and Disaster Resilience 3) , Nagoya University 4)
Fluids are thought to play an important role in controlling episodic tremor and slow slip (ETS) in
subduction zones. Therefore, constraining the along-dip distribution of fluids is necessary to better
understand source mechanism of ETS, and particularly the role played by fluids in ETS generation. Here,
we report clear observations of coherent ScSp phases with a dense seismic array in western Shikoku,
Japan, where ETS has been most active over the past decade. Using numerical simulations of elastic-wave
propagation to reproduce the observed ScSp phases, we demonstrate that, relative to shallow depths, either
the Vp/Vs ratio or the thickness of a low-velocity zone (LVZ) within the subducting oceanic crust increases
beneath the mantle wedge corner where ETS has been observed. In addition, amplitudes of receiver
functions associated with the LVZ increase at deeper depths, which support the down-dip variations ofstructural elements. These depth dependences of the structural elements provide us with new evidence
that either high-pressurized fluid is confined or that a wide ductile shear zone, lubricated by fluid, develops
in the subducting oceanic crust at ETS source depths.

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*J06-4-04
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Interplate thermal regime and slab dehydration at the source region of
episodic tremor and slow slip events in the Cascadia subduction zone
* Yingfeng Ji 1) , Shoichi Yoshioka 1) 2)
RCUSS, Kobe University 1) , Department of Planetology, Grudate School of Science, Kobe University 2)
Giant earthquakes are considered to have occurred historically and may take place in a near future in the
Cascadia subduction zone. In contrast to the cold and thick Pacific (PAC) plate subducted beneath thenortheast Japan characterized by numerous interplate earthquakes and comparatively fewer slow
earthquakes, the warm and hot Juan de Fuca (JF) plate subducted beneath the North American plate
witnesses much more episodic occurrences of tectonic tremors and slow slip events (ETS), accompanying
less regular earthquakes. This has enabled us to compare and understand the different generation
mechanisms between regular and slow earthquakes. Possible candidates to interpret such differences may
attribute to slab brittle failure largely determined by different slab thermal regime, while pore fluid pressure
variation in the fractures greatly affected by slab metamorphism. We constructed a 3D time-dependent
thermal convection model with a size of 1150*700*400 km along the Cascadia Trench, initiating subductionin the northeast direction with calculation time up to 15 Myr. The geometry of the JF plate has beenprescribed, being based on the extrapolated data of Slab1.0. Results show a distinct 3D slab dehydration
belt and temperature transition zone along the clustered hypocenters of episodic tremors immediately
beneath Vancouver Island in the northern part and almost 100 km east of coast of Washington and Oregon
in the southern part with temperatures of 500-700 deg. Water content in MORB decreased from 2 wt% to 0
wt%. Interestingly, megathrust earthquakes occurred mostly near the triple plate junctions, such as the JFNA-Explorer and PAC-NA-Gorda plate junctions, and beneath Washington where slab convex portion
exists. Regular earthquakes are fewer observed beneath Oregon. At the source region of ETS in Cascadia,
the interplate temperatures of the JF plate are averagely 200-400 deg higher than those of the PAC plate
beneath Japan at the same depth range.

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*J06-4-05
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

The dynamic stiffness as the indicator of slip mode and transition of the fault
to a metastable stage.
* Gevorg Kocharyan , Alexey Ostapchuk , Dmitry Pavlov
Institute of Geosphere Dynamics Russian Academy of Sciences, Moscow, Russia
Studied is the gradual transition from unstable to stable frictional sliding in laboratory experiment. The
behavior of gouge-filled fault was investigated at the experimental setup based on the spring-bock slider
model. We document transitions between different modes of sliding as the result of changing proportion of
gouge components. The values of scaled kinetic energy typical for events inherent to those modes differ by
several orders of magnitude, while differences in contact strengths and amplitudes of shear stress drops
remain relatively small. The parameter of the fault, which is very sensitive to changes of gouge compositionis the maximal rate of frictional resistance weakening ks. The obtained results allow concluding that the slip
mode is controlled by the ratio of ks to the stiffness of enclosing rock massif.
The value of ks is closely coupled with the fault specific shear dynamic stiffness. The latter can be
determined from measurements of the parameters of seismic waves passing through or reflected from afault. The technique of stiffness estimation was developed in our previous studies and tested in laboratoryand 'in situ' observations.
We document that the dynamic stiffness of model fault drop drastically before both stick-slip events andslow slip events. The Shear stiffness decrease begins long before the macroscopic displacement isrecorded. In our experiments, the time of precursor manifestation was up to 1/3 of the duration of the“seismic cycle."
If similar mechanisms operate in nature, the effect of fault evolution to a metastable stage can be revealed
through active and/or passive seismic monitoring of fault zones. This effect manifests both in theparameters of seismic waves reflected from the fault, and in the spectra of microseismic noise, which had
already been registered before several powerful earthquakes.

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*J06-4-06
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

1972 Slow Mega Slip Event in Mexico Recoded with Tide Gauges* Vladimir Kostoglodov 1) , Nathalie Cotte 2) , Andrea Walpersdorf 2) , Jose Antonio Santiago 1)
Instituto de Geofisica, UNAM, Mexico City, Mexico. 1) , Institut des Sciences de la Terre, Universite Joseph
Fourier, Grenoble, France. 2)
The aseismic slow slip events (SSEs) are essential elements of the seismic cycle of large thrust earthquakes
in subduction zones. GPS networks so far are the main tools for the SSE detection. Tide gauges data may
also provide useful information about large subduction thrust SSEs in the pre-GPS epoch (PGE).
Since 1997 there were five large Mw~7.5, long-term slow slip events recorded by GPS in the the subduction
zone of Mexico. Older SSEs are not detectable using campaign GPS measurements. Research quality tidegauge data in the Pacific coast of Mexico exists back to the year 1953 that gives a chance to recover the
SSE in the PGE. Before a search for the PGE SSEs the monthly averaged tide gauge (TG) records had beenprocessed to get rid of the long-term tide harmonics, partially reduced for the el Ninio effect, long-period
solar harmonics were removed and the residual TG records smoothed.
There are two unconformities observed in the final reduced TG record at the Acapulco station in 1962 and1972. The first step-like signal corresponds to the coseismic coastal uplift of ~22 cm produced by a doubletof earthquakes with Mw 7.1 and 7.0 in May 1962 below Acapulco. The second distinct coastal rise of 10-12
cm lasted almost one year in 1972 without any noticeable seismic activity in Guerrero. The amplitude andtime span of this event closely reminds recent long-term SSEs observed at the same area. Analysis ofdifferential residuals (with respect to the Manzanillo) of TG records reveals similar concurrent but smaller
amplitude coastal rise at Puerto Angel and Salina Cruz TG stations in the Oaxaca state. The records at TG
stations located NW from the Acapulco do not show any anomalous signals corresponding to the apparent
1972 slow slip in Guerrero-Oaxaca.
Our result suggest that the along coast extent of the 1972 SSE may be about of 500 km, probably thelargest subduction SSE recorded so far. The propagation of this event is difficult to assess based only on
three TG records.

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*J06-P-01
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Real-time slow slip monitoring with the Geodetic Data Stacking (GDS)
method* Kazuki Miyaoka 1) , Takahiro Tsuyuki 2) , Hisao Kimura 2)
Meteorological Research Institute, Tsukuba, Japan 1) , Japan Meteorological Agency, Tokyo, Japan 2)
Japan Meteorological Agency (JMA) has been operating a strainmeter network to detect precursory
phenomena of anticipated Tokai megathrust earthquake south off the central Japan. The network consistsof 16 volumetric strainmeters and 11 multi-component strainmeters. We are performing 24-hourmonitoring of strain change due to possible precursory slow slip events, or episodic ones, with correcting
strain changes from the effects of barometric pressure, earth and ocean tides and precipitation in real-timemode.
Miyaoka and Yokota(2012) developed a new analyzing method that enhances signal-noise ratio (S/N) bystacking strainmeter time-series data of plural components. We call this method Geodetic Data Stacking(GDS) method.
If a slip does not spread out or migrate widely, time-series data are similar to each other in shape except for
their polarities and amplitudes. Some data indicate positive changes (+: extensional) and others indicate
the negative (-: compressional). We reverse the polarity of changes for the components that should show
negative changes so that all the data should indicate positive polarities, and stack them. The component tobe reversed is selected from calculated polarity with assuming a slip of small fault at each grid points on
the plate boundary.
As the result, the signal component will be emphasized and S/N will be improved. Using this method, weare monitoring small short-term slow slip events as well as a pre-slip event in real-time. In addition, we
detected the long-term slow slip event going on since 2013 and are monitoring that.
In the presentation, we would like to show the outline of the GDS method and some products.

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*J06-P-02
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Construction of short-term slow slip event catalog detected automaticallyfrom tilt and strain data within the Nankai subduction zone, Japan* Takeshi Kimura 1) , Satoshi Itaba 2) , Takanori Matsuzawa 1) , Hisanori Kimura 1)
NIED, Tsukuba, Japan 1) , AIST, Tsukuba, Japan 2)
In the Nankai subduction zone, a large amount of high-quality geodetic and seismic data enables us to
study the slow earthquakes such as the slow slip events (SSEs) and the low-frequency tremors in detail. In
order to reveal the source physics of various interplate slip phenomena, it is important to understand therelationship among members of slow earthquakes. Source models of SSEs estimated from geodetic data
objectively and independently of seismic slow earthquake catalog (e.g., Kimura et al., 2011) are essential toclarify the relationship. We have developed an automated method to detect SSEs from tilt and strain data,and in order to apply the method to data with the length of one year or longer, it is necessary to treat
temporal changes of background noise levels appropriately. To assume incorrect noise parameters is
possible to cause a miss detection or an excessive detection.
In this study, we evaluate temporal changes in noise levels, and apply the automated SSE detection method
to the 16-year-length data using the noise strengths. We assumed that continuous geodetic data contains
background linear trend, random-walk noise and white noise, and estimated the noise strengths for a
30-day moving time-window using maximum likelihood method. Typical strengths of the random-walk andwhite noises are approximately 1.0-5.0 nrad/hr^0.5 and 1.0-5.0 nrad, respectively, for tilt data, and 0.5-1.0
nstrain/hr^0.5 and 0.5-1.0 nstrain, respectively, for strain data. The random-walk noise strengths of tilt dataat MASH station in Kii Peninsula had been 1.0-2.0 nrad/hr^0.5 and almost constant from 2001 to 2012.
They were increasing in 2013 and reached 10-20 nrad/hr^0.5. This increase in noise levels lowered thedetection capability for SSEs in Kii Peninsula.
Based on the evaluated noise characteristics, we automatically select geodetic data with significantly low
and stable noise levels for the SSE detection.
This work was supported by JSPS KAKENHI Grant Number JP16H06474.

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*J06-P-03
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Shallow Slow Slip Event Off the Kii Peninsula, Japan* Satoshi Itaba 1) , Satoshi Annoura 2) , Tetsuo Hashimoto 2) , Noriko Kamaya 2) , Akio Katsumata 3)
National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan 1) , Japan
Meteorological Agency, Tokyo, Japan 2) , Meteorological Research Institute, Tsukuba, Japan 3)
On 1 April 2016, an earthquake (Mw=5.9, hereafter mainshock, USGS) occurred off the Kii Peninsula,
Japan. The mainshock occurred around the expected focal region of the so-called Tonankai earthquake.
After the mainshock, strain changes caused by the slow slip event (SSE) were observed by the threeborehole strainmeters of AIST. The source region of this SSE is located on the plate interface at southeast
side of the mainshock. An equivalent magnitude of this SSE is Mw 6.0, and duration is about 7 days. Fromafter just a few days from the mainshock, in and around this SSE source region, intensive activity of shallow
low frequency tremor (LFT) has been observed for about two weeks, it is assumed that these shallow tremor
events were induced by this SSE.
In off the Kii Peninsula, SSE had not been observed by geodetic method. The slip deficit rate of this SSE
source region is about 3 cm / year (Yokota et al., 2016), and the plate convergence rate is 5.0 to 6.5 cm /year (Heki and Miyazaki, 2001). Therefore, in addition to this case, there is a possibility that SSE frequently
occurred in this region. To support of this hypothesis, VLF and LFT have been often observed in this area.
In this presentation, we will report the results of verifying other cases.
References
Heki, K. and S. Miyazaki, Plate Convergence and Long-Term Crustal Deformation in Central Japan,.
Geophys. Res. Lett., 28, 2313-2316, 2001.
Yokota, Y., T. Ishikawa, S. Watanabe, T. Tashiro, and A. Asada, Seafloor geodetic constraints on interplate
coupling of the Nankai Trough megathrust zone, Nature, 534, 374-377, doi:10.1038/nature17632, 2016.

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*J06-P-04
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Spatio-temporal evolution of recurrent slow slip events from 2010 to 2013
along the Ryukyu Trench, southwestern Japan* Masayuki Kano 1) , Jun'ichi Fukuda 1) , Shin'ichi Miyazaki 2) , Mamoru Nakamura 3)
Earthquake Research Institute, University of Tokyo, Tokyo, Japan 1) , Department of Geophysics, Graduate
School of Science, Kyoto University, Kyoto, Japan 2) , Faculty of Science, University of the Ryukyus,
Okinawa, Japan 3)
Various types of slow earthquakes, including slow slip events (SSEs, Heki and Kataoka, 2008, Nishimura,2014), very low frequency earthquakes (VLFEs, Ando et al. 2012, Nakamura and Sunagawa, 2015), and low
frequency earthquakes (LFEs, Nakamura, submitted), are detected along the southern part of the Ryukyu
Trench, Japan. In this area, Global Navigation Satellite System (GNSS) stations have been newly installedsince 2010 by Kyoto University in addition to the stations operated by Geospatial Information Authority ofJapan. This study applies a modified Network Inversion Filter to these GNSS time series from March 2010
to February 2013, to estimate the spatio-temporal evolution of slow slip on the plate interface in detail. Five
SSEs with Mw 6.6–6.8 and durations of 30–100 days are found during this period. The main slip region of
the five SSEs are similar, located beneath the northwestern side of the Iriomote island. In contrast to thesimilarity in the spatial location, our detailed analysis newly clarifies the difference in the temporal
evolution among the events; three SSEs suddenly accelerated to the maximum slip rate, and the other two
SSEs showed a slow acceleration for 20–50 days. The spatial relationship among the SSEs, LFEs, VLFEs,
and tsunamigenic earthquake, is complementary along the trench, depending on the depth; tsunamigenic
region in the shallowest part, weakly coupled region of VLFEs and LFEs with depths shallower than 30 km,
and SSEs deeper than 30 km, reflecting the depth variation of physical properties. VLFEs are sometimes
activated 10–20 days after the onset of SSEs that initiate with slow acceleration phase, although thenumber of SSEs is too small to assert this correlation. Since new GNSS stations are planning to beestablished, additional data and further analyses will possibly make the correlation clear in the future.

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*J06-P-05
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Estimation of the spatiotemporal evolution of slow slip events in the Tokai
region, central Japan, since 2013 using GNSS data
* Hiromu Sakaue 1) , Jun'ichi Fukuda 2) , Teruyuki Kato 2) , Takuya Nishimura 3)
Kyoto University, Kyoto, Japan 1) , Earthquake Research Institute,The University of Tokyo, Tokyo, Japan 2) ,Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan 3)
In the Tokai region, central Japan, the previous long-term slow slip event (L-SSE) occurred on the
subducting Philippine Sea Plate (PSP) from 2000 to 2005. Moreover, many short-term SSEs (S-SSEs) havebeen observed in the Tokai region since 1996. Ozawa et al.(2016) reported that a SSE seems to havestarted in the similar area of the previous Tokai L-SSE in the beginning of 2013. We applied a timedependent inversion method to GNSS data to obtain the spatiotemporal evolution of an L-SSE and S-SSEson the PSP beneath the Tokai region, since 2013.
GNSS data from Jan. 1, 2008 to Dec. 30, 2015 were used in this study. The GIPSY-OASIS II software wasused to estimate daily coordinates of 222 GNSS stations from the GEONET in the Tokai region. It is wellknown that GNSS time series have many systematic signals that do not result from SSEs. These systematic
signals include, for example, seasonal variations and post-seismic deformation of the 2011 Tohoku-oki
earthquake(Mw9.0). After removing these systematic signals, we applied a modified Network Inversion
Filter (NIF) [Fukuda et al., 2008]. The original NIF [Segall & Matthews, 1997] assumes a constant
hyperparameter for the temporal smoothing of slip rates and thus often results in oversmoothing of slip
rates. The modified NIF assumes a time-variable hyperparameter, so that changes in slip rates are
effectively extracted from GNSS time series.
The results indicate the moment magnitude and maximum cumulative slip of the SSE were estimated to be
Mw～6.5 and ～6.5 cm from Jan. 1, 2013 to Dec. 30, 2015, respectively. In addition to the L-SSE from 2013
to 2015, two large S-SSEs were detected near the Ise Bay in the down-dip area of the L-SSE. Our results
suggest that the slip peaks of the L-SSE and S-SSEs do not overlap and that the temporal variation of
moment evolution in the central area of the L-SSE is smooth and is not affected by the S-SSEs. Low
frequency tremors [Obara et al., 2010] do not occur near the center of the L-SSE.

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*J06-P-06
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Estimating long-term and short-term slow slip events in the Bungo Channel
area by MCMKF-based inversion.
* Takatoshi Yokoi 1) , Shinichi Miyazaki 1) , Hiromu Sakaue 1) , Jun'ichi Fukuda 2)
Kyoto University, Kyoto, Japan 1) , ERI, The University of Tokyo, Tokyo, Japan 2)
We estimated space-time evolution of long-term and short-term slow slip events (L-SSE and S-SSE,
respectively) in the Bungo Channel region between Jan. 1, 2009 and Dec. 31, 2012, by employing theMonte Carlo Mixture Kalman Filter (MCMKF)-based Network Inversion Filter (NIF) [Fukuda et al.,2014].
We use GNSS time series at GEONET stations between Jan. 1, 2009 and Dec. 31, 2012 as provided by
Takuya Nishimura [Personal Communication]. First we have pre-processed the original GNSS time series toremove secular velocities, annual and semi-annual variations, offsets associated with earthquakes andantenna changes and postseismic deformations. Then those pre-processed time series would contain onlytransient deformation and local benchmark wobble provided there is no other noise source. We inverted
pre-processed GNSS time series to estimate transient slip on the plate boundary at the Nankai Trough. We
employ plate configuration data by Hirose et al. [2008] and select the area of about 200km long to the eastand 280km long to the north as the model region. We subdivide the model region into 719 subfault
patches, and expand the slip by a series of 24 spatial depleted basis functions. During this period, in
addition to a L-SSE that occurred for about one year, S-SSEs have been inferred in the eastern Shikoku andwestern Kyushu. The inferred L-SSE is consistent with previous studies such as Yoshioka [2015], and thetiming and location of S-SSE is similar to those estimated by Nishimura [2014]. This is the first case thatspace-time evolutions of both L-SSE and S-SSE have been estimated in the Bungo Channel region from asingle inversion analysis. In the presentation we will show the results in detail and discuss the similarities
and differences between L-SSE and S-SSE.

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*J06-P-07
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

A trial to find long-term variation in slip-deficits in the Bungo Channel
region, Nankai Trough.
* Shinichi Miyazaki 1) , Takatoshi Yokoi 1) , Hiromu Sakaue 1) , Jun'ichi Fukuda 2)
Kyoto University, Kyoto, Japan 1) , ERI, The University of Tokyo, Tokyo, Japan 2)
We estimated space-time variation of secular slip and slip-deficits in the Bungo Channel region between
two successive long-term slow slip events (L-SSEs) by employing the Monte Carlo Mixture Kalman Filter(MCMKF)-based Network Inversion Filter (NIF) [Fukuda et al.,2014]. We use GNSS time series at GEONET
stations between Jan. 1, 2012 and Dec. 31, 2015 as provided by Takuya Nishimura [PersonalCommunication]. First we have pre-processed the original GNSS time series to remove secular velocities,
annual and semi-annual variations, offsets associated with earthquakes and antenna changes andpostseismic deformations. Then those pre-processed time series would contain only transient deformationand local benchmark wobble provided there is no other noise source. We inverted pre-processed GNSS
time series to estimate transient slips, if any, and slip-deficits on the plate boundary at the Nankai Trough.
Following Yokoi et al. [2017, this meeting], we employ plate configuration data by Hirose et al. [2008] andselect the area of about 200km long to the east and 280km long to the north as the model region. We
subdivide the model region into 719 subfault patches, and expand the slip by a series of 24 spatial depleted
basis functions. Up to now only short-term slow slip events (S-SSEs) have been found, and long-term
variation of slip deficits are within uncertainties.

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*J06-P-08
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Slip velocities of early afterslips in northeastern Japan* Shunsuke Morikami , Yuta Mitsui
Shizuoka University, Shizuoka, Japan
We focus on temporal evolution of early afterslip velocities following large interplate earthquakes (2003
Tokachi-oki, 2005 Miyagi-oki, 2011 Tohoku-oki (March 9), and 2011 Tohoku-oki (March 11)) in
northeastern Japan. First, we obtain surface deformation data at an interval of 30 seconds about 2 days
after the earthquakes, using GSILIB. Next, we invert slip velocities at the plate interface from the data. We
find that initial velocities of the afterslips positively correlate with magnitude of the mainshocks. The initialafterslip velocities are four orders of magnitude lower than mean slip velocities of their mainshocks. The
early afterslips decay almost linearly with time during the investigation periods. Besides, we check effectsof viscoelastic relaxation of asthenosphere by a numerical simulation, and confirm that the viscoelastic
relaxation effects are negligible during the investigation periods in a viscosity range larger than 10^18 [Pas].

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*J06-P-09
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)Low-frequency earthquake distribution covered with undrained layer of theoverlying plate along Tokai plate boundary of the Nankai subduction zone
* Sadaomi Suzuki 1) , Makoto Okubo 2) , Kazutoshi Imanishi 3) , Junichi Nakajima 4)
Tono Research Institute of Earthquake Science (TRIES), Association for the Development of Earthquake
Prediction (ADEP), Mizunami 509-6132, Japan 1) , Kochi Earthquake Observatory, Kochi University, Kochi
780-8073, Japan 2) , Geological Survey of Japan, National Institute of Advanced Industrial Science andTechnology (AIST), Tsukuba 305-8567, Japan 3) , Department of Earth and Planetary Sciences, School of
Science, Tokyo Institute of Technology, Tokyo 152-8551, Japan 4)
We have developed a novel method that uses a 3D array to detect the P and S waves of deep low-frequency
earthquakes (LFEs) along the Nankai subduction zone. We tried to find their P and S wave pairs by using a
3D array (6 km x 4 km area) with 14 seismic stations in the Tokai area including ones with deep (600 m at
the deepest) borehole seismographs. We observed remarkable LFE activity over November 10-30, 2010
and identified P and S phases of LFEs with high quality result by using a semblance method. Referring tothose identified P and S phases we manually picked the arrival times of not only both P and S waves of the
3D array stations but also S waves and rarely P waves of Hi-net stations. Using the arrival times werelocated precise hypocenters of the 15 LFEs. Those hypocenters distribute in the depth range from 26 km
to 34 km approximately along the plate boundary inclining in depth from 30 km to 32 km. We compared
the distribution of LFEs with the observed P-wave (dVp) and S-wave (dVs) velocity perturbation crosssections along the subduction zone. Most of the LFEs occurred in the areas with dVp and dVs lower thanabout -3% along the plate boundary. And in the overlying plate just above the whole of LFE distribution
there is a thin (several km thickness) layer with dVp and dVs higher than about 3%. We interpret that thehigher velocity layer corresponds to an undrained layer keeping high pore-fluid pressures for LFE activity
along the plate boundary.

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*J06-P-10
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Variation of deep low frequency tremor activity along dip direction inwestern Shikoku, southwest Japan* Akira Hikita 1) , Akiko Takeo 1) , Takuto Maeda 1) , Aitaro Kato 1) , Takanori Matsuzawa 2) , Kazushige Obara
1)

Earthquake Research Institute, Univ. of Tokyo, Tokyo, Japan 1) , National Research Institute for Earth
Science and Disaster Resilience, Tsukuba, Japan 2)
It is reported that deep low frequency tremor occurs more episodically at the updip part of the tremor
region compared to the downdip part in Shikoku in southwest Japan (Obara et al., 2010, 2011) andCascadia (Wech and Creager, 2011). In this study, we focused on the updip cluster in western Shikoku
analyzed in Obara et al. (2010) in order to investigate tremor activity in a finer scale along the dip
direction.
We applied a matched filter technique (Shelly et al., 2007), using continuous seismic waveform data from2013 to 2015 at 12 Hi-net stations, which are operated by National Research Institute for Earth Scienceand Disaster Resilience. Waveform data were bandpass filtered between 2 and 8 Hz. As template events, weselected several low frequency earthquakes located within a streak-like tremor cluster along the dip
direction of the subducting plate from the catalog of Japan Meteorological Agency (JMA). We used the time
window of four seconds from one second before the arrival time of S-wave detected by JMA at each station.
We found stepwise tremor activities at all spots corresponding to episodic tremor and slip (ETS), whichrecurs at intervals of about a half year in western Shikoku. At the northern (deeper) part, the number ofdetected events during ETS was smaller, and small tremor bursts were more frequently detected during
inter-ETS compared to the southern (shallower) part. This result is consistent with the general trend of
tremor activity in wider scale in southwest Japan and Cascadia.
Some tremor episodes were detected only at the up-dip part of the tremor cluster, although individual ETSs
are mainly initiated at the deeper part and migrate upwards in western Shikoku (Obara et al., 2011) andCascadia (Wech and Creager, 2011). This may suggest that some ETSs initiate at the updip part.

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*J06-P-11
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Seismic anisotropy monitoring and detection of tremor activity in thesouthwest Japan subduction zone
* Motoko Ishise , Kiwamu Nishida , Kimihiro Mochizuki
Earthquake Research Institute, The University of Tokyo, Tokyo, Japan
We have been investigating the source region of Nankai trough mega-thrust earthquake from a view ofseismic anisotropy. In this study, a seismic anisotropy monitoring, which is simultaneous continuous
measurements using shear (S) wave splitting analysis and polarization analysis, was performed duringtremor episodes at Hi-net stations developed in eastern Shikoku, southwest Japan. The method is similar to
Bostock and Christensen [2012]. We inferred parameters of S-wave anisotropy (polarization direction of
fast S wave and delay time between fast and slow S waves) and those of incoming wave (back azimuth andincident angle) using a 1 min long sliding window with 50% overlap. They reveal a close relationshipamong temporal variations of anisotropy, polarizations of incoming wave and spatial-temporal developmentof tremor activities. They show systematic changes during located tremor activities [e.g., world tremor
database, Idehara et al., 2014].
We thus interpret monitoring the relationship among temporal variations of anisotropy, incoming wave, andtremor activity as a tremor detection method. That is, we assumed that the systematic change indicatesoccurrence of tremor. If so, it may be possible to detect occurrence of tremor by analyzing seismograms ata single station as well as detect occurrence of tremor, whereas commonly-used source location
determination methods [e.g., Obara, 2002] require observation of coherent seismic signals at several
stations.
Recently, we started to apply the monitoring method to ocean bottom seismometer data in order toinvestigate offshore tremor activity. Since the quality and quantity of marine observation data is limited invarious aspects compared with those of land-based observation data, this will eventually discover some
unknown phenomena. In this presentation, we show preliminary result of the monitoring using an offshore
seismic network, DONET, off southwest Japan along the Nankai Trough.

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*J06-P-12
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)Low frequency tremor activity in the Tohoku subduction zone based on
ocean bottom seismograms* Hidenobu Takahashi 1) , Ryota Hino 1) , Masanao Shinohara 2) , Yukihiro Nakatani 2) , Syuichi Suzuki 1)
Tohoku University, Sendai, Japan 1) , The University of Tokyo, Tokyo, Japan 2)
Various kinds of slow earthquakes have been found along the plate boundary zones in the world. In the
Tohoku subduction zone, where slow event activities have been considered insignificant, low frequency
tremors prior to the 2011 Tohoku-Oki earthquake and very low frequency earthquakes were identified byrecent studies based on geodetic signals from seafloor pressure observations and onshore broad-bandseismographs. In the Nankai subduction zone, records of ocean bottom seismometers(OBS) are proved tobe effective for detecting low frequency tremors beneath the OBS networks. In this study, we try to detect
low frequency tremors and to locate their sources using the OBS records deployed in the Tohoku-Oki.
As the initial trial, we focused on the continuous records on Dec. 2007 when VLFEs were previously
detected by onshore broad band seismograms. We applied a envelope correlation method (ECM) to theshort period OBS records obtained near the epicenters of VLFEs to detect tremors. Majority of the events
detected by ECM seemed to be ordinary earthquakes containing a lot of high frequency signals. In order to
identify tremors from the detected events, we calculated an amplitude ratio of the envelope in low
frequency band (2- 8 Hz) to that in high frequency band (10- 20 Hz). As a result, we detected an event
having significantly larger ratio than those of ordinary earthquakes at all OBS stations, as a possible
candidate of a low frequency tremor event. After making visual inspection of the waveforms, we confirmed
evident prevalence of low frequency contents and depletion of high frequency signals, as usually observed
for low frequency tremors in general. The source was located just beneath the OBS network based on therelative arrival times, the larger amplitudes were observed at stations nearer to the located source.
Therefore, the identified event is likely to be a low frequency event occurred in the vicinity of the locationof the OBS network.

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*J06-P-13
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)Low-frequency tremor activity in the shallow part of Nankai Trough and
Ryukyu Trench revealed by long-term ocean bottom observation* Yusuke Yamashita 1) , Masanao Shinohara 2) , Hiroshi Yakiwara 3) , Tomoaki Yamada 2) , Kazuo
Nakahigashi 4) , Hajime Shiobara 2) , Kimihiro Mochizuki 2) , Takuto Maeda 2) , Kazushige Obara 2)
Kyoto University, Miyazaki, Japan 1) , The University of Tokyo, Tokyo, Japan 2) , Kagoshima University,
Kagoshima, Japan 3) , Tokyo University of Marine Science and Technology, Tokyo, Japan 4)
Low-frequency tremor is one of the slow earthquakes occurred in the deep and shallow part of the
subduction zone. The detail of shallow tremor was documented by Yamashita et al. (2015), they havecarried out the ocean bottom observation in the Hyuga-nada, southwestern part of Nankai Trough, andsucceeded in detecting shallow tremor as a complete episode lasting for one month exhibiting similar
migration property of deep tremor for the first time. From 2014, we started long-term ocean bottom
seismological and geodetic observation in the Hyuga-nada. In addition, we also started that in the northpart of Ryukyu Trench from 2014, in the central part of Ryukyu Trench from 2015.
During these observations, we found some tremor activities in those areas. In the Hyuga-nada, we detected
tremor activity in 2014, 2015, and 2016. The 2016 activity may be triggered by 2016 Kumamoto
earthquake. In the Ryukyu Trench, although it is hard to estimate the epicenter of tremor source because
the separation between the ocean bottom seismometer is large, we found the locality of the shallow tremor
activity.
From 2017, we started a new project for observation of shallow slow earthquake. We installed ocean
bottom seismometers and pressure gauges around the focal area of shallow tremor in the Hyuga-nada. Thisobservation will continue until 2020. For this presentation, we will introduce the ocean bottom
observations and discuss the property of shallow tremor activity along the Nankai Trough and Ryukyu
Trench using preliminary result by analyzing the data which were recovered from the ocean bottom.

Acknowledgement: This study is supported by the research project for compound disaster mitigation on thegreat earthquakes and tsunamis around the Nankai Trough region, the MEXT of Japan, under its
Earthquake and Volcano Hazards Observation and Research Program, and JSPS KAKENHI Grant Number
JP16H06473 in Scientific Research on Innovative Areas “Science of Slow Earthquakes".

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*J06-P-14
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Network-MT survey in the vicinity of area with a forthcoming slow slip eventin the SW part of Shikoku Island, SW Japan* Makoto Uyeshima 1) , Maki Hata 1) , Hiroshi Ichihara 2) , Ryokei Yoshimura 3) , Koki Aizawa 4)
Earthquake Research Institute, the University of Tokyo, Tokyo, Japan 1) , Graduate School of Maritime
Sciences, Kobe University, Hyogo, Japan 2) , Disaster Prevention Research Institute, Kyoto University,
Kyoto, Japan 3) , Institute of Seismology and Volcanology, Kyushu University, Fukuoka, Japan 4)
In the Bungo channel region at the western margin of the Nankai megathrust rupture zones, the long-term
slow slip events (SSE) repeatedly occurred about every 6 or 7 years and we expect the next event soon.
The SSE also activate deeper episodic tremors and slips (ETS) on the plate interface.
In order to examine influence of interstitial fluids on occurrence of the SSE and/or ETS activities, we havestarted the Network-MT survey in the western part of the Shikoku Island facing the Bungo channel sinceApril, 2016. We use metallic telephone line network of the Nippon Telegraph and Telephone Corp. tomeasure the electrical potential difference with long baselines of from several kilometers to 10 and several
kilometers. We selected 17 areas in the western part of Ehime and Kochi prefectures and installed 3 or 4
electrodes in the respective areas. The electrical potential differences measured in this way are known tobe less affected by small scale near-surface lateral resistivity heterogeneities. We also measure geomagnetic
field at two stations in the target region. With the aid of the BIRRP code, we could estimate the frequencydomain response functions between each voltage difference and the horizontal magnetic fields from 5 s to10^5 s. We will show spatial characteristics of the responses and their preliminary 3-D interpretation toestimate regional electrical resistivity structure with the aid of a DASOCC 3-D inversion code.
This study is supported by JSPS KAKENHI Grand Number JP16H06475 in Scientific Research on
Innovative Areas “Science of Slow Earthquakes. It is also partly supported by the Ministry of Education,
Culture, Sports, Science and Technology (MEXT) of Japan, under its Earthquake and Volcano Hazards
Observation and Research Program. We acknowledge staffs of the Nippon Telegraph and Telephone WEST
Corporation for their cordial support in the survey. We also thank Drs. H. Abe, A. Takeuchi and Y. Suwa for
their help in preparing and installing instruments.

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*J06-P-15
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Moment tensor inversion of tectonic tremors in the Guerrero subductionzone* Emmanuel Caballero-Leyva , Victor M. Cruz-Atienza
National Autonomous University of Mexico, Mexico City, Mexico
Slow earthquakes have exposed the actual complexity of the tectonic processes involved in subduction
zones around the world. Despite different studies addressing these phenomena, its causal relationship isstill debated.
Recent studies in different subduction zones suggest that tectonic tremors (TT) are caused by point
dislocations at depth. Consequently, a systematic study of focal mechanisms of tremor sources turns out tobe important to understand the processes that originate this phenomenon and the implications they havein the occurrence of slow earthquakes.
Cruz-Atienza et al. (2015) introduced the “Tremor Energy and Polarization" (TREP) method to locate
tectonic tremors assuming horizontal point dislocations, which is a reasonable hypothesis for deep tremorsin the state of Guerrero. However, this assumption could be a limitation in other cases where the fault dip isdifferent (i.e., San Andreas Fault). The simultaneous determination of tremor locations and focal
mechanisms would allow studying this phenomenon in any tectonic environment.
In this work, we generalize the TREP method employing a global inversion technique (i.e., simulated
annealing) to determine simultaneously the source location and the associated moment tensor from theenergy spatial distribution and the azimuth of the particle motion polarization.
Although the method has some difficulties to resolve the focal mechanims because of the ambient noise,preliminary results employing real data in Guerrero show that most of the obtained mechanisms are
consistent with the geometry of the plate interface and with the plate convergence direction, which aresimilar to those reported for LFEs (Frank. et al 2013) and VLFs (Maury et al. 2016) in Mexico.

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*J06-P-16
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Anisotropy in the subducted oceanic crust and the overlying continental
crust coincides with slow slip phenomena in the flat portion of the Mexican
subduction zone.
* Allen Husker 1) , Jorge Castillo 2) , Xyoli Perez-Campos 1) , William Frank 3)
UNAM 1) , Caltech 2) , MIT 3)
A novel approach has been developed to isolate the anisotropy observed by receiver functions (RF) into theseparate layers through which the seismic waves pass (Castillo et al., 2017). This approach has provenparticularly effective in the Mexican flat slab, which remains in near contact with the continental crust to
300 km from the trench. There are 3 regions that can be observed with this approach: (1) The lower
subducted oceanic crust; (2) the remnant mantle wedge between the oceanic and continental crust; and (3)the continental crust. Slow earthquakes are also found in the flat slab region, and they strongly correlatewith changes in the anisotropy in the different layers. The flat slab region is a double slow earthquake zone:
from updip to down-dip (1st slow earthquake zone) Mw ~7.5, 4-year recurrence-time slow slip events (SSE)with little tectonic tremor (TT) on the down-dip edge; and (2nd slow earthquake zone) Mw < 6.5, 2 – 3month recurrence-time SSEs with a large amount of TT on down-dip edge. The highest anisotropy
percentage in the subducted crust aligns with the TT in the two slow earthquake regions. In the remnant
mantle wedge, high anisotropy only aligns with the TT in the second slow earthquake region. The overlying
crust is the reverse with low anisotropy directly above the TT in each of the slow earthquake regions. Thispattern may be explained by a seal at the base of the continental crust (fluids trapped beneath the crust
where the TTs are located, leading to high anisotropy beneath the seal and low anisotropy above) broken
by SSEs (high anisotropy above the SSEs and low anisotropy beneath as fluids are transported into theupper crust). The anisotropy direction changes with distance from the trench and correlates with LFE
activity, but it is difficult to explain at this time.

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*J06-P-17
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

The long duration, April 18, 2002 (Mw 6.7), Mexico earthquake; a small
tsunami earthquake next to the Guerrero Gap* Ketzallina Flores , Vala Hjorleifsdottir , Shri Singh , Arturo Iglesias
University National Autonomous of Mexico, Mexico City, Mexico
We estimate the duration, extent and rupture velocity of the April 18, 2002 (Mw 6.7) earthquake. The
hypocenter location (Pacheco & Singh, 2010) is inside what is known as the Guerrero Gap, a segment of
the Mexican subduction zone that has not had a large earthquake in at least 100 years.
The 2002 earthquake is anomalous in the sense that it produced very small accelerations for its size
(Iglesias et al 2003) and it is one of the earthquakes with longest duration relative to its magnitude
recorded globally in the last 40 years (Duputel et al, 2013). Events of this type are particularly hazardous
because they produce relatively large tsunamis (Kanamori, 1972) and small ground motions for their size,
so they may be mistaken for smaller events by people near the coast, who may not prepare for the large
tsunami. As near trench earthquakes are relatively rare, and due to their destruction potential, it isimportant to study in detail the few recorded events of this type.
The extent of the rupture area of the 2002 earthquake, is key to understanding the seismogenic potential of
the Guerrero Gap. Often the rupture area of an earthquake is estimated by the extent of the aftershock area.
However, locating earthquakes near the trench is difficult, due to their emerging P-waves and as they occur
outside of the network of observation. In this study we calculate the duration of the 2002 earthquake byobservations of far-field records. We use the difference in time between the first and last coherent signals in
the peculiar P wavetrain of event, observed to conclude that the rupture had a duration and along strike
length of approximately 56s and 60 km, respectively. The rupture propagated to the north-west with arupture velocity of 1 km/s. To put further constraints on the rupture area, we relocate the aftershocks, using
a relative location method (Cleveland & Ammon, 2013), based on cross-correlation of surface waves.
Finally we discuss the implications of our results.

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*J06-P-18
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Trench-parallel sliver motion in the Mexican oblique subduction zone
* Ekaterina Kazachkina 1) , Vladimir Kostoglodov 1) , Allen Husker 1) , Jose Antonio Santiago 1) , Nathalie
Cotte 2) , Andrea Walpersdorf 2)
UNAM National Autonomous University of Mexico, Mexico city, Mexico 1) , ISTerre Institute of Earth
Sciences, Saint Martin d'Heres, France 2)
Large, equivalent to Mw~7.5, subduction thrust slow slip events (tSSE) in Guerrero, Mexico have a periodof ~4years. The secular GPS velocity vectors are oblique to the Middle America trench (MAT). The lateralvelocity components abruptly diminish to the north by 4-5mm/year across La Venta-Chacalapa fault zone
(LVC), striking along the Pacific coast of Guerrero and Oaxaca for ~650km. This velocity slump reveals apartitioning of the oblique convergence between the Cocos and North America plates with a sinistral
motion of the Xolapa forearc sliver.
Long-term GPS records show that the tSSEs are accompanied by strike-slip SSEs (sSSE) on
the LVC fault. GPS displacement records in Guerrero reveal that during the interSSE periods (~3 years) the
LVC fault is mainly locked, and the shear strain rate across it remains constant at ~14nrad/year. During thetSSE there is an increase of lateral sinistral displacement of the GPS stations on the coast, south of the fault
while the stations to the north off the LVC undergo minor dextral displacements. The secular shear strain
rate drastically changes across the fault from 64 nrad/year south of it to 11nrad/year to the north. The LVC
fault is currently active but the slow accumulation of shear strain on it is periodically interrupted by sSSEs
highly synchronized with the tSSEs.
According to the analysis of thrust events from local catalogs slip vectors lay between the vectors of plateconvergence and trench normal. Obliquity of thrust slip vectors (1-5') grows southward along the coast. The
oblique subduction motion is partitioned into trench parallel displacement along LVC fault zone at the rateof ~8mm/yr. Secular trench parallel velocity calculated from GPS data is ~6.5mm/yr. Slower motion at thesurface (GPS) compared to the subduction interface (thrust events) may be due to the properties of themedia.

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*J06-P-19
Joint Symposium / J06. The spectrum of fault-zone deformation processes (from slow sl
ip to earthquake)

Drilling into Active Faults - In-situ Investigations on the Mechanics andStructure of Faults in Central Japan* Kentaro Omura
National Research Institute for Earth Science and Disaster Resilience
The drilling is of great advantage to study on the mechanics and structure of fault. We did integrated
investigations on active faults in central Japan by drilling into the faults, in-situ downhole measurements
and core observations. Those faults have different elapsed time since the last earthquakes; Nojima fault, the1995 Hyogo-ken Nanbu Earthquake, M7.2 (Kobe Earthquake); the Neodani fault, 1891 Nobi earthquake(M=8.0); the Atera fault, 1586 Tensho earthquake (M=7.9); the Atotsugawa fault, 1858 Hida earthquake(M=7.0); the Gofukuji Fault that is said to have activated more than a thousand years ago.
In-situ stress measurements indicate the maximum horizontal compressive stress was nearly perpendicular
to the fault strikes as for Nojima Fault case, but for other fault cases, the orientation of the maximum
horizontal compressive stress was oblique to the fault strike. These results support the idea that thedifferential stress is small at narrow zone adjoining fracture zone and fault is quite weak after theearthquake. On the other hand, the frictional strength is still high outside the narrow fractured zone. The
shear stress is as the same level as the frictional strength of host rock of the fault. Downhole logging andmacro- and micro-scopic observation of recovered cores indicate complicated and internally hierarchicalfault zone structure. Sets of narrow hardly fractured zones with adjacent broad weakly fractured zones are
distributed within the fracture zone. The narrow hardly fractured zones are characterized as low electricalresistance, low density, low P-wave velocity, and high porosity. Fault seems not to have slipped on a
specific plane, but on several fault planes at different earthquakes in the past. The complicated fault zone
structure should have formed progressively during repeating earthquake. The stress state and structure ofdifferent faults seem to reflect different stage in earthquake preparing process in the earthquake recurrence
cycle.

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*J07-1-01
Joint Symposium / J07. Tracking the sea floor in motion

Observational Results of Seafloor Crustal Deformation Near the Nankai
Trough Axis
* Keiichi Tadokoro 1) , Mitsuru Kado 1) , Hiroshi Kimura 1) , Motoyuki Kido 2) , Kenjiro Matsuhiro 1)
Nagoya University, Nagoya, Japan 1) , Tohoku University, Sendai, Japan 2)
The Central Disaster Management Council, Japanese government extended the presumed source region of
the Nankai mega-thrust earthquake to the trough axis in 2012. It is, therefore, essential to understandinterplate locking condition near the trench axis, also for the anticipated mega-thrust earthquake at the
Nankai Trough.
We installed three seafloor benchmarks for the seafloor crustal deformation measurement with the
GNSS/acoustic technique in the vicinity of the Nankai Trough axis. Two benchmarks, TCA and TCB, arelocated about 15 and 35 km landward from the trough axis on the Amurian plate, respectively. The otherbenchmark TOA is located about 25 km seaward from the trough axis on the subducting Philippine Sea
Plate. We can directly “measure" the slip deficit and the motion of the subducting Philippine Sea Plate
through observations at the three benchmarks.
We performed campaign observations seven times at TCA and TOA benchmarks, and six times at TCB until
the end of 2016. The worm ocean current, Kuroshio, flows over the observation sites, and we estimatedheterogeneity of sound speed in the sea for the precise seafloor benchmark positioning. We, then, derived
steady horizontal displacement rate with relative to the Amurian Plate from the time series of benchmark
coordinate. The horizontal displacement rate is measured at 56+/-21 mm/y in the direction of N69+/-14W
at TOA benchmark. The predicted motion of the Philippine Sea Plate is 60-61 mm/y in the direction of
N59W at the position of TOA benchmark, which coincides with our measurement at TOA within the error
interval. The measured horizontal displacement rates are 38+/-19 mm/y toward the west-northwest and72+/-25 mm/y in the direction of N48+/-21W at TCA and TCB benchmarks, respectively. These results are
the strong evidence for interplate locking, with coupling ratios of more than 40% on the basis of the backslip model, at the most-shallowest segments of plate interface.

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*J07-1-02
Joint Symposium / J07. Tracking the sea floor in motion

Interseismic seafloor GPS-A data used for tsunami generation modelingalong the Nankai trough, Japan* Shun-ichi Watanabe 1) , Yehuda Bock 2) , Diego Melgar 3) , Tadashi Ishikawa 1) , Yusuke Yokota 1) , Keiichi
Tadokoro 4)
Japan Coast Guard, Tokyo, Japan 1) , Scripps Institution of Oceanography, La Jolla, U.S. 2) , University ofCalifornia, Berkeley, Berkeley, U.S. 3) , Nagoya University, Nagoya, Japan 4)
Dense near-fault GPS-A seafloor geodetic and on-shore GPS GEONET observations provide significantly
improved resolution of the interseismic slip deficit in the Nankai trough, Japan [Yokota et al., 2016]. In aprevious study, we included additional seafloor data at the Kumano basin collected by Nagoya University[Tadokoro et al., 2012] to estimate expected seafloor deformation during a large subduction zone
earthquake as input to tsunami models [Watanabe et al., 2016 AGU]. In order to derive the appropriate
model, the displacements caused by episodic events should be quantitatively estimated. Therefore, we first
constructed a 3D FEM model to quantify the postseismic displacements following the southeastern off theKii Peninsula earthquakes (on Sep. 5, 2004 JST, M 7.1, 7.4). Because these events occurred near the troughaxis, the larger deformation was caused on the seafloor in the Kumano basin. Our results indicated that thedisplacements of up to 1 cm/year occurred in the period of July 2006 to July 2009 at the GPS-A sites. The
corrected displacements were aligned to the Nankai-block (forearc sliver) to derive the slip deficit from thetectonic model of Loveless and Meade [2010]. For the slip deficit estimation, we modified the static model
approach of Melgar and Bock [2013] using Okada's Green's functions. The plate interface was divided into
approximately 25 x 25 km rectangular subfaults with displacements constrained to minimize Akaike's
Bayesian Information Criterion. We then estimated the coseismic motions assuming that the 100-years ofslip deficit was released instantaneously. These were then used as the initial conditions to model the
propagation of the subsequent tsunami. In the presentation, we will show the updated distribution of theslip deficit rate in the Nankai trough region and the tsunami model.

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*J07-1-03
Joint Symposium / J07. Tracking the sea floor in motion

Postseismic deformation of the 2011 Tohoku Earthquake measured by
GPS/Acoustic observations* Fumiaki Tomita 1) , Motoyuki Kido 1) , Yusaku Ohta 1) , Takeshi Iinuma 2) , Ryota Hino 1)
Tohoku University, Sendai, Japan 1) , Japan Agency for Marine-Earth Science and Technology, Yokohama,Japan 2)The postseismic displacements after the 2011 Tohoku Earthquake measured by offshore geodetic studies[e.g., Watanabe et al., 2014] unveiled a deformation pattern significantly different from that onshore
geodetic observations showed [e.g., Ozawa et al., 2012], which provided strong constraints on modelingpostseismic deformation processes [e.g., Sun et al., 2014, Nature]. Furthermore, Tomita et al. [2016]
revealed the along-trench variation of the postseismic displacements from GPS/Acoustic (GPS/A)
observations. In this study, we show updated results of the GPS/A observations and discuss thespatiotemporal variation of the postseismic deformation.
We have carried out repeated campaign surveys from Sep. 2012 to Sep. 2016 at 20 GPS/A sites located in
Tohoku-oki region. We estimated the displacement at each site for each survey by means of Kido et al.
[2006] and then estimated the horizontal postseismic displacement rate at each site.
The displacement rates demonstrate clear spatial variation: slight trenchward motions (<~5 cm/yr) in thenorth region of the primary rupture area (PRA), significant trenchward motions (5-15 cm/yr) in the south
region of PRA, and significant landward motions (10-15 cm/yr) above PRA. The observed landward
movement can be roughly explained by the viscoelastic relaxation model (VR model, Sun et al., 2014), but
it cannot be fully accounted for, which may indicate a contribution of interplate locking producing further
landward motions. In the north region of PRA, both of the observed and the VR modeled motions are small.
This suggests trivial contributions of other processes (e.g., afterslip and interplate locking). In the south
region of PRA, the observed trenchward motions are much larger than the VR modeled motions. It
indicates that the contributions of afterslip is major in this region with showing temporal decay of afterslip,
while such a temporal decay is not detected where contributions of the viscoelastic relaxation are
dominant.

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*J07-1-04
Joint Symposium / J07. Tracking the sea floor in motion

Preliminary Results of Realistic Interseismic Modeling and GPS-Acoustics
Measurements on the Continental Slope of the Cascadia Subduction Zone
* Diego Melgar 1) , David Chadwell 2) , David Schmidt 3)
UC Berkeley 1) , Scripps Institution of Oceanography 2) , University of Washington 3)
Land-based GPS measurements suggest the megathrust is locked offshore along the Cascadia Subduction
Zone. However, land-based data alone lack the resolution to constrain the how the slip deficit is distributed.
Current efforts to constrain offshore crustal deformation using the GPS-Acoustic technique motivatesrefined, and more realistic models of the prism and forearc. Here we expand on efforts to create realistic,
physics-based models of the deformation of the shallow subduction system. Our goal is to study what therelative importance is of different physical processes at play in the interseismic period, such as
viscoelasticity of the upper mantle and plasticity of the wedge. In anticipation of renewed interest in
expanding GPS-A studies in Cascadia, we have begun to use such realistic physics based models of thedeformation of the shallow subduction system to make recommendations on what the optimal distributionof seafloor benchmarks should be in order to provide the most cost efficient solution to imaging the state oflocking of the megathrust.
Here, we also discuss updates to current efforts to expand GPS-A coverage in Cascadia by utilizing
Wavegliders to dramatically reduce ship costs. In July 2016, the GPS-A Wave Glider was launched on amonth-long mission to two sites on the continental slope of the Cascadia Subduction Zone. One site isapproximately 45 NM offshore central Oregon and the other approximately 50 NM offshore central
Washington State. We will report on initial results of the GPS-A data collection and operational experiencesof the mission. Wave Glider based GPS-A measurement have the potential to significantly increase thenumber and frequency of measurements of strain accumulation in Cascadia Subduction Zone andelsewhere.

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*J07-1-05
Joint Symposium / J07. Tracking the sea floor in motion

Short-period ocean fluctuation induced by internal wave and its effect on
GNSS/acoustic analysis* Motoyuki Kido 1) , Ryo Matsui 2) , Misae Imano 2) , Chie Honsho 1)
IRIDeS, Tohoku Univ. 1) , Graduate School of Sci., Tohoku Univ. 2)
In the GNSS/acoustic measurement, monitoring the fluctuation of water column in ocean, hence soundspeed structure, is crucial to achieve high precision positioning. In the most case, ocean condition isapproximated by time-varying stratified structure, which can be simultaneously solved with horizontal
position of the seafloor transponder array using traveltimes at least from three transponders. However, nonnegligible amount of horizontal variation of ocean structure often appears, effect of which (~30 cm) is
usually cancelled out (~5 cm) by taking very long (~12 hour) time averaging. Kido et al. (2007) proposedthat horizontal variation of the ocean structure can be considered employing five or more transponders at
once if the structure is expressed by two quantity, i.e., horizontal gradient. However, this hypothesis
requires that the variation must has a large spatial scale (> ~2-5km) so that the horizontal variation can be
regarded as linear within the extent of acoustic path to seafloor transponders.
We have conducted several times of intensive XBT (eXpendable Bathy-Thermograph) casts in the past
surveys, each of which consists of 12 times of profiling at 5-10 minute intervals. After correcting XBT
sensor bias both in temperature and fall-rate, fluctuation of vertically integrated sound speed (= nadir total
delay) well coincides with the GNSS/acoustic estimate in the 0.1 msec level. At the same time, apparent
fluctuation in the horizontal array position is often observed. In the extensive XBT profiling, we found shortperiod vertical oscillation of water column that amounted up to 20 m, which can be interpreted as internal
gravity wave passing through the observation site. With density profile in the water column by XCTD cast,we can roughly estimate typical time period of the internal wave and hence the wavelength. This will be key
quantity whether the horizontal variation can be approximated by linear structure.

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*J07-1-06
Joint Symposium / J07. Tracking the sea floor in motion

Refining ship navigation with precise point positioning to measure seafloor
displacement using repeated sidescan sonar surveys* John DeSanto , David Sandwell , David Chadwell
University of California San Diego, San Diego, United States of America
Accurate seafloor geodetic methods are critical to the study of marine natural hazards such as megathrustearthquakes, landslides, and volcanoes. Digital image correlation of repeated sidescan sonar surveys has
been demonstrated as a technique for measuring seafloor displacement that is both economical andcapable of obtaining measurements accurate to the meter scale regardless of seafloor depth. However,previous studies have been performed using ship navigation accurate to 0.5-0.7 meters and may drift on
the scale of 1 meter per hour; these biases are likely expressed as noise in the displacement
measurements. Precise point positioning is a GPS processing technique whereby satellite parameters are
solved for using a pre-existing network of stations; these parameters can then be used to quickly andaccurately solve for the position of additional GPS receivers. This technique is particularly well suited forprocessing ship GPS systems in very remote locations that may make differential GPS processing difficult.
We perform precise point positioning using the kfPANDA package to improve our knowledge of the shipposition during sets of repeated multibeam sonar surveys from two cruises, the May 2016 RR1605 cruise
south of Palau and the February 2017 SR1704 cruise offshore San Diego, California. Using the improved
navigation, we assess the accuracy of seafloor displacement measurements made from digital image
correlation of repeated sidescan surveys for ship speeds of 4-6 knots and sonar frequencies of 12 kHz and
70 kHz.

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*J07-2-01
Joint Symposium / J07. Tracking the sea floor in motion

New Technologies for Seafloor Deformation: Optical Fiber Strainmeters andSelf-Calibrating Pressure Recorders* Mark Zumberge 1) 2) , Glenn Sasagawa 1) 2) , William Hatfield 1) 2) , Matthew Cook 1) 2)
The University of California, San Diego, United States 1) , Scripps Institution of Oceanography 2)
We have advanced two new technologies for studying the deformation of the seafloor. The first is themeasurement of strain using an optical fiber stretched horizontally across the seafloor. In October of 2015
we deployed a 200 m long optical fiber strainmeter at the toe of the accretionary prism of the Cascadia
Subduction Zone off the coast of Oregon. The instrument was installed on the seafloor between two 100 kg
anchors, tensioned, and operated continuously for 96 days. A temperature compensation scheme using two
optical fibers with contrasting temperature responses allowed the separation of optical path length changes
due to temperature from those due to strain. After removal of drift, an RMS noise level of 36 nanostrainover a one month record indicates the sensors will be useful for detecting slow slip events.
The second technology relies on seawater pressure as a proxy for height measurements. While time varying
seafloor pressure can detect vertical motions with sub-centimeter precision, it is difficult to separate gauge
drift from secular deformation. The Self-Calibrating Pressure Recorder (SCPR) was designed to circumventthe problem of gauge drift by employing an in situ deadweight calibrator to periodically provide a stablereference pressure to estimate and correct for gauge drift. One such instrument was deployed at Axial
Volcano, collecting a continuous, drift-corrected recording of pressure for 17 months. In anotherexperiment we are deploying an SCPR in campaign mode, collecting absolute pressure measurements at aseries of seafloor benchmarks. We expect the method to yield epoch pressure values accurate to theequivalent of about 1 cm in height.

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*J07-2-02
Joint Symposium / J07. Tracking the sea floor in motion

Initial characteristics of LTBMS borehole sensors installed in the Nankai
Trough, Japan* Toshinori Kimura , Eiichiro Araki , Yuya Machida
JAMSTEC, Yokosuka, Japan
In the Nankai Trouhg area, the subduction of the plate has caused repeating great earthquakes along megathrusts faults between plate interfaces. We have planned to install long-term borehole monitoring system(LTBMS) in the Nankai Trough to monitor seismic activity for elucidating the generation process of themega-thrust earthquake in the subduction zone. As first LTBMS site in this area, the C0002G observatory
was activated on January 2013. In April and June 2016, the second LTBMS observatory, C0010A wassuccessfully installed in the Nankai Trough, and was connected to DONET seafloor cable, respectively. The
LTBMS observatory has a sensor suite comprising a broadband seismometer, geophone, accelerometer,volumetric strainmeter, tiltmeter, pressure gauge, and thermometer. These sensors were designed to collectweak and broadband signals that cannot be captured by land and/or seafloor observatories. After the
installation and connection, realtime multi-borehole data via DONET seafloor cable network are available.
In this presentation, we report initial characteristics of LTBMS sensors after the cable connection. The
results includes: 1) Power spectral density analysis calculated from short-term records. 2) Runningspectrum analysis using continuous long-term data. 3) Estimation of sensor orientation. 4) Initial drift andlong-term stability of geodetic sensors. We compared PSD plots calculated from ambient noise records
observed by C0002G, C0010A and DONET seismometers. Results confirmed that borehole seismometers
are now functional to detect very weak seismic signal, such as VLF events. We also summarized initial
response of tiltmeter and volumetric strainmeter, which can be used to detect weak geodetic signals as coseismic events. Now auto evaluation processes are running on the data storage server not only to monitor
sensor characteristics, but also to analyze very small seismic and geodetic events that are captured only by
the LTBMS sensors.

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*J07-2-03
Joint Symposium / J07. Tracking the sea floor in motion

Laboratory experiments for evaluating long-term characteristics of pressure
sensors used for seafloor pressure monitoring* Hiroaki Kajikawa , Tokihiko Kobata
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
Lots of precise pressure sensors are currently used for seafloor pressure monitoring to detect tectonic
movements. Although the pressure sensors show high resolution and good stability, long-term fluctuations
have been observed in the sensors' outputs during seafloor measurements, and their magnitudes are at thesame level as the pressure change caused by tectonic movements of interest. Evaluating and compensating
the effects of the long-term characteristics of the sensors are indispensable to improve the accuracy of theseafloor pressure measurement over years.
In this study, the long-term characteristics of quartz Bourdon-tube pressure sensors have been evaluated at
the pressure calibration laboratory in National Metrology Institute of Japan. The pressure of 100 MPa has
been applied to the test pressure sensors for a long period of time, during which calibrations are repeatedat 100 MPa using a pressure balance as the standard. The calibration results, the deviation of the sensor's
output from the standard value, at 100 MPa rapidly changed immediately after the pressure application,and then, the change rate became small and almost constant as time proceeded. This long-term behavior
was quite different from that obtained for the same kind of sensors used under normal, atmosphericpressure conditions. The changes in the sensor's outputs at atmospheric pressure, intermittently obtained
during the pressure application, showed that the observed long-term behavior at 100 MPa can mainly be
attributed to the zero drift of the sensor.
On the basis of the results from laboratory experiments for over two years, measures are proposed anddiscussed to appropriately compensate the long-term characteristics of pressure sensors used for seafloorpressure monitoring.

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*J07-2-05
Joint Symposium / J07. Tracking the sea floor in motion

Studying fault slip during and after the 2012 M 7.6 Costa Rica earthquake
using land-based GNSS and near-trench fluid pressure observations* Tianhaozhe Sun 1) , Kelin Wang 2) 1) , Earl Davis 2) , Yan Jiang 2) , Martin Heesemann 3)
School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada 1) , Pacific GeoscienceCentre, Geological Survey of Canada, Sidney, BC, Canada 2) , Ocean Networks Canada, University ofVictoria, Victoria, BC, Canada 3)
Knowing whether the subduction fault slips to trench during or after an earthquake is important to thestudy of fault mechanics and tsunami generation, and it requires near-trench geodetic observations. In
Costa Rica, two CORK borehole observatories were installed <1 km apart on the seaward and landwardsides of the trench. During the 2012 M 7.6 earthquake, seafloor pressures on the two sides showed no
relative change, indicating that rupture was limited to the epicentral area near the coast. Starting from 1.5
days after the rupture, several episodes of uplift of the subduction prism toe were observed as inter-site
seafloor pressure changes. This uplift was accompanied by a subseafloor pressure rise (contraction) within
the prism toe and a pressure drop (dilatation) within the incoming plate, suggesting pulses of afterslip
propagating to the trench along the plate interface. Over >1 years, this uplift showed the same temporalcharacteristics as GNSS time series recorded on land, implying that the offshore and onshore deformation
was controlled by the same afterslip process. We use both data to determine the co- and post-seismic slip
distributions of this event. For the coseismic deformation, peak slip of ~5 m is determined at a depth of
25-30 km. Calculation of shear stress change on the subduction fault suggests up to 8 MPa stress drop in
the rupture zone but stress increase (<1 MPa) further updip. Afterslip is found to be shallower than thecoseismic rupture with a cumulative peak (>1 m over 1.3 years) located in the area of coseismic stressincrease just offshore and fairly large slip (~0.7 m) at the trench. While postseismic stress decrease occurs
at shallow depths, stress variation near the trench is smaller because of the low rigidity of sediments. The
trench-breaching afterslip in Costa Rica, together with the trench-breaching rupture in the 2011 Tohoku-oki
earthquake, provides important information on the slip behaviour of the shallowest part of megathrusts.

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*J07-2-06
Joint Symposium / J07. Tracking the sea floor in motion

On the Interpretation of oceanic variations in terms of ocean bottompressure* Tomoya Muramoto 1) , Yoshihiro Ito 1) , Daisuke Inazu 2) , Stuart Henrys 3) , Laura Wallace 3) , Stephen
Bannister 3) , Ryota Hino 4) , Syuichi Suzuki 4) , Kimihiro Mochizuki 5)
Research Center for Earthquake Prediction, Disaster prevention research institute, Kyoto University, Kyoto,
Japan 1) , Department of Ocean Sciences, Faculty, Tokyo University of Marine Science and Technology,
Tokyo, Japan 2) , GNS Science, Lower Hutt, New Zealand 3) , Graduate School of Science, Tohoku
University, Miyagi, Japan 4) , Earthquake Research Prediction Center, Earthquake Research Institute, The
University of Tokyo, Tokyo, Japan 5)
To extract the pressure change due to crustal deformation from Ocean Bottom Pressure Record, it isessential to understand exactly what caused the observed pressure change. In this study, we consider
about the factor of sea floor pressure change, especially temporal variation of several months to annual
cycle from observed data. In this study, we use observed pressure records which spanned from June 2014
to June 2016 at off the coast of north island in New Zealand and Kumanonada using independent type
Ocean Bottom Pressure Recorders. By using Baytap-G, we calculated the tidal component and subtracted itfrom the raw data. Then, we calculated sea-level anomaly (non-tidal oceanic variation) driven by airpressure and wind using barotropic ocean model. Comparing with Ocean Bottom Pressure Record after
removing tidal component and calculated sea-level anomaly using ocean model, we found that there is along-term component included in the Ocean Bottom Pressure Record that cannot be expressed by
calculating ocean model. This long-term component's amplitude is about 1.5hPa and has about a 90-day
cycle. In evaluating the pressure change derived from crustal deformation due to SSE, the amplitude of thiscomponent we detected in this study cannot be ignored. In this study, we consider the origin of this tongterm component from multiple viewpoints such as gravity observation satellite GRACE or tide gauge record
etc. As a result, we found that there is a “fluctuation" which can be approximated as summation ofharmonic mode. After subtracting the long-term component we identified in this study, we detected crustal
deformation due to SSE at off the coast of north island in New Zealand. Then, we estimated fault slip due tothe SSE from vertical displacement observed by Ocean Bottom Pressure and horizontal displacement
observed by GNSS.

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*J07-3-01
Joint Symposium / J07. Tracking the sea floor in motion

New buoy platform system for crustal displacement observation* Narumi Takahashi 1) 2) , Kentaro Imai 2) , Yasuhisa Ishihara 2) , Tatsuya Fukuda 2) , Hiroshi Ochi 2) , Misae
Imano 3) , Yusaku Ohta 3) , Motoyuki Kido 3) , Shuichi Kodaira 2)
National Research Institute for Earth Science and Disaster Resilience 1) , Japan Agency for Marine Earth
Science and Technology 2) , Tohoku University 3)
It is known that huge earthquakes occurred repeatedly around the Nankai Trough area and that coastal
residents have received severe tsunami damages. The huge tsunami was brought by vertical displacementof the seafloor. Therefore, it is very important for local residents to receive the tsunami detection, to escapefrom tsunami and to evaluate crustal displacement. However, there are areas without the monitoring
system like the dense oceanfloor network system for earthquakes and tsunamis (DONET). Therefore, we
has developed a new buoy platform system for observation of tsunami and crustal displacement for five
years. The large merit of the buoy platform is mobility and easy replacement. The system has a pressuregauge and acoustic transponders on the seafloor to observe crustal displacement and tsunami, and theirsignals are sent to our land station via the buoy using acoustic transmission and the iridium
communication. Because it measures sea surface height using GNSS, the vertical crustal displacement canbe also measured using the height and pressure gauge data. The buoy plays a role as the center of thissystem, which control timing to send acoustic signals, collect data from the seafloor and transfer the data to
the land station. The buoy has to stand up to severe environment with sever typhoons and strong sea
current with a speed of over 5 knots to realize long periods observation of the crustal displacement. To
overcome above conditions and difficulties, we adopted some unique means for the system. Important
technologies of this system are acoustic transmission between seafloor and the buoy, slack mooring to bearstrong sea current, and the system stability. We introduce collected data and our remaining tasks currently
for long observation under the severe conditions.

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*J07-3-02
Joint Symposium / J07. Tracking the sea floor in motion

S-net project: Large-scale seismic and tsunami observation system onseafloor along the Japan Trench* Kenji Uehira 1) , Masashi Michizuki 1) , Toshihiko Kanazawa 1) , Takashi Shinbo 1) , Katsuhiko Shiomi 1) ,Takashi Kunugi 1) , Shin Aoi 1) , Takumi Matsumoto 1) , Shoji Sekiguchi 1) , Narumi Takahashi 1) , Naotaka
Yamamoto 1) , Masanao Shinohara 2) , Tomoaki Yamada 2)
National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan 1) , The University ofTokyo, Tokyo, Japan 2)
Seafloor Observation Network for Earthquakes and Tsunamis along the Japan Trench (S-net) has 150 realtime monitoring observatories that cover the area about 1000km x 300 km from off-Hokkaido to off-Kanto.
It is expected that early tsunami and earthquake warnings and earthquake researches will be enhanced. Snet consists of six segment networks of about 25 observatories and 800 km fiber optic cable (1,500 km
fiber optic cable for the Japan Trench outer rise segment network). Each observatory has four sets of threecomponent seismometers for earthquake observation and two sets of pressure gauge for tsunami
observation. Fiber-optic cable connects to landing station, and the data is transmitted from landing station
to the data center via IP-VPN network.
S-net project has started in 2011. We have already finished deployment of all of the observatories and fiberoptic cables in 2016. We have also constructed five landing stations; Minamiboso station in Minamiboso
City, Chiba Pref., Kashima station in Kashima City, Ibaraki Pref., Watari station in Watari Town, Miyagi Pref.,Miyako station in Miyako City, Iwate Pref., and Hachinohe station in Hachinohe City, Aomori Pref.. The
Watari station is located on the third floor of reinforced concrete building, and other stations are containertype data centers. The S-net (except outer-rise segment) started to operate in May 2016, and the pressuregauge and accelerometer data have been transmit to Japan Metrological Agency (JMA) for monitoring
purpose. The S-net detected many earthquakes. S-net also observed tsunamis like with the earthquake of
the November 22, 2016 off Fukushuma (M7.4).

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*J07-3-03
Joint Symposium / J07. Tracking the sea floor in motion

Real-time observation system of pressure gauges and accelerometers on
seafloor using ICT through seafloor fiber cable installed in the off-Sanriku
region, Japan* Masanao SHINOHARA 1) , Tomoaki YAMADA 1) , Shin'ichi SAKAI 1) , Hajime SHIOBARA 1) , Toshihiko
KANAZAWA 2)
Earthquake Research Institute, The University of Tokyo, Tokyo, Japan 1) , National Research Institute for
Earth Science and Disaster Prevention, Tsukuba, Japan 2)
A seafloor cabled system is useful for study of earth science and disaster mitigation, because real-time andlong-term observation can be performed. A new system has been required from views of costs andflexibility of measurements. We have been developing a system using Information and Communication
Technologies (ICT) for data transmission and system control. The new system has flexibility since software
processes various measurements. Reliability of the system is kept by using redundant system which iseasily constructed using the ICT. The first system based on this concept was deployed in Japan Sea.
Development of the second system started in 2012. The second system has both seismometers andpressure gauges. An observation node has a CPU and FPGA, and the system uses standard TCP/IP protocol
with a speed of 1 Gbps for data transmission, system control and monitoring. IEEE-1588 (PTP) is
implemented to synchronize a real-time clock, and accuracy is less than 300 ns. We developed two types ofobservation node. One equips a pressure gauge for observation of tsunami-waves and vertical crustal
deformation, and another has an external port for additional sensors using PoE. Deployment of the second
system was carried out in September 2015 by using a commercial telecommunication cable ship. At
completion of the deployment, the system started collecting data on seafloor immediately. The noise levels
at the deployed system are comparable to those at the existing cabled system off Sanriku. Reflecting a low
noise environment, many earthquakes were recorded clearly. From the pressure data, pressure
measurement has a resolution of less than 1 hPa, which corresponds to a change of water height of lessthan 1 cm, and all the pressure gauges in the system have collected consistent tidal data. Tsunami-waves in
November 2016, which were generated by an earthquake with magnitude of 7.4 off Fukushima were clearlyobserved by all pressure gauges in the system.

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*J07-3-04
Joint Symposium / J07. Tracking the sea floor in motion

Seafloor deformation due to ocean tidal loading observed by seafloor cabled
network.
* Eiichiro Araki
JAMSTEC, Yokosuka, Japan
Seafloor observation hosted by seafloor cabled network such as DONET (Dense Ocean-Floor Network for
Earthquake and Tsunamis) have potential to observe process of slow crustal deformation occurring at platemargin which in many cases situated in the seafloor. Observation in deep seafloor borehole have recently
documented occurrence of slow slip events. Investigation of seafloor broadband seismic records in tidal
frequency obtained from DONET observatories, was conducted to see if such events of may be observed in
the seafloor. The broadband seismic records (from Guralp CMG3T) have flat velocity response < 360s andwere corrected to obtain acceleration response in tidal frequencies between 2 days and 1 hour. The
corrected acceleration response in vertical direction were consistent in most of DONET observatories, withestimated tidal gravity change by GOTIC2, indicating these broadband seismometers have good sensitivity
to gravity change in tidal frequencies. The horizontal acceleration response, corresponds to tilting, on theother hand, showed differences between sites. The amplitude of diurnal tidal response varied between 0.1 –2 microradians, significantly larger than those estimated for earth tide. The observed tidal tilt responses
were at many sites in phase with seafloor pressure variation in both horizontal axes. This observation
indicates significant effect of seafloor deformation due to ocean tide loading in these sites. The linearlycorrelating tilting were observed in may sites in accretionary prism of dipping subseafloor structure. It isconsidered that ocean tidal loading at such setting results in horizontal variation of deformation that wasobserved as the large amplitude tidal tilting. Therefore, seafloor tilt/strain measurement may be used toindicate slow crustal deformation, but with cautious estimate of the effect of ocean loading at each sites.

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*J07-3-05
Joint Symposium / J07. Tracking the sea floor in motion

Monitoring submarine fault deformation using direct-path ranging* Florian Petersen , Heidrun Kopp , Dietrich Lange , Katrin Hannemann , Morelia Urlaub
GEOMAR Helmholtz Centre for Ocean Research Kiel
The seafloor stores crucial information on sub-seafloor processes, including stress, elastic strain, andearthquakes. This information may be extracted through the nascent scientific field of seafloor geodesy.
The GeoSEA (Geodetic Earthquake Observatory on the SEAfloor) array uses acoustic signals for direct-path
ranging and relative positioning at mm-scale resolution for a period of up to 3.5 years. The transponders
also include high-precision pressure sensors to monitor vertical movements and dual-axis inclinometers inorder to measure their altitude as well as any change in submarine fault zones and characterizing their
behavior (locked or aseismically creeping). A further component of the network is GeoSURF, a self-steering
autonomous surface vehicle (Wave Glider), which monitors system health and is able to upload the seafloor
data to the sea surface and to transfer it via satellite. Seafloor transponders are currently installed across a
dextral strike-slip fault to measure the instability of the eastern flank of Mt Etna in Sicily, and along theNorth Anatolian Fault offshore Istanbul to measure the strain build-up along the fault in a seismic gap. In
addition, three arrays are currently deployed on the marine forearc and outer rise of the North Chilean
subduction zone system. This segment of the Nazca-South American plate boundary has last ruptured in an
earthquake in 1877 and was identified as a seismic gap prior to the 2014 Iquique earthquake (Mw 8.1).
The southern portion of the segment remains unbroken by a recent earthquake. The first 12 month of all
geodetic installations were analyzed and we discuss baselines with precision less than 5 mm for ranges up
to 2000 m of distance and compare them with synthetic baselines. In all three tectonic settings, theobtained baseline changes remain within the resolution limits. In the case of the North Anatolian Fault, thissuggests a locked fault zone.

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*J07-3-06
Joint Symposium / J07. Tracking the sea floor in motion

Slip rate of the North Anatolian Fault at the western part of the Sea ofMarmara through seafloor geodetic measurement for two years* Ryusuke Yamamoto 1) , Motoyuki Kido 2) , Yusaku Ohta 1) , Narumi Takahashi 3) , Yojiro Yamamoto 4) ,Dogan Kalafat 5) , Ali Pinar 5) , Haluk Ozener 5) , Sinan Ozeren 6) , Yoshiyuki Kaneda 7)
Graduate School of Science, Tohoku University, Sendai, Japan 1) , International Research Institute ofDisaster Science, Tohoku University, Sendai, Japan 2) , National Research Institute for Earth Science andDisaster Resilience, Tsukuba, Japan 3) , Japan Agency for Marine-Earth Science and Technology,
Yokohama, Japan 4) , Kandilli Observatory and Earthquake Research Institute, Bogazici University, Istanbul,
Turkey 5) , Istanbul Technical University, Istanbul, Turkey 6) , Institute of Education, Research and Regional
Cooperation for Crisis Management Shikoku ,Kagawa University, Takamatsu, Japan 7)
The North Anatolian Fault (NAF) regionally has right-lateral block motion (~25 mm/yr) but local slip rate
along the fault varies from place to place, which may control the inter-seismic stress accumulation. Rupturearea along NAF is known to migrate roughly from east to west in the last century. The Marmara segment is
known as seismic gap since 1766 (Marmara earthquake) or 1912 (Ganos earthquake / Murefte-Sarkoy
earthquake), while the Izmit and Duzce earthquakes just east of the Marmara segment occurred in 1999.
Thus, we investigate slip rate of NAF in the Sea of Marmara using seafloor acoustic extensometers, where
on-shore geodetic observations (e.g. GNSS or InSAR) cannot be accessible.
In 2014, we installed four instruments at the Western High, where the Marmara main fault can be clearly
identified, and added one more instrument in 2015. Since then, we recovered almost two years ofcontinuous ranging data and evaluated the creep rate at this site as 10 +/- 5 mm/yr, which corresponds
nearly a half coupling rate to the regional block motion. Using this constraint and surrounding onshore
GNSS data, we constructed a simple fault model, that has partial creep layer from the seafloor to some
10-30 km depth and full creep below. We have installed two additional GNSS site in the Sea of Marmara
since 2016 in order to constrain depth extent of the partial creep layer, which may be discussed with theseismicity distribution obtained by ongoing OBS surveys.
Acknowledgement: This observation is carried out in the MarDiM (Marmara Disaster Mitigation) project,
SATREPS promoted by JICA, JST and Ministry of Development of Turkey

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*J07-P-01
Joint Symposium / J07. Tracking the sea floor in motion

Towards an Ocean Bottom Geodetic Observatory In Mexico: The First Steps* Vala Hjorleifsdottir 1) , Yoshihiro Ito 2) , Victor Manuel Cruz-Atienza 1)
Universidad Nacional Autonoma de Mexico, Mexico City, Mexico 1) , Kyoto University, Kyoto, Japan 2)
Ocean bottom geodesy has proven important for observing static offsets occurring during large earthquakes(e.g. Sato et al 2011; Ito et al 2011; Kido et al 2011), to observe slow earthquakes (Ito et al 2013; Wallace
et al., 2016), as well as slower tectonic motions (Chadwell & Spiess, 2008).
The Guerrero Seismic Gap, a one hundred kilometer segment of the Mexican subduction zone, has notexperienced a large earthquake since at least 1911 (Singh et al 1981). Whether the zone is ripe for a newearthquake or not, depends on the amount of aseismic slip occurring on the fault plane in the inter seismic
period, either as continuous creep or slow slip events. In the down-dip part of the segment, large (M~7)
slow slip events have been observed about every four years (e.g. Kostoglodov 2003, Larson et al 2006,
Radiguet et al 2012). However, it is not clear to which degree the near trench area participates in these
events. The Guerrero Gap is the closest segment of the subduction zone to Mexico City. A large event inthis zone could cause severe damage to Mexico City and could generate a tsunami that could strongly
impact Acapulco and neighboring regions.
As a collaboration between SATREPS/JICA in Japan, and UNAM and CONACyT in Mexico, a network of 2
GPS-Acoustic sites as well as 7 ocean bottom pressure recorders is planned offshore the Mexican coast, in
the Guerrero Gap. A wave glider will be used to measure the position of the GPS-A sites. The installation of
the first instruments is planned for June 2017. This presentation will detail the types of instruments thatare planned and their distribution, the type of signals that we hope to collect as well as the plans for the
future.

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*J07-P-02
Joint Symposium / J07. Tracking the sea floor in motion

Quantitative evaluation of error sources for the GPS-A seafloor geodesy* Yusuke Yokota , Tadashi Ishikawa , Shun-ichi Watanabe
Hydrographic and Oceanographic Department, Japan Coast Guard, Tokyo, Japan
Seafloor geodetic observations using the GPS-Acoustic ranging combination technique (GPS-A)
accomplished several monumental works in the fields of seismology and geodesy [e.g., Gagnon et al., 2005;
Sato et al., 2011; Yokota et al., 2016]. In this technique, we observe using vessels on the sea around theseafloor acoustic mirror-type transponders. Seafloor absolute positions were determined using this acoustic
data, the attitude data and the GPS data on the vessels. Although the GPS-A technique achieved
establishment of the sophisticated seafloor observation network, an observation precision (1 σ = 2 - 3 cm:
horizontal) remains lower than other geodetic observation techniques. The observation precision is affected
mainly by three error sources. These are GPS errors, a measuring error between GPS and a bottomed
acoustic transducer (T-D error), and an effect of ocean disturbances for undersea sound speed structures(SSS errors).
First, we performed a numerical simulation study to check reactions of a seafloor positioning analysis inseveral cases of the GPS errors and the T-D error. The obtained results suggested that the seafloor
positioning in our present system is affected in 5 mm-scale (1 σ) by the GPS and T-D error sources.
Therefore, the positioning is affected majorly by the SSS error sources. We have reduced this effect using
analytical approaches in this decade. In that process, spatial and temporal changes and spatial biases of
SSS were approximated as fields modelled using high-order temporal functions. We review our current
analysis flow and evaluate effects of ocean disturbances quantitatively.
Acknowledgements: We thank the Geospatial Information Authority of Japan (GSI) for high-rate GPS datafor kinematic GPS analysis, and for daily coordinates of the sites on the GSI website.

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*J07-P-03
Joint Symposium / J07. Tracking the sea floor in motion

Recent seafloor movement in and around the rupture zone of the 2011
Tohoku-oki earthquake detected by GPS-Acoustic seafloor geodesy* Tadashi Ishikawa , Yusuke Yokota , Shun-Ichi Watanabe
Japan Coast Guard, Tokyo, JapanThe Hydrographic and Oceanographic Department of Japan Coast Guard has been developing a system for
precise seafloor geodetic positioning with the GPS-Acoustic combination technique and deploying seafloor
observation sites on the landward slope of the major trenches around Japan, such as the Japan Trench andthe Nankai Trough.
After the 2011 Tohoku-oki earthquake (M9.0), we directly measured huge coseismic seafloor displacements
at seafloor sites just above the source region (Sato et al., 2011). These displacements were more than fourtimes larger than those at any onshore GNSS station. It provided definitive evidence of huge coseismic
deformation beneath the ocean.
We have repeatedly performed the GPS-A seafloor geodetic observation to monitor the postseismic
movement in and around the rupture zone. In contrast to the coastal GNSS sites where trenchward-upward
movements were reported, the offshore seafloor sites above the main rupture zone exhibit landward
displacements with significant subsidence(Watanabe et al., 2014).
Although the terrestrial movements were reasonably interpreted by afterslip beneath the coastal area, theoffshore results are rather consistent with effects predicted from viscoelastic relaxation in the upper
mantle, providing definitive evidence of its occurrence.
In this presentation, we will report and discuss the most recent results of postseismic seafloor movement
obtained after the paper by Watanabe et al., (2014).
Acknowledgements: We thank the Geospatial Information Authority of Japan (GSI) for high-rate GPS datafor kinematic GPS analysis, and for daily coordinates of the sites on the GSI website.

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*J07-P-04
Joint Symposium / J07. Tracking the sea floor in motion

Detection of offshore vertical displacements after the 2011 Tohoku-oki
Earthquake using GPS/A observations* Fumiaki Tomita , Chie Honsho , Motoyuki Kido
Tohoku University, Sendai, Japan
After the 2011 Tohoku-oki Earthquake, GPS/Acoustic (GPS/A) observations have revealed extensive
postseismic displacement pattern [Watanabe et al., 2014, GRL; Tomita et al., 2016, AGU], which provides
strong constraints on modeling of the postsesimic deformation processes [e.g., Sun et al., 2014, Nature].
Most of the GPS/A observation results are limited in horizontal components because vertical component
has large errors due to the trade-off nature with sound speed in the seawater. However, vertical motions are
sensitive to postseismic processes; therefore, in this study, we challenge to estimate vertical displacements
after the Tohoku Earthquake, from Sep. 2012 to Nov. 2016, at the 20 GPS/A sites located in the Tohoku-oki
region.
In order to estimate vertical motions, numerous acoustic ranging data covering extensive sea-surface points
are needed to distinguish the vertical motions and sound speed variation[Sato et al., 2013, J. Geod.].
Although, in our survey style, acoustic ranging was mainly performed at a fixed sea-surface point (thecenter of each transponder array) with the aim to focus on detecting the horizontal motions [e.g., Kido et al.,2006, EPS], we have also occasionally conducted moving surveys to collect acoustic ranging data covering
the minimum extent above each transponder array. Using these data, we calculated displacement rates ofthe vertical motions.
The obtained vertical displacement rates show a spatially characterized pattern: subsidence above thecoseismic rupture area and uplift near the trench, but they have 3-15 cm/yr errors in 1σthat are muchlarger than the errors in the horizontal components. Due to the large errors, it is difficult to discuss thepostseismic deformation processes at the moment. Nevertheless, this study successfully showed thepotential capability of our data for detecting vertical motions. Further collection of data and appropriate
evaluation of the errors will be required to obtain more accurate results.

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*J07-P-05
Joint Symposium / J07. Tracking the sea floor in motion

Little evidence of shortening motion across the Japan Trench after the 2011
Tohoku-oki earthquake from direct-path acoustic ranging* Ryusuke Yamamoto 1) , Ryota Hino 1) , Motoyuki Kido 2) , Chie Honsho 2)
Graduate School of Science, Tohoku University, Sendai, Japan 1) , International Research Institute ofDisaster Science, Tohoku University, Sendai, Japan 2)
After the 2011 Tohoku-oki earthquake, large postseismic deformation in ocean has been detected by
GPS/Acoustic observations both the landward and oceanward slope of the Japan trench, which mainly
attributed to the viscoelastic relaxation induced by the mainshock (e.g. Sun et al., 2014, Nature; Watanabe
et al., 2014, GRL; Tomita et al., 2015, GRL) especially in the large slip region (off-Miyagi). Crustal
deformation near the trench axis play important role on a huge earthquake, whose rupture area extend to
the trench. However, convergence rate just at the trench axis is not clear from GPS/A observation.
Therefore, we have carried out seafloor acoustic direct-path ranging across the frontal wedge to reveal
locking state.
Direct-path acoustic ranging measures two-way travel times between a pair of instruments installed on theseafloor continuously for more than one year and as precisely as ~ 1 mm/yr for 1 km baseline. So far, wehave completed three periods of observation, during 2013–2014, 2014–2015, and 2015–2016, in theregion where significant coseismic slip was observed (e.g. Iinuma et al., 2012, JGR). In this paper, we show
results of the long-term continuous observations from 2013 to 2016. All of results show little evidence ofshortening motion across the trench after the Tohoku-oki earthquake.
Furthermore, we are planning to install another instrument in the Fukushima-oki region, where relatively
large postseismic slip is expected (Sun and Wang, 2015, JGR) to reveal heterogeneous locking state. It will
be planned to deploy in March 2017 and to recover in 2018. We expect that spatially heterogeneousconvergency speed that will be caused by postseismic slip can be detected by this additional observation.
Acknowledgement: This observation is supported by JSPS KAKENHI (26000002). The installation andrecovery of the instruments were executed during the KAIREI (KR15-15) and SHINSEIMARU (KS-16-14)
cruises.

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*J07-P-06
Joint Symposium / J07. Tracking the sea floor in motion

Characteristics of a quartz pressure sensor assuming an ocean bottom
environment for highly accurate measurements of small and long-term
crustal deformation* Yuya Machida , Shuhei Nishida , Eiichiro Araki , Toshinori Kimura
JAMSTEC, Kanagawa, Japan
In the Nankai Trough region, several large interplate earthquakes occurred repeatedly due to a subductionof the Philippine Sea Plate beneath the Eurasian Plate. In this area, Japan Agency for Marine-Earth Scienceand Technology (JAMSTEC) have deployed cabled observatory system (DONET) and long-term borehole
monitoring systems (LTBMS) to monitor earthquakes and tsunamis, and to understand a seismogenic
process of large interplate earthquakes. Seafloor pressure measurements are continuously conducted since
the installation of the observatories, and are important for the detection of long-term crustal deformations
to obtain geophysical knowledge associated with the occurrence of large earthquakes. However, pressure
values contain instrumental drifts in the sensors in addition to the pressure changes associated with crustal
deformations on the seafloor. Therefore calibrations of the pressure sensor is indispensable. We aredeveloping a mobile pressure gauge to calibrate existing pressure sensor. The gauge has a quartz pressure
sensor as a water pressure sensor. A target accuracy of the gauge is less than 1 hPa compared to theabsolute pressure value to detect small crustal deformations. Machida et al. (2016) assessed a quartzpressure sensor characteristics assuming an ocean bottom environment in the laboratory. The results
showed that several factors, such as a temperature hysteresis and a pressure hysteresis, cause less-accurate
water pressure measurements. We conducted further assessments regarding attitude of the sensor. Results
showed that the attitudes have an impact on the target accuracy. Based on the assessments, specificationsof the gauge has to be designed to achieve the accurate water pressure measurements on the order of
1hPa. It would contribute to obtain long-term small amounts of seafloor displacements related togeophysical phenomena.

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*J07-P-07
Joint Symposium / J07. Tracking the sea floor in motion

Investigation of long period behaviors of seafloor pressure records based onfield data and laboratory test results* Ryota Hino 1) , Syuichi Suzuki 1) , Makiko Sato 1) , Yusaku Ohta 1) , Yoshihiro Ito 2) , Hiroaki Kajikawa 3) ,Tokihiko Kobata 3)
Tohoku University, Sendai, Japan 1) , Kyoto University, Kyoto, Japan 2) , National Institute of Advanced
Industrial Science and Technology, Tsukuba, Japan 3)
Seafloor pressure monitoring is an effective mean to detect vertical crustal deformation in offshore areas. A
small sensor of high precision and low power consumption enables to build an ocean bottom observation
system to make continuous observations for one to two years. Several studies demonstrated that the bottompressure monitoring can detect transient signals associated with tectonic events having time constants
shorter than a month. However, it is difficult to detect tectonic events of much slower deformation rates
due to lack of the knowledge about exact origins of longterm variations in the pressure records obtained at
the seafloor. In this paper, we discuss about longterm characteristics of ocean bottom pressure records
based on the actual data obtained by repeating deployment of free-fall/pop-up type instruments in theJapan Trench area as well as by laboratory experiments. A similar pattern of the temporal variation canoften be identified on the seafloor records obtained by the identical pressure sensor. Previous laboratory
experiments on the response of pressure sensors of the same kind showed a transient behavior after
applying high pressure has several similarities to those on the seafloor observation records. These suggestthat the sensor specific characteristics can be dominant in the field data and may be removed after
estimating it through laboratory tests. Motivated by this idea, we are carrying out a laboratory experiment toclarify exact behavior of the pressure sensor previously used in the field observations. Another experiments
are done to know stability of a counting clock for frequency measurement.

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*J07-P-08
Joint Symposium / J07. Tracking the sea floor in motion

Reexamination of the fault model for transient slow slip event in the Japan
Trench before the 2011 Tohoku-Oki earthquake
Yui Nishimagi , Yusaku Ohta , * Ryota Hino
Graduate Shool of Science, Tohoku University, Sendai, Japan
Slow slip events are one of the important phenomena in the plate interface. Ito et al. (2013) investigated
two transient slow slip events that occurred before the 2011 Tohoku-Oki earthquake deduced from thedense ocean bottom pressure (OBP) gauge data. They adopted differential pressure record between
neighboring two OBPs for the effective removal of the remaining non-tidal oceanic mass variation. Theirapproach, however, can only know the relative displacement between two adjacent stations. Thus, it isdifficult to understand the absolute displacement in each OBP station. Based on these background, we
reexamined the SSE fault model using reprocessed OBP data set.
We used 8 OBP stations (TJT1, GJT3, P09, P08, P06, P02, P03, and P07) which is the almost same data set
with Ito et al. (2013). The ocean tide and by non-tidal oceanic mass variation are removed by the model.
We fitted the drift model (combination of an initial exponential and a linear component) to each of theobserved time series to estimate the drift function of individual sensors. Even though the such procedure,
the residual component still appeared. Thus, we calculated the differential time series of the OBPs in theeastern part (TJT1, GJT3, P09, and P08) relative to the averaged time series in the distant OBP stations(P06, P02, P03, and P07). Furthermore, we calculated the displacement field in each OBP station of easternpart according to the same definition of the time window with Ito et al. (2013).
We obtained the characteristic result between 19 Feb. to 8 March, 2011. TJT1 site, which located in themost eastern site, showed clear uplift. In contrast, GJT3 site, which is the neighboring site of the TJT1,
shows small subsidence. Based on these data, we reexamined the SSE fault model. Obtained result shows
the possibility of two fault locations. First model located in the very shallow part of the plate interface, thesecond model located in the slightly deeper part compared with the first one.

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*J07-P-09
Joint Symposium / J07. Tracking the sea floor in motion

Changes in physical properties of the Nankai Trough megasplay fault
induced by earthquakes, detected by continuous pressure monitoring* Chihiro Kinoshita 1) , Demian Saffer 2) , Achim Kopf 3) , Rosner Alexander 3) , Laura Wallace 4) , Eiichiro
Araki 5) , Toshinori Kimura 5) , Yuya Machida 5) , Reiji Kobayashi 6) , Earl Davis 7) , Sean Toczko 5)
Kyoto University, Kyoto, Japan 1) , Pennsylvania State University, State College, USA 2) , University ofBremen, Bremen, Germany 3) , GNS Science, Lower Hutt, New Zealand 4) , JAMSTEC, Yokohama, Japan 5) ,Kagoshima University, Kagoshima, Japan 6) , Geological Survey of Canada, Sidney, Canada 7)
One primary objective of Integrated Ocean Drilling Program (IODP) Expedition 365, conducted as part of
the NanTroSEIZE project, was to recover a temporary observatory, termed the "GeniusPlug" to monitor
formation, pore fluid pressure and temperature within a major splay fault that branches from the main plateinterface, at a depth of ~400 m below sea floor (mbsf). The instruments were installed in Dec. 2010 andrecovered in April 2016, yielding 5.3 years record of formation pressure and temperature within fault zone.
Here, we use the pressure timeseries, and in particular the response to ocean tidal loading, to evaluatechanges in physical properties of fault zone induced by several regional earthquakes. To accomplish this,we quantify: (1) the amplitude of the formation's response to tidal loading, defined in terms of a tidal
loading efficiency, governed primarily by the formation and fluid elastic properties; (2) the phase lag
between the ocean tidal signal and the measured response in the observatory, which is governed by a
combination of formation hydraulic diffusivity and the relative compressibilities of the formation andsensing volume; and (3) pressure steps associated with earthquakes, identified in formation pressure after
removal of the tidal signal. We observe essentially no phase lag, but in for many events we detect bothpressure steps and transient decreases in loading efficiency. To reveal the cause of these changes, weinvestigate the effects of static and dynamic crustal strains. Most of the detected changes represent
pressure increases and loading efficiency decreases. We speculate that disruption of grain contacts andsubsequent pore collapse induced by dynamic strain produces changes of hydraulic properties in the fault
zone. Alternatively, these changes could reflect exsolution of gas from pore fluids that drives pore pressures
up while simultaneously reducing loading efficiency by increasing the compressibility of pore filling fluids.

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*J07-P-10
Joint Symposium / J07. Tracking the sea floor in motion

Possibility of tilt observation at the seafloor by a mobile ocean bottom
seismometer* Hajime Shiobara 1) , Aki Ito 2) , Hiroko Sugioka 3) , Yoshio Fukao 2) , Masanao Shinohara 1)
The University of Tokyo, Tokyo, Japan 1) , Japan Agency for Marine-Earth Science and Technology,
Kanagawa, Japan 2) , Kobe University, Hyogo, Japan 3)
Since 1999, we had developed the broadband ocean bottom seismometer (BBOBS) and its new generation(BBOBS-NX), and, with them, performed many practical observations to create a new category of the ocean
bottom broadband seismology. High mobility of the BBOBS and BBOBS-NX can be a breakthrough torealize the geodetic observation network on the seafloor. Two kinds of attempts to expand observation
range toward the geodetic one have been started since 2009. One is for detecting vertical displacement byattaching an absolute pressure gauge with the BBOBS, and another is for tilt observation by using the
BBOBS or BBOBS-NX. In this presentation, we will report results for the later. The tilt is measured from twohorizontal mass position (acceleration) signals as offsets from the level. The first test was performed at theland pit in 2010. The result was comparable to that of the water tube tilt-meter there, with resolution of
better than a micro radian. Next, a practical observation at the seafloor off Boso was done as the feasibility
study from April 2013 for one year. In January 2014, a slow slip event (SSE) occurred near the site. The tilt
data was processed by removing for the mechanical relaxation and tides. The result shows clear peakstarted from the late Dec. 2013, but the tilt was not remained after the SSE ended. As the data length of oneyear seemed short, two tilt observations are in operation by the BBOBS-NX since 2015, one is at the samesite above and another is off Tohoku area, both for two years. Moreover, we made tilt observations by the
BBOBS on the seafloor 4 times at 3 sites, 2 of 4 cases were with a current profiler. Compared with the tilt
data by the BBOBS-NX using a penetrated sensor, the effective resolution is more than ten micro radian,which is similar to the horizontal noise difference due to the bottom current. But, the BBOBS is still useful
to detect such oceanographic events as internal bores unstably generated along seafloor slopes.

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*J07-P-11
Joint Symposium / J07. Tracking the sea floor in motion

Monitoring of the shallow tremors around the source areas of the Nankai
and Tonankai earthquakes by ocean bottom observations* Kensuke Suzuki 1) , Eiichiro Araki 1) , Toshinori Kimura 1) , Yuya Machida 1) , Demian Saffer 2) , Narumi
Takahashi 1) 3) , Shuichi Kodaira 1)
JAMSTEC 1) , The Pennsylvania State University 2) , NIED 3)
Japan Agency for Marine-Earth Science and Technology (JAMSTEC) installed two ocean bottom
observation systems in the source area of the Nankai and Tonankai earthquakes along the Nankai trough,southwest Japan (e.g., Kaneda et al, 2015; Kawaguchi et al., 2015; Kopf et al., 2011); one is the cabled
observation system called Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET), theother is the borehole observation system called Long-Term Borehole Monitoring System (LTBMS). LTBMS
and DONET stations have several kinds of the sensors such as a broadband seismometer, a quartz-type
pressure gauge and a pore pressure gauge on and under the seafloor for the seismic and geodetic
observations. The digitized data recorded at stations, which are distributed between coast and trough axis,
are continuously transferred to our laboratory in real-time. By using these data, we can continuously
monitor the tremors on the plate interface shallower than the source areas of the mega-thrust earthquakes
along the Nankai trough at where the past studies have little detected tremors. In this study we purpose tomonitor the non-volcanic tremors around the LTBMS and DONET stations, especially shallow ones.
By applying the envelope correlation method (Ide, 2010; Ide, 2012) to records of the broadband
seismometers between Jan. 2011 and Dec. 2016, we tried to detect non-volcanic tremors around thesource areas of the mega-thrust earthquakes. We detected both of the stable and episodic tremor activities.
Tremors have stably occurred at the shallower part than the source area of the Tonankai earthquake, whichalmost corresponds to the aftershock area of the 2004 off Kii peninsula earthquake. Episodic tremors
occurred either alone or with the large earthquakes (e.g., the off Mie earthquake on 1 Apr. 2016). Somelong-term deviations of the pore pressure, which might indicate the slow slips, were detected at almost
same time with the occurrences of the tremors.

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*J07-P-12
Joint Symposium / J07. Tracking the sea floor in motion

Site amplification at Nankai seafloor observation network DONET1 in Japanevaluated by spectral inversion* Hisahiko Kubo , Takeshi Nakamura , Wataru Suzuki , Takeshi Kimura , Takashi Kunugi , Narumi Takahashi, Shin Aoi
National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan
Seafloor strong motion observation networks such as DONET and S-net have been deployed in the
subduction zones of Japan. Their observations are expected to be useful for the real-time analyses on themagnitude estimation and the strong-motion forecast for subduction earthquakes. For these applications,site amplifications at the seafloor stations need to be evaluated because site amplifications caused by thicklow-velocity sediments in the subduction zones can strongly affect the real-time analyses. In this study, we
focus on DONET1, which are operated by NIED and JAMSTEC in the Nankai subduction zone, Japan, andevaluate their site amplification factors by the spectral inversion method.
We estimate site amplifications by separating source, propagation path, and site characteristics fromobserved Fourier amplitude spectra based on the spectral inversion technique (Iwata and Irikura 1986).
The frequency band of this analysis is 0.2–10 Hz. We use the vector summation of two horizontal
components of Fourier amplitude spectra, which are obtained from S-wave records of 20.48 s. The
amplitude spectra are smoothed by the filter of Konno and Ohmachi (1999). We use records of strong
motion seismographs at DONET1 and records of broadband seismograph at F-net of NIED. To solve a
problem of trade-off between the source spectra and site effect, we assume the F-net KMT station as areference rock site whose amplification factor is 2, following the procedure of Moya and Irikura (2000).
The spectral inversion indicates that all DONET1 stations, especially near-land stations (Nodes A and B)
and near-trench stations (Node C), have larger site amplification factors than the reference station. The site
amplification factors at the stations of Nodes A and B are ~10 in the broad frequency band (0.2–5 Hz). The
site amplification factors at the stations of Node C have a sharp peak at ~5 Hz with the value of ~20.

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*J08-1-01
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

3-D S-wave velocity structure under the Changbaishan volcanic area inNortheast China inverted with dense NECsaids array* Qi-Fu Chen , Xing-Li Fan , Wu Wang
Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of
Sciences, Beijing, China
Previous studies show the prevalence of low velocities beneath the Changbaishan volcano, but debate
continues about the details of the structure. We use data predominantly from our dense temporary
NECsaids array (NorthEast China Seismic Array to Investigate Deep Subduction), but also incorporating
data from surrounding permanent broadband seismic stations, to map Rayleigh-wave phase speeds in thecrust and lithospheric mantle under the Changbaishan volcanic area in Northeast China. Then the Rayleighwave phase velocity dispersions are inverted to determine 1-D shear wave velocity and assembled into 3-Dmodel. The results show the S wave velocity structure of the crust has lateral and vertical heterogeneity, thevelocity structure of shallow crust is well related with the tectonic units on the surface, and the deep
structure reveals the volcanism and regional deep thermal erosion effect. The low velocity anomaly bodies
are found in the crust and upper mantle beneath the Changbaishan volcano and have a tendency to extend
to deeper, which may be the magma chamber in crust of the Changbaishan volcano. There is also a weak
low velocity anomaly body in the middle-lower crust and upper mantle beneath the Longgang volcano,which may be related to the remains after its eruption.
This study is supported by the National Science Foundation of China (41130316 and 41474041).

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*J08-1-02
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

First insights into the deep structure of the eastern Australian passive
margin using wide-angle seismic data: Crustal segmentation from theTasman Basin to the northern Lord Howe Rise
* Flora Gallais 1) , Gou Fujie 1) , Shuichi Kodaira 1) , Seiichi Miura 1) , Brian Boston 1) , Yasuyuki Nakamura 1), Ron Hackney 2) , Saneatsu Saito 1) , Kazuya Shiraishi 1) , Yuka Kaiho 1) , Yasuhiro Yamada 1) , Scott Nichol
2), Georges Bernardel 2) , Cameron Mitchell 2)
JAMSTEC, CEAT, Yokohama, Japan 1) , Geoscience Australia, Canberra, Australia 2)
The eastern Australian margin was shaped by the fragmentation of eastern Gondwana during the Late
Cretaceous. This led to the opening of the Tasman Basin and to the formation of sub-parallel ridges andbasins, including the Lord Howe Rise. To image the deep structure of the region, a large-scale crustal
experiment was conducted by JAMSTEC and Geoscience Australia onboard the R/V Kairei with the
deployment of 100 ocean-bottom seismometers (OBS) along a 680 km profile at 27.2S. The OBSs register
clear refracted arrivals from the crust and the mantle that are recorded at very large offsets, as great as 300
km. Both pre- and post-critical reflected phases from the Moho (PmP) are also very clearly recorded by the
OBSs. We performed first-arrival tomographic inversion to analyze the data. An initial layered P-wave
velocity model was built using the two-way travel time reflection from the basement interpreted fromcoincident multi-channel seismic data to constrain the thickness of the sedimentary layer. During theinversion, the PmP arrivals are used to add constraints on the thickness of the crust. The uncertainty in the
final P-wave velocity model is tested by applying Monte Carlo analysis. The final Vp model shows large
variations in crustal thickness and allows the identification of distinct crustal domains along the profile
from the Tasman Basin to the northern Lord Howe Rise: the Tasman Basin is an oceanic domain with ~7km
thick crust; further east, a 15km crust is present below the Dampier Ridge; the crust again thins to 8km
below the Middleton Basin; and the northern Lord Howe Rise is floored by a 21km thick crust. Further
work will compare the modeled P-wave velocities with previously published results from the southwest
Pacific region and other well-known tectonic provinces from around the world to discuss the variation ofnature of the crust along the profile. This will help to better understand the processes that led to thefragmentation of eastern Gondwana.

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*J08-1-03
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Formation of the Lord Howe Rise continental ribbon during eastern
Gondwana breakup from multi-channel seismic reflection data
* Brian Boston 1) , Yasuyuki Nakamura 1) , Shuichi Kodaira 1) , Seiichi Miura 1) , Flora Gallais 1) , Gou Fujie 1), Yuka Kaiho 1) , Ron Hackney 2) , Yasuhiro Yamada 1) , Saneatsu Saito 1) , Kazuya Shiraishi 1) , Scott Nichol
2), George Bernardel 2) , Cameron Mitchell 2)
Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan 1) , Geoscience Australia,
Canberra, Australia 2)
The Lord Howe Rise continental ribbon, offshore eastern Australia, formed during the Late Cretaceous
rifting of eastern Gondwana. This project focuses on multi-channel seismic reflection and bathymetry datacollected on a multi-leg marine geophysical survey in 2016 to constrain the nature of rifting and theformation of the Lord Howe Rise. We present processed pre-stack depth-migrated seismic reflection images
and interpretations of a regional, ~900 km long east–west-oriented profile at 27.2S, from the oceanic
Tasman Basin to the extended continental crust of the Lord Howe Rise. We find that the Tasman Basincontains buried basins that may be related to early transform faulting. The Tasman Basin has a sharpeastern boundary against the Dampier Ridge, within which are multiple rift basins up to 3 km deep. Thesebasins are similar to those found on the Lord Howe Rise. The Middleton Basin separates the Dampier
Ridge and the Lord Howe Rise and is a broad, well-stratified sedimentary basin of up to ~3.5 km thickness.
This basin contains an unconformity that separates deeper sediments, likely deposited during rifting of theDampier Ridge, that are conformable with the basement and younger strata that filled the basin post-rifting.
Both syn-rift and post-rift sedimentary sequences are found on the Lord Howe Rise. To better understandthese rifting events, we present grids of pre-stack time-migrated seismic reflection lines covering two riftbasins of the Lord Howe Rise. The two basins show contrasting evolution, including variations in normal
faulting intensity within the syn-rift sequences. These results help constrain the dynamic processes thatcaused the formation of the Lord Howe Rise continental ribbon.

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*J08-1-04
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Coupled anisotropic and isotropic body-wave tomography of the upper
mantle beneath northern Fennoscandia - Application of a novel code
AniTomo to data from passive seismic experiment LAPNET (Finland)* Helena Munzarova 1) , Jaroslava Plomerova 1) , Eduard Kissling 2) , Ludek Vecsey 1) , Vladislav Babuska 1)
Institute of Geophysics, Czech Academy of Sciences, Prague, Czech Republic 1) , Institute of Geophysics,
Department of Earth Sciences, ETH Zurich, Switzerland 2)
Seismological investigations of continental mantle lithosphere, particularly of its anisotropic structure,advance our understanding of plate tectonics and formation of continents. Orientation of anisotropic
fabrics reflects stress fields during the lithosphere origin and its later deformations. To contribute to studiesof large-scale upper-mantle structures, we have developed novel code AniTomo for regional anisotropic
tomography. AniTomo allows a simultaneous inversion of relative travel-time residuals of teleseismic P
waves both for 3D distribution of isotropic-velocity perturbations and anisotropy in the upper mantle. Weakhexagonal anisotropy with symmetry axes oriented generally in 3D is assumed. The novel code was
successfully tested on large series of synthetic datasets and synthetic structures. In this contribution we
present results of the first application of AniTomo to data from passive seismic experiment LAPNET(northern Fennoscandia, 2007 - 2009). This Precambrian region is tectonically stable and has a thickanisotropic mantle lithosphere (Plomerova and Babuska, Lithos 2010) without significant thermal
heterogeneities. The strongest anisotropy and the largest velocity perturbations concentrate in the mantlelithospheric part of the tomographic model down to 170km. Regions with laterally and vertically consistentanisotropy can be delimitted there. The anisotropic regions from the tomography correspond to domains ofconsistent fabric derived from variations of P- and SKS-wave anisotropic parameters (Plomerova et al., SE
2011). Particularly, the western part of the model exhibits a distinct and uniform fabric sharply separated
from the surroundings. The eastern boundary of this region gradually shifts westward with increasing
depth. We connect the retrieved domain-like anisotropic structure of the mantle lithosphere in the northern
Fennoscandia with preserved fossil fabrics of the Archean micro-plates, accreted during the Precambrianorogenic processes.

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*J08-1-05
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Waveform-based estimation of velocity heterogeneity for prestack imaging
from multifold wide-aperture seismic data
* Susumu Abe 1) , Takao Nibe 2) , Hiroshi Sato 3) , Tatsuya Ishiyama 3)
Japan Petroleum Exploration Co., Ltd, Tokyo, Japan 1) , JGI, Inc., Tokyo, Japan 2) , Earthquake ResearchInstitute, the University of Tokyo, Tokyo, Japan 3)
Deep seismic reflection profiling with rugged acquisition topography, crookedness of seismic lines has
been imposed serious restrictions and compromises on both data processing and acquisition. In addition tocomplex subsurface structure, irregular distribution of shots, and large noise level of surface wave and backscattered wave often result in deterioration of the data quality and poor reflection image in seismic profile.
In recent years, the quest for increased precision and channel capacity of receiver system led to the
combination of telemetry and autonomous recorders with the deployment of dense seismic array for deep
seismic profiling in Japan. For deep seismic profiling with wide-aperture geometry, dense spatial sampling
and low-frequency bandwidth, velocity structures estimated through turning-ray tomography (TRT) arerestricted in resolution, since TRT depends on direct arrivals of seismic wave with the assumption of
asymptotic ray theory. On the other hand, full waveform inversion (FWI) based on full wavefield modelingand inversion has an advantage to estimate high-resolution velocity heterogeneity. In our study, the hybrid
velocity estimation of TRT, FWI and reflection velocity analysis by PSDM (Prestack Depth Migration) wasapplied to onshore-offshore integrated deep seismic data across Niigata basin, central Japan. The
uncertainty of the tomography solutions was evaluated using a nonlinear Monte Carlo approach withrandomized initial models, and the velocity structure of deep basin structure is constrained by subsequent
forward reflection and refraction modeling. The combination of PSDM-driven velocity analysis and FWI was
confirmed to have the potential imaging capabilities for improved prestack depth migration. Main featuresof basin development, such as early Miocene normal faulting, associated with the formation of Japan Sea,and shortening deformation since Pliocene, are well demonstrated on the final seismic sections.

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*J08-1-06
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Seismic Imagings of Sub-Crustal Reflectors Beneath the Iberia Microplate
Imma Palomeras 1) , Puy Ayarza 1) , Jordi Diaz 2) , Juan Carlos Afondo 3) , * Ramon Carbonell 2)
Universidad de Salamanca, Salamanca, Spain, 1) , CSIC-ICTJA: Inst. Earth Sciences Jaume Almera,
Barcelona, Spain 2) , Macquarie University, Sydney, Australia 3)
Deep upper mantle seismic scattering features have been imaged beneath the Iberia microplate. Normal
incidence and wide-angle seismic reflection experiments in the area: ILIHA, IBERSEIS, and ALCUDIA,
provide seismic constraints on these sub-crustal structures. Mantle reflectors were identified on the
IBERSEIS wide angle shot records at offsets of 180 km. These correspond to an interpreted boundary
located at 61-72 km depth with a Vp increase from 8.2 km/s to 8.3 km/s. This layer was interpreted to be
characterized by a Vp gradient because the reflector was not identified in the coincident vertical incidence
dataset. The ‘Hales gradient zone', i.e. the boundary between spinel and garnet peridotites, was thepreferred interpretation. The ALCUDIA experiment also imaged prominent sub-crustal arrivals with similar
characteristics. However, these reflections also appear, locally and at 19 s TWT, in the vertical incidence
stack. In addition, the ALCUDIA wide-angle dataset show deeper reflectors that maybe, preliminarily,
associated to mantle anisotropy fabrics or even with the lithosphere-asthenosphere boundary. Both upper
mantle reflectors are modeled at 65 km and 100 km depth, respectively, shallowing to the north to 55 km
and 90 km depth. Integration of the information provided by the IBERSEIS and ALCUDIA datasets witholder and lower resolution data from the ILIHA project, where three sub-crustal phases were identified in
SW Iberia, indicates that, in this area, mantle reflectivity is outstanding. Also, modeling of all the datasets
contributes to map, at a regional scale, the Hales discontinuity or gradient zone in southwest Iberia.
(Research supports: CGL2014-56548-P, 2009-SGR-1595, CGL2013-47412-C2-1-P).

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*J08-2-01
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Tomographic imaging of the seismic velocity structure in southern
Hokkaido, Japan: Implications for distributions of the crustal deep lowfrequency earthquakes* Takahiro Shiina 1) , Hiroaki Takahashi 1) , Tomomi Okada 2) , Toru Matsuzawa 2)
Hokkaido University, Sapporo, Japan 1) , Tohoku University, Sendai, Japan 2)
At southern Hokkaido, Japan, the crustal deep low-frequency earthquakes (CDLFE) are often observed
beneath both active volcanoes and non-active volcanic area, which corresponds to shallow swarm-like
activity of the regular crustal earthquakes. It is considered that the CDLFEs relate to activity of volcanoes
and regular crustal earthquakes (e.g., Takahashi and Miyamura, 2009). However, those relations have notbeen revealed in clearly. In order to improve understandings for the CDLFEs and those relating
phenomena, we investigated seismic velocity structure beneath southern Hokkaido and discussed therelations based on the heterogeneous structure.
For estimating the seismic velocity structure in detailed, we adapted the double-difference tomographymethod (Zhang and Thurber, 2003; 2006). The number of earthquakes occurred in southern Hokkaido in
the period from March 2003 to June 2016 were 15,645 (A magnitude range of 1.5-6.5), and travel times of306,335 for P wave and 242,093 for S wave were adapted to the estimations.
The obtained results obviously show that the low-velocity and high-Vp/Vs zones are estimated in depths ofabout 20-40 km beneath active volcanoes. Moreover, it is confirmed extensions of the low-velocity and highVp/Vs zones to the CDLFEs within the non-active volcanic area. At a depth of 10 km, seismic velocity
beneath the volcanoes tends to be decreased from that calculated in surroundings while high-velocity
anomaly is widely detected. The crustal earthquakes involving swarm-like activity above the CDLFEs arecorrespondingly located with the high-velocity zones. Because it is considered that presence and migrationof fluids or melts contribute to trigger the CDLFEs (e.g., Ukawa and Ohtake, 1987), these observations
suggests that the CDLFEs closely relates to the crustal earthquakes and volcanoes though the fluids ormelts, and the related phenomena may be linked to the crustal heterogeneity.

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*J08-2-02
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Structural heterogeneities around inland earthquake areas in Hokkaido
Island based on magnetotelluric observations* Hiroshi Ichihara 1) , Yusuke Yamaya 2) , Toru Mogi 3)
Kobe University 1) , AIST 2) , Hokkaido University 3)
Hokkaido Island, northern Japan is suited on the arc-arc boundary between the NE Japan and Kurile arcs.
In the south part of the boundary zone, colliding structure is clearly recognized in the south part of theIsland (Hidaka mountain range) but not in the north part. However, fold-and-thrust structures are
distributed through the western margin of the arc-arc boundary. The north part of the fold-and-thrust zone
is converging to the strain concentration zone in the eastern margin of Japan sea. In order to investigate
the relationship between earthquakes and structural heterogeneity including deep area beneathearthquake zone, we conducted magnetotelluric measurements and modeled electrical resistivity
distribution in the south part of Hidaka mountain range (Erimo area, Ichiara et al., 2016), south part of thefault-and-thrust zone (Ishikari-Toen fault zone, Yamaya et al., in press) and north part of the fault-and-thrustzone (Rumoi and Dohoku area, Ichihara et al., 2008, 2016).
In these areas, resistivity distributions reflect geological structure; thickness of the surface conductive zone
is corresponding to that of sediment layer associated with fold-and-thrust activities. They indicate that MT
survey is useful to investigate fold-and-thrust structure. A deep conductive areas were also revealed along
the Hidaka main thrust and beneath the Ishikari-Toen fault zone and. They imply ductile zone affecting thestrain concentration.

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*J08-2-03
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Structure of the incoming/subducting Pacific Plate in the central part of theJapan Trench: Results from repeated ocean bottom seismographobservations* Koichiro Obana 1) , Gou Fujie 1) , Tsutomu Takahashi 1) , Takashi Tonegawa 1) , Yojiro Yamamoto 1) ,Shuichi Kodaira 1) , Masanao Shinohara 2)
Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan 1) , Earthquake ResearchInstitute, University of Tokyo, Tokyo, Japan 2)
Oceanic plate subduction is an important process to transport the water from the Earth's surface into themantle. Recent active seismic surveys present that systematic reduction of the seismic velocities within
oceanic crust and the uppermost mantle of incoming oceanic plate with the approach toward the trench.
These seismic velocity changes are considered as a result of the oceanic plate hydration/alteration in the
trench-outer rise region. However the active seismic studies can resolve the structure at depths down to afew km below the oceanic Moho. After the 2011 Tohoku-Oki earthquake, seismicity within theincoming/subducting Pacific plate in the trench-outer rise region of the Japan Trench is very active. Ocean
bottom seismograph (OBS) observations have been conducted repeatedly in the trench-outer rise region of
the central part of the Japan Trench since 2011. The active seismicity would give a chance to obtainstructure information of the oceanic lithosphere based on the passive earthquake observations. We
investigated seismic velocity structure through the travel time tomography by using the passive OBS
observation data consisting of 120 stations and more than 8000 events in total. The results show that theseismic velocities within the oceanic mantle seaward of the Japan Trench reduce toward the trench axis.
The reduction of the P-wave velocities, which may relate to the hydration/alteration of the oceanic plate,extended down to a depth of about 20 km below the oceanic Moho. We also investigated anisotropy and Q
structures by using the OBS data. We will discuss the structures of the incoming Pacific plate and its
hydration/alteration in the trench-outer rise region by combining the results from these analyses.

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*J08-2-04
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Seismic structure around the slow slip source in the northeastern Japan
forearc by an airgun-ocean bottom seismometer survey* Ryosuke Azuma 1) , Ryota Hino 1) , Kimihiro Mochizuki 2) , Yoshio Murai 3) , Hiroshi Yakiwara 4) , Toshinori
Sato 5) , Masanao Shinohara 3)
RCPEVE, Tohoku University 1) , ERI, University of Tokyo 2) , ISV, Hokkaido University 3) , Kagoshima
University 4) , Chiba University 5)
Various kinds of slips have been observed along the plate boundary (PB) in the Japan Trench subduction
zone; slow slip events (SSEs) happened in 2008 and 2011 at 37.7–38.7N in the source area of the 2011
Tohoku-oki earthquake. Faults hosting SSEs are often characterized by low seismic velocity anomalies.
Although it is expected that the distribution of the interplate low velocity material can be identified bystrong seismic reflectivity of the interface, a detail structure in the SSE source area remains unknown. To
clarify seismic structure near the PB source, which will improve understanding of the mechanism of SSE
generation, we made an airgun-OBS (Ocean Bottom Seismometer) survey in 2014. Survey lines covered theSSE source area in their southern sections.
The P-wave velocity (Vp) model estimated by a first arrival traveltime tomography (Fujie et al., 2013)
showed distinct lateral Vp variation in the overriding plate; the high Vp (> ~ 4 km/s) island arc upper crust(IUC) material was estimated to the south of 39 N, whereas the low Vp (< ~ 3 km/s) unconsolidated
sediment (US) distributed in the northern part of the survey line. A reflection traveltime mapping method(Fujie et al., 2006) imaged the PB as a continuous reflector at depths from 8 km to 14 km, where Vp is ~ 5
km/s. The PB is more reflective beneath the IUC than that beneath the US. Since the Vp contrast between
the IUC and the oceanic layer 2 may be small, the clear reflections from the PB suggest the existence of alow Vp channel layer along the PB. The spatial extent of high-Vp overriding crust and the highly reflective
PB, identified to the south of 39N, almost coincides with the SSE source location. Therefore, our survey
results suggest that the SSE source area is characterized by the presence of low-Vp channel layer along the
PB beneath the high Vp overriding crust.

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*J08-2-05
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Structural variation in the rupture zone of the 2011 Tohoku-oki earthquake
and its implications for depth-dependent seismic-slip behaviors* Shuichi Kodaira , Yasuyuki Nakamura , Yojiro Yamamoto , Koichiro Obana , Gou Fujie , Tetsuo No , Yuka
Kaiho , Takeshi Sato , Seiichi Miura
JAMSTEC, Yokohama, Japan
Seismological data of the 2011 Tohoku-oki earthquake (Mw 9.0) have revealed a clear depth-dependent
variation in the source location between high- and low-frequency seismic energy radiation. However,structural variation, which may control seismic energy radiation, in the rupture zone have not been wellstudied. In this study, we therefore examined depth-varying structural characteristics by using seismicreflection data acquired along five profiles in the rupture zone. The resultant seismic images arecharacterized as a low-velocity frontal prism, a reflective zone at the trenchward tip of the continental
block, and subducted horst-and-graben structures. The frontal prism is imaged as a low-velocity (Vp 2.0–3.5km/s) wedge-shaped unit north of 37.5N, and abruptly transforms to a channel-like sedimentary unit southof 37.5N. Compiling the distribution of the frontal prism and the fault slip of the 2011 earthquake and the1896 Sanriku earthquake, which is well-known as a tsunami earthquake, suggests that the coseismic slip to
the trench may have occurred where the frontal prisms well developed. In 30 to 80 km landward from thetrench, reflective zones with thickness of ~ 5 km were imaged at the base of the overriding block just above
the subducted oceanic basement. Growth of subducted horst-and-graben structures (the throws of thenormal faults associated with the horst-and-graben are larger by up to ~2 km) is imaged beneath thereflective zone. By comparing the seismic images and seismicity, we conclude that 1) in the area where awell-developed low-velocity frontal prism is imaged, seismicity along the plate interface is very low but theaftershocks of the 2011 earthquake occurred within the uppermost mantle and in the overriding plate, 2) inthe area where growth of the subducted horst-and-graben structures are imaged, low levels of short-period
seismic energy during the Tohoku-oki and weak background seismicity along the plate interface areobserved.

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*J08-2-06
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Investigation of seismicity and subsurface structure around northern Tohoku
using seismic data recorded by AS-net* Shinako Noguchi , Yoshihiro Sawada , Keiji Kasahara , Shutaro Sekine , Yoshihiro Tazawa , Hiroshi Yajima, Shunji Sasaki , Kimiko Ishida
Association for the Development of Earthquake Prediction
From 2013 to 2014, we have installed a permanent local high-sensitivity seismic observation network, ASnet, at northern Tohoku and southwestern Hokkaido, Japan, for the purpose of monitoring earthquake
activity and investigation of subsurface structure. AS-net covers the area where the other seismic stations
are relatively sparse, and enhances the earthquake detection capability and provides dense continuousseismic data. The region is located on the Japan island arc containing fore-arc, back-arc showing relatively
higher seismicity in Japan. In this presentation, we report the seismic activity and subsurface structurearound northern Tohoku containing Aomori prefecture and southwestern Hokkaido investigated using data
derived by AS-net and other stations.
We are making an original local earthquake catalogue for northern Tohoku from 2014 using data from 134
stations including 36 stations of AS-net. 11191 events were detected automatically using data from January
2014 to June 2016. By manual check of these events, 5961 earthquakes were determined. 4535
earthquakes were occurred in the crust (H <50 km), and the other were occurred at the upper boundary
and the inside of Pacific plate. Some low-frequency events also occurred at some volcanic and non-volcanic
regions (H <40 km). Above these low-frequency events, shallow normal earthquakes also occur actively.
For crustal earthquakes (H <50 km), we could detect 2.5 times as many earthquakes as JMA hypocenter
catalogue (1752 events). The site corrections for P and S arrival estimated using the difference between
manual pick and theoretical travel time are considered in this hypocentral location. The site correction
values differ depending on subregions reflecting their local site conditions. We also conduct seismic
tomography using manual phase pick values for hypocentral location. We show the relationship between
hypocentral distribution and the subsurface structure shown by the seismic tomography.

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*J08-3-01
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Failed rift system in northern Honshu, Japan, imaged by improved seismic
velocity structure using offshore earthquake events* Makoto Matsubara 1) , Hiroshi Sato 2)
NIED, Tsukuba, Japan 1) , ERI, UTokyo, Tokyo, Japan 2)
We investigate the 3D seismic velocity structure beneath the ocean using offshore events with seismic
tomographic method. Offshore events have a large uncertainty for focal depth determined by NIED Hi-net,
however, NIED F-net determined the focal depth with moment tensor inversion. In this study, the data is
the combination of the hypocenter catalog by NIED F-net and pick data by NIED Hi-net for offshore events
as well as the hypocenter catalog and pick data by NIED Hi-net for events within the seismic network.
The target region, 20–48N and 120–148E, covers the Japanese Islands. The available data for use in theseismic tomography are manually picked 4693781 P-wave and 2342621 S-wave arrival times for 796779
earthquakes recorded at approximately 1300 stations from October 2000 to December 2014. The inversion
reduces the RMS of the P-wave traveltime residual from 0.507 s to 0.193 s and that of the S-wave data from0.609 s to 0.238 s after eight iterations.
Our new analysis clarified the failed rift structures, marked by higher Vp at lower crust and lower Vp at theupper crust, along the Japan Sea cost of central Honshu. Judging from the age of the rift basin, they were
produced during the formation of the Japan Sea. Similar, rift structure also detected along the Pacific coastof Northern Honshu, it is marked by uplifted Moho surface, trending NS to NNW-SSE direction.
Geologically, it is interpreted as a rift structure formed in the late Mesozoic. Further tectonic investigation
for this probable Mesozoic rift is needed. These failed rift zones show similar features in seismic velocity
structure and have shallow Moho (Matsubara et al., 2017).
Reference:
Matsubara M., H. Sato, T. Ishiyama, and A. D. Van Horne (2017) Configuration of the Moho discontinuity
beneath the Japanese Islands derived from three-dimensional seismic tomography, Tectonophysics, inpress, doi:10.1016/j.tecto.2016.11.025.

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*J08-3-02
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Geometry and spatial variations of seismic reflection intensity of the uppersurface of the Philippine Sea plate off the Boso Peninsula, Japan* Akihiro Kono 1) , Toshinori Sato 1) , Masanao Shinohara 2) , Kimihiro Mochizuki 2) , Tomoaki Yamada 2) ,Kenji Uehira 3) , Takashi Shimbo 3) , Yuya Machida 4) , Ryota Hino 5) , Ryosuke Azuma 5)
Graduate School of Science, Chiba University, Chiba, Japan 1) , Earthquake Research Institute of Tokyo
University, Tokyo, Japan 2) , National Research Institute for Earth Science and Disaster Resilience,
Tsukuba, Japan 3) , Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan 4) , Graduate
School of Science, Tohoku University, Sendai, Japan 5)
In the region off the Boso Peninsula (BP), Japan, the Pacific plate is subducting westward beneath both the
Honshu island arc (HIA) and Philippine Sea plate (PHS), while the PHS is subducting northwestward underthe HIA. These complex tectonic interactions have caused numerous seismic events such as the Boso Slow
Slip Events (SSEs). To better understand these seismic events, it is important to determine the structure inthis region.
Although some seismic surveys have been conducted off the BP, still further work is needed for farther
offshore. We conducted a marine seismic experiment off the BP, from July to August 2009. Airgun shooting
was conducted along 4 survey lines, and 27 Ocean Bottom Seismometers (OBSs) in total were deployed.
We estimated 2-D and 3-D P-wave velocity structure from the airgun data using the PMDM (Progressive
Model Development Method; Sato and Kenett, 2000) and the FAST (Zelt and Barton, 1998). Within our
survey data, we recognized numerous reflections and estimated its depth by conducting the Traveltime
mapping method (Fujie et al. 2006) (TTMAP) in both the on-line area and off-line area.
From the 2-D velocity model, we found that the dip of the upper surface of the PHS is shallow far off the BP.
The TTMAP results in the 2-D models indicate that an area of high reflection intensity corresponds to themain slip area of the Boso SSEs. The TTMAP in the 3-D model is still under analysis.
Acknowledgement
The marine seismic experiment was conducted by R/V Hakuhou-maru of Japan Agency for Marine-Earth
Science and Technology, and the OBSs were retrieved by Shincho-maru of Fukada salvage co. Ltd..We
would like to thank captains and the crew of Hakuho-maru and Shincho-maru. This study was supported by
the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, under its Observation
and Research Program for Prediction of Earthquakes and Volcanic Eruptions, and from the Grants in Aid
for Scientific Research (25287109).

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*J08-3-03
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Hydrocarbon accumulation controlled by tectonic activity in the subduction
zone: Insight from advanced seismic velocity analysis
Chanmaly Chhun 1) , * Takeshi Tsuji 1) 2) , Arata Kioka 3)
Earth Resources Engineering Department, Kyushu University, Fukuoka, Japan 1) , International Institute for
Carbon-Neutral Energy Research (I2CNER), Kyushu University, Fukuoka, Japan 2) , Institute of Geology,
University of Innsbruck, Innsbruck, Austria 3)
The presence of gas hydrates is widespread in the Kumano Forearc Basin which is situated above the
Nankai accretionary prism off the Kii peninsula, Japan. Bottom-Simulating Reflectors (BSR) at the base of
the gas hydrate stability zones has imaged as strong acoustic impedance contrast on the seismic profiles.
When we applied seismic velocity analysis to 3D seismic data via automatic velocity picking, the results
reveal the high velocity anomaly zone (1900-2500 m/sec) above BSR interpreted as Gas hydrate bearing
sediments, and the low velocity anomaly zone (1300-2000 m/sec) beneath BSR interpreted as free gas
bearing sediments. Based on the results, we suggest that the gas hydrates accumulated due to the free gas
influx which migrated upward through the steeply dipping strata and faults or fractures cutting through thebasin. The gas (or hydrate) accumulated area is further controlled by the large faults in the accretionary
prism. Therefore these factors generated by intensive tectonic movements control the distribution andsaturation pattern of gas hydrate and free gas formation. When we characterize the features of gas hydrate(i.e., double BSR caused by variation in temperature and pressure), we could discuss the history of tectonic
and seismic activity in the accretionary prism.
Key words: gas hydrates, seismic velocity analysis, automatic velocity picking, free gas influx

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*J08-3-04
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Imaging of the subducted Philippine Sea plate and the overriding SW Japanarc - Reinterpretation of the wide-angle reflection data in the Kii Peninsula,
SW Japan * Takaya Iwasaki 1) , Susumu Abe 2) , Eiji Kurashimo 1) , Ken Yokota 3) , Takashi Iidaka 1) , Hiroshi Katao 4) ,Motonori Higashinaka 3) , Ayako Nakanishi 5) , Yoshiyuki Kaneda 6)
ERI, the University of Tokyo, Tokyo, Japan 1) , JAPEX, Tokyo, Japan 2) , JGI, Inc. Tokyo, Japan 3) , DPRI,
Kyoto University, Uji, Japan 4) , JAMSTEC, Yokohama, Japan 5) , IECMS, Kagawa University, Takamatsu,
Japan 6)
Our recent reinterpretation for seismic refraction/wide-angle reflection data in eastern Kii Peninsula, SW
Japan, provided new structural information on the subducted Philippine Sea (PHS) plate and overriding the
SW Japan arc.
The Kii peninsula is located in the eastern part of the well-known seismogenic zone along the Nankai
trough. The plate boundary beneath this peninsula is in the stable or conditionally stable regime except for
its southernmost tip (the northwestern end of the rupture area at the 1944 Tonankai earthquake (M7.9)).
Our data were acquired in 2006 along 80-km line almost perpendicular to the Nankai trough. To image thestructure of overriding the SW Japan arc, we retrieved virtual shot records from free-surface backscatteredwaves by the deconvolution interferometry. The subsequent CRS (Common Reflection Surface)/MDRS(Multi-Dip Reflection Surfaces) methods delineated a northward dipping reflector band just south of theMedian Tectonic Line (MTL). This reflection band, about 10-15 km thick, includes the High-P Sambagawa
Metamorphic belt, extending from 2-10 km to 25-35 km depth. The MTL itself is recognized as theuppermost part of this band inclining northward to a depth of nearly 25 km.
The PHS plate is well imaged as northward dipping reflectors in a depth range of 20-35 km beneath thesouthern half of our profile both by seismic refraction and reflection analyses. A thin (less than 1 km) low
velocity (3.5~5km/s) layer is situated at the top of the PHS plate under the southernmost part of the profile,
namely the trenchward half of the conditionally stable zone. In the central part of the profile (the landward
half of the conditionally stable zone), strong reflectors with 2-3 km/s velocity contrast are distributed in adiffused manner at 30-35 km depths, around which low frequency earthquakes are occurring. The obtainedlateral structural change is probably controlled by dehydrated fluids from the subducted PHS plate.

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*J08-3-05
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Three dimensional attenuation structure in and around the source region of
low frequency earthquakes beneath the Kii Peninsula, southwest Japan,
revealed by dense seismic array observation* Noriko Tsumura 1) , Hiroki Nakasako 1) , Eri Umeyama 1) , Naoki Mizuno 1) , Eiji Kurashimo 2) , Aitaro Kato
, Shinichi Sakai 2) , Takashi IIdaka 2) , Takaya Iwasaki 2)
Chiba University, Chiba, Japan 1) , ERI, Univrtsity of Tokyo, Tokyo, Japan 2)
2)

Non-volcanic deep low frequency earthquakes (DLFE) have occurred along the isodepth contour of 30 to
40km of the subducting Philippine Sea plate (PSP) beneath the Kii Peninsula, southwest Japan. The DLFE's
activity is not uniform and some clusters align from the WWS to the EEN of Kii Peninsula. Further
seismicity of local earthquakes which occur around the PSP's Moho in the eastern part of the Kii Peninsula
is lower than that of western part. To clarify the physical property which controls the seismicity of DLFEs
and local earthquakes, we applied a combined inversion method to P wave spectra and obtained an
attenuation (Q) structure there. Adding to routine seismic network's data, we used seismic waveforms
recorded in three dense seismic array observation which were settled in perpendicular or parallel direction
to DLFE clusters' alignment. Since length of the arrays reach approximately 90km (or 60km) with 1km
station interval, it made us possible to estimate a detailed Q structure along the arrays.
Derived Qp images show that patch-like high Qp zones were distributed in the region just around the depth
from 30 to 40km at the western part of the Kii Peninsula. These high Qp regions coincide with the regions
where the DLFE clusters exist. On the contrary, we can find a low Qp zone at the same depth range inwhich high activity of the DLFEs is seen in the eastern part of the Kii Peninsula. This low Qp zone
corresponds to the lower Vp and high Vp/Vs region derived from travel time tomography. Low Vp and highVp/Vs generally suggest the existence of fluid and similar low Vp and high Vp/Vs region were found at theDLFE cluster of the western side. Then these results suggest the occurrence of the DLFEs may be
associated with fluids dehydrated from the PSP, but its activity might be affected by different physicalproperties in both sides of the Kii Peninsula.

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*J08-3-06
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Imaging the distribution of transient viscosity following the 2016 Mw 7.1
Kumamoto earthquake* James Moore 1) , Hang Yu 2) , Chi-Hsien Tang 3) , Teng Wang 1) , Sylvain Barbot 1) , Dongju Peng 1) , Sagar
Masuti 1) , Justin Dauwels 2) , Ya-Ju Hsu 3) , Valere Lambert 5) , Bunichiro Shibazaki 4)
Earth Observatory of Singapore 1) , School of Electrical & Electronic Engineering, Nanyang Technological
University 2) , Institute of Earth Sciences Academia Sinica, Taipei, Taiwan 3) , International Institute of
Seismology and Earthquake Engineering, Building Research Institute, Japan 4) , California Institute ofTechnology 5)
Postseismic studies of geodetic data following large earthquakes indicate a wide range of mechanisms
contribute to the observed deformation and stress relaxation. Both on-fault afterslip and off-fault
viscoelastic relaxation can contribute to the postseismic transient phase of the earthquake cycle. One
problem with these (quasi-) dynamic models is that there is a wide range of parameter space to beinvestigated, with each parameter pair possessing their own tradeoffs. This becomes especially problematicwhen trying to model both on-fault and off-fault deformation simultaneously. Here, we draw insight frompostseismic geodetic observations following the 2016 Mw 7.0 Kumamoto earthquake by utilizing a novel
inversion technique.
We present a novel approach to invert for on-fault and off-fault deformation simultaneously using analyticalGreen's functions for distributed deformation at depth [Barbot, Moore and Lambert., 2016] and on-fault
deformation [Okada 1992, Nikkhoo and Walter 2015]. Using these Green's functions, we jointly invert
InSAR images and GEONET GPS time series following the Kumamoto earthquakes for afterslip and lowercrustal viscoelastic flow.
The calculated strain-rates in the lower crust are directly converted to effective viscosities and weinvestigate the implications of the effective viscosity structure within an outlier-senstitive Bayesianstatistical framework to estimate in-situ parameters, such as temperature. Using our new method, we areable to interrogate the transient deformation in the first few months of the postseismic deformation to
obtain these parameters.
The postseismic deformation at Kumamoto brings new insights into the distribution of brittle and ductile
crustal processes beneath Japan and can be used to infer lower crustal properties.

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*J08-P-01
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Multicore parallelization of 3D ray tracing algorithm using OpenMP
Madineh Banihashem Kalibar 1) , * Hossein Sadeghi 1) 2) , Sayyed Keivan Hosseini 1)
Earthquake Research Center, Ferdowsi University of Mashhad, Mashhad, Iran 1) , Department of Geology,
Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran 2)
Parallel computing is now being used to solve problems much faster than the traditional serial
computations in a wide variety of scientific computing applications. Parallel programing allows us to breaka problem into a discrete series and execute by different processing units simultaneously. Multi-coreprocessors which support parallel computing are quite common now, however writing a parallel code ismore difficult than a sequential code. OpenMP is a standard programming interface for shared memory
parallel computing which helps to create more easily multithreaded codes of existing serial programs. In
this work, we present the use of OpenMP to parallelize the Lotos bending algorithm (Koulakov, 2009) for
ray tracing in a 3D velocity model. In order to take the advantage of multicore capabilities, theparallelization of the bending ray tracing was carried out for both data-parallel and task-parallel. We
successfully achieved performance of the parallelized algorithm on two multicore laptops; intel i7 and intel
i5.

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*J08-P-02
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Waveform inversion to image laterally inhomogeneous crustal structure comparison among waveform inversion, traveltime inversion, and seismic
migration * Takeshi Sato 1) , Gou Fujie 1) , Kazuya Shiraishi 1) , Shuichi Kodaira 1) , Seiichi Miura 1) , Eiichi Asakawa 2) ,Takao Nibe 2) , Norimitsu Yui 2) , Susumu Abe 3) , Romain Brossier 4) , Jean Virieux 4)
JAMSTEC, Yokohama, Japan 1) , JGI Inc., Tokyo, Japan 2) , JAPEX, Tokyo, Japan 3) , University Grenoble
Alpes, Grenoble, France 4)
High-resolution seismic velocity structure in geologically complex areas is of crucial importance for theunderstanding of evolution and formation processes associated with plate tectonics. However, it wasdifficult to image laterally inhomogeneous structural features such as sub-vertical intrusions into the crustby seismic migration of multi-channel seismic reflection (MCS) data or by traveltime analysis of ocean
bottom seismographs (OBSs) using controlled sources. On one hand, migration has difficulties for imaging
steep reflectors and, on the other hand, the spatial resolution of the traveltime analysis is low, especiallywhen considering first-arrivals. Alternatively, full waveform inversion (FWI) is a promizing technique for an
improved quantitative detailed seismic structure even in geologically complex area because full wave
propagation is performed for honoring recorded traces.
In the fore-arc region of the Izu-Bonin island arc, Tatsumi and Stern (2006) suggested a sub-vertical
intrusion of the middle crust below the Eocene paleo arc. For assessing the existence of such intrusive
structural feature, we conducted MCS survey and wide-angle OBS-airgun survey (OBS deployed 1 km
interval) in this region (Yamashita et al., 2009). We applied pre-stack depth migration to the MCS data, but
we could not image the intrusive feature. On the contrary, we attempted to apply FWI to this wide-angle
OBSs dataset and we succeeded in imaging this intrusive feature. From these results, we may deduce that
the FWI is an effective tool for detecting steep tectonic structures such as sub-vertical intrusion.

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*J08-P-03
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Feasibility of the waveform analysis to the existing conventional wide-angle
seismic survey data - Ocean Bottom Seismometer (OBS) and controlledsource seismic surveys in the Nankai subduction zone * Gou Fujie , Ayako Nakanishi , Takeshi Sato , Shuichi Kodaira
JAMSTECThe OBS and controlled-source seismic survey is a powerful tool for imaging crustal structure beneath theseafloor. Conventionally, these data have been processed by traveltime analysis methods like a traveltime
inversion, which provides us a large-scale crustal structure valuable for understanding the geodynamical
processes oaccurring in the lithosphere.
In the traveltime analysis, we use arrival times only and do not utilize amplitude and phase. Therefore, if we
could utilize the observed seismic waveform itself, we could extract more subseafloor information from the
OBS survey data and might be able to image more detailed crustal structure.
Recently, new analysis methods utilizing the observed waveform, such as seismic interferometry, mirror
imaging, and waveform inversion, have come into practical use. These modern waveform analysis methods
enables us to image more detailed crustal structure than the conventional travletime analysis methods.
However, to receive full benefits from these modern methods, we need to design seismic surveys to be
optimal for waveform analysis, meaning dense OBS spacing.
To investigate the efficacy of the waveform analysis method for the existing conventional, actual OBS
survey data, we applied these modern methods to a large number of OBS survey data obtained in the
Nankai Trough subduction zone. These existing surveys were basically designed for travel-time analysis
and OBS spacings were sparse (mostly 5 km). In addition, the data quality was not necessarily highbecause of narrow dynamic range of instruments. Despite these adverse conditions, we confirmed thatthese modern methods have a potential to extract detailed structural information, especially for theshallower part, from the existing sparse OBS survey data. In this talk, we are going to discuss the benefits
and limitations of these waveform analysis methods to the conventional sparse OBS survey data.

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*J08-P-04
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Inversion of Gravity Anomalies Using Primal-Dual Interior Point Methods* Azucena Zamora , Aaron Velasco
University of Texas at El Paso, El Paso TX USA
Structural inversion of gravity datasets based on the use of density anomalies to derive robust images of thesubsurface (delineating lithology and their boundaries) constitutes a fundamental non-invasive tool forgeological exploration. The use of gravity data to estimate and interpret the substructure based on its
density properties have proven efficient; however, the inherent non-uniqueness associated with most nonseismic geophysical datasets make this the ideal scenario for the use of recently developed robust
constrained optimization techniques. We present a constrained optimization approach for a least squares
inversion problem to characterize 2-Dimensional Earth density structure models based on gravity
anomalies. The formulation inverts Bouguer gravity anomalies using polygons along with Primal-Dual
Interior-Point methods for the optimization of the results, which include equality and inequality physicaland structural constraints. We validate our results using synthetic density crustal structure models withvarying complexity and illustrate the behavior of the algorithm using different initial density structure
models and increasing noise levels in the observations. Moreover, we apply the approach to the Southern
Rio Grande Rift (SRGR) region using previously obtained receiver function results as constraints for the
inverted density profiles. We produce constrained crustal models that characterize the SRGR that show ashallower Moho (30 km) in the region, which is thicker than previously suggested. Based on the validationand implementation, we conclude that the algorithm using Primal-Dual Interior-Point methods is robust
and always honors the geophysical constraints. Advantages of using this approach for structural inversionof gravity data are the incorporation of a priori information related to the model parameters (coming from
actual physical properties of the subsurface) and the reduction of the solution space contingent on theseboundary conditions.

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*J08-P-05
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Gravitational signal produced by global shallow-Earth density model
Litho1.0
Josef Sebera 1) , Roger Haagmans 1) , Rune Floberghagen 1) , Diego Fernandez Pietro 1) , Joerg Ebbing 2) , *Michael Kern 1)
European Space Agency 1) , University of Kiel 2)
The global Earth's density distribution models based on data from seismic tomography and crustal
compilations still improve in accuracy, lateral as well as in the vertical resolution. In our work, we evaluate
the gravitational signal generated by such a model, Litho1.0, while focusing on the spectral properties.
Litho1.0 provides about 10% of the total Earth's gravitational acceleration and allows to shed light on the
spectral relations between the main “players" – the crust, the lithosphere and the upper mantle (asrepresented by the model). We also compare the results in terms of gravitational gradients with thoseobtained from the ESA's mission GOCE. The gravitational gradients depend less on deeper and moredistant density variations than the gravity and therefore they provide suitable means for studying theshallow Earth. Finally, we discuss some numerical issues associated with the spherical tessellation used in
Litho1.0 and LLNL-G3D.

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*J08-P-06
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Deep Conductive Structure beneath the Kutcharo Caldera, Revealed by 3-D
Inversion Analysis* Ryo Honda 1) , Hiroshi Ichihara 2) , Yusuke Yamaya 3) , Hideaki Hase 4) , Toru Mogi 5) , Makoto Uyeshima 6), Mitsuhiro Nakagawa 7)
Mount Fuji Research Institute, Yamanashi, Japan 1) , Kobe Ocean Bottom Exploration Center (KOBEC),
Kobe Univ., Kobe, Japan 2) , Fukushima Renewable Energy Institute, AIST, Fukushima, Japan 3) ,Geothermal Energy Research & Development Co., Ltd., Tokyo, Japan 4) , Faculty of Engineering, Hokkaido
Univ., Hokkaido, Japan 5) , Earthquake Research Institute, University of Tokyo, Tokyo, Japan 6) , Graduate
School of Science, Hokkaido Univ., Hokkaido, Japan 7)
Kutcharo caldera is the biggest caldera in Japan, which has potential to cause catastrophic eruption. We
think it is very important to clarify the current subsurface state of the volcano. There are some report forthe caldera structure by gravity surveys and AMT explorations (e.g. Yokoyama, 1958, J. Phys. Earth; Honda
et al., 2011a, J. Fac. Sci. Hokkaido Univ.; Ichihara et al., 2009, EPS), however, no obvious structures whichassociate any volcanic activities has been reported. We report the result of the 3-D analysis of the resistivity
structure in and around the Kutcharo caldera.
Our survey was executed by wide-band and the long-period observations during 2009 and 2010. With oursurvey data, we compiled the wide-band MT data from Ichihara et al. (2009, EPS) and Ichihara et al. (2013,
Tectonophys.), which are the observation data around the focal area of Teshikaga Earthquake. We adopted
the remote reference analyses (Gamble et al., 1978, Geophysics) to these MT data. We used the reference
magnetic data of Kakioka Magnetic Observatory and the Esashi station for the long wavelength and thewide-band data, respectively.
The three dimensional analysis is executed by WSINV3DMT (Siripunvaraporn et al., 2005, PEPI;
Siripunvaraporn et al., 2009, PEPI). The characteristic resistivity structures found in the result is almost
consistent with the result of the 2-D analyses (Honda et al., 2011). The extraordinary low resistivity bodypiercing the high resistivity layer towards the Atosanupri volcano from the deep layer was remarkable inthe 2-D result. By the 3-D analysis, the conductor under the Kutcharo caldera became sharp.
Acknowledgement
For this study, we have used the computer systems of the Earthquake and Volcano Information Center ofthe Earthquake Research Institute, the University of Tokyo. We are thankful for the magnetic data provided
by the GSI and JMA.

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*J08-P-07
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Crustal structure beneath the eastern foot of the Japan Trench outer rise by
airgun-ocean bottom seismometer survey* Shuhei Otomo 1) , Ryosuke Azuma 1) , Ryota Hino 1) , Gou Fujie 2) , Shuichi Kodaira 2)
Tohoku University, Miyagi, Japan 1) , JAMSTEC, Kanagawa, Japan 2)
Several studies on the seismic structure of the oceanic crust reported presence of evident reflectors in theoceanic lower crust or in the uppermost mantle although the seismic structure of the deeper part of theoceanic crust is thought to be relatively homogeneous. The presence of such reflective structure would be
related to the processes of formation and/or growth of the oceanic crust. In this study, we investigate thecrustal structure of the old Pacific Plate in the NW Pacific before it suffers from bending deformation at the
trench to discuss the development process of the Pacific Plate by analyzing an ocean bottom seismometer(OBS) survey conducted in the eastern foot of the Japan Trench outer rise.
A traveltime analysis using a 2-D ray tracing method was made to construct a 2-D P-wave velocity model
along the survey line. By assuming a low velocity zone (LVZ) in the lower oceanic layer 3, the observed
appearance of the OBS records can be well explained. On the other hand, we applied a series of waveform
analysis, combining a Seismic Interferometry (SI) technique and a NMO stacking, to obtain a reflection
seismic profile by the OBS data, and then continuous and evident signal are imaged at ~9.0 s in two-way
travel time (TWT). The TWT of the event is not consistent with that of the reflections from Moho
discontinuity but is similar to that of the reflections from the top of the LVZ, if such reflection signals are
actually observed.
We tried to apply the series of SI-NMO analysis to synthetic OBS seismograms calculated based on thevelocity model with the LVZ in the layer 3. On the reflection profiles by the synthetic data, clear reflector
events are identified at TWTs of ~9.0 s and ~9.7 s. The shallower reflector coincides with the top of LVZ.
This test reinforces our interpretation that the reflections from the LVZ were imaged on the profiles derived
by the field OBS data.

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*J08-P-08
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Velocity structure and Earthquake Distribution in Nagaoka Region* Shutaro Sekine , Yoshihiro Sawada , Keiji Kasahara , Shunji Sasaki , Yoshihiro Tazawa
Association for the Development of Earthquake Prediction (ADEP), Tokyo, JapanThe Nagaoka region is located on the high strain rate zone at eastern margin of Japan Sea, and it is also thearea where the Chuetsu Earthquake and the Chuetsu-oki Earthquake have occurred. Between the two large
faults, another faults are confirmed on the western margin of the fault zone of the Nagaoka plain. To
investigate the activity of faults, the Association for the Development of Earthquake Prediction (ADEP)
determined to newly construct a high-density seismic observation network (AN-net) in the region from2010. In this study, we introduce the network and estimate the distribution of the earthquakes, and velocity
structures in this region. AN-net consists of the 40 stations in the Nagaoka plane from November 2010. The
size of the network is roughly 20km wide and 40 km long, covering the Nagaoka plain. In each station, thevelocity seismometer and accelerometer at the bottom of a borehole which depth is about 100m, andanother accelerometer is set on the ground. Half of the stations has GNSS stations. These data from eachobservation station are sent in real time. In this study, we calculate P- and S- velocity structure by Double
Difference tomography. This method is used both absolute and relative arrival times. After 2010 when the
AN-net was constructed, arrival times of each earthquakes is picked manually in the AN-net region. Before
2010 and region of the Surrounding AN-net, we get the arrival data from JMA unified earthquake catalog.
The number of absolute P- and S-wave arrival times used in the tomography is 241,626 and 216,802,
respectively, with the relative arrival times for the manually picked P- and S- waves reaching 993,390 and
858,086, respectively, from 13,353 earthquakes which occurred from October 1997 to 2016. The weighted
root mean square (RMS) travel time residual was reduced 0.53s to 0.08s after 45 iterations. Based on thevelocity structure, most of the earthquakes occurred at the depths where P-wave velocity is greater than
5.5km/s.

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*J08-P-09
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Plate boundary property of the Philippine Sea plate revealed from later
phase analysis beneath southwestern Ibaraki and northwestern Chiba
prefectures, central Japan* Hisanori Kimura 1) , Naoshi Hirata 2)
National Research Institute for Earth Science and Disaster Resilience, Japan (NIED) 1) , Earthquake
Research Institute, the University of Tokyo 2)
To investigate details of a possible disastrous earthquake beneath the Tokyo urban area, central Japan,
knowledge about the plate boundary property is important. For this purposes, we studied later phases ofnatural earthquakes beneath the southwestern Ibaraki and the northwestern Chiba prefectures.
We found clear phases in vertical component of 1-4 Hz coherently in the MeSO-net (Metropolitan Seismic
Observation network) line, between direct P and S arrivals (hereinafter, X phase). Traveltime difference
between the X phase and direct P decreases for shallower earthquake. These features indicate that the X
phase is converted from S to P above the hypocenter.
We compared observed traveltime difference and amplitude ratio between SP and direct P with synthetic
values to cancel out surface structure effects, which were calculated using velocity structure and the upperboundary of the Philippine Sea plate (UPHS) determined by MeSO-net (Nakagawa et al., 2010; Hirata,2012) with sedimentary layer (J-SHIS; Fujiwara et al., 2012). For amplitude calculation, radiation pattern
expected from focal mechanism of NIED F-net or Hi-net, geometrical spreading, anelastic attenuation, andconversion or transmission coefficients on the UPHS were considered. Q of P and S waves were assumed
to be 1000. Observed traveltimes were well explained. This indicates that the X phase is generated at the
UPHS. On the other hand, small change in velocity structure was necessary to explain observed amplitude
ratio. Estimated velocity exhibits large fluctuation, however, Vs was estimated to be 3 % slower on averagejust below the UPHS.
Since the target region is within the network of MeSO-net, reliability of the velocity structure and the UPHS
are likely to be high. On the other hand, grid spacing is 5-10 km or larger, and hence structure smaller than
this scale could not be imaged. Examination of amplitude ratio of later phase indicates small scale
inhomogeneous structure around the UPHS.

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*J08-P-10
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Heterogeneous structure in the incoming Philippine Sea plate along the
Nankai Trough* Ayako Nakanishi 1) , Mikiya Yamashita 1) , Yojiro Yamamoto 1) , Gou Fujie 1) , Seiichi Miura 1) , Shuichi
Kodaira 1) , Yoshiyuki Kaneda 2) , Nomukazu Seama 3)
JAMSTEC, Yokohama, Japan 1) , Kagawa Univ., Kagawa, Japan 2) , Kobe Univ., Kobe, Japan 3)
Rupture of large-thrust earthquakes along the Nankai Trough is known by always initiating from off the Kii
Peninsula. The segmentation boundary between the 1944 Tonankai (Mw=8.1) and the 1946 Nankai(Mw=8.4) earthquake rupture is locate off the Kii Peninsula. Activity of the nonvolcanic deep low-frequency
tremors and very low-frequency earthquakes observed around the down-dip limit of the coseismic rupturezone of the last Tonankai and Nankai earthquakes is not homogeneous, and the belt-like tremor zone isdivided into several segments bounded by gaps [Obara, 2010]. Largest gap is recognized around the Kii
channel between the Shikoku Island and Kii Peninsula.
Our recent integrated result of first-arrival tomography based on the 2012 and 2014 wide-angle OBS datashows dramatic along-trough variation in P-wave velocity just beneath the basement of the incoming
Philippine Sea plate. Velocity change can be recognized south off the Cape Muroto and the Shima
Peninsula just seaward of the trough axis. Such dramatic velocity change corresponds with the structuralchange in the configuration of the basement reflection in the time-migrated section. Similar along-troughstructural variation can be recognized in the central Shikoku Basin far south from the trough axis
[Nishizawa et al., 2011]. Heterogeneous structure along the trough may be related to the formation of theincoming Philippine Sea plate, because the structural boundary may correspond with the plate age of about
20-21.5Ma proposed by Okino [2015] based on magnetic lineation. This structural characteristic is thought
to continue northwards to the subducting Philippine Sea plate beneath the southwest Japan, and may
cause the segmentation of an earthquake rupture, and heterogeneous activity of low-frequency earthquake
phenomena.
This study is part of ‘Research project for compound disaster mitigation on the great, earthquakes andtsunamis around the Nankai Trough region' funded by MEXT, Japan.

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*J08-P-11
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Detailed crustal and upper mantle structure of the subducting Philippine Sea
plate and the overlying southwestern Japan arc, revealed by dense seismicarray observation* Eiji Kurashimo 1) , Takashi Iidaka 1) , Noriko Tsumura 2) , Takaya Iwasaki 1)
The University of Tokyo, Tokyo, Japan 1) , Chiba University, Chiba, Japan 2)
The Nankai trough region, where the Philippine Sea Plate (PHS) subducts beneath the SW Japan arc, is awell-known seismogenic zone of interplate earthquakes. A narrow zone of nonvolcanic tremor has beenfound in the SW Japan fore-arc [Obara, 2002]. Obara [2002] suggested fluids as a source for tremor. The
behavior of fluids at the plate interface is a key factor in understanding fault slip processes. Seismic
velocity variations can provide important information on the fluid-related heterogeneous structure. To
reveal the subduction structure, we conducted passive seismic experiment in the eastern Kii Peninsula. 90
offline recorders were installed on a 90-km-long line during a six-month period from May, 2015. Arrival
times of 275 local earthquakes were used in a joint inversion for earthquake locations and 3D Velocity
structure. In order to investigate the relation of the crustal heterogeneity to the seismicity, we relocated
4,720 events occurring between January 1, 2000 and May 26, 2015, including 284 low-frequency
earthquakes (LFEs), using the P- and S-wave arrival time data picked manually by the Japan Meteorological
Agency and inverted 3D velocity model. We also applied a seismic interferometry technique to the local
earthquake data set to obtain the geometry of the subducting PHS. Common-midpoint stacked profile ofinterferometric seismic imaging shows the northward-dipping reflector at a depth of about 25 km, which isinterpreted as the top of the PHS. Most LFEs are located beneath the northward-dipping reflector. LFEs arelocated in and around the low Vp and high Vp/Vs zone. The low Vp and high Vp/Vs generally suggests theexistence of fluid [e.g., Zhao et al., 1996], and indicates the occurrence of the LFEs may be associated withfluids. The epicentral distribution of LFE corresponds to the locked-sliding transition estimated byHyndman et al. (1995). These studies suggest that fluids dehydrated from the PHS control frictional
properties of the plate boundary.

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*J08-P-12
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

3D seismic velocity structure beneath Kii Peninsula, southwestern Japanderived from receiver function analysis and seismic tomography* Takuo Shibutani , Kazuro Hirahara
Kyoto University, Kyoto, Japan
1. Introduction
In order to investigate behavior of slab-derived fluids discharged from the Philippine Sea plate subducting
beneath Kii Peninsula, southwestern Japan, we carried out seismic observations, receiver function analysis
and seismic tomography. We estimated the geometry of the slab and the seismic velocity structure beneath
the Kii Peninsula, and discussed the behavior of the fluids with the distribution of low velocity anomalies.
2. Receiver function (RF) analysis
We carried out linear array seismic observations in the Kii Peninsula from 2004 to 2013. We deployedseismometers along six profile lines with an average spacing of about 5 km. We applied RF analysis andobtained images of S wave velocity discontinuities. We estimated 3D configurations of the continental
Moho, the slab top and the oceanic Moho from RF images for the six profile lines.
The continental Moho, the slab top and the oceanic Moho are clearly found in the RF images. A new
knowledge obtained by the analysis is that the continental Moho dips upward in the southeast direction
above the Philippine Sea slab.
3. Seismic tomography
We carried out the tomography with FMTOMO (Rawlinson et al., 2006). We used a velocity model with the
3D geometries of the three discontinuities derived from the RF analysis. We used 231,650 P travel times
and 210,142 S travel times observed at the temporary stations in addition to permanent stations.
Results of the tomography show that low velocity anomalies (> 5 % in both P and S wave velocities andhigh Vp/Vs ratio > 1.8) are located in deep low frequency events areas at 30 – 40 km depths on thePhilippine Sea slab and that another strong low velocity anomaly (> 10 % in P wave velocity and low Vp/Vs
ratio < 1.6) is widely distributed in the lower crust beneath the northern Wakayama Prefecture where small
to micro earthquake activity is very high in the upper crust.
We used waveform data from stations of NIED; JMA; ERI, Univ of Tokyo; Nagoya Univ and DPRI, Kyoto
Univ.

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*J08-P-13
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Crustal velocity structure and configuration of the subducting Philippine Sea
plate beneath the Japanese Islands identified from receiver function analysis* Toshihiro Igarashi , Takashi Iidaka
The University of Tokyo, Tokyo, Japan
We apply receiver function analyses to estimate the velocity structure in the crust and uppermost mantle
and configuration of the subducting Philippine Sea plate beneath the Japanese Islands. The velocity
structures beneath each seismic station searched a best-correlated model between an observed receiver
function and synthetic one by using a grid search method. We further constructed many vertical crosssections of the estimated velocity structure models and the depth-converted receiver function images toestimate seismic velocity discontinuities. Repeating earthquake data which occurred in the subducting
plate boundary were also used to estimate plate geometries.
The configuration of Philippine Sea plate dips toward the northwest beneath the Japanese Islands. The
direction coincides with plate motion. The thickness of the Philippine Sea plate gradually decreases to thenortheast after the contact with the underlying Pacific plate beneath the Tokyo metropolitan area. The
northeastern margin of the Philippine Sea plate can identify from the decreasing plate thickness. In the
subducting plate boundary contacted with the island arc Moho, we identify non-volcanic tremors in thesouthwestern Japan region and normal earthquakes including small repeating earthquakes in the Ryukyu
Islands. The former areas are characterized by high-velocity mantle wedge and low-velocity oceanic crust,
whereas relatively low-velocity mantle wedge characterizes the latter areas. Source regions of past interplate destructive earthquakes seem to correspond to the high-velocity area in the Philippine Sea slab.
These observations may indicate the relationship between slip characteristic of the plate interface andserpentinized materials which reflect dehydration of the subducting oceanic crust.

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*J08-P-14
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Geometry of the frontal thrust at the trench axis around the Hyuga-nadaregion revealed by high-resolution seismic reflection imaging* Mikiya Yamashita 1) , Ayako Nakanishi 1) , Ryuta Arai 1) , Shuichi Kodaira 1) , Yasuyuki Nakamura 1) ,Seiichi Miura 1) , Yoshiyuki Kaneda 2) 1)
Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan 1) , Kagawa University, Japan 2)
Great earthquakes with tsunamis with recurrence intervals of 100–200 years have occurred along the
Nankai Trough near central Japan. Hyuga-nada is located in the western part of Nankai Trough, subducting
the Kyushu-Palau ridge which is remnant arc constructed by backarc spreading in Shikoku Basin. New
tsunami source model of historical tsunamigenic earthquake (e.g. 1707 Hoei) is extended to Hyuga-nadaregion revised by inundated deposits at coastal lake in Kyushu. Recent ocean-bottom monitoring results
have also yielded presence the episodic low-frequency tremor associated with the activity of very-lowfrequency earthquake at shallow plate interface at the northern end of subducting Kyushu-Palau ridge.
In order to understand the geometry of the frontal thrust around the Kyushu-Palau ridge, a dense highresolution seismic reflection survey was conducted by Japan Agency for Marine-Earth Science andTechnology over 600 km of line length from Sep. to Oct., 2016 using R/V Yokosuka.
Clear seismic reflection images of frontal thrust in the accretionary prism, trench-fill deposits are shownaround the Kyushu-Palau ridge from preliminary profiles. The distribution of trench-fill sediments is limited
to only the east side of Kyushu-Palau ridge. There is no deformation structure in the trench-fill sedimentsfrom the trench axis to the seaward region. In the west side of Kyushu-Palau ridge, there are few sedimentson the subducting oceanic crust. These characteristics suggests that the crustal structure at the trench axis
around the Kyushu-Palau ridge is not “typical" Nankai subduction zone. Although our surveys covered apart of Nankai seismogenic zone, it is important to understand the deformation process of the western partof Nankai Trough.
This study is part of "Research project for compound disaster mitigation on the great earthquakes andtsunamis around the Nankai Trough region" funded by the Ministry of Education, Culture, Sports, Science,
and Technology of Japan.

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*J08-P-15
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Three-dimensional P- and S-wave attenuation tomography in the Ryukyu
Arc, Japan* Masanao Komatsu , Hiroshi Takenaka
Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
We investigate 3D seismic Qp and Qs structures in the Ryukyu Arc. It is important to estimate the 3D Q
structure in this region, since there are highly active volcanoes and seismicity between the Okinawa
Trough and the Ryukyu Trench. We use seismic waveform data recorded by seismic observation networks
of NIED, JMA and Kagoshima University, from 2004/06 to 2014/05. We select 4,353 seismic events, which
the range of JMA magnitude is greater than or equal to 3.0 and less than or equal to 6.0. The cornerfrequency of the source spectrum for each event is estimated by using scaling law before calculating theattenuation quantity t*. The t* is estimated from the amplitude decay rate from the source-corrected spectra
between 3.0-30.0 Hz. 21,089 P- and 17,939 S-wave t* are obtained. We then invert the P- and S-wave t* data
to 3D Qp and Qs distributions by a tomographic technique using the non-negative least squares method.
For the inversion, the coordinate center is located at (127.0E, 26.5N). The coordinate system is rotatedcounterclockwise 42 degrees from north. We confirm that this axis rotation can improve the result of thecheckerboard resolution tests (CRTs). Our estimated Qp and Qs structures has remarkable features: low-Qp
and Qs zones exist beneath the Okinawa Trough, where is an extensional field along the rift. Low-Qp andQs patches are located beneath active volcanoes in the Tokara islands. These patches may indicate
upwelling of high temperature materials from top of the high-Qp and Qs Philippine Sea (PHS) slab. Low-Qp
and Qs spots are also located in the forearc side. Especially, these spots in Kikai Island and Hateruma
Island may denote sediment or accretionary prism.

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*J08-P-16
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Inhomogeneous rifting structure in the northern Okinawa Trough, an active
backarc basin southwest of the Japan Islands* Chiaki Okada 1) , Azusa Nishizawa 1) , Kentaro Kaneda 1) , Mitsuhiro Oikawa 1) , Daishi Horiuchi 1) , Yukari
Fujioka 1) , Kosaku Arai 2)
Hydrographic and Oceanographic Department, Japan Coast Guard, Tokyo, Japan 1) , Research Institute ofGeology and Geoinformation, National Institute of Advanced Industrial Science and Technology, Tsukuba,
Japan 2)The Ryukyu (Nansei-Shoto) island arc–trench system is located at a convergent plate margin where thePhilippine Sea (PHS) plate is subducting under the Eurasian plate. The Okinawa Trough is a backarc basinof the system extending from north to south and the stage of its ongoing rifting process varies along thetrough. The crustal extension in the northern trough is not progressing so much compared with thesouthern trough. The position of the trough axis is not determined clearly in the northern trough, though itcorresponds to several en echelon narrow rifts in the southern trough. The seafloor topography in thenorthern trough shows different features between the eastern and the western parts. Because the volcanic
front related to the PHS plate subduction exists in the eastern part, there are many seamounts and knolls inthis part. In contrast the western part is rather flat seafloor.
We have conducted multi-channel seismic (MCS) reflection surveys to acquire detailed images ofdeformation in shallow structures reflecting variable tectonic backgrounds of the Okinawa Trough since2008. We fired a trigun cluster with a total volume of 1,050 cubic inches at a 50 m shot interval and used
240-channel (3,000 m long) seismic streamer. The MCS data were processed by a standard procedureincluding band-pass filter, deconvolution, normal move out correction and CMP stacking.
The MCS results reveal a number of normal faults and intrusions beneath all the seismic lines inside thenorthern trough. In the western part of the trough with a flat seafloor, there are thick sedimentary layerswith over 3,000 m thick at most. However we detected several intrusions below the seafloor and some ofthem penetrate into the uppermost sediments. On the contrary, the eastern part shows the rough seafloor
and the existence of many volcanic features. The MCS profiles reveal many igneous intrusions reaching
above the seafloor, which corresponds to the volcanic front in this region.

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*J08-P-17
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

Mantle heterogeneity in the oceanic lithosphere of the southwest sub-basin,
South China Sea, from the wide-angle seismic and the gravimetric model* Chuanchuan Lu 1) , Tianyao Hao 1) , Jian Lin 2)
Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China 1) , Woods Hole
Oceanographic Institution, Massachusetts, U.S.A 2)
The southwest sub-basin (SWSB) of the South China Sea (SCS), an oceanic basin, locates in thesouthwestern part of the SCS, separated by several rigid blocks, influenced by a direction changing
spreading center and ridge propagation until the asthenosphere stopped upwelling around 15Ma. The
processes of seafloor spreading through a series of mantle lithospheric dynamics in the oceanic lithosphereis generally considered to be the consequence of melt extracting and crustal accretion in the upper mantle
structure. Lateral crustal heterogeneity only plays a minor role in geophysical attributes, since the crustal
structure can be revealed by the modeling of wide-angle seismic traveltime and amplitude. After the
calculation of the residual mantle gravity anomaly (RMA), we can do inversion about the upper mantle
density variations across the axis in 3-D. Taking account of the crustal structure, cold thermal structure witha strong lithosphere means anisotropic magma distribution along the slow-spreading ridge, which leads aheterogeneity mantle's density structure across the ridge. Therefore, the upper mantle structure, inferredfrom wide-angle seismic and gravity can thus provide us with knowledge of the processes that have formed
oceanic lithosphere at different times and under a variety of conditions which is a straightforward responseof the deep mantle structure of the lithosphere. By inverting the RMA of the SWSB in the SCS, its distinct
low anomaly over the fossil spreading centre, little variation along the direction of the paleo-spreading axis
direction, and relatively wider area of high anomaly on the southeast side, the density variation indicatesthe changing of the direction may leave space for melt accretion in the northern flank of the spreading
ridge, and squeeze the limited off-axis space in the southern side, which may be the reason that more melt
was retained on southern flank of fossil ridge.

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*J08-P-19
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

The 3-D velocity structure of the 2008 Taoyuan Earthquake Sequence in
Kaohsiung, Taiwan* Min Hung Shih , Bor-Shouh Huang
Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
The three-dimensional velocity structure of the upper crust was determined by using the arrival readings
were identified from the 2008 Taoyuan Earthquake Sequence. On March 4, 2008, a moderate earthquake(ML 5.2) occurred in Taoyuan district of Kaohsiung City in southern Taiwan. It was followed by numerous
aftershocks in the next 48 hours, including three events with magnitude larger than 4. The high-resolution
waveform data of this sequence were well-recorded by a large number of recording stations. These stations
belong to several different permanent networks (operated by IES, NCU, and NCCU) and temporary
networks (deployed by TAIGER project, Taiwan Integrated Geodynamic Research project) all aroundTaiwan. All waveform data are managed and processed by Antelope software suite. We applied a 1-D
velocity model for locating events in the preliminary analysis. In this study, we introduced the doubledifference tomography method not only to determine the fault geometry of the main shock but also toinvestigate the detailed 3-D velocity structure in this area. The results indicate that aftershocks areextended along the NE-SW direction and located on a 45 SE-dipping plane, which agrees with one of thenodal planes of Global CMT solution (strike = 45, dip = 40, and rake = 119). We can identify a clear lowvelocity area which is enclosed by events next to the main shock in the final 3D velocity model. We also
recognized a 45 degree-dipping zone, which is extended to the ground surface with low-velocity;
meanwhile, velocity structure variation in study area corresponds to major geologic units in Taiwan.

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*J08-P-19
Joint Symposium / J08. Imaging and interpreting lithospheric structures using seismic
and geodetic approaches

The shallow structure of Tatun Volcano Group from residual gravity andmagnetic data
* Hsien-Hsiang Hsieh 1) 2) 3) , Benjamin Fong Chao 1) , Horng-Yuan Yen 4)
Academia Sinica, Taipei, Taiwan 1) , NCREE, Taiwan 2) , E-TEC, National Dong Hwa University, Taiwan 3) ,National Central University, Taiwan 4)
Tatun Volcano Group (TVG) is composed by 21 volcanoes, located in northern Taiwan. It is a very
important topic to understand the background of volcano group, especially which is nearby Taipei city, thelargest city in Taiwan. In this study, the new magnetic surveys (372 points) and gravity data combinations(246 points) of TVG are processing. After data processing and correction, new gravity and magnetic
anomaly maps are showed. The anomaly maps are fitting well with volcanic and igneous rocks. For
modeling TVG structures near shallow surface, the filters are used to show the regional and residual map
from the gravity and magnetic maps. The gravity inversion and magnetic analyses are also used in the next
step. Final, in the gravity results, TVG is covered by high density andesitic lavas, especially around two
major peaks (Tatun and Chihsing Mts.). The Curie Point Depth in TVG from magnetic data also provide thehigh thermal gradient area beneath Tatun and Chihsing Mts.

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*J09-1-01
Joint Symposium / J09. Geodesy and seismology general contributions

Normal-faulting earthquakes in the northern area of Ibaraki Prefecture,
Japan in 2011 and 2016 - Duplicate events detected by InSAR observations* Tomokazu Kobayashi
GSI of Japan, Tsukuba, Japan
Following the 2011 Tohoku earthquake, many inland crustal earthquakes have occurred with a source
mechanism of normal fault motion in the Fukushima hamadori and northern Ibaraki areas, Japan. Under
such a seismological background, an inland earthquake with a moment magnitude (Mw) of 5.9 occurred in
the northern area of Ibaraki Prefecture at 21:38 on Dec. 28, 2016. The startling finding derived InSAR
observations is that location, spatial distribution, and magnitude of the InSAR-derived crustal deformationis almost same as those observed for the inland earthquake that occurred with Mw6.1 on March 19, 2011.
The InSAR result shows that the deformation has ear-shaped distribution, elongated along the north-southorientation. Another remarkable feature is that a displacement discontinuity with a length of about 2 km isclearly recognized in the northeast of the source region, probably suggesting that a rather shallow slip
occurred. The same features were identified in the 2011 event, and in particular, it is surprising that boththe position and the length of the discontinuities are the same between the two events.
The fault model for the 2016 event that consists of two fault segments shows (1) west-dipping fault planes
with dip angles of 50–60 deg, (2) NNW-SSE (NW-SE) strike direction, (3) nearly pure normal fault motions,and (4) a shallow local slip. The 2011 event also has almost the same features on the fault model(Kobayashi et al, 2011). It strongly suggests that almost the same fault slips have occurred on almost thesame fault plane for both the events, which is probably the world's first observation in that we can identify
the similarity "visibly".
Acknowledgements: ALOS-2 data were provided from the Earthquake Working Group under a cooperative
research contract with JAXA (Japan Aerospace Exploration Agency). The ownership of ALOS-2 data
belongs to JAXA.

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*J09-1-02
Joint Symposium / J09. Geodesy and seismology general contributions

Recent findings on dual tsunami sources: November 1945 Makran (NW
Indian Ocean) and December 1908 Messina (Italy) tsunamis
Mohammad Heidarzadeh 1) , * Kenji Satake 2) , Sebastian Krastel 3) , David Tappin 4)
Brunel University London, Uxbridge, UK 1) , The University of Tokyo, Tokyo, Japan 2) , University of Kiel,
Kiel, Germany 3) , British Geological Survey, Nottingham, UK 4)
The concept of dual (combined earthquake-landslide) tsunami source has gain weights in tsunami
community mostly since the July 1998 Papua New Guinea tsunami where only a dual source was capableof re-producing the coastal runups [Satake & Tanioka, 2003, PAGEOPH; Tappin et al. 2001, Mar. Geol.].
Since then, efforts have been made to re-analyze historical tsunami events in order to address
discrepancies between available observations and numerical results based on the state-of-the-art models.
Such efforts have helped to find potential locations of co-seismic submarine landslides [e.g., Billi et al.,2008, GRL]. Improved understanding on the mechanism and case studies of dual tsunami sources are vitalin accurately mapping the coastal hazards. Here, we discuss two case studies of dual tsunami sources:
1945 Makran (NW Indian Ocean) and1908 Messina (Italy) tsunamis. In a recent study, Heidarzadeh andSatake (2017) [BSSA] showed that the extreme runup of 12-15 m reported in the near-field for the 1945
Makran tsunami was possibly due to a dual source: a 220-km earthquake fault with average slip of ~6 m
and a submarine landslide with dimensions of 15 km (length) x 15 km (width) and a thickness of 600 m.
Landslide volume was estimated at ~40 km3. The other heavily debated tsunami event is that of December
1908 in Messina whose origin is still debated. Although several earthquake faults have been proposed forthis event, none of them has reproduced the observations [e.g. Tinti and Armigliato, 2003, Mar. Geol.].
Landslide sources were proposed for this event based on the limited marine geophysical data with varying
success [e.g. Billi et al., 2008, GRL; Favalli et al., 2009, GRL]. New marine geophysical data obtained for theregion [Lili et al., 2017, GRL, in revision] helped to more accurately map potential submarine landslide andmore accurately model potential tsunamis in this region. We propose a new dual tsunami source for the1908 Messina tsunami.

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*J09-1-04
Joint Symposium / J09. Geodesy and seismology general contributions

Tsunami source of the 1979 Tumaco Earthquake estimated from historicaltide gauge records and geodetic data
* Bruno Adriano 1) , Yushiro Fujii 2) , Masahiro Yoshimoto 3) , Shunichi Koshimura 1)
Tohoku University, Sendai, Japan 1) , Building Research Institute, Tsukuba, Japan 2) , Nagoya University,
Nagoya, Japan 3)
On December 12, 1979 an earthquake occurred in southern coast of Colombia , in front of Tumaco area
(1.60N 79.36W, 07:59:03.300 UTC according to U.S. Geological Service). The surface-wave magnitude ofthis event was estimated as Ms7.7 (USGS), and its moment magnitude was calculated as Mw8.1 (GCMT
Catalog). The epicenter was located 80 km southwest of Tumaco, offshore the Pacific coast of Colombia.
This event generated a tsunami that killed more than 100 residents of San Juan Island, 60 km north of
Tumaco. The observed coastal subsidence, due to the coseismic deformation, was approximately 0.50 m
near Tumaco area (Herd et al., 1981).
This study aims to investigate the tsunami source of the 1979 Great Tumaco Earthquake using inversion ofhistorical recorded tsunami waveform and geodetic data. We employ the tsunami signal recorded at threetide gauge stations (Esmeraldas and Santa Cruz in Ecuador, and Acujutla in El Salvador). To estimate theextent of the tsunami source and the slip distribution, we divide the tsunami source into 5 x 2 subfaults
along the strike and dip directions, respectively. The assumed fault area covers the aftershock distribution
during one month after the mainshock. The subfault size is 40 km x 40 km with top depths of 12.9 km and24.0 km. The focal mechanisms for all the subfaults were taken form the GCMT solution of the mainshock.
The inversion result using only tsunami data, and the joint inversion of tsunami and geodetic data showedthat the largest slip was located north the epicenter with an average slip of 5.4 m. The estimated moment
magnitude from both inversion models was nearly identical Mw=8.03 (1.38E+21 N-m), which is slightly
smaller than the published by GCMT (Mw=8.1, moment 1.60E+21 N-m). The estimated slip distribution
suggested that the fault rupture started near the epicenter and propagated northeast, which is also
supported by the aftershock distribution (Herd at al., 1981).

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*J09-1-05
Joint Symposium / J09. Geodesy and seismology general contributions

Crustal blocks motion model and interplate coupling in Colombia based on
GNSS observation network (GEORED)* Takeo Ito 1) , Hector Mora Paez 2) , Juan Ramon Pelaez Gaviria 2) , Takeshi Sagiya 1)
Nagoya University, Nagoya, Japan 1) , Servicio Geologico Colombiano, Bogota, Colombia 2)
Introduction
Colombia is located at the boundary between South-America plate, Nazca Plate and Caribrian plate. Thisregion is very complexes such as subducting Caribrian plate and Nazca plate, and collision between
Panama and northern part of the Andes mountains. The previous large earthquakes occurred along the
subducting boundary of Nazca plate, such as 1906 (M8.8) and 1979 (M8.2). And also, earthquakes
occurred inland, too. So, it is important to evaluate earthquake potentials for preparing huge damage due tolarge earthquake in near future.
GNSS observation
In the last decade, the GNSS observation was developed in Columbia. The GNSS observation is called by
GEORED, which is operated by servicing Geologico Colomiano. The purpose of GEORED is research ofcrustal deformation. The number of GNSS site of GEORED is consist of 93 continuous GNSS observationsite at 2016. The sampling interval of almost GNSS site is 30 seconds. These GNSS data were processed by
PPP processing using GIPSY-OASYS II software. GEORED can obtain the detailed crustal deformation map
in whole Colombia.
MethodWe developed a crustal block movements model based on crustal deformation derived from GNSS
observation. Our model considers to the block motion with pole location and angular velocity and theinterplate coupling between each block boundaries, including subduction between the South-American
plate and the Nazca plate. And also, our approach of estimation of crustal block motion and coefficient ofinterplate coupling are based on MCMC method. The estimated each parameter is obtained probably
density function (PDF).
ResultWe tested 11 crustal block models based on geological data, such as active fault trace at surface. The
optimal number of crustal blocks is 11 for based on geological and geodetic data using AIC. In thispresentation, we will discuss spatial interplate coupling ratio and also earthquake potential at inland faults.

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*J09-1-06
Joint Symposium / J09. Geodesy and seismology general contributions

Rise Time of Coseismic Tectonic Deformation during Megathrust
Earthquakes , as estimated from Observed Low-Frequency Acoustic-Gravity
Waves* Takeshi Mikumo
Kyoto University, Kyoto, Japan
Unusual low-frequency acoustic-gravity waves with periods up to as long as 14 min have been recorded
after four megathrust events. These are the 1964 Alaskan earthquake (Mw=9.2), the 2004 SumatraAndaman earthquake (Mw=9.2), the 2011 Off-Tohoku earthquake (Mw=9.0), and the 2010 Maule, Chile(Mw=8.8) earthquake, respectively. These extremely long-period atmospheric waves have been clearlyobserved at several microbarograph stations located at not only several regional stations but at manyInternational Monitoring System stations even up to a far-field of 6,700 km. The phase and group velocitiesof these disturbances are found to be between 314 m/s to 364 m/s consistent with so far predicted foracoustic-gravity waves.
These observed low-frequency atmospheric waves may be interpreted as excited by upheaval anddepression of the sea surface within the extensive source region of these extremely large thrustearthquakes due to coseismic uplift and subsidence of the sea bottom. We calculate the synthetic
waveforms for the propagating atmospheric disturbances due to the coseismic vertical displacements of thesea surface, incorporating a standard sound velocity and density structures up to an altitude of 220 km
above the earth's surface. The calculated waveforms for many stations well explain most of theobservations. Our analysis suggests the initial coseismic change of the sea surface in the main part of thesource region may exceed 4 – 6 meters with the rise time between 2 and 4 min depending on theirlocations, which is related to the source process of these megathrust earthquakes.

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*J09-2-01
Joint Symposium / J09. Geodesy and seismology general contributions

Resolution analysis for earthquake kinematics inversion* Josue Tago Pacheco 1) , Ludovic Metivier 2) 3) , Romain Brossier 2) , Victor Cruz Atienza 1) , Jean Virieux 2)
Universidad Nacional Autonoma de Mexico, CDMX, Mexico 1) , Institut des Sciences de la Terre, Grenoble,
France 2) , Laboratoire Jean Kuntzmann, Grenoble, France 3)
Until recently, little attention has been devoted to the assessment of the quality of the solution in mostgeophysical inverse problems. The clear difference between optimal solutions, obtained by different
proposed algorithms, has driven researchers interest to not just get a solution but to state its confidence init. For earthquake kinematics inversion, the uncertainty quantification has been very little explored.
However the research community has clearly pointed out that it is a main research topic because of thedifferent solutions obtained in some specific benchmarks (Mai et al. (2016)).
The purpose of an earthquake kinematics inversion is to get the slip-rate time-space history using theseismograms available. A simple way to evaluate its resolution length is to perform a checkerboard test.
However multiple tests must be done in order to identify the specific resolution length in different regionsof the solution. Fitchner and Van Leeuwn (2015) have proposed to use random probing techniques forresolution analysis. They have pointed out that the Hessian acts as a smoother of random functions whichcarry information of the resolution.
In this work we show how to perform a resolution analysis for earthquake kinematics inversion based onstochastic probing of the Hessian operator. The strategy is to compute the Hessian vector product of somerandom vectors, then perform the autocorrelations of the product vectors and finally average all the
autocorrelations to get the time and spatial resolution lengths. The Hessian vector product is done througha second-order adjoint strategy that allows to avoid the explicit Hessian computation.

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*J09-2-02
Joint Symposium / J09. Geodesy and seismology general contributions

Effect of frictional properties of minerals in the crust on the depth of seismic
faulting* Koji Masuda
Geological Survey of Japan, AIST, Tsukuba, Japan
Depth and width of seismogenic zones seem to result from the nature of the friction of materials which form
the crust. Frictional properties of materials, which depend on the environmental conditions such astemperature and water content, control the depth which divided between the stable region where
earthquakes don't occur and the unstable region where earthquakes take place. For example, laboratory
experiments revealed that a small amount of quartz added to the composite materials has a stabilizing
effect, resulting the unstable to stable behavior of the mixture materials. Here we measured frictional
properties of quartz and feldspar, major minerals of the crustal rocks, under high pressure and hightemperature conditions, in order to understand the effects of frictional properties of minerals in the cruston the depth range of seismogenic region. We found that there are temperature ranges correspond to theunstable regions for both quartz and feldspar under the wet condition and that the unstable temperature
region of quartz is narrower than that of feldspar. These results suggest that the frictional properties of
constituent materials in the crust critically affect the seismic faulting depth and the seismogenic processes.

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*J09-2-03
Joint Symposium / J09. Geodesy and seismology general contributions

Flexural mechanics and curvature evolution of the bending-unbendingtransition zone of subducting oceanic lithosphere* Ryohei Sasajima , Takeo Ito
Nagoya University, Nagoya, Japan
1. Introduction
Oceanic lithosphere is bended just before subduction, and is un-bended sooner or later after it subducts
from the trench. Many previous studies analyzed flexure of the oceanic lithosphere in outer rise from
topography and gravity anomalies for estimating the strength and rheology of the oceanic lithosphere [e.g.,
Goetze and Evans, 1979; Hunter and Watts, 2016]. The targets of their studies were limited to offshore fromthe trench, and flexural mechanics of subducting part of the oceanic lithosphere is poorly understood.
Thus, the purpose of this study is to clarify the flexural mechanics of the bending-unbending transition zoneof subducting oceanic lithosphere.
2. Method
This study expanded the flexural analysis to subducting part (up to 50 km depth) and estimated curvature
evolution of the oceanic lithosphere in the bending-unbending transition zone. The target is the Pacificplate subducting from the Japan Trench (120-130 Ma).
First, we estimated the bending moment evolution of the Pacific plate from topography and gravity
anomalies. Next, we conducted a numerical model of bending-unbending of the oceanic lithosphere inorder to investigate how the bending moment develops with curvature. Finally, we estimated the curvature
evolution of the bending-unbending transition zone of the Pacific slab by fitting modeled bending momentwith estimated it from topography and gravity anomalies.
3. Results
When unbending initiates after bending, residual bending stress is released elastically. Thus, only slightcurvature changing causes rapid bending moment changing. However, spatial changing of the bending
moment must be gradual to satisfy force equilibrium. Consequently, curvature changing in the bendingunbending transition zone must be much slow. This result will be useful to constrain maximum curvature of
subducting oceanic lithosphere for estimating e.g., bending energy dissipation.

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*J09-2-04
Joint Symposium / J09. Geodesy and seismology general contributions

Vertical Deformation Following Groundwater Drawdown by Excavating of
500 m Depth Shafts in Granite in Mizunami, central Japan in 2004-2016* Fumoako KIMATA , Tasuhiro ASAI , Ryo Honda , Hiroshi ISHII
Tono RI of Earthquake Science, Mizunami, 509-6132 Japan
Two investigation shafts of 500 m depth were excavating in the granite body in Mizunami, central Japan by
JAEA (Japan Nuclear Cycle Development Institute) in 2004-2012. Groundwater of 800 ton is generally
pumping a day to prevent the shafts from submerging now. As a result of pumping the groundwater, theground water level lowered to 80 m in the borehole with the distance of 200 m from the excavating shaftsin 2016.Leveling network extending 2 km x 2 km around the shafts was established to detect the verticaldeformation around the shafts in 2004, and precise leveling was done every year. An 18 mm groundsubsidence was detected in the benchmark close to the shafts for 8 years in 2004-2012, and time series ofsubsidence at benchmark was consistent with the groundwater drawdown. The groundwater drawdown andground subsidence were caused by the pumping ground water in excavating shafts.
In 2012, we extended the leveling network to a width of 4 x 5 km around the excavating shafts, and we had
precise leveling at the network every year since 2012 to 2016. As results, subsidence of 8 mm is detectedin the area in the southeastern are from the shafts side.
A depth distribution of granite in the area is estimated from aeromagnetic surveying. As results, twogroundwater veins are suggested in NW to SE and NNE to SSW. Beneath the shafts, groundwater is flowing
to southeast from northwest. A subsidence of 8 mm is detected along the groundwater, not only vicinity ofthe shafts. It is a good fruitful result to make clear the ground deformation by precise leveling.

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*J09-2-05
Joint Symposium / J09. Geodesy and seismology general contributions

ISC-EHB: Reconstructing the EHB Earthquake Database
Jennifer Weston 1) , * Bob Engdahl 2) , Domenico Di Giacomo 1) , James Harris 1) , Dmitry Storchak 1)
International Seismological Centre, Thatcham, UK 1) , University of Colorado, Boulder, USA 2)
The EHB database was originally developed with procedures described by Engdahl, Van der Hilst & Buland(1998), and it currently ends in 2008. It is a widely used seismological dataset, which we aim to expand
and recreate, partly by exploiting the updated procedures at the International Seismological Centre (ISC),
to produce the ISC-EHB. We begin with events in the modern period (2000-2014) and apply new and more
rigorous procedures for event selection, data preparation, processing, and relocation.
The ISC-EHB criteria selects seismic events from the ISC Bulletin which have more than 15 teleseismic (>28º) time defining stations, with a secondary teleseismic azimuth gap of < 180º, and a prime magnitude >3.75 (Di Giacomo & Storchak, 2016). These criteria minimize the location bias produced by 3D Earthstructure, and select many events that are relatively well located in any given region.
There are several processing steps; (1) EHB software relocates all the events using ISC starting depths; (2)Near station and secondary phase arrival residuals are reviewed and a depth is adopted or assigned
according to best fit, and in some instances depths may be reassigned based on other sources (e.g., USGS
broadband depths); (3) All events are relocated with their new depths and plotted in subduction zone crosssections, along with events from the ISC-GEM catalogue for comparison; (4) These plots are used toconfirm or modify weakly constrained depths.
The new ISC-EHB database will be useful for global seismicity studies and high-frequency global
tomographic inversions. This will be facilitated by online access to the ISC-EHB Catalogue and Bulletin via
the ISC, and will include maps and cross sections of the seismicity in subduction zones. Example maps andcross sections for events in years 2000-2003 will be presented.

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*J09-2-06
Joint Symposium / J09. Geodesy and seismology general contributions

The ISC Bulletin and the derivative datasets for Geoscience research* Dmitry Storchak , Domenico Di Giacomo , James Harris , Konstantinos Lentas , Jennifer Weston
International Seismological Centre (ISC), Thatcham, Berkshire, UK
The International Seismological Centre (ISC) produces the global definitive Bulletin of earthquakes andother seismic events based on reports from over 130 seismic networks worldwide. The ISC Bulletin
remains the most long-term and comprehensive source of information for global seismicity between 1904
and 2017. In addition to earthquake hypocentres and magnitudes, the historical period (before 1964) now
contains seismic arrival times at stations from the International Seismological Summaries (ISS) andmultitude of individual station bulletins digitized during the ISC-GEM project. The modern period(1964-onwards) is currently being updated, expanded and homogenized under the Bulletin Rebuild project.
To help users with different research needs/requirements, we also maintain and distribute several
derivative datasets:
The ISC-GEM catalogue – the most homogeneous and complete record of moderate to large instrumentally
recorded earthquakes over the last ~110 years; it was designed for use in global and regional assessment ofseismic hazard.
The ISC-EHB bulletin - a groomed subset of the ISC Bulletin containing well-recorded teleseismic eventswith particular attention given to depth determination; it is widely used in studies of seismicity andstructure of the Earth.
The IASPEI Reference Event List (GT) – a bulletin of events for which the hypocentral information is
known with high confidence (to 10km or better); it is used for a variety of calibration purposes, especiallyin nuclear monitoring studies.
The ISC Event Bibliography - an interactive facility that enables searches for references to scientific articles
devoted to individual natural and anthropogenic seismic events that occurred within a region and time
period of interest; it is widely used in education and by scientific article authors, reviewers and journal
editors.
We describe major advances recently made by the ISC to extend and improve these open-access datasetsthat are widely used in Geoscience research.

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*J09-3-01
Joint Symposium / J09. Geodesy and seismology general contributions

Temporal change in transfer function using ACROSS associated with magma
intrusive event in 2015 in Sakurajima volcano, Japan* Koshun Yamaoka 1) , Masashi Watanabe 1) , Hiroki Miyamachi 2) , Takahiro Kunitomo 1) , Toshiki Watanabe, Hiroshi Yakiwara 2) , Yuta Maeda 1) , Takeshi Tameguri 3) , Ryoya Ikuta 4) , Masato Iguchi 3)
Graduate School of Environmental Studies, Nagoya University, Chikusa, Nagoya, Japan. 1) , Graduate
School of Science and Engineering, Kagoshima University, Kagoshima, Japan. 2) , Sakurajima Volcano
Research Center , Kyoto University. Kagoshima, Japan. 3) , Faculty of Science, Shizuoka University,
Shizuoka, Japan. 4)
1)

We detected a temporal change in propagation property of seismic wave associated with a magma intrusive
event on 15 August 2015 of Sakurajima volcano, Japan. The propagation property, which is called transfer
function (Green's function), has been monitored continuously since 12 September 2012 using an
accurately-controlled seismic source (ACROSS) and seismic stations in Sakurajima volcano island. Thechange in the transfer function was calculated with 2-hour resolution. Large change is detected in theinitial stage of the intrusive event, when the rate of crustal deformation was maximum. The amount ofchange associated with the intrusive event shows a spatial variation, depending on the location of theseismic stations. We calculated cross covariance between the transfer functions before and after the event.
The cross covariances for the stations in the direction of summit crater from the ACROSS source show
larger reduction than those in the peripheral area even for the stations of comparable distance from the
ACROSS source. The stations that show large reduction of cross covariance also show phase advancetoward coda part, meaning velocity increase of the media. The amount of velocity increase is estimated to
be about 1%. This indicates that the velocity increase is caused by the stress increase due to the magma
intrusion. The stations in the peripheral area, which shows little reduction of cross covariance, also show
little velocity change even in the same direction from the intrusion source. This may result from spatial
variation of stress sensitivity of the medium in the volcanic body. The material in the central part of
Sakurajima volcano is more sensitive to stress probably due to less compaction of eruption material.

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*J09-3-02
Joint Symposium / J09. Geodesy and seismology general contributions

Secular and co-seismic velocity changes in Tokai region detected by
ACROSS* Shuhei Tsuji 1) , Ryoya Ikuta 2) , Koshun Yamaoka 1) , Takahiro Kunitomo 1) , Toshiki Watanabe 1) , Yasuhiro
Yoshida 3) , Akio Katsumata 4)
Nagoya University, Nagoya, Japan 1) , Shizuoka University, Shizuoka, Japan 2) , Meteorological College,
Kashiwa, Japan 3) , Meteorological Research Institute, Tokyo, Japan 4)
We detected secular and co-seismic travel time changes and their anisotropy using active seismic
measurement in the Tokai region, Japan. In this study, we used seismic signals generated by ACROSS,
which is a highly stabilized artificial seismic source, to measure propagation properties of seismic waves.
The high stability of ACROSS signal makes us possible to detect very small changes of physical properties
in the crust. The ACROSS signal is received by High sensitivity seismograph network Japan (Hi-net)
stations to calculate a transfer function from the ACROSS source to each Hi-net station in the Tokai region
during 2007 to 2014. The transfer functions show secular and annual change in the travel time of S-wave
throughout the observation period. A large co-seismic change is also observed at the time of the 2011
Tohoku-Oki Earthquake. Considering S/N ratio, we focused on the stations near the ACROSS source. We
found that the travel time was gradually advanced in the observation period and were suddenly delayed
associated with earthquakes, which caused strong motion in this area such as Tohoku-Oki earthquake. Due
to high S/N ratio at the nearest station, which is about 3 km from the ACROSS source, post-seismic travel
time change shows a gradual recovery just after the sudden delay at the time of the Tohoku-Oki Earthquakewith a time constant of one month. However travel time was not recovered to their original level. Next, weanalyzed polarization anisotropy of the travel time changes. At the almost stations, the advance rate of thesecular changes were the largest in NE-SW direction, and the co-seismic delay associated with the TohokuOki earthquake were also the largest in NE-SW direction. The two anisotropies are very similar in direction,
though the sense of travel time changes are opposite. We are trying to create a model that can explainthese anisotropies by comparing with crustal strain change measured by GNSS and other geophysicalobservations.

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*J09-3-03
Joint Symposium / J09. Geodesy and seismology general contributions

Tracking of water level of dam reservoir by using a broadband seismometer* Kazunari Nawa 1) , Takeshi Kimura 2)
AIST, Tsukuba, Japan 1) , NIED, Tsukuba, Japan 2)
We found distinctive incessant monochromatic oscillations with a frequency around 10 mHz by analyzing
STS-2 broadband seismometer data of the F-net IGK station at Ishigakijima, Okinawa, Japan. The possible
origin of oscillation is seiche (water level oscillation) of dam reservoir in the vicinity of the seismic station.
We show the frequency variations of the mode for five years (2012-2016) based on STS-2 seismograms.
Observed frequency variations are in good agreement with water level change of dam reservoir compiled
from dam observation daily reports. And we discuss implications for long-term monitoring hydrologicalcondition and/or the state of the seismometer system.

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*J09-3-04
Joint Symposium / J09. Geodesy and seismology general contributions

About 38mHz (26 s) oscillation in northeastern Japan after the 2011 Tohoku
megathrust earthquake* Yuta Mitsui 1) , Kosuke Heki 2)
Shizuoka University, Shizuoka, Japan 1) , Hokkaido University, Sapporo, Japan 2)
By stacking high-rate GNSS data at north-eastern Japan, we find a peaky signal with frequency of about 38
mHz (26 s) following the 2011 Tohoku earthquake in the horizontal-to-vertical (H/V) spectral ratio. The
signal appeared several minutes after the passing of surface wave fronts, and its duration was about 2 min.
Since the frequency of 38 mHz was almost equal to the world-wide microseism (Oliver, 1962; Shapiro et al.,2006), we speculate that some features of the Earth's structure contributed the characteristic oscillation.

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*J09-3-05
Joint Symposium / J09. Geodesy and seismology general contributions

Different Application of Ultrasonic Underwater Particle-Tracing Probes at
Deep Ocean Floor* Dursun Acar 1) 2) , Bedri Alpar 1) , Tuncay Taymaz 3) , Seda Yolsal Cevikbilen 3) , Sinan Ozeren 4) , Denizhan
Vardar 1) , Tuna Eken 3) , Namik Cagatay 2) 6) , Sebnem Elbek 5) , Erol Sari 1) , K.Kadir Eris 2) 6)
Istanbul University, Institute of Marine Sciences and Management 1) , Istanbul Technical university EMCOL
2), Istanbul Technical University Faculty of Mines Department of Geophysical Engineering 3) , Istanbul
Technical University Eurasia Institute of Earth Sciences 4) , Canakkale Onsekiz Mart University, Canakkale,
Turkey 5) , Istanbul Technical University Faculty of Mines Department of Geological Engineering 6)
Vertical or horizontal dislocations of the oceanic crust can provide some slow current changes at deep
seafloor as an auxiliary pre-indicator of tsunami or earthquake.
The use of different forms of piezoelectric probes is an advanced method when performing particle motion
and dimension analysis. Array based probes, for example, can measure density and velocity withdirectional item for suspended or drifting materials on the seabed. Their working capabilities are rather
high, due to crystals' efficient trigger force at high pressure. Advantage of P-wave is observing ability to"sequentially hidden (or masked) particles" moving at the background. This is impossible for other methods
based on such as light diffraction, conductivity or magnetic field sensing, under the presence of mass
shadow effect. In fact, linear, differentiated linear, circular, spherical, concave shaped array forms are all
possible in practice. The future design of spherical and "digitally driven and displaceable point sourceprobes" may take time. The computer-controlled surface area of a displaceable point source can be devisedfor any given desired field scale. Suitable software can create artificially 'relatively portable and formed
source field areas' from the transducer surface. Using three linear probes which would be along the main
dimensional axes (magnetic north considered x,y,z) will consume three times higher energy than a single
probe with separated sections on three axes; as it needs three interpreter circuits.
The scanning velocities of the probes have variability depending on the gaps between their piezoelectric
crystals. In addition, sensor station's 'positioner flaps' cannot be efficient at low-velocity deep-currents
because bio-foliation and corrosion decreases life time for accurate measuring of device by some friction
problems on mechanical devices (positioner rudders). Spherical probes will particularly be the best particle
observers with their non mechanised settings.

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*J09-4-01
Joint Symposium / J09. Geodesy and seismology general contributions

CURRENT IMPORTANCE OF THE CHILEAN NATIONAL GEODESICNETWORK IN A COUNTRY SUBJECT TO EARTHQUAKES.
Cristian Iturriaga , Hector Parra , * Carlos Prado
Instituto Geografico Militar de Chile, Santiago, Chile
The Military Geographic Institute of Chile (IGM) is the Official Organization responsible for maintaining the
National Geodesic Network (RGN) and participates in the Geocentric Reference System for the Americas(SIRGAS). At the IGM, the “SIRGAS-Chile Data Processing and Analysis Centre" manages the geodesic
networks that constitute the horizontal and vertical reference systems and the permanent GNSS stations.
The IGM, together with the National Seismological Centre (CSN), has integrated the RGN with the National
Seismological Network (RSN), setting up a single geodesic network, processed and analyzed by the IGM toserve in supporting the geo-referencing of geoscience-related tasks being performed in this country. This
geodesic infrastructure has been affected by a series of earthquakes derived from the dynamics of plate
tectonics in Chile, among them: 2010, south-central Chile, 8.8 Mw; 2014 far northern Chile, 8.2 Mw; 2015,
central-northern Chile, 8.4 Mw; and 2016, Chiloe Island (southern Chile), 7.6 Mw.
The IGM, together with Chilean and international organizations, scientifically studies and analyzes thedeformation of the tectonic plates over its various phases, using data from the network of permanent GNSS
stations to calculate the Co-seismic and Post-seismic displacements, determining changes to thecoordinates during earthquakes and the drift of the plates over the periods following the seismic
movement. These differences are portrayed by means of vectors to scale, that indicate magnitude anddirection of the deformation. Thus shifts are detected that range from centimeters to meters, affecting theaccuracy of the SIRGAS-Chile Reference Framework, so it has been necessary to calculate coordinates
referenced to the 2002.0, 2010.0, 2013.0 and 2016.0 epochs, which makes it possible to guarantee that thecoordinates given to users are as accurate as possible.

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*J09-4-02
Joint Symposium / J09. Geodesy and seismology general contributions

Estimation of coupling ratio on subducting plate interface and blockboundary in southwest Japan using MCMC method.
* Hiroshi Kimura , Takeo Ito , Keiichi Tadokoro
Nagoya University, Nagoya, Japan
Introduction
In southwest Japan, the Philippine sea plate is subducting under the overriding plate, such as Amurian
plate. The last interplate earthquakes occurred along the Nankai trough at 1944 and 1946. The recurrence
interval is guessed around 90-200 years from historical earthquake. Although, it already passed over 70
years, the event did not occur yet. So, it is important to evaluate earthquake potentials for preparing hugedamage due to large earthquake in near future.
In last decade, seafloor geodetic observation revealed detailed interplate coupling distribution in expectedsource region of Nankai trough earthquake (e.g., Yokota et al., 2016). In this study, we try to make the new
block motion model based on 24 seafloor geodetic observation along the Nankai trough and 609 inland
GNSS sites in southwest Japan.
Crustal block motion model
We developed crustal block motion model, including elastic plate coupling and crustal block relative
motion [Kimura et al., 2017 (JpGU-AGU Joint Meeting 2017)]. At first, we make several crustal block rigid
motion models, based on geological information, such as surface trace of active fault. In typically, theseblock motion models are too fine, because geodetic data does not have resolution for fine model based on
geological information. We try to select the optimal crustal block motion model using Akaike's information
criteria. After this model selection, we set the more detail of configuration, such as plate interface. In thisstudy, we employ the algorithm for optimized number of subfaults along plate interface [Kimura et al., 2016
(126th Meeting of the Geodetic Society of Japan)].
ResultWe will present the result and discussion for crustal block motions and the interplate coupling distributions
in southwest Japan. Especially we focus on the defference in derived interplate coupling distribution along
the Nankai trough due to the effect of coupling along Median Tectonic Line and Izu Micro Plate motion.

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*J09-4-03
Joint Symposium / J09. Geodesy and seismology general contributions

EPOS-Norway - GNSS and seismological data from Norway in a common einfrastucture* Jan Michalek 1) , Kuvvet Atakan 1) , Xiaoliang Wang 1) , Christian Ronnevik 1) , Tormod Kvaerna 4) , Michael
Roth 4) , Halfdan Pascal Kierulf 2) , Tor Langeland 3) , Ove Daae Lampe 3)
University of Bergen, Norway 1) , Norwegian Mapping Authority, Oslo, Norway 2) , Christian Michelsen
Research, Bergen, Norway 3) , NORSAR, Kjeller, Norway 4)
The European Plate Observing System (EPOS) is a European project about building a pan-European
infrastructure for accessing solid Earth science data. The EPOS-Norway project (EPOS-N) is a Norwegian
project funded by National Research Council and is closely linked to the European EPOS project. The aimsof EPOS-N project are divided into three work packages where the first one is about integrating Norwegiangeoscientific data into an e-infrastructure (web portal).
There are 2 institutions in Norway providing seismological data – University of Bergen (UIB) and NORSAR,
and one institution providing GNSS data - Norwegian Mapping Authority (NMA). In thepresentation/poster we present the integration of the two data types into a single e-infrastructure. The firststep is to standardize access to both data types and bring them into one system. The second step is todevelop tools for visualization and analysis of the two different data types allowing efficient comparison ofthem. The EPOS-Norway project started in January 2016 and we are presenting mainly the effort we madetowards the integration and ideas we want to make alive during the project.

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*J09-4-04
Joint Symposium / J09. Geodesy and seismology general contributions

Expanding seismic surface waves measurements towards low periods withgravity measurements* Przemyslaw Dykowski 1) , Marek Grad 2) , Andrzej Krankowski 4) , Jan Krynski 1) , Tomasz Olszak 3) , Marcin
Polkowski 2) , Marcin Rajner 3) , Marcin Sekowski 1) , Monika Wilde-Piorko 2)
Instutute of Geodesy and Cartography, Warsaw, Poland 1) , Faculty of Physics, University of Warsaw,
Warsaw, Poland 2) , Faculty of Geodesy and Cartography, Warsaw University of Technology, Warsaw,
Poland 3) , Faculty of Geodesy, Geospatial and Civil Engineering, University of Warmia and Mazury, Olsztyn,
Poland 4)
Seismic and gravity measurements are usually considered as separate scientific problems, although bothare related to the same object – the Earth. Seismometers do not measure gravity field change and seismic
events in gravity measurements are considered as disturbances and are usually removed from the records.
The nature of tidal gravity measurements, especially superconductive gravimeters records, allows
determining very long periods of seismic surface waves. Variety of broadband seismometers allow
measuring surface waves up to period of 120-150 seconds, while superconducting gravimeters record
surface waves up to 400-500 seconds. This is of great importance for structure studies, because waves of
longer periods make possible studying deeper structures of the Earth.
In this presentation, it has been shown how simultaneous seismic and gravity records at the same locations
allow studying very long period surface waves. For test purposes 4 seismometer-gravimeter pairs have been
deployed in Poland. These configurations are placed at three locations, Borowa Gora Geodetic-GeophysicalObservatory (BG), Jozefoslaw Astronomical-Geodetic Observatory (JOZE), and Lamkowko Satellite
Observatory (LAMK). Three seismometers are paired with two types of LaCoste&Romberg spring
gravimeters (ET and model G) at all those Observatories. Additionally one seismometer is co-located on thesame pillar with the iGrav-027 superconducting gravimeter at BG location. During the test period from
December 2016 to January 2017 several large teleseismic events were observed with well-formed surface
waves. Together with expected next events they should give dispersion curves for long surface waves, aswell as periods of free oscillations. The correlation of a broadband seismometer signal with different typesof gravimetric sensors gives a possibility to analyze gravimeter noise components, in the instrumental andmicroseismic domains.

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*J09-4-06
Joint Symposium / J09. Geodesy and seismology general contributions

Sampling Frequency – the key to capturing anomalies of groundwater before
earthquakes* Fuqiong HUANG 1) 1) 1) , Youliang SHU 2) 2) 2) , Shimin ZHANG 3) 3) 3)
China Earthquake Networks Center, CEA, Beijing China 1) , Shanxi Provincial Earthquake Administration,
Xi'an Shanxi, China 2) , Zhouzhi Observation station of Shanxi Provincial Earthquake Sdministration,
Zhouzhi County Shanxi, China 3)
It is well-known that Geosciences are strongly observation-dependent. The discoveries in Geosciences alsostrongly rely on the development of observation techniques. Whether earthquakes can be predicted or nothas been debated in several decade years, due to limited instrument recorded data aiming at precursor
extraction and earthquake cycle analysis, etc. in this situation it is very important to collect observation
data for precursors in widely approaches. Since 1966 Xingtai earthquake occurred in China, theobservation strategy of capturing earthquake precursor for the aim of prediction has been lasted more than
40 years. Even though the precursor is debated worldwide, a complex monitoring network has been built
and improved step-by-step in station configuration as well as in techniques both in instrumentation andsampling frequency, a large amount of pre-seismic anomalies have been published in a series of cases in
China by seismological Press in Beijing. Here we reviewed the observation progress in sampling frequencyof groundwater and its effect on the understanding process of groundwater precursors from the early stageof continuous analog recording systems to the present stage of once per minute sampling frequency ofdigital techniques. Through comparing the anomaly process of once per minute sampling frequency datawith 50Hz sampling frequency experiment observation data in Zhouzhi well before the 2008 Wenchuan
earthquake, we declaimed that the presently designed once per minute sampling frequency digitalobservation techniques is not enough for capturing the earthquake precursors exactly. A systematicallysampling frequency technique for future digital monitoring networks of groundwater level aiming at
earthquake prediction is designed and proposed based on the above research.
This research is supported by National Natural Science Foundation projects with contract numbers of
41274061, 40674024 and 40374019.

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*J09-5-01
Joint Symposium / J09. Geodesy and seismology general contributions

A prototype system for PPP kinematic positioning of Japanese GEONET
stations* Hiroshi Munekane
Geospatial Information Authority of Japan, Tsukuba, Japan
Kinematic GNSS time series have high time resolution (typically 1~30 sec) and useful when one would liketo 1) discern crustal deformations caused by successive earthquakes, and 2) detect ongoing rapid crustal
deformation associated with intensive volcanic activities, to name a few. Here we developed a prototype
system for kinematic positioning of Japanese GEONET stations by the precise point positioning method.
This prototype is designed to generate three types of solutions, namely, ultra-rapid, rapid and final solutions
depending of their latencies. Each solution will be generated 6~12 hours, 2 days and 2 weeks after dataacquisition, respectively. All solutions have time resolution of 30 seconds. We evaluated the precision of
the solutions in terms of coordinate repeatability and found that that of the horizontal components istypically under 1 cm for every solutions. With the solutions we may expect to etect crustal deformations
caused by an earthquake at a precision of ~5 mm. We also demonstrate that these solutions are useful inmonitoring long-term (~ 1year) crustal deformations. Hence we may use these solutions to model
sequential short- and long-term events like an earthquake and following postseismic deformation
simultaneously.

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*J09-5-02
Joint Symposium / J09. Geodesy and seismology general contributions

Detection and Measurement of Land Subsidence Using InSAR and GPS in
the Sabana de Bogota, Colombia, South America* Hector Mora-Paez 1) , Takeshi Sagiya 2) , Takeo Ito 2) , Estelle Chaussard 3) , Shimon Wdowinski 4)
Colombian Geological Survey, Space Geodesy Research Group, Bogota, Colombia 1) , University of Nagoya,Japan 2) , University at Buffalo, USA 3) , Florida International University, USA 4)
The Sabana de Bogota is located in the Eastern Cordillera of Colombia, and represents a tectonicsedimentary basin consolidated after the final upheaval of the Northern Andes, around 5 Ma, (van derHammen et al, 1973; Wigninga, 1996). Inside the Sabana de Bogota is located Bogota, the capital city of
the country, with approximately 8 million inhabitants. Since land subsidence is a major human-induced
geological hazard that affects buildings and urban infrastructure and results in severe economicalconsequences for both individuals and local government administrations, it is important to estimate thesubsidence in the Sabana de Bogota plain using both InSAR and GPS techniques. Analysis of ALOS dataacquired during 2008-2011, TERRASAR-X acquired during 2013-2015 and SENTINEL-1 acquired during
2014-2016 shows a distributed subsidence pattern, both in urban areas and agricultural areas outside
Bogota city. The observed subsidence occurs most likely due to groundwater withdrawal from the local
aquifer. A reprocessed height time series of GPS stations indicates that the International GNSS Services
BOGT station shows a linear height trend of -44.2 ± 0.2 mm/yr (Rudenko et al., 2013). Since there was only
one GPS station in the Sabana de Bogota area, (BOGT), the Colombian Geological Survey (through theSpace Geodesy Research Group) installed a continuous GPS station at the El Rosal site (VROS) and built
some field stations. These new sites will enable increased comparison between InSAR and GPS
observations. In addition, under an agreement between the Colombian Geological Survey and the Bogota
Land Cadastre Administrative Office, a network of GNSS stations has been deployed. InSAR shows
subsidence up to 6-7 cm/yr while GPS stations show subsidence up to 4-5 cm/yr. We plan to continue
monitoring the subsidence using GNSS and InSAR techniques and collecting water well data for analysis,in order to provide our finding to both local authorities and the public.

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*J09-5-03
Joint Symposium / J09. Geodesy and seismology general contributions

Surface deformation of a mud volcano in Azerbaidzhan detected by InSAR
and its source medeling* Kento Iio , Masato Furuya
Hokkaido University, Hokkaido, Japan
Mud volcanoes are observed at some specific areas in the world. Mud volcano brings fluids, gasses andmaterials originated at a depth of several km. Understanding the dynamics of mud volcano is important interms of a point of carbon circulation from Earth's depth to surface, its impact on greenhouse warming,
disaster and so on. Mud volcano has been studied by various approaches such as geophysical exploration,
structural geology, geochemical approach and so on, but geodetic observation has not been widely used.
The purpose of this study is to detect surface deformation of a mud volcano in Azerbaizhan by L-band
InSAR and to estimate its source modeling.
Azerbaidzhan, located on the western edge of the Caspian Sea in Central Asia, is one of the most abundant
countries in term of the population of mud volcanoes over the land. We used the SAR images derived fromtwo L-band satellites, ALOS/PALSAR and ALOS-2/PALSAR-2, launched by JAXA in 2006 and 2014
respectively. We focused on a large and unique, Ayaz-Akhtarma mud volcano. Benedetta et al. (2014) also
detected the ground deformation of this mud volcano, using ENVISAT/ASAR C-band SAR data, spanningfrom 2003 to 2005, only along descending path; InSAR observes the surface from nearly the north to thesouth in a slant direction along this path. Although the ground displacement at the mud volcano was 20 cm
in Line of Sight (LOS) for the two years, subsequent displacements were not clear. However, the results ofour study, using ALOS data from ascending path that is opposite look direction from the previous study and
ALOS-2 data for ascending and descending paths, indicated more active and larger horizontal
displacements. The cumulative LOS displacement is up to nearly 300 cm for five years by ALOS and 100
cm for two years by ALOS-2. Thus we performed the source modeling to explain the displacement,
assuming an elastic half-space. The modeling showed this deformation consists of normal slip and tensile
opening components.

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*J09-5-04
Joint Symposium / J09. Geodesy and seismology general contributions

Crustal deformation and a fault model of the 2016 central Tottori prefectureearthquake* Hiroshi Yarai , Tomokazu Kobayashi , Yu Morishita , Yohei Hiyama , Yuji Miura
Geospatial Information Authority of JapanThe Mj 6.6 inland earthquake occured on Oct. 21th, 2016 in the central Tottori prefecture, western Japan.
Coseismic deformation derived from the earthquake was observed by GNSS and ALOS-2/PALSAR-2
interferometric SAR.
Continuous GNSS observation network (GEONET) is deployed in all over Japan with an average placement
interval of approximately 20 km. The displacement field detected by GEONET exhibits NW-SE shortening
and NE-SW lengthening around focal area, which is consistent with the focal mechanism of the earthquake.
But it remains difficult to obtain detailed displacement field near focal area.
For capturing coseismic deformation of the earthquake, ALOS-2 conducted SAR observations from four
different directions, ascending/descending and right-/left-looking. We succeeded in mapping threedimensional (3-D) displacement using those InSAR data. The 3-D displacement filed shows left lateralmotion along a NNW-SSE strike fault clearly.
We inverted the GNSS and InSAR data to construct a slip distribution model. Our model shows almost purestrike slip motion on NNW-SSE strike fault plane. The slip distribution model shows a maximum coseismic
slip of more than 1 m at a depth of around 5 km, shallower than the epicenter. The estimated seismic
moment is 2.64 x 1018 Nm (Mw6.21) from the slip distribution model.
Acknowledgements.
The PALSAR-2 data obtained by the ALOS-2 were provided by the Japan Aerospace Exploration Agency(JAXA) through the Agreement between GSI and JAXA. The ownership of PALSAR-2 data belongs to JAXA.

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*J09-5-05
Joint Symposium / J09. Geodesy and seismology general contributions

Two methods of three-dimensional surface deformation field derivation with
the integration of InSAR and GNSS measurements
Haipeng Luo , * Ting Chen
School of Geodesy&Geomatics, Wuhan University,Wuhan,China
Geodetic measurements play an important role in monitoring crustal deformation. Interferometric synthetic
aperture radar (InSAR) measurements provide high-resolution surface deformation in satellite's Line ofsight direction; whereas Global Positioning System (GPS) measurements record high-precision threedimensional surface deformation at discrete stations. These two types of measurements could be integrated
to monitor crustal deformation. Here we present two methods to derive three-dimensional surface
displacement field from the integration of InSAR and GPS measurements: (1) ABIC method: a unified
framework based on Akaike's Bayesian Information Criterion; and (2) ESISTEM method: an extended
SISTEM(Simultaneous and Integrated Strain Tensor Estimation From Geodetic and Satellite Deformation
Measurements) method. The former considers smoothness among surface deformation at neighboring
pixels and there is no need to interpolate GNSS measurement into the same spatial resolution as InSAR
measurements, which is commonly used in previous studies, avoiding the interpolation error. The latter isbased on another strategy, named SISTEM method. In SISTEM method, only surrounding GPS
measurements are used as constraints based on elastic theory; while in ESISTEM method, we extend theconstraints by using both surrounding GPS and InSAR measurements.
We apply the ABIC and the ESISTEM methods into the derivation of three-dimensional surface
deformation field associated with the 2008 Wenchuan earthquake and the 2015 Gorkha, Nepal earthquake,
respectively.

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*J09-5-06
Joint Symposium / J09. Geodesy and seismology general contributions

Using TerraSAR-X Interferometry and GPS to study slowly moving landslidein a vegetated terrain
Sara Mirzaee 2) , Mahdi Motagh 1) , Bahman Akbari 2) , * Mahmud Haghshenas Haghighi 1) , Sigrid Roessner, Hans.Ulrich Wetzel 1)
GFZ German Research Center for Geosciences 1) , Forest, Range and Watershed Management of Iran 2)
1)

Landslide is a type of erosion processes that occurs mostly in mountainous areas, and can threaten life andcause significant damage to properties. In this regard, proper monitoring of mass movement activities using
multitemporal remote sensing imagery is a crucial task for landslide hazard assessment.
As one of the most ancient and tourist cities in northern Iran, Masouleh is located in a high mountainous
region. 40 percent of the whole sub-basin consists of unstable areas and mass movement appears in
different forms of falls, creep and flows. In this paper we have used SqueeSAR technique using a dataset of
33 TerraSAR-X spotlight images covering a period of 18 months between June 2015 and December 2016
to investigate the kinematic of Masouleh landslide. Among different persistent scatterer interferometry
techniques for deformation analysis, SqueeSAR works more efficiently in non-urban areas, which are prone
to have more distributed scatterers. In addition, interferometric measurements are compared withobservations from 21 GPS stations, which were collected in 3 epochs within 8 months from November
2015 to July. The maximum slope displacement velocity detected by SqueeSAR analysis is about 75
millimeters per year. InSAR loses coherence in fast moving areas which have moved about 39 cm
according to GPS observations. In general, both GPS and InSAR showed similar pattern and direction of
movement in the sliding slope.

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*J09-6-02
Joint Symposium / J09. Geodesy and seismology general contributions

Geodetic and Seismological Risk of Operation of Nuclear Power Plants inJapan* Shuzo Takemoto
Kyoto University, Kyoto, JapanThe national project of earthquake prediction started on 1965 in Japan. Most prospective approach forshort term predictions was considered to be continuous monitoring of crustal deformations. This idea wasbased on observational results of Sassa and Nishimura (Kyoto University). They first reported thatanomalous tilt change with the order of 0.1" was observed at the Ikuno mine located 60km away from theepicenter of the 1943 Tottori eq. of M7.2. Since then, reliable anomalous tilt or strain changes were notreported. Destructive earthquake of M7.3 occurred around Kobe city on 17 January 1995. Using a precise
laser strainmeter, we had been carried out strain measurement at the Rokko-Takao station in Kobe. The
station was existing just above the fault plane of the earthquake. We could not find any anomalous strainchanges before the earthquake. This fact indicates that precise observations using tiltmeters andstrainmeters are not effective tools for short term predictions of earthquakes. It is abnormal worldwide that
more than 50 nuclear power plant units were installed in Japan. The Fukushima 1st nuclear plant sufferedcatastrophic damage due to the 2011 off the Pacific coast of Tohoku Eq. (Mw9.0). It is estimated that about
1% of total radioactive substances were released into the atmosphere during one week from March 11,
2011, and 99% of radioactive substances are remaining in the vessels of reactors as the form of nuclear fueldebris. In near future, we must consider the possibility of the outbreak of the earthquake that Fukushima
will be shaken by strength of seismic intensity of 7 or 6. We must consider the Geodetic and Seismological
Risk of Operation of Nuclear Power Plants, not only the Fukushima 1st Nuclear Power Station but also all
Nuclear Power Stations in Japan.

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*J09-6-04
Joint Symposium / J09. Geodesy and seismology general contributions

Gorkha, Nepal Earthquake 2015 – Causes, Consequences, Socio- Economic
Impacts, Lessons Learned and Way Forward* Meen Bahadur Poudyal Chhetri
Tribhuvan University, Institute of Crisis Management Studies, Kathmandu, Nepal
Nepal is prone to various types of disasters such as: earthquakes, floods, landslides, fires, epidemics,
avalanches, windstorms, hailstorms, lightning, glacier lake outburst floods, droughts and extreme weather
events. Among all these disasters – earthquake is the most scary and damaging. The effects of a disaster,whether natural or human induced, are often far reaching. In addition to the natural factors, the losses fromdisasters are increasing due to the human activities and absence of proactive legislation. Fundamentally,
the weak structures have been found as the major cause of infrastructure collapse in earthquakes. Thisemphasizes the need for strict compliance of town planning bye-laws and earthquake resistant building
codes. Thus, proactive disaster management legislation focusing on disaster preparedness is necessary.
This paper analyses the critical gaps responsible for emphasizing the seismic risk and of factors that would
contribute towards seismic risk reduction to enable various stakeholders to address the critical areas for
improving seismic safety in Nepal and other earthquake prone countries. Additionally, this paper aims to
pinpoint the deficiencies in disaster management system in Nepal with reference to the devastating
earthquake of 25 April 2015 and suggest appropriate policy and advanced technical measures.

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*J09-P-01
Joint Symposium / J09. Geodesy and seismology general contributions

InSAR analysis all over Japan by ALOS-2 (Daichi-2) / PALSAR-2 data
Yuji Miura , Basara Miyahara , Hiroyuki Nakai , Masaki Honda , * Yasuaki Kakiage , Yu Morishita
Geospatial Information Authority of Japan (GSI), Tsukuba, JapanSAR interferometry (InSAR) is a powerful and unique remote sensing technique for detecting andmonitoring ground surface deformation with high spatial resolution without any ground based observation
infrastructures.
The Geospatial Information Authority of Japan (GSI) has conducted to monitor ground surface deformationof earthquakes, volcanic activities, subsidence and landslides throughout Japan by InSAR analysis using
ALOS-2 data. With images obtained from InSAR analysis (hereinafter referred to as “SAR interferograms"),
we have detected a lot of ground surface deformations caused by earthquakes and volcanic activities,
subsidence derived from overuse of ground water, seasonal uplift and subsidence in snow zones caused bysnow melting, subsidence in landfills and phase variations assumed to be caused by slope deformation.
SAR interferograms are formatted into tile data and can be browsed on a web map of GSI, "GSI Maps". GSIMaps enables us to superimpose SAR interferograms on various geospatial information provided by GSI
such as topographic maps, aerial photographs, volcanic land condition maps and so on. This visualization
enables us to easily compare SAR interferograms to other information like topography and geology andmore robustly identify an area of ground surface deformations on the SAR interferograms.
We report SAR interferograms of ALOS-2, which are routinely covering all over Japan, and also challenges
on InSAR analysis and system in the paper.

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*J09-P-02
Joint Symposium / J09. Geodesy and seismology general contributions

EPOS-Norway – Integration of Norwegian geoscientific data into a common
e-infrastructure* Jan Michalek 1) , Kuvvet Atakan 1) , Xiaoliang Wang 1) , Christian Ronnevik 1) , Karen Tellefsen 1) , Tor
Langeland 2) , Ove Daae Lampe 2)
University of Bergen, Bergen, Norway 1) , Christian Michelsen Research, Bergen, Norway 2)
The European Plate Observing System (EPOS) is a European project about building a pan-European
infrastructure for accessing solid Earth science data. The EPOS-Norway project (EPOS-N) is a Norwegian
project funded by National Research Council and is closely linked to the European EPOS project. The aimsof EPOS-N project are divided into three work packages where the first one is about integrating Norwegiangeoscientific data into an e-infrastructure (web portal). The other two work packages are about improving
the geoscientific monitoring in the Arctic and about creating a Solid Earth Science Forum to communicate
the progress within the geoscientific community and also providing feedback to the development group of
the e-infrastructure. There are 5 institutions in Norway actively participating and providing data in the
EPOS-N project – University of Bergen (UIB), University of Oslo (UIO), National Mapping Authority (NMA),
Geological Survey of Norway (NGU) and NORSAR. The data which are about to be integrated are divided
into categories – seismology, geodesy, geological maps and geophysical data. Before the data will be
integrated into the e-infrastructure their formats need to follow the international standards which werealready developed by the communities of geoscientists. Also, description of the data, i.e. metadata, needs to
be clarified and recognized within the CERIF database system. For now, there are 33 Data, Data Products,
Software and Services (DDSS) described in EPOS-N list. In the poster we present the Norwegian approachto the integration of the geoscientific data into the e-infrastructure, closely following the European EPOS
project development. The partner in the project - Christian Michelsen Research (CMR) is specialized invisualizations of data and developing of an interactive web portal allowing to users making workflows(using Jupyter Notebook). One of the main challenges is to integrate the various data and bring them to asingle environment.

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*J09-P-03
Joint Symposium / J09. Geodesy and seismology general contributions

Comparison of Superconducting and Spring Gravimeters at the Mizusawa
VLBI Observatory of the National Astronomical Observatory of Japan* Satoshi Miura 1) , Tae-Hee Kim 1) , Hiroshi Ikeda 2) , Yoshiaki Tamura 3)
Tohoku University, Sendai, Japan 1) , Tsukuba University, Tsukuba, Japan 2) , National Astronomical
Observatory, Mizusawa, Japan 3)
Continuous microgravity monitoring is utilized to gain new insights into changes in the subsurface
distribution of magma and/or fluid that commonly occur beneath active volcanoes. Rather new
superconducting and spring gravimeters, iGrav#003 and gPhone#136 are collocated with asuperconducting gravimeter, TT#70 at the Mizusawa VLBI Observatory of the National Astronomical
Observatory of Japan, since the end of September, 2016 in order to evaluate those performances before
field deployment planned in 2017.
Calibration of iGrav#003 was carried out by collocation with an absolute gravimeter FG5 of the Earthquake
Research Institute, University of Tokyo (Okubo, 2016, personal comm.) at a Fundamental Gravity Station in
Sendai in July, 2016. Based on the scale factors of iGrav#003 obtained by the calibration and of
gPhone#136 provided by the manufacturer (Micro-g LaCoste, Inc.), tidal analyses are performed by meansof BAYTAP-G (Tamura et al., 1991, GJI). Amplitudes and phases of each major tidal constituent mutuallyagree well within ±4 % and ±3 degrees, respectively.
The instrumental drift rate of iGrav#003 is very low, about 5 micro-Gal/month, whereas that ofgPhone#136 is very high, about 500 micro-Gal/month. The high drift rate of gPhone#136, however, is wellapproximated by a quadratic function at present and can be removed. The detrended time series ofgPhone#136 shows good agreement with iGrav#003 time series in the overall feature: gravity fluctuations
with amplitudes of about a few micro-Gal and with durations of a few days, which may be due to variationsin the moisture content of the topmost unsaturated sedimentary layer and the water table height. It
suggests that both instruments may capture volcanic signals associated with pressure changes in magma
chambers, dike intrusion/withdrawing, and so on.

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*J09-P-04
Joint Symposium / J09. Geodesy and seismology general contributions

Exponential pore pressure/groundwater level changes associated with the2016 Kumamoto Earthquake (Mj7.3) observed at Tono region, central Japan* Yasuhiro Asai , Hiroshi Ishii , Osamu Murakami
Tono Research Institute of Earthquake Science, Association for the Development of Earthquake Prediction
Clear exponential pore pressure/groundwater level changes associated with the 2016 Kumamoto
Earthquake (Mj7.3) were observed at borehole observation sites “STG200 and STG200N" in Mizunami
Underground Research Laboratory (MIU), and TGR350 borehole observation site located approximately
500m south of MIU, in the Tono region, central Japan (Hypocentral Distances are approximately 665km).
These observation sites are located approximately 3 km southeast of 16 closely clustered well where wereobserved co-seismic groundwater level/pressure changes (King et al, 1999; JGR).
Amount of pore pressure changes in STG200 and STG200N are 30 and 28 kPa-rise, respectively, andgroundwater level in TGR350 is 2.3m-rise. At the STG200N site, continuous in-situ stress recorded by theborehole stress meter (Ishii and Asai, 2013; EPS). In order to recognize the relationship between the coseismic pore pressure changes and the seismic waves, we compared the 20 Hz sampling pore pressure andstress records before and after the occurrence of 2016 Kumamoto Earthquake (Mj7.3). As the result, porepressures begin to increase just after the maximum amplitude of seismic waves (dynamic stress variations)passed through our site.
We will present the details of these pore pressure/groundwater level changes, and attempt to clarify thequalitative/quantitative model for the co-seismic pore pressure/groundwater level changes.

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*J09-P-05
Joint Symposium / J09. Geodesy and seismology general contributions

A possible mechanism of Omori-Utsu'slawthroughan example of the greatTangshan earthquake
Caibo Hu 1) , * Yongen Cai 2)
University of Chinese academy of Sciences, Beijing, China 1) , Peking University, Beijing, China 2)
We propose a conceptual model of earthquake source body with Kelvin viscoelastic property to investigate
the physical mechanism of Omori-Utsu's law. Supposing that tectonic stress field after main shock does notchange with time and equivalent viscosity in the aftershock region is much lower than that of its outside in
the period of total aftershock activity. This model can simulate aftershock sequence induced by postseismic creep and stress readjustment, and the whole process including creep stopping, materials
recovering to its elastic state, and faulting turning to stick state for next earthquake. Finite element method
is used to calculate stress field evolution caused by a main shock and its aftershocks in the model withheterogeneous material properties. Furthermore, the model and the method is used to simulate decay of
the aftershock frequency of the 1976 Tangshan MS7.8 earthquake. The results show that the mechanism of
Omori-Utsu's law may be attributed to the stress changes caused by the creep of the fault and earthquake
source body, which implies that aftershock frequency depends on the creep rate and decay time of theaftershocks is controlled by the equivalent viscosity. The lager the viscosity is, the longer the creep time or
the aftershocks last.

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*J09-P-06
Joint Symposium / J09. Geodesy and seismology general contributions

Updating Hypocenter Location around Indonesia Region Derived from 3D
Seismic Velocity Structure: Time Period of April 2009-July 2016
* Andri Dian Nugraha 1) , Hasbi Ash Shiddiqi 1) , Sri Widiyantoro 1) , Shindy Roslia 1) , Mohamad Ramdhan 1), Wandono Wandono 2) , Daryono Daryono 2) , Samsul Wiyono 2) , Mahsyur Irsyam 1)
Institut Teknologi Bandung, Bandung, Indonesia 1) , Agency for Meteorology, Climatology and Geophysics(BMKG), Jakarta, Indonesia 2)
2)

We conducted hypocenter relocation of ~40,000 events (Magnitude of 1.4 to 8.5) recorded by 451 stations
around and outside Indonesia region that compiled by Indonesian Meteorology, Climatology, andGeophysics Agency (BMKG) from April 2009 to July 2016. We used teleseismic double-difference
relocation inversion including local, regional and teleseismic arrival time data. Our previous study of 3D
seismic velocity model beneath the Indonesian region with grid size 1o by 1o and the 1D seismic velocity
model were used for the regions inside and outside Indonesia region, respectively. This method improved
limitation from BMKG earthquake data catalog in which events were recorded from scattered seismic
station array and insufficient azimuthal gap around Indonesia. Our results show that travel-time RMS
residuals were greatly reduced compared to those of the BMKG catalog. Seismicity at shallower depth (lessthan 50 km) shows significant improvement, refining shallow geological structures, e.g. trench and major
strike slip faults. Clustered seismicity is also detected beneath volcanic regions, and probably related tovolcano activities and also major faults nearby. Beneath Western Sunda arc, Wadati-Benioff Zone (WBZ)
extents to 300 km and it depicts gently dipping slab beneath this region. The WBZ beneath Eastern Sunda
Arc is extent deeper to 500 km and depicts steep slab geometry. At Sunda-Banda transition zone, we foundanomalously low seismicity beneath oceanic-continental transition region. WBZ of highly curvature Bandaarc extents to 600 km and depicts two-slab model. In Molucca collision zone, seismicity from this region
clearly shows two-slab of Halmahera plate: east- and west-dipping slab. Furthermore, we used global
centroid moment tensor catalog where data available for earthquakes with magnitude 6 or greater. Mostly,
focal mechanism solution for large earthquakes around this region are thrust mechanism that related to
subduction processes.

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*J09-P-07
Joint Symposium / J09. Geodesy and seismology general contributions

Aftershock Observation of Mw 6.5 Pidie Jaya, Aceh, Indonesia Earthquake:
Preliminary Results* Andri Dian Nugraha 1) , Muksin Umar 2) , Muzli Muzli 3) , Zulfakriza Zulhan 4) , Riskiray Ryannugroho 1) ,Kadek Hendrawan Palgunadi 1) , Supendi Pepen 3) , Sri Widiyantoro 1) , Nanang T Puspito 1) , Wahyu
Triyoso 1) , Daryono Daryono 1) , Kemal Erbas 5) , Rachmat Sule 1) , Irwan Meilano 1) , Mahsyur Irsyam 1) ,Philippe Jousset 5)
Institut Teknologi Bandung, Bandung, Indonesia 1) , Syah Kuala University, Aceh, Indonesia 2) , Agency for
Meteorology, Climatology and Geophysics (BMKG), Jakarta, Indonesia 3) , Department of Mining andEnergy Resourcses, Aceh, Indonesia 4) , GFZ Postdam, German 5)
The Mw 6.5 Pidie-Jaya, Aceh, Indonesia earthquake occurred on December 7, 2006. This destructive event
causing many victims, houses and infrastructure collapses as reported by the authority. The previous
geological and geophysical studies did not show the fault surface indication around the mainshock, so it isvery important to investigate the fault plane and source mechanism of the event. A week after, we deployed
9 seismometers to observed the aftershock distriburion. We carrefully picked P-and S-arrival time of thesmall event and then determined the hypocenter location. In total, we determined ~320 event for one
month monitoring. Our preliminary results show the aftershocks location have striking of NE-SW direction
with the focus depth of 10 to 30 km. These events cluster also appear perpendicular to the main Sumatra
fault, so it is antithetic fault likely. The comparison with geological and geodetical studies are needed to getmuch better interpretation.
Keywords: Pidie-Jaya, earthquake, aftershock

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*J09-P-08
Joint Symposium / J09. Geodesy and seismology general contributions

Estimation of the seismic-motion-generated changes in permeability
structure nearby a fault fracture zone by means of a groundwater migrationmodel* Atsushi Mukai 1) , Shigeaki Otsuka 2) , Yoichi Fukuda 3)
Fukuyama City University, Fukuyama, Japan 1) , Kobe Gakuin University, Kobe, Japan 2) , Graduate Schoolof Science, Kyoto University, Kyoto, Japan 3)
We report that permeability structure in a fault fracture zone can be changed every time strong seismic
motions occur due to great earthquakes, even though the fault itself is not the seismic one.
Groundwater can easily migrate in a fault fracture zone with higher permeability. The permeability is
expected to vary due to crustal stress, alteration of the crust and so on. In fact, permeability in the crust
nearby Nojima fault, which was one of the seismic faults for the 1995 Hyogo-ken Nanbu earthquake, wasreported to have been reduced gradually after the earthquake (Mukai and Fujimori, 2007). It is considered
to reflect the recovery process of the fault.
We have continuously observed groundwater discharge and pore pressure as well as crustal movements at
Rokko-Takao station in the western Japan. This station was established in a tunnel across Manpukuji fault.
The groundwater discharge and the pore pressure had increased just after some great earthquakes apartfrom this station. A part of these changes was considered to be caused by permeability changes in thefracture zone, which might result from the outflow of mud due to the strong seismic motions.
We had made a groundwater migration model with homogeneous permeability structure to estimate
permeability change (Mukai et al., 2016). We applied the observational data of groundwater discharge andpore pressure to the model and could estimate permeability change just after the 2011 off the Pacific coastof Tohoku Earthquake. In this study, we modified the model as considering the effect of heterogeneous
permeability structure, and tried to estimate permeability changes due to some great earthquakes such as
the 2016 Kumamoto earthquake. We report the characteristics of the permeability changes and a possible
mechanism to cause such changes in consideration of the observed crustal movements which wereaffected by groundwater migration.

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*J09-P-09
Joint Symposium / J09. Geodesy and seismology general contributions

INTAROS – INTEGRATED ARCTIC OBSERVATION SYSTEM* P. H. Voss 1) , T. Dahl-Jensen 1) , M. B. Sorensen 2) , P. Knudsen 3) , O. B. Andersen 3) , S. A. Khan 3)
Geological Survey of Denmark and Greenland, Copenhagen , Denmark 1) , University of Bergen, Bergen,
Norway 2) , DTU SPACE, Technical University of Denmark, Kgs. Lyngby, Denmark 3)
By DEC 1st 2016 the five year INTAROS project was launched with Horizon 2020 funding from theEuropean Commission. The overall objective of INTAROS is to develop an integrated Arctic Observation
System (iAOS) by extending, improving and unifying existing systems in the different regions of the Arctic.
INTAROS will have a strong multidisciplinary focus, with tools for integration of data from atmosphere,
ocean, cryosphere and terrestrial sciences, provided by institutions in Europe, North America and Asia.
Satellite earth observation data plays an increasingly important role in such observing systems, because theamount of EO data for observing the global climate and environment grows year by year. In situ observing
systems are much more limited due to logistical constraints and cost limitations. The sparseness of in situ
data is therefore the largest gap in the overall observing system. INTAROS will assess strengths andweaknesses of existing observing systems and contribute with innovative solutions to fill some of thecritical gaps in the in situ observing network. INTAROS will combine many scientific disciplines of which
both seismology and geodesy are included. The seismological component of INTAROS includes e.g. a
reviewed catalogue of the earthquakes activity in the Arctic, to find the areas that are poorly observed andto perform a yearlong deployment of broadband OBS'es in the Arctic using ROV technology, to show how
to fill the earthquake/seismic monitoring gap in the Arctic Ocean. The geodetic component of INTAROS
includes e.g. that sea level information from tide gauges and from satellite altimetry (also Sentinel-3) will be
combined to obtain sea level anomalies and associated geostrophic ocean currents and provide new
estimations of ice sheet mass balance and changes using GNSS/GPS data and development of new
methods to improve these estimations. We will give an overall presentation of INTAROS and outline theseismological and geodetic contributions.

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*J09-P-10
Joint Symposium / J09. Geodesy and seismology general contributions

Simulation of Hayabusa2 crossover orbit analysis using laser altimeter data
* Keiko Yamamoto 1) , Koji Matsumoto 1) , Toshimichi Otsubo 2) , Noriyuki Namiki 1) , Hayabusa2
Astrodynamics Team 3)
National Astronomical Observatory of Japan, Tokyo, Japan 1) , Hitotsubashi University, Tokyo, Japan 2) , - 3)
The asteroid explorer “Hayabusa2" was launched in 2014, and will arrive the target C-type asteroid, Ryugu
in the middle of 2018. Hayabusa2 will stay there for one and a half years, and perform exploration withsmall rover and lander, sample acquisition from Ryugu's surface, and various remote-sensing observations.
In the mission, in order to estimate Hayabusa2 orbit and Ryugu's geodetic parameters as precise as
possible, crossover orbit analysis using laser altimeter (LIDAR) between Hayabusa2 and Ryugu is planned,in addition to conventional radiometric tracking data analysis.
In this study, as a preparation for actual data analysis, we simulated Hayabusa2 orbit analysis in offline. We
developed a simulation program for Hayabusa2 orbit analysis, including crossover orbit analysis. Test dataof Hayabusa2 orbit, Ryugu ephemeris, and Ryugu shape model were also created for the simulation. The
orbit analysis was simulated in the following order: 1) Hayabusa2 orbit determination with range and range
rate observations from ground tracking stations to Hayabusa2, 2) Determination of Hayabusa2 orbit withrespect to Ryugu center by crossover orbit analysis using LIDAR-observed ranges between Hayabusa2 andRyugu, 3) improvement of Ryugu ephemeris using 1) and 2) results, 4) improvement of Hayabusa2 orbit byperforming 1) again with updated Ryugu ephemeris, and 5) iteration of 1) to 4). We discuss how much theprecision of determined Hayabusa2 orbit changes by changing error magnitudes of each observations and
Ryugu ephemeris.

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*S01-1-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Automatic hypocenter determination for the Seismological Bulletin of Japan
using Bayesian estimation and its applications* Koji Tamaribuchi
Meteorological Research Institute, Tsukuba, Japan
A quick estimation of spatial and temporal hypocenter distributions in swarms and aftershocks is essential
for estimating the source geometry and possible damaged area. The automatic hypocenter determination
method is important to understand seismic activities in real time. We developed a new method using
Bayesian estimation to identify multiple concurrent earthquakes to be used for the Seismological Bulletinof Japan. This method makes integrated use of P- and S-wave arrival times and maximum amplitude. We
applied this method to earthquakes in the vicinity of Japan. The ratio of detected earthquakes comparedwith those in the manually checked event list is almost 100% (M>=1.0) at inland and shallow areas. At
offshore or deep areas, it is about 80% (M>=1.0). We also applied this method to the aftershock activity of
the northern Nagano Prefecture on November 22, 2014. In this case, this method could detect more than
1,700 events in 24 hours, although the previous automatic determination system could detect only 250
events at that time. This indicates that our method is useful to understand seismic activities in real time.
The new seismic monitoring system using this method have started its operation at the Japan
Meteorological Agency in April 2016. In the 2016 Kumamoto earthquake, which began on April 14, theability of the method was fully demonstrated. By the end of May, number of hypocenter determinations
reached about 70,000, which was far more than the level possible by manual processing, and the system
played an important role to grasp the spatio-temporal characteristics of the activity.

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*S01-1-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Automated seismic event location combining waveform stacking and relative
location techniques* Francesco Grigoli 1) , Simone Cesca 2) , Frederic Massin 1) , Anne Obermann 1) , Wilfried Strauch 3) , John
Clinton 1) , Stefan Wiemer 1)
ETH-Zurich, Swiss Seismological Service (SED), Switzerland 1) , GFZ-Potsdam, German Research Centre forGeosciences, Germany 2) , Instituto Nicaraguense de Estudios Territoriales (INETER), Nicaragua 3)
Microseismic monitoring became a common operation in many applications (e. g. induced seismicity). The
analysis of microseismic data is challenging, because of the large number of recorded events often
characterized by low signal-to-noise ratio. In the last years, to improve the performance of the automatedlocation procedures, various waveform based methods for microseismicity characterization have been
proposed. These picking-free methods exploits the coherence of the waveforms recorded at different
stations and appear to be more noise robust than the traditional methods (based on automatic phasepicking). However, like any other absolute location method, the accuracy strongly depends on theknowledge of the velocity model. The use of simplified 1D velocity models in areas characterized bycomplex 3D velocity structures or by pronounced topography may strongly affect the locations accuracy.
The poor knowledge of the velocity model is, in fact, the largest source of error in the seismic event
location process. In this work we present a location method which combines features of relative location
techniques with the waveform based location methods. This approach inherits all the advantages of the
fullwaveform location methods without its main drawback (i.e. effect of poorly known velocity model). In
fact, this method is less dependent on the knowledge of the velocity model, improving the location
accuracy: 1) it accounts for phase delays due to local site effects, e.g. surface topography or variablesediment thickness 2) theoretical velocity model are only used to estimate travel time within the source
volume, and not along the entire source-sensor path. In order to validate this approach we tested it withdifferent synthetic and real datasets, including induced seismicity related to geothermal energy exploitationin St. Gallen (Switzerland) and seismic swarms of volcanic origin in Nicaragua.

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*S01-1-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Over 20 years of HYPOSAT: Newest developments* Johannes Schweitzer
NORSAR / Univesity of Oslo, Norway
About 20 years ago, the first versions of HYPOSAT, a free software package to locate seismic events at
local, regional and teleseismic distances were developed and presented (Schweitzer, 1997). In 2001, a
paper was published describing the principal features of the program package and the software package
was officially released (Schweitzer, 2001). Later, a detailed manual became part of the IASPEI New Manualof Seismological Observatory Practice (Schweitzer, 2002).
During the last decade, many new features steering the inversion process and correcting for effects that
can influence seismic travel times were implemented in HYPOSAT and many options to handle input andoutput data were included. Today's program version can run on Unix and Linux platforms.
The program package has been used by many researchers worldwide. These users have helped to improve
the software by reporting problematic results and bugs and requested additional input / output options.
In this talk an overview will be presented over the principal ideas behind HYPOSAT. Additionally, many of
the recently implemented features will be explained and discussed.
Schweitzer, J. (1997): HYPOSAT – A new routine to locate seismic events. NORSAR Scientific Report,
1–97/98, 94–102.
Schweitzer, J. (2001): HYPOSAT – an enhanced routine to locate seismic events. Pure appl. geophys., 158,
277–289, doi 10.1007/PL00001160
Schweitzer, J. (2002): PD 11.1: User manual for HYPOSAT (including HYPOMOD). In: P. Bormann (ed.)(2002). IASPEI New Manual of Seismological Observatory Practice (NMSOP), GeoForschungsZentrum
Potsdam, Vol. 2, 16 pp., ISBN: 3-9808780-0-7, http://ebooks.gfz-potsdam.de/pubman/item/escidoc:4135:3,
doi: 10.2312/GFZ.NMSOP_r1_PD_11.1

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*S01-1-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

A tremor location method using products of cross correlations
Ka Lok Li 1) , Hamzeh Sadeghisorkhani 1) , Giulia Sgattoni 1) 2) 3) , * Olafur Gudmundsson 1) , Roland Roberts
1)

Uppsala University, Uppsala, Sweden 1) , University of Iceland, Reykjavik, Iceland 2) , University of Bologna,
Bologna, Italy 3)
We introduce a back-projection method to locate tremor sources using products of cross-correlationenvelopes of signals between seismic stations. Tremor is characterized by signals which lack a clear onset.
For such signals it is usually not possible to use first-arrival picks to locate a source. Instead, inter-station
cross-correlation is commonly used for this purpose. We introduce a method which resembles high-ordercross-correlations, but it is much less computationally expensive. In this method we calculate up to the(n-1)th-order products of cross-correlation envelopes for a given subset of n stations. The products are backprojected to hypothetical source locations in a geographic grid and the resulting maps are stacked overcombinations of station subsets. We show that compared to existing correlation methods and for realistic
signals and noise characteristics this way of combining phase information can significantly suppress theeffects of correlated and uncorrelated noise and therefore give a robust estimate of source locations. We
present synthetic examples which demonstrate the robustness of the method and apply the method totremor at Katla volcano, Iceland in 2011.

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*S01-1-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Rapid estimation of seismic moment, magnitude and energy for small tolarge events: improvement from Central Italy, 2016 seismic sequence* Antonella Gallo 1) , Giovanni Costa 1) , Rita de Nardis 2) , Luisa Filippi 3) , Giusy Lavecchia 2) , Elisa
Zambonelli 3)
Department of Mathematics and Geosciences, University of Trieste, Italy 1) , CRUST-DiSPUTer-Universiy ofChieti-Pescara “G. d'Annunzio", Chieti Scalo, Italy 2) , Dipartimento di Protezione Civile, Roma, Italy 3)
The implementation of techniques that are able to determine the characteristics of a given event in nearreal time is essential for seismology and is of enormous importance to deal with the seismic emergency as
quickly and accurately as possible. The SeisRaM (Seismological Research and Monitoring) Group of the
Department of Mathematics and Geosciences of the University of Trieste is concerned to the seismic
monitoring in real time of the Italian territory. Techniques and procedures have been developed for theaccurate determination of source parameters that are computed within few minutes after the earthquakes
and rapidly revised. A long collaboration with a National Civil Protection leads to improve the quality of theresults and to optimize such procedures for civil defense purpose. The recent seismic sequence, occurredin the intra-Apennine extensional fault system of Central Italy, gave the opportunity to further test the nearreal time system. In fact, records from the seismic sequence following the Amatrice earthquake of 2016, 24
August (Lavecchia et al, 2016), are analyzed using an automated routine to determine moment magnitudes
and strong motion parameters. Seismic moment and the corresponding moment magnitude are obtained
from the spectrum of far-field body waves (Gallo et al, 2014), as well as radiated energy, the Brune stressdrop and apparent stress. The application of the automated algorithm in near real time provides important
insight into the ground motion characteristic to obtain a rapid characterization of seismic source
parameters in case of a strong event, for research, engineering purposes and emergency services.

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*S01-1-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Towards routine determinations of earthquake focal mechanisms obtained
from P-wave first motion polarities* Konstantinos Lentas , Dmitry StorchakInternational Seismological Centre
We investigate the possibility to calculate earthquake focal mechanisms in a routine and systematic way
based on P-wave first motion polarities. We use any available parametric data in the ISC database. We alsouse ISC auto-picked polarities from waveform data up to teleseismic epicentral distances (up to 90
degrees) for stations in the international registry that are not reported to the ISC. A bi-product of our study
can potentially be an additional set of picked polarities and direct P-wave teleseismic arrival times, and/or
the identification of stations associated with polarity reversals. We use the HASH algorithm for thedetermination of the earthquake mechanisms as it provides an elegant way to take into accountuncertainties in earthquake location and Earth's structure. We slightly modified the algorithm to deal with awide range of epicentral distances and to take into account the ellipsoids that define the ISC location
errors. We first carry out benchmark tests for a set of ISC reviewed earthquakes (mb > 4.5). We use the
HASH classification to define the mechanism quality and we find that the mechanisms of quality A, B, andC with an azimuthal gap up to 90 degrees are well compared to our benchmark mechanisms. Nevertheless,the majority of our mechanisms fall into class D as a result of limited polarity data from stations inlocal/regional epicentral distances. Specifically, we compute the minimum rotation angle between our
mechanisms and the benchmarks and we find 24% of D cases with a rotation angle up to 35 degrees andazimuthal gap up to 120 degrees. We finally specify selection criteria with respect to the stations'distribution, misfit and nodal plane uncertainties in order to separate the trusted mechanisms from the rest.

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*S01-2-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Calculating the ISC's own magnitudes* Elizabeth Entwistle , Domenico Di Giacomo , Dmitry StorchakInternational Seismological Centre, Thatcham, United Kingdom
The International Seismological Centre (ISC) routinely reports body and surface wave magnitudes forearthquakes recorded at teleseismic distances. Current ISC procedures for calculating magnitudes rely on
amplitude-period pairs reported to the ISC by contributing agencies. Here, we develop a new method to
calculate magnitudes in house at the ISC, in accordance with the IASPEI standards outlined by the
IASPEI/COSOI Working Group on Magnitudes. These new ISC magnitudes are calculated using waveforms
downloaded from international data centres (IRIS, EIDA, GeoNet) and our own automatic algorithms formeasuring amplitude (A) and period (T). We present results for broadband body wave magnitudes(mB(BB)) calculated using the relation mB(BB) = log10((A/T)max) + Q(d,h), where Q(d,h) is the attenuation
function for P-waves recorded on vertical component seismographs, established by Gutenberg and Richter(1956), at epicentral distances d and for a focal depth h, and (A/T)max = (Vmax/2pi), where Vmax is theground velocity associated with the maximum velocity trace-amplitude in the entire P-wave train (Bormann
and Saul, 2008). We use a dataset of recordings of up to 1000 earthquakes of magnitude greater than 5 inthe period 2012 – 2013, that are reviewed in the ISC Bulletin. We compare our own ISC mB(BB) with MWfrom GCMT, mb from NEIC, and conventional ISC mb and MS. These new ISC-calculated magnitudes will
be an extra dataset available to users of the ISC Bulletin, and will provide a robust measure of magnitude
that is in agreement with IASPEI standards. To complement the existing amplitude and period
measurements reported to the ISC by contributing agencies, ISC-picked amplitude and period
measurements and their associated amplitude-phase arrival time will also be reported and made available
to users.
References:
Bormann, P., J. Saul (2008): The New IASPEI Standard Broadband Magnitude mB. Seismological Research
Letters, 79, 5, p. 698-706.

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*S01-2-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Policy issues for the European Seismological Services within EPOS
* Florian Haslinger 1) , EPOS Seismology Consortium 2)
ETH Zurich, Zurich, Switzerland 1) , EPOS Seismology, EPOS 2)
In the framework of EPOS, the European Plate Observing System initiative, which aims to become aEuropean Research Infrastructure Consortium (ERIC) covering the Solid Earth Sciences,the European
seismological community is further developing its portfolio of common European services for seismological
data and products, as one of the domain specific EPOS Thematic Core Services. Efforts are focusing ontechnical innovation, harmonization and coordination, building upon decades of collaboration in thecollection and dissemination of earthquake parameter information at the European-Mediterranean
Seismological Centre (EMSC), of seismological waveforms and associated information at the Observatories
and Research Facilities for Seismology in Europe (ORFEUS), as well as on more than 10 years of mainly
project-driven collaboration in seismic hazard assessment leading to the establishment of the European
Facilities for Earthquake Hazard and Risk (EFEHR). One key aspect in EPOS-Seismology is the conscious
and comprehensive addressing of non-scientific issues: Data (sharing) policies, licenses and intellectual
property (including attribution issues), and data management planning and implementation. A major
challenge is the harmonization between developments and ideas in EPOS, established practices within theEuropean level seismological institutions, and national / institutional policies (where and if existent),
recognizing that e.g. ORFEUS and EMSC have each more than 50 participating member institutions from
more than 30 countries.
In this contribution we will review the state of the discussion on these issues, present current strategies
and plans regarding policy harmonization and implementation, and also address connections of our efforts
to other relevant initiatives originating for example from GEO or RDA.

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*S01-2-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

The Mexican National Seismological Service: An overview* Xyoli Perez-Campos , SSN Personnel
Universidad Nacional Autonoma de Mexico, Mexico City, Mexico
The Servicio Sismologico Nacional (SSN, Mexican National Seismological Service) has a history of 107
years. In the last 10 years, it has gone through an important modernization process, which has involved theinstallation of new broadband stations; co-localization of GPS receivers with the velocity and acceleration
sensors; collaboration with other Mexican networks to increase the number of stations from which it
receives data; migration to larger and faster acquisition, processing and storing systems; and a newbuilding that hosts the central facilities. 2017 marks the beginning of a new period of the SSN, since asignificant increase on the number of stations and computer capabilities will be part of a new project. On
this work, we will present an evaluation of the current performance of the network, the communication andsystem architecture, as well as monitoring and reporting processes, which include the use of social
networks and a mobile app; this towards the optimal design of the upcoming improvements.

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*S01-2-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Compilation of a Seismic Bulletin for the European Arctic* Johannes Schweitzer 1) , Yana Konechnaya 2) , Andrey Fedorov 3) , Steven Gibbons 4) , Berit Paulsen 4) ,Myrto Pirli 5)
NORSAR / University of Oslo, Norway 1) , Federal Center for Integrated Arctic Research, Arkhangelsk,
Russia 2) , Kola Regional Seismological Centre, Apatity, Russia 3) , NORSAR, Kjeller, Norway 4) , Skjetten,
Norway 5)
During the years 2014 - 2016, a joint Norwegian-Russian project between the three partners NORSAR in
Kjeller, Norway, the Federal Center for Integrated Arctic Research of the Ural Branch of RAS in
Arkhangelsk and the Kola Branch of the Geophysical Survey of RAS in Apatity, was jointly financed by
Norwegian and Russian research agencies. One task of this project was to compile a joint seismic bulletin
for the European Arctic for the last decades. The main sources for this new bulletin were the data collected
at the International Seismological Centre (ISC), the analyst reviewed bulletins of NORSAR and the two
Russian project partners, the bulletins of the IDC in Vienna and its forerunners, the Nordic Bulletincompiled at the University of Helsinki, and the bulletins collected at the University of Bergen. In addition,
seismic onsets from permanent and temporary stations read at NORSAR within different projects as e.g.,during the IPY, were added to the new bulletin compilation.
The greatest challenge for this new unified bulletin is removing all the onset readings from different
agencies analyzing the same seismic stations: due to international data exchange, data from the permanent
stations in the European Arctic are in between analyzed by five or more institutions and then reported into
the international databases. These institutes are not only processing the data differently, but they may evenuse different rules to name the seismic onsets.
All these data entries have to be homogenized, to achieve a unified bulletin. The new bulletin contains themost complete collection of seismic events observed in the European Arctic north of latitude 70 degrees
for the time period 1990 to autumn 2015.

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*S01-2-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

The ISC-GEM Global Instrumental Earthquake Catalogue: Current status
and efforts to extend the period 1904-1919* Domenico Di Giacomo 1) , Bob Engdahl 2) , Dmitry Storchak 1) , James Harris 1)
International Seismological Centre, Thatcham, UK 1) , University of Colorado, Boulder, USA 2)
The first version of the ISC-GEM Global Instrumental Earthquake Catalogue (1900-2009)(www.isc.ac.uk/iscgem/index.php) was released in January 2013 (Storchak et., 2013) after a 27-monthproject co-funded by the GEM Foundation. The catalogue was required to reassess the homogeneity (to thelargest extent possible over time) of the earthquake parameters (especially location and magnitude) and list
them along with formal uncertainties to facilitate seismic hazard and Earth's seismicity studies.
The first release included earthquakes selected according to the following time-variable cut-off magnitudes:
Ms=7.5 before 1918; Ms=6.25 during 1918-1963; and Ms=5.5 from 1964 onwards. Because of theimportance of having a reliable seismic input for seismic hazard studies, funding from USGS, NSF, GEM
and a few commercial companies in the US, UK and Japan allowed us to start working on the extension of
the ISC-GEM catalogue both for earthquakes that occurred after 2009 and historical earthquakes listed in
the International Seismological Summary (ISS), which fell below the original ISC-GEM cut-off magnitude of
6.25 before 1964. This is a four-year project that aims to add as many earthquakes as possible that
occurred between 1904 and 1959. In this contribution we present the updated ISC-GEM catalogue at theend of the third year extension program (Version 4.0), which includes over 2,000 more earthquakes during
2010-2013 and thousands more between 1920 and 1963 as compared to the first version. We also discuss
the current work to include as many earthquakes as possible during 1904-1919. The extension of the ISCGEM catalogue will be useful to regional seismic hazard studies because the ISC-GEM catalogue can serveas basis for cross-checking location and magnitude of those earthquakes listed both in global and regional
catalogues.

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*S01-2-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Development of a web-application system for seismic waveform data
observed at real-time with the seafloor seismic network, DONET
Daisuke Sugiyama 1) , Morifumi Takaesu 2) , Hiroki Horikawa 1) , Kentaro Sueki 1) , Narumi Takahashi 3) , *Seiji Tsuboi 1)
JAMSTEC, Kanagawa, Japan 1) , NME, Japan 2) , NIED, Japan 3)
It is well-known that devastating earthquakes have struck the Southwest coast of the Japanese Islands
repeatedly in the past. Of these earthquakes, those that occurred in the Nankai Trough region are verysignificant, because they have caused extreme hazards in these coastal areas due to large tsunamis. In
order to detect tsunamis in the earthquake source areas, JAMSTEC deployed the seafloor seismic network,
DONET in 2010. The DONET system consists of an array of 20 stations in total, each of which arecomposed of multiple types of sensors, including strong-motion seismometers and quartz pressure gauges.
We have developed a web application system, REIS (Real-time Earthquake Information System) thatprovides seismic waveform data to some local governments close to the Nankai Trough. The main purposeof REIS is to inform local government officers as to what has actually occurred in the Nankai trough region
when there is a large earthquake. REIS itself is not designed to issue early tsunami warnings, but it should
be useful for local government officers to get every possible piece of information to quickly assess large
earthquakes. We have ensured that the display of real-time waveform data from DONET is performed with amaximum delay time of approximately 2 seconds. This delay time is considered appropriate to allow local
government officers to promptly identify current seismic activity around Nankai Trough region. In 2016,
the network has been enlarged to the west of DONET and about 30 new stations, DONET2, are added to
the network. We have renovated the REIS system so that it may handle additional seismic waveform data
without any problems. Also, since April 2016, the ownership of DONET has officially transferred to the
National Research Institute for Earth Science and Disaster Prevention (NIED). JAMSTEC has a contract forthe operation of DONET with NIED and will keep the operation of REIS and event data system as it is.

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*S01-3-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

The Global Seismographic Network (GSN): New VBB Borehole Sensors,
Sensor Emplacement Techniques and Data Quality Assessment using
MUSTANG* Katrin Hafner 1) , Peter Davis 2) , David Wilson 3) , Robert Woodward 1)
IRIS, Washington, DC, United States 1) , IDA, University of California, San Diego, United States 2) , ASL, US
Geological Survey, Albuquerque, New Mexico 3)
The Global Seismographic Network (GSN) is a 152 station, globally-distributed, permanent network of highquality seismological and geophysical sensors. The central design goal of the GSN is “to record with full
fidelity and bandwidth all seismic signals above the Earth noise, accompanied by some efforts to reduce
Earth noise by deployment strategies". After over 20 years of operation, most of the network's technicaldesign goals have been met. The challenge is to continue to modernize the network and maintain high data
quality in an era of flat or declining budgets.
We will present a number of approaches to maintain GSN data quality and improve overall network noise
performance. These include: 1) Standardizing equipment across the network, e.g. deploying new Quanterra
Q330HR dataloggers; 2) Developing next-generation very broadband borehole sensors to replace thefailing KS-54000 sensors (one third of the network); 3) Using the results of noise analyses to determine
where new sensor emplacement techniques, e.g. shallow boreholes, might achieve lower noise performancefor the existing site conditions. We also show how shallow borehole installations may be adapted to vaults(which make up two thirds of the network), as a means of reducing tilt-induced signals on the horizontal
components.
The GSN is creating a prioritized list of proposed infrastructure and equipment upgrades at selected
stations with the ultimate goal of optimizing overall network data availability and noise performance. For
this effort, we are utilizing data quality metrics and Probability Density Functions (PDFs)) generated by the
IRIS Data Management Centers' (DMC) MUSTANG (Modular Utility for Statistical Knowledge Gathering)
tool. We will present our MUSTANG metric analysis and show GSN sites which could benefit the most from
instrumentation and infrastructure upgrades.

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*S01-3-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Anatomy of a subduction zone – seismicity structure of the northern Chilean
forearc from >100,000 relocated earthquake hypocenters* Bernd Schurr , Christian Sippl
Deutsches GeoForschungsZentrum, Potsdam, Germany
We present a catalog of >100k well-located earthquake hypocenters for the northern Chilean forearc
region, between the latitudes of 18.5 deg. S and 24 deg. S. The events span the period between 2007-2014
and were extracted from the Integrated Plate boundary Observatory Chile (IPOC) permanent station
network dataset. Using this new, high-resolution set of hypocenters, we can outline the slab structure in
unprecedented detail, including slab topography or the resolution of structures inside the zone ofintermediate-depth seismicity. For the compilation of the catalog, we relied on an automated multi-stepprocess for event detection, association and phase picking. The earthquake hypocenters were thenrelocated in a 2.5D velocity model for the Northern Chile forearc with a probabilistic approach allowing
uncertainty estimation. In a final step, double-difference relocation incorporating cross-correlation based
phase lag times was performed, which further sharpened event clusters. The majority of all >100k
earthquakes are located at intermediate depths (80 and 140 km) inside the subducted slab. This area of
pervasive activity extends along the entire strike of the investigated area, but shows a clear offset at 21 deg.
S, which may hint at a slab tear at this location. Further updip, a triple seismic zone at depths between 40
and around 80 km is visible, which grades into the highly active event cluster at intermediate depths: below
the plate interface, which is clearly delineated by seismic activity, a second parallel band of hypocenters
only about 5 km below likely corresponds to earthquakes occurring within the oceanic crust or close to theoceanic Moho. A third band of earthquakes, paralleling the other two at about 20-25 km below theinterface, clearly indicates the presence of seismicity in the oceanic lithospheric mantle. Seismicity in theupper plate is pervasive through the entire crustal thickness near the coast but gets shallower towards thevolcanic arc.

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*S01-3-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

The 30 May 2015 Bonin Deep Earthquake and the 660-km Discontinuity
Around its Source Region* Keiko Kuge
Department of Geophysics, Kyoto University, Kyoto, JapanThe 30 May 2015 Bonin deep earthquake occurred near the bottom of the mantle transition zone (depth
664 km, Mw 7.8; USGS), and its seismic waves traversed the mantle to many broadband stations in a
distance range that may be affected by the 660-km discontinuity in and around the source region. Our
results from finite-fault inversion with the P and SH waveforms and observations of aftershock waveformssuggest that a significant, subhorizontal 660-km discontinuity could not be located below the source region.
Seismic waves from the Bonin earthquake were recorded by a number of broadband stations in a wide
range of distance around the world. Along with the data collected by IRIS DMC, we examined broadband
data of F-net in Japan. Since high-frequency waves, which could be associated with the descending Pacificslab, were observed in eastern Japan, we used the data only from western Japan, which range from 7 to 16
degrees in distance. Changing the depth of the 660-km discontinuity in iasp91, we obtained spatiotemporal
distribution of slip on a finite fault by the multiple-time-window method (Kuge, 2003; Kuge et al., 2010).
Relatively small amounts of slip were estimated above the assumed 660-km discontinuity. When the660-km discontinuity was assumed below the earthquake source, the waveform fit became worse,compared with the cases above. These results are consistent with the observation of a simple pulse for P
waves over western Japan from an aftershock.

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*S01-3-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

The January 2017 Barrow Strait Earthquake and Subsequent Seismic
Activity in Arctic Canada
Allison Bent , Nicholas Ackerley , Michal Kolaj , * John Adams
Geological Survey of Canada, Ottawa, Canada
At 23:47 UT on 8 January 2017, a magnitude (MW) 5.9 earthquake, one of the largest in eastern Canada
during the last 50 years, occurred just offshore of Somerset Island, in Barrow Strait 92 km from Resolute innorthern Canada. The earthquake occurred near the Boothia Uplift of the Boothia-Ungava Seismic Zone
and was well recorded by the newly refurbished seismograph in Resolute (RESN). An earthquake of thissize is expected about once every 300 years based on the statistics for the Somerset-Cornwallis Island
seismic source zone; the rate for Barrow Strait by itself is higher than for the larger region. The mainshock
was followed by a rich and ongoing aftershock sequence. As of 6 February 2017 there were eightaftershocks of magnitude 3.0 or greater and numerous smaller ones with the largest being a magnitude 5.1
event that occurred at 17:55 UT on 9 January. Moment tensor inversion of the mainshock and largest
aftershock indicates that they were predominantly thrust faulting events on a northwest-striking planeconsistent with past events in Barrow Strait including the 1987 magnitude 5.2 event that occurred 30 km
NW of the January 8 mainshock. We will discuss the characteristics of the mainshock, seismotectonics ofthe region, an analysis of the aftershock sequence, depth estimation using a variety of methods such as
moment tensor inversion and analysis of teleseismic depth phases. On 20 January 2017 anothermoderately large (MW 4.7) earthquake occurred in the Arctic Islands about 97 km from Isachsen, Nunavut.
This event has an oblique-thrust mechanism. There are few recorded aftershocks for this event but we notethat the closest station is at a distance of 475 km. While too far (575 km) to be considered an aftershock of
the Barrow Strait earthquake, the occurrence of the two events over a short time period raises the questionof a causal relation.

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*S01-3-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Long Duration of Ground Motion in the Paradigmatic Valley of Mexico* Victor M. Cruz-Atienza 1) , Josue Tago 2) , Jose David Sanabria-Gomez 3) , Emmanuel Chaljub 4) , Vincent
Etienne 5) , Jean Virieux 4) , Luis Quintanar 1)
Instituto de Geofisica, UNAM, Mexico 1) , Facultad de Ingenieria, UNAM, Mexico 2) , Universidad Industrial
de Santander, Bucaramanga, Colombia 3) , Institut des Sciences de la Terre, Grenoble, France 4) , ARAMCO,
Advanced Research Center, Saudi Arabia 5)
Built-up on top of ancient lake deposits, Mexico City experiences some of the largest seismic site effects
worldwide. Besides the extreme amplification of seismic waves, duration of intense ground motion fromlarge subduction earthquakes exceeds three minutes in the lake-bed zone of the basin, where hundreds ofbuildings collapsed or were seriously damaged during the magnitude 8.0 Michoacan earthquake in 1985.
Different mechanisms contribute to the long lasting motions, such as the regional dispersion and multiplescattering of the incoming wavefield from the coast, more than 300 km away the city. By means of highperformance computational modeling we show that, despite the highly dissipative basin deposits, seismicenergy can propagate long distances in the deep structure of the valley, promoting also a large elongationof motion. Our simulations reveal that the seismic response of the basin is dominated by surface-waves
overtones, and that this mechanism increases the duration of ground motion by more than 170% and 290%of the incoming wavefield duration at 0.5 and 0.3 Hz, respectively, which are two frequencies with thelargest observed amplification. This conclusion contradicts what has been previously stated fromobservational and modeling investigations, where the basin itself has been discarded as a preponderant
factor promoting long and devastating shaking in Mexico City. Supporting our theoretical findings, bymeans of an array beamforming analysis using data from several subduction earthquakes recorded at hardrock sites next to the basin we show that most of the coda waves (i.e., between the 30% and 45% of the total
seismic energy) in those sites correspond to backscattered energy radiated from the basin. (Work publishedin www.nature.com/scientificreports ; 2016; DOI: 10.1038/srep38807)

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*S01-3-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Difference in energy radiation from earthquakes with similar moment
magnitude and focal mechanism: the broadband body-wave magnitudes ofthe 2014 Ludian and Jinggu, Yunnan Province, China, earthquake* Zhongliang Wu 1) , Changsheng Jiang 1) , Xiaoxiao Song 1) 2)
Institute of Geophysics, China Earthquake Administration 1) , Earthquake Administration of Hubei
Province, Wuhan, China 2)
The August 3, 2014, Ludian, Yunnan Province, China, MS6.5/MW6.2 earthquake and the October 7, 2014,
Jinggu, Yunnan Province, China, MS6.6/MW6.1 earthquake, although with similar moment/surface wave
magnitude and similar near-vertical strike-slip focal mechanism, caused sharply different disasters. The
former was with fatality/missing up to about 700 and injury about 3,000, and the latter with fatality 1 andinjury about 300. To investigate the role of seismic radiated energy in causing such a difference, we
analyzed 142 broadband (BB) vertical recordings of the Ludian earthquake and 138 BB vertical recordingsof the Jinggu earthquake, with epicentral distance 6o to 80o. We calculated the broadband cumulative bodywave magnitude mBc. It is shown that the mBc of the Ludian earthquake is about 0.3 higher than the
Jinggu earthquake. This indicates that, beyond other causes such as social vulnerability, secondary
disasters such as landslides, and local effects caused by both the Doppler effect of the seismic source andthe site response of the buildings, radiated energy contributes significantly to the difference of theearthquake disasters. The result suggests that in seismological observation and interpretation, routine
measurement and fast report of mBc will play an important (and sometimes unique) role in the earthquake
emergency response and the rescue and relief actions.

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*S01-4-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Recent earthquakes at Disko Island, Greenland, with focal mechanisms* Trine Dahl-Jensen , Peter H Voss , Tine B Larsen
Geological Survey of Denmark and Greenland, Denmark
During the first weeks of April, 2016, the little village of Qeqertarsuaq on the south coast of Disko Island,West Greenland, experienced a large number of earthquakes. A large (for the region) Mb 4.7 event wasrecorded internationally, preceded by six smaller events in the hours before the larger event. A massive
aftershock series followed during the following weeks with more than 150 events, two of which were Mb
4.5. The majority of the earthquakes occurred within an area of 50 x 50 km just south of Disko Island. The
location of the main event suggests a source depth in the upper crust. Sparse coverage of seismic profiles
in the region show faults in the upper crust that have been active in recent geological time. Focal
mechanisms for the larger earthquakes are compared with focal mechanisms for Baffin Bay between
Greenland and Canada.
Earthquakes are not uncommon in the area. Since recording began in Greenland more than 100 years ago,nearly 700 earthquakes have been recorded in the nearby area. Since 2009 the station coverage inGreenland has increased from 5 stations to 19 today due the GLISN project (www.glisn.info). In this period
two additional swarms of earthquakes have been recorded (23 events in August 2010 and 20 in February2015), none of which had a large initial event. Prior to the GLISN project a similar sequence of 33
earthquakes was recorded by a temporary net of seismometers in February 2006, with magnitudes ranging
from 1.2 to 3.5.

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*S01-4-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

New insights into volcano-tectonic seismicity patterns in the Virunga
Volcanic Province, Democratic Republic of the Congo, from a new
broadband seismic network (KivuSNet)* Adrien Oth 1) , Julien Barriere 2) 1) , Nicolas d'Oreye 2) 1) , Francois Kervyn 3)
European Center for Geodynamics and Seismology, Walferdange, Luxembourg 1) , National Museum of
Natural History, Walferdange, Luxembourg 2) , Royal Museum for Central Africa, Tervuren, Belgium 3)
The Kivu Basin is located in the bordering region of the Democratic Republic of Congo and Rwanda, in theWestern branch of the East African Rift. Here the active volcanoes Nyamulagira (the most active in Africa)
and Nyiragongo (host to the largest persistent lava lake on Earth) threaten the city of Goma andneighbouring agglomerations. For many years already, urbanisation in that region undergoes sustained
rapid growth, and the region counts 1 million inhabitants today. In 1977 and 2002, eruptions of
Nyiragongo caused major disasters. Destructive earthquakes can also affect the region, as was the case in2002 in Kalehe (Mw 6.2) along the western shore of Lake Kivu, or in 2008 in Bukavu (Mw 5.9), south ofLake Kivu. Until recently, modern seismic monitoring infrastructure was lacking in the area, leaving many
aspects about the volcanic activity and seismicity up to speculations.
In the frame of several Belgo-Luxembourgish collaborative research projects (the most recent one being
RESIST: “Remote Sensing and In Situ Tracking of geohazards", funded by the Belgian Science Policy andLuxembourg National Research Fund), we deployed the first dense real-time telemetered broadband
seismic network in the region, with the first two stations in 2012 and 2013. It is now a network of 15
stations and still under continuous development. Many KivuSNet stations are co-located with GNSS
KivuGNet stations, and three KivuSNet sites are in addition equipped with infrasound arrays.
We present an introduction to the key features of the network and first scientific results, including
unprecedented insights into tectonic and volcanic seismicity patterns as well as the continuous tracking oftremor sources and implications for magma migration patterns of the past 2 ½ years. KivuSNet opens a new
window for the state of knowledge on the seismic and volcanic activity in this highly threatened region andrepresents an indispensable tool for monitoring operations of the Goma Volcano Observatory.

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*S01-4-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Monitoring eruption activity using temporal stress changes at Mount Ontake
volcano* Toshiko Terakawa , Yoshiko Yamanaka , Yuta Maeda , Shinichiro Horikawa , Takashi Okuda
Nagoya University
On 27 September 2014, Mt. Ontake in Japan produced a phreatic (steam type) eruption with a Volcanic
Explosivity Index value of 2 after being dormant for seven years. The local stress field around volcanoes is
the superposition of the regional stress field and stress perturbations related to volcanic activity. Temporalstress changes over periods of weeks to months are generally attributed to volcanic processes. Here wedemonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using themisfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring.
We estimated focal mechanism solutions of 316 VT earthquakes beneath Mt. Ontake from August 2014 toDecember 2016, assuming that the source was double-couple. Pre-eruption seismicity was dominated bynormal faulting with east-west tension, whereas most post-eruption events were reverse faulting with eastwest compression. The moving average of misfit angles indicates that during the precursory period the
local stress field beneath Mt. Ontake was rotated by stress perturbations caused by the inflation ofmagmatic/hydrothermal fluids. Post-eruption events of reverse faulting acted to shrink the volcanic edifice
after expulsion of volcanic ejecta, controlled by the regional stress field. The deviation of the local stressfield can be an indicator of increases in volcanic activity. The proposed method may contribute to themitigation of volcanic hazards. The time history of average misfit angles showed non-negligible
enhancements in several periods after the 2014 eruption. These observations suggest that some repressurization/de-pressurization processes repeated after the 2014 eruption.

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*S01-4-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Long-term monitoring of of seismic velocity around a source fault of the
1995 Kobe earthquake* Ryoya Ikuta 1) , Koshun Yamaoka 2) , Takahiro Kunitomo 2) , Kinya Nishigami 3) , Toshiki Watanabe 3)
Shizuoka University, Shizuoka, Japan 1) , Nagoya University, Nagoya, Japan 2) , Kyoto University, Kyoto,
Japan 3)
Temporal variation in seismic velocity structure around Nojimafault, which ruptured at the time of 1995
Kobe earthquake (Mw6.9), has been measured for 17 years from 2000 to 2017 using Accurately Controlled
Routinely Operated Signal System (ACROSS). We constructed the ACROSS sources which generatehorizontally polarized seismic wave on the southern end of Nojima fault and started the measurement in1998. The generated seismic wave were detected by borehole-type seismometers deployed at the bottom of
800-m- and 1700-m-deep boreholes near the ACROSS sources. The temporal changes in travel time andamplitude of P-, S-, and later phases have been monitored.
As a result, gradual decreases in the travel times of the body waves as well as that of the later phases weredetected. The decreasing rate decayed during the 22 years after the Kobe earthquake. This decay
corresponds to the decay of permeability change measured by water injection test into the fault, which was
repeated from 1997 to 2009. The velocity variation should be a result of crack healing around the fault
after the earthquake.

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*S01-4-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Exhaustive analysis of surface wave propagation in a combined use of active
and passive surveys for detailed site characterization* Paolo Bergamo , Stefano Marano , Manuel Hobiger , Donat Faeh
Swiss Seismological Service, Zurich, Switzerland
Determining the soil geophysical properties related to seismic amplification, at sites where ground motion
is being recorded, is a key effort in engineering seismology. Besides explaining local seismic response, it
improves the robustness of the estimation of seismic attenuation and of earthquake magnitude. For the
purposes of site characterization, surface wave (SW) methods are nowadays regarded as an establishedtechnique.
We present site characterization surveys conducted at selected sites of the Swiss strong motion network
SSMNet; active and passive SW data were jointly acquired. The novelty we introduce with respect toprevious works is the technique we use to derive the parameters of SW propagation. We have developed
and apply a maximum likelihood technique for the joint analysis of Love and Rayleigh waves. They are
identified in the collected data and selected with a Bayesian information criterion; wave parameters are
estimated modeling jointly all recorded components. As outcome, SW dispersion data, Rayleigh wave
ellipticity and prograde/retrograde sense of particle motion are retrieved. Originally developed for passive
data, we have also adapted this technique for active acquisitions, accounting for the propagation of circularwave fronts. This allows us, in the surveys we present, i) to merge information from active and passive
measurements, covering shallow and large depths; ii) to use the same 2D array for active and passive
acquisitions (simplifying survey logistics). Finally, limited to active data, we have included the modeling ofRayleigh wave intrinsic attenuation. This enables the reconstruction of the damping ratio profile of the
subsoil, besides that of shear wave velocity. We show that the joint assessment of the characteristics of SW
propagation (velocity, ellipticity, sense of particle motion, attenuation) improves the robustness of theirestimation, and also the reliability and completeness of the obtained subsurface geophysical models.

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*S01-4-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Investigation of deep sedimentary and crustal structures with passive
seismic methods* Dario Chieppa , Manuel Hobiger , Marco Pilz , Donat Faeh
Swiss Seismological Service (SED), ETH Zurich, Switzerland
Passive ambient-vibration measurements are well established to investigate the uppermost shear-wave
velocity structure, usually limited to few hundred meters depth. Tomographic methods based onearthquake recordings are widely used for the study of the deeper crust, at depths of the order of several
kilometers. We plan to fill the gap between both depth ranges using passive array measurements. The study
area is the Swiss foreland.
From a geological perspective, the Swiss foreland mainly consists of quaternary deposits on top of Molasseand Mesozoic deposits of variable thickness ranging from about 1 to 5 km above the crystalline basement.
The goals of our measurements are the identification of the main impedance contrasts in the subsurface,
their comparison with a-priori information and the computation of local shear-wave velocity profiles. In
order to investigate different depth ranges, several array configurations of increasing size were deployed,
ranging from small scale of about 10 m to very large scale up to 10 km of inter-station distance.
We will present the results of first array measurements in the Molasse basin in northern Switzerland. Threearrays of different size have been deployed. The recorded data were processed using different techniques.
The H/V and ellipticity curves for all single stations were computed, while the array processing yielded
Rayleigh and Love wave dispersion curves in a wide frequency range. We used different methods, including
three-component high-resolution FK, SPAC and Wavefield Decomposition (WaveDec). The final step of theanalysis is the joint inversion of all available data and the definition of shear-wave velocity profiles
including their regional variations. We discuss the applicability and resolution power of seismic passive
methods to the investigation of shallow and deep structures.

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*S01-P-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Fast hypocenter determination with a 3D velocity model and its implication
for seismicity monitoring* Akio Katsumata
Meteorological Research Institute, Tsukuba, Japan
Hypocenter location still has important role in any kinds of seismic analysis. Clear image of aftershock
distribution helps us to understand the fault geometry of big earthquakes and tectonic meaning of theevent. A precise velocity model is indispensable to get good image of hypocenter distribution. Velocity
models have been estimated with seismic surveys and tomographic analyses of natural earthquakes. A
crustal structure model of the Japanese model was obtained with the tomographic method (Katsumata,2010), in which the Moho discontinuity depth distribution was estimated as well as the velocity distribution
in the layers. The velocity model indicated various characteristics of the Japanese Islands, which reflected
the history of the islands formation.
It usually takes a long time to estimate a hypocenter location with a 3D complex velocity structure. It
sometimes takes more than one hour to locate a single hypocenter using a 3D velocity model because of
the very time-consuming calculation in ray-tracing. The time had been reduced by introducing 3D travel
time table for each station (Katsumata, 2015). Almost any events can be located within one seconds. It was
confirmed that calculation time was reduced by about 1,800 times.
The effect of the inhomogeneous velocity structure on the event location is often observed in determinationof shallow inland events. Events under a thick sediment layer tend to be located at the deeper with 1D
velocity model than that with 3D model. Aftershock distribution of the 2004 Mid-Niigata Earthquake wasone of such cases. Similar depth difference was recognized in the activity of the 2016 Kumamoto
Earthquake. However, precision improvement in offshore areas seems to be limited. Noticeable
improvement is sometimes seen, for example, events off Ibaraki Prefecture. It is considered that local
velocity structure difference makes the difference in the effects for offshore event locations.

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*S01-P-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Moment tensor inversion of shallow offshore earthquakes in the Nankai
subduction zone using a three-dimensional velocity structure model* Shunsuke Takemura , Takeshi Kimura , Katsuhiko Shiomi , Hisahiko Kubo , Tatsuhiko Saito
National Research Institute for Earth Science and Disaster Resilience, Tsukuba, JapanOn April 1, 2016, Mw 5.8 earthquake (2016 Southeast Off Mie earthquake) occurred near the epicenter ofthe 1944 Tonankai earthquake (e.g., Ando, 1975). To investigate seismic activity around the Tonankai area,source mechanism of the 2016 Off Mie earthquake should be required. Since seawater, accretionary prism(low-velocity sediments) and subducting Philippine Sea plate exist beneath the epicenter region, it isdifficult to obtain accurate source mechanism via conventional one-dimensional analysis (Nakamura et al.
2015; Takemura et al. 2016). Thus, in this study, we conduct moment tensor (MT) inversion using Green's
function via finite-difference method (FDM) simulations of seismic wave propagation in a threedimensional (3D) heterogeneous velocity structure model.
The model of 3D simulation and technical details are same as in Takemura et al. (2016). The 3D
heterogeneous velocity structure, including topography, sedimentary layer, crust and subducting Philippine
Sea plate, is referred from the Japan Integrated Velocity Structure Model (JIVSM; Koketsu et al., 2012). By
using displacement waveforms of NIED F-net for periods of 30-100 s, we estimate an MT solution of thisearthquake. The result with minimum variance reduction is the optimal solution with source mechanism
and centroid depth.
The optimal result is characterized by a low-angle dipping faulting at a depth of 11 km, where the uppersurface of the Philippine Sea plate exists closely. Obtained result reproduced not only long-period (30-100s) displacement waveforms but also polarity of short-period (< 2 s) P waves. Observed P-first arrivals at land
stations show apparent velocity of approximately 7 km with up polarizations and are interpreted head wave
propagating along oceanic Moho of the Philippine Sea Plate.

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*S01-P-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Local Magnitude, ML Scale for the Philippines: Investigation of Hypocentral
Distance Dependence* Johnlery Deximo 1) , Tatsuhiko Hara 2)
Philippine Institute of Volcanology and Seismology, Department of Science and Technology (PHIVOLCSDOST), Quezon City, Philippines 1) , International Institute of Seismology and Earthquake Engineering,
Building Research Institute, Tsukuba, Japan 2)
We conducted a grid search for the local magnitude coefficients using broadband waveforms of local
earthquakes recorded by the Philippine Seismic Network (PSN). We selected sets of the coefficients which
explained the data relatively well without large hypocentral distance dependence. Compared to the
distance correction functions of southern and central California and the central United States obtained
from previous studies, the distance correction functions for the selected sets of the coefficients are similar
to that of southern California.
To further investigate hypocentral distance dependence, we calculated the medians of local magnituderesiduals for 10 bins ranging from 0 to 1000 km. When the distance correction function for southern
California is used, there is a hypocentral distance dependence larger than 0.1 magnitude unit, although thescatter of the residuals is large. We show that it is possible to find local magnitude coefficients with smaller
hypocentral distance dependence by a grid search.

Keywords: Local magnitude, distance correction, grid search

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*S01-P-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

The Mechanism of Rare Earthquakes in Pidie Jaya, Aceh Derived from
Source Parameter and Shear Wave Splitting Tomography* Rexha Verdhora Ry 1) 2) , Andri Dian Nugraha 1) 2) , Sri Widiyantoro 1) 2) , Riskiray Ryannugroho 1) , Kadek
Hendrawan Palgunadi 1) , Muksin Umar 3) , Zulfakriza Zulfakriza 4) , Kemal Erbas 5)
Institut Teknologi Bandung, Bandung, Indonesia 1) , Global Geophysical Research Group, Bandung,Indonesia 2) , Syah Kuala University, Aceh, Indonesia 3) , Department of Mining and Energy Resources,
Aceh, Indonesia 4) , GFZ Postdam, Germany 5)
On December 7, 2016, a rare and unexpected earthquake with a moment magnitude (Mw) of 6.5 struck
Pidie Jaya, Aceh. According to Indonesian Meteorological, Climatological, Geophysical Agency (BMKG),
the earthquake was located in 5.19o N, 96.36o E, with a depth of 10 km. Approximately 11,000 houses and
104 dead casualties were reported. It was assumed that the earthquake relates to Samalanga Sipopok fault
which is located in the northern part of Aceh and has a mechanism of strike-slip. In regard to this event, we
deployed 9 seismometers for a month in this area to identify aftershocks. The objective was to confirm thegeometry of fault plane and the earthquake mechanism. We recorded 330 aftershocks between December
14, 2016 and January 15, 2017. We manually picked P- and S- wave arrival times and applied probabilistic
non-linear method to locate hypocenters. Furthermore, we calculated the moment magnitudes using
Brune's model and processed several samples of focal mechanisms using full waveform inversion. It can beobserved that the aftershocks are distributed in Southwest – Northeast direction from the mainshock. The
magnitudes decreased along with time and the focal mechanism shows a strike-slip faulting. Moreover, we
also analyzed anisotropy parameter using 3-D shear wave splitting (SWS) tomography to delineate the fault
plane. The high degree of anisotropy and crack density were observed around the interpreted fault
structure. The distribution of earthquakes and anisotropy may reveal an unprecedentedly unknown fault inthe study region.

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*S01-P-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Rupture process of the 1979 Tumaco, Colombia, earthquake using
teleseismic body waves* Masahiro Yoshimoto 1) , Hiroyuki Kumagai 1) , Nelson Pulido 2)
Nagoya University, Nagoya, Japan 1) , National Research Institute for Earth Science and Disaster
Resilience, Tsukuba, Japan 2)
We investigated the rupture process of the 1979 Tumaco earthquake using the teleseismic P-wave records
at WWSSN stations with epicentral distances between 30 and 100 degrees. The records consist of six
vertical and three horizontal seismograms. We used the fault geometry model of Yoshimoto and Kumagai[AGU fall meeting, 2016], which was constructed from slab model Slab 1.0 [Hayes et al., JGR, 2012]. We
calculated Green's functions using the method of Kikuchi and Kanamori [BSSA, 1991] and applied the
waveform inversion scheme of Kikuchi et al. [EPS, 2003] to determine the spatial and temporal slip
distribution. Our analysis indicated Mw 8.3 and the total rupture duration of about 120 s. The rupture
propagated northeast from the rupture initiation point with a rupture velocity of 2.0 km/s. The large sliparea was estimated in the northeastern part of the source region with the maximum slip of 3.5 m. This large
slip area is consistent with reported regions of large tsunami height and strong shaking intensity. White etal. [EPSL, 2003] estimated the average plate coupling ratio in the 1979 earthquake source region to be only
30 %. From this coupling ratio and the average slip of 2.4 m in our slip model, the recurrence interval of the
1979 earthquake was estimated to be 174 years. This suggests that the 1906 Ecuador-Colombia earthquake
did not rupture the source region of the 1979 Tumaco earthquake. This interpretation is consistent withthat proposed by Yoshimoto and Kumagai [2016].

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*S01-P-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Stress drop characteristics of the 2008-2016 Storfjorden earthquake
sequence* Lars Ottemoller 1) , Norunn Tjaaland 1) , Hasbi Ash Shiddiqi 1) , Won-Young Kim 2)
University of Bergen, Norway 1) , Lamont Doherty Earth Observatory, Columbia University, US 2)
An earthquake sequence started in 2008 with a ML=6.0 earthquake in the Storfjorden area to the southeastof Spitsbergen that is part of the Svalbard archipelago. Since then, more than 2000 earthquakes have been
detected by the regional seismic stations with about 30 of them being of moderate size. Most recently(2016) a double earthquake of magnitude ML=5.2 and ML=4.8, respectively, occurred to the northeast of
the initial main cluster. While in this intraplate region the dominant compressive stresses were thought tooriginate from the Northern Mid-Atlantic ridge, the mechanisms found for the larger earthquakes range
between strike-slip and normal solutions and indicate pull-apart tectonics due to north-south extension.
While this presentation will give an updated overview of the complete sequence, the focus is on estimating
static stress drop. For the larger earthquakes stress drop was measured from the source displacement
spectra. However, for earthquakes below ML=4.0 we systematically searched for correlated events pairsthat were about one magnitude apart. The smaller of the two events was then used as empirical Green's
function and deconvolved from the larger event to obtain the source time function. This allowed to look for
differences in stress drop between various clusters of correlated events. One of the significant findings wasthat the largest and initial earthquake had the highest stress drop comparable to other intraplate
earthquakes. This result was verified by comparing the observed ground motion data to intraplate
attenuation curves.

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*S01-P-07
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Adding manual picks from OBS stations into the ISC Bulletin: the example ofthe 7D Cascadia Initiative Community Experiment* Domenico Di Giacomo 1) , Luke Cottell 2) , Elizabeth Entwistle 1) , James Harris 1) , Dmitry Storchak 1)
International Seismological Centre, Thatcham, UK 1) , Imperial College, London, UK 2)
The International Seismological Centre (ISC) integrates instrumental seismological parametric data (e.g.,
hypocenters, phase arrival times, amplitudes/periods, moment tensor solutions etc.) from ~130 agencies
around the world to produce the most comprehensive bulletin of the Earth's seismicity, the ISC Bulletin.
Whilst the main contributors to the ISC are monitoring agencies operating at various scales, the ISC
Bulletin can benefit from additional parametric data coming from temporary deployments. In thiscontribution we show how manual picks from the OBS data of the Cascadia Initiative Community
Experiment (http://www.fdsn.org/networks/detail/7D_2011/, IRIS OBSIP, 2011) were integrated into the
ISC Bulletin and used for the ISC hypocentre relocation. In total approximately 6400 picks of primary andsecondary arrivals have been picked for large teleseismic earthquakes and moderate-to-large earthquakes
in the local/regional distance range. Despite the high noise level of OBS waveforms over 50% of the picks
contribute to ISC relocations. We encourage researchers processing data from temporary deployments tosend parametric data to the ISC in order to improve the configutation network of the ISC locations; this inturn will improve specialised ISC datasets (e.g., ISC-EHB, GT and ISC-GEM) and offer an even denser
dataset to ISC users (e.g., for tomographic studies).
References:
IRIS OBSIP (2011): Cascadia Initiative Community Experiment - OBS Component. International Federationof Digital Seismograph Networks. Other/Seismic Network. doi:10.7914/SN/7D_2011

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*S01-P-08
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

The current status of the ISC Bulletin* Elizabeth Entwistle , Rose Hulin , Blessing Shumba , Rebecca Verney , Jennifer Weston , Elizabeth Ayres ,James Harris , Dmitry Storchak , Lonn Brown , Kathrin Lieser , Edith Korger
International Seismological Centre, Thatcham, United Kingdom
The International Seismological Centre (ISC) is a non-governmental, non-profit-making organization fundedby 69 research and operational institutions in 45 countries around the world and several sponsors from thepublic and commercial sectors. The ISC's primary role is the production of the Bulletin – the definitive
summary of global seismicity from 1904 till present, based on reports from over 130 seismic networks
worldwide.
The historical part of the Bulletin (pre-1964) now contains seismic arrival times at stations from theInternational Seismological Summaries (ISS) and from individual station bulletins digitized as part of the
ISC-GEM project. The modern part (post-1964) is currently being re-worked under the Bulletin Rebuild
project: we re-compute ISC hypocentres using the ISC location algorithm and the ak135 velocity model,
and re-assess ISC-reported magnitudes making them more robust and reliable. We also collect andintegrate previously missing bulletins from permanent and temporary seismic networks, filling the gaps intime and space.
Hours to days after seismic event occurrence, the ISC Bulletin contains integrated preliminary reports fromnetworks that are substituted with final reports within 12-24 months. After review by ISC analysts,
preliminary data in the Bulletin are substituted with Reviewed, presently after ~36 months. With theintroduction of the new Visual Bulletin Analysis System, the time required for analyst review is set to
reduce.
ISC data are distributed via the ISC and several mirror websites, e.g., those at IRIS DMC, University ofTokyo, LLNL, China Earthquake Administration, CTBTO, and are available on a series of DVD-ROMs. We
also issue the printed Summary of the ISC Bulletin that gives information on the ISC, procedures and data
formats, analysis of incoming data and the data in the ISC Bulletin; as well as invited publications on
notable seismic events and history, and the status of individual seismic networks and their procedures.

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*S01-P-09
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Automatic classification and onset estimation of seismic P and S wave
signals recorded at local seismic network using artificial neural networks* Timo Tiira
University of Helsinki, Helsinki, Finland
Automatic detection and onset estimation of seismic P and S wave signals are essential in automatic
seismic event location systems. The problem of phase classification is studied by utilizing multiple
parameters of different types each computed in several frequency bands. P and S wave signals havefundamentally different polarization properties. The input parameters depending on signal polarization inthis study included rectilinearity, principal ellipticity, global polarization parameter, eigenresultants,
quadratic resultant and predicted coherency. Several statistical parameters were also used. They included
skewness, kurtosis and Jarque-Bera test. Variance in time of several of the parameters were added to the
input database. Different amplitude ratios were used also. Statistical parameters were computed separatelyfrom vertical and horizontal channels. All parameters were computed at 6 different frequency range andtime window combinations resulting 210 input parameters. The parameters were computed from 10634
seismic traces of local events creating 2.2M new time-series. Independent training, testing and validation
datasets selected from these time-series consisted ~1.5M inputs each. Artificial Neural Networks (ANN) area robust and efficient tool in classification using large amount of input parameters. A deep ANN with 4
hidden layers was used for classification of the P and S wave signals. Final validation showed that 98% of
signals were classified correctly. Magnitudes of the events are usually in range 1.5>ML>0.5 and event tostation distance less than 200 km. Similar method was applied to automatic onset estimation. The data set
was recorded in local seismic network on Botnian Bay coast, Finland. The network is collecting informationof microearthquakes in an area around a planned nuclear power plant.

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*S01-P-10
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

The use of seismic arrays in geodynamic monitoring of the East European
platform* Irina Sanina , Ivan Kitov , Margarita Nesterkina , Natalia Konstantinovskaya , Svetlana Kishkina
Institute of the Geospheres Dynamics of the Russian Academy of Scieces,Moscow,Russia
The Institute of the Dynamics of Geospheres (IDG) of the Russian Academy of Sciences (RAS) operates
several small-aperture seismic arrays, which are used in monitoring of the geodynamic regime of the East
European platform (EEP) for a decade. One permanent array MHVAR (“Mikhnevo") and four portable
arrays are equipped with 3-C seismometers improving their overall performance. Four from five arrays are
installed on thick sediments that may negatively affect their sensitivity. Nevertheless, since its inception in
2004, MHVAR has been demonstrating all advantages of array processing. It reduces the amplitudedetection threshold by a factor of 3 to 5 and respectively improves the seismological catalog issued by the
Geophysical Survey (GS) of RAS for the EEP. In routine processing, beamforming enhances detection of Pand S-waves from near regional (ML>1.5) and teleseismic (mb>4.5) events. Within the EEP, mining blasts
generate a bigger part of detected signals, and the method of waveform cross correlation (WCC) is optimalfor detection and identification of repeating signals. The WCC is also suitable for the study of natural
seismicity and related tectonic and geodynamic processes. For example, we used WCC to recover 12
aftershocks of the mb4.9 earthquake, which occurred on August 7, 2016 near the town of Mariupol. For
this, we merged data from two IDG arrays and three primary stations (AKASG, BRTR, and KBZ) of theInternational Monitoring System. A similar station configuration was successfully used to detect andidentify dozens of mines and quarries within the EEP. Overall, the combine use of seismic arrays and the
WCC method enhances the effectiveness of artificial events identification, reduces the threshold of seismic
catalogue completeness, and improves the accuracy of relative location and magnitude estimation mostimportant for correct tectonic interpretation of natural seismicity.

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*S01-P-11
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Development of JAMSTEC Ocean-bottom Seismology Database (J-SEIS) to
download DONET Event Data and Borehole Continuous Data (4)* Hiroki Horikawa 1) , Kentaro Sueki 1) , Kensuke Suzuki 1) , Eiichiro Araki 1) , Akira Sonoda 1) , Narumi
Takahashi 1) 2) , Seiji Tsuboi 1)
JAMSTEC, Kanagawa, Japan 1) , NIED, Ibaraki, Japan 2)
Japan Agency for Marine-Earth Science and Technology (JAMSTEC) have developed a database of seismic
data observed in the Nakao Trough in southwest Japan. We have operated JAMSTEC Ocean-bottom
Seismology Database (J-SEIS)* for research and education since April 2016.
J-SEIS is download system of seismic waveform data, the downloadable data are continuous data of LongTerm Borehole Monitoring System (LTBMS) and event data of DONET (Dense Ocean-floor Network System
for Earthquake and Tsunamis).
During IODP Exp. 332 in December 2010, the first LTBMS was installed into the borehole site
(C0002:KMDB1) located 80 km off the Kii Peninsula, 1938 m water depth in the Nankai Trough.
Furthermore, During IODP Exp. 365 in 2016, the second LTBMS was installed into the borehole site
(C0010:KMDB2) located sea area off the Kii Peninsula. It consists of various sensors in the borehole suchas a broadband seismometer, a tiltmeter, a strainmeter, geophones and accelerometer, thermometer arrayas well as pressure ports for pore-fluid pressure monitoring. The signal from sensors is transmitted to
DONET in real time. J-SEIS allows users to download seismic waveform data as continuous data of SEED
format.
Event data consists of strong motion (EH type) and broadband (BH type) seismograph data observed at
DONET1, it is produced referring to event catalogues from USGS and JMA (Japan Meteorological Agency),
Magnitude greater than 6 for far-filed and greater than 4 for local seismicity, respectively. This systemallows users to download these seismic waveform data as event data of SEED format.
J-SEIS allows users to download continuous and event data on the graphical user Interface. Further, it isalso possible to download directly seismic continuous data by specifying parameters (terms, channel, andstation) of URL address (e.g. data download page like “Web Service" of IRIS).
* J-SEIS : JAMSTEC Ocean-bottom Seismology Database
URL https://join-web.jamstec.go.jp/join-portal/en/

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*S01-P-12
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Very wide observation range of the developed borehole stress meter andcomparison with STS seismometer* Hiroshi Ishii , Muneyoshi Furumoto , Yasuhiro Asai
Tono Research Institute of Earthquake Science, Association for the Development of Earhquake Prediction,
Mizunami City, Gifu Pref., Japan
We have developed a stress meter which can record continuous stress variation in a deep underground.
The Tohoku earthquake (M9.0) occurred on 11 March 2011 in Pacific Ocean. The stress meters operatedby Tono Research Institute of Earthquake Science (TRIES) could beautifully record whole wave forms
caused by the earthquake. The stress meters can respond from DC frequency. However, almost all of STS
seismometers in Japan scaled out and could not record larger amplitudes of the wave forms. It is importantto record long period seismograms for especially earthquakes happened in sea for estimating occurrence oflarge Tsunami. Therefore, we compared observation ranges among STS seismometer, stress meter andstrain meter. We also investigated how large amplitude variations can be observed by stress meter andstrain meter and characteristics of the meters. The main results obtained are as follows:
1. Vertical component of the stress meter of TOS borehole station (depth: 512m) recorded maximum
amplitude of about 300kPa for the 2011 Tohoku earthquake. However, the stress meter can record
amplitude of about 5 MPa for even high sensitivity setting up.
2. Stress meter and strain meter for even high sensitivity setting up have as 10 times wider observation
range than that of STS seismometers.
.
3. The stress meter can observe not only stress but also strain. And observation range of strain meters areabout 2x10^-4 , though maximum amplitudes of observed strain were about 5x10^-5.
4. The stress meter developed by us makes use of estimating Tsunami generation, determining magnitude
and research of earthquake generation because it can record whole stress seismogram without scaling out
even for gigantic earthquake.

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*S01-P-13
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

High-frequency geophone with correction scheme for mine explosion
monitoring* Alina Besedina 1) , Yaroslav Denisenko 2) , Evgeny Vinogradov 1)
Institute of geospheres dynamics 1) , Moscow institute of physics and technology 2)
The paper reviews correction method of frequency response of high frequency geophones: the method ofmultiplying the transfer sensor functions with the transfer function of correction filter of the 2nd order. Thismethod broadens geophone's response function from 10 Hz to 0.8 Hz that was proved by shake table
experiments: self-resonant frequency of the geophone with correction device was found as 0.8 Hz withsensitivity 19 V/(m/s) that corresponds to 3 dB.
In case of micro-seismic noise studying this scheme appeared proper to broaden lower edge of response
function of geophone GS-20DX from 10 Hz to 2 Hz for signals of different amplitudes. If signal amplitude
exceeds local noise level it's possible to register signals with the frequency down to 0.8 Hz (as shown inshake table experiments).
Correction scheme field tests were carried out on the base of mining bursts monitoring. We comparedrecords of the short-period seismometer (0.5-40 Hz) and the geophone with correction scheme (0.8-40 Hz)
that had been registered during summer 2016. Gained data are compliant.
Application of described scheme for low-aperture arrays can significantly decrease equipment cost for
proper frequency range.
This work was supported by the Russian Foundation for Basic Research (project no. 16-35-00508).

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*S01-P-14
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

RESIF Seismology Distributed System : Data and Services.
* Catherine Pequegnat 1) , Working GroupGroup RESIF SI- 2)
Institut des Sciences de la Terre, CNRS, Universite Grenoble Alpes (ISTerre) 1) , Centre National de laRecherche Scientifique and RESIF Consortium 2)
RESIF (Reseau Sismologique et Geodesique Francais DOI:10.17616/R37Q06 ) is a nationwide French
project aimed at building a high quality observation system to observe and understand the inner earth.
RESIF seismic component deals with permanent and mobile seismic networks data, including dense/semidense arrays. Its goals are to create a
network throughout mainland France comprising 750 seismometers and geodetic measurement
instruments, 250 of which will be mobile, and to distribute all seismic and geodetic data acquired by
French reasearch institutions. RESIF seismology project is distributed among six different nodes providing
real-time and qualified data and metadata to themain data centre in Universite Grenoble Alpes, France. A web portal allows to explore and download
seismic data and metadata. RESIF is fully integrated into the much wider European scale project EPOS.
Data control and qualification is performed by each individual nodes. The poster will provide insights on
the validation process of seismic data with two examples from volcanological and seismologicalobservatories as well as dense networks from the mobile component of RESIF. We will also present tools
developed to monitor stations, to collectand to format metadata; currently used by operators of permanent broadband stations.
In addition, will then present data that has been recently made publicly available (mobile broadband
networks in the
Alps the Pyrenees, and Antarctica). Data from RESIF is distributed through worldwide FDSN and European
EIDA
standard protocols.

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*S01-P-15
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Data quality Improvement of the Algerian Digital Seismic Network (ADSN)* AZOUAOU ALILI , ABDELKARIM YELLES-CHAOUCHE , MOHAMED OUAKEDI , HAMOUD BELDJOUDI, ABDELAZIZ KHERROUBI , IZEDDINE AMEURCRAAG, Algiers, Algeria
The performance of a seismic network is linked with the quality and number of its stations. In Algeria, inorder to implement a high quality network (ADSN), site selection and installation remain crucial taking into
account many environmental aspects as security, radio link connections…etc.
From a database of seismic records collected from 2008 to 2016, an analysis year by year of the quality
parameters of the several stations was carried out taking into account also the season's factor.
To monitor quality of the ADSN (Algerian Digital Seismic Network) stations, the noise level background ischaracterized for each station. The study includes seasonal and diurnal variations. Actually a web
monitoring page help to control stations involved in the event location. A mobile application is also
developed to different end users information relative of seismic events occurrence. In other hand, several
technical works are made daily to test quality of the ADSN stations and to enhance the correct automatic
event location. Among these tasks, state of health and rate of operation monitoring, seismometers andrecorder calibration and sites selection for new broadband stations.
For nearby future, we plan to integrate existing stations and install new seismological stations for dams
monitoring. Finally GIS (Geographic Information system) is set to manage the operation of our rapid
warning system.

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*S01-P-16
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Design and Implementation of the National Seismic Monitoring Network in
the Kingdom of Bhutan* Shiro Ohmi 1) , Hiroshi Inoue 2) , Jamyang Chophel 3) , Phuntso Pelgay 3) , Dowchu Drukpa 3)
Kyoto University, Kyoto, Japan 1) , National Research Institute for Earth Science and Disaster Prevention,
Tsukuba, Japan 2) , Department of Geology and Mines, Ministry of Economic Affairs, Thimphu, Bhutan 3)
Bhutan-Himalayan district is located along the plate collision zone between Indian and Eurasian plates,
which is one of the most seismically active region in the world. Recent earthquakes such as M7.8 Nepal
earthquake in April 25, 2015 and M6.7 Imphal, India earthquake in January 3, 2016 are examples of felt
earthquakes in Bhutan. However, there is no seismic monitoring system ever established in Bhutan, whose
territory is in the center of the Bhutan-Himalayan region.
In this project, we are establishing the first national permanent seismic monitoring network in the Kingdomof Bhutan that is utilized for not only for seismic disaster mitigation of the country but also for studying theseismotectonics in the Bhutan-Himalayan region which is not yet precisely revealed due to the lack ofobservation data in the past.
We started establishing permanent seismic monitoring network of minimum requirements which iscomposed of six (6) observation stations in Bhutan with short period high sensitivity and strong motion
seismometers as well as three (3) broad-band seismometers. Obtained data are transmitted to the central
processing computers in the DGM (Department of Geology and Mines, Ministry of Economic Affairs) officein Thimphu. In this project, DGM will construct seismic vault with their own budget which is approved as
the World Bank project, and Japan team assists the DGM for site survey of observation site, designing theobservation vault, and designing the data telemetry system as well as providing instruments for theobservation such as seismometers and digitizers.
We already started the operation of the five (5) stations out of six (6) located in Thimphu, the capital city,and other four (4) stations in Bumthang, Trashigang, Samtse, and Gelephu, and will soon start operation in
Samdrup Jongkhar. We also deployed two offline seismic stations with short period seismometers in Gasa
(Northern Bhutan) and Wangdu (Central) to assist permanent seismic network.

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*S01-P-17
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

New steps towards local seismic hazard assessment of Bucharest (Romania)* Elena Manea 1) , Clotaire Michel 2) , Manuel Hobiger 2) , Valerio Poggi 3) , Donat Fah 2) , Alexandru
Marmureanu 1) , Carmen Cioflan 1)
National Institute for Earth Physics, Calugareni, 12, Magurele, Ilfov, Romania 1) , Swiss Seismological
Service, ETH Zurich, Zurich, Switzerland 2) , Global Earthquake Model Foundation, Via Ferrata 1, Pavia,
Italy 3)
Bucharest, the capital of Romania, is affected by strong intermediate-depth earthquakes originating in the
Vrancea seismic area. Bucharest is located in the the Moesian Platform, a large sedimentary basin (450 by
300 km) that reaches 20 km deep. Intensities up to VIII-IX have been reported in the city after four
earthquakes with Mw>7 in the last century. The recorded ground motion is characterized by predominantlong periods and has been interpreted as the combined effect of source mechanism and local geologicalconditions.
In order to better understand the effects of the geological structure beneath Bucharest, non-invasive
geophysical techniques have been applied on seismic recordings (single-station and array) of both ambient
vibrations and low-magnitude earthquakes. Using a 35 km diameter array of broadband seismometers, weanalyzed the surface-wave field at very low frequencies (0.05 – 1 Hz). Estimates of Love and Rayleigh wave
dispersion curves (fundamental and higher modes) and Rayleigh wave ellipticity were first retrieved andanalyzed. In addition, the variation of the SH-wave fundamental frequency of resonance was mapped
across the area. This information has been used together with the available borehole logs (<300 m) andgeological interpretations of deep structures to characterize the shear-wave velocity structure down to 7 kmof depth and to create a comprehensive 3D geophysical model of the basin underlying Bucharest.
Finally, we investigated the contributions of different seismic surface waves, such as those produced at theedges of the basin or by multipath interference (Airy phases of Love and Rayleigh waves), using the arrayprocessing technique MUSIQUE. We focused on frequencies between 0.1 and 1 Hz to better understandthe complex nature of the H/V ratios in this range.
The results represent the starting point to simulate past strong events and will be further used to estimate
the expected ground motion for different earthquake scenarios.

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*S01-P-18
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Seismic Activity in the Central Tottori prefecture, Japan, with an M6.6
earthquake on October 21, 2016 analyzed by the Matched Filter Method* Shiro OHMI
Kyoto University, Kyoto, Japan
Seismic activity in the central Tottori prefecture, southwest Japan was analyzed by using the Matched Filter
Method (MFM). This swarm activity started with an M6.6 event on October 21, 2016. In this analysis, we
implemented MFM as a pseudo-automatic hypocenter determination system that enables to locate
earthquakes one by one. Our interest is if the MFM is a useful tool for immediate grasp of an ongoing
intense swarm activity.
In the MFM analysis, selection of the template earthquakes is important since the spatial distance andmagnitude difference among the template earthquakes affect the detectivity of earthquakes. For thispurpose, we separately implemented the conventional event detection algorithm using STA/LTA to detect
possible template earthquake in order to configure a set of template earthquakes. In the current analysis,
we inspected the candidate earthquakes to select a new template whose spatial distance is greater than 2.5
km and magnitude difference is greater than 1.0 among existing templates. We repeated this procedure
during 17 days from October 21 to November 7 to select a set of templates and finally selected 37 template
earthquakes in this manner in the test period. When we obtained a new template, all the continuous recordin the test period are scanned by the new template to detect new earthquakes.
During the test period of 17 days, about 7,000 earthquakes are detected and located with 37 templates.
Comparison with manually inspected catalogue provided by JMA (Japan Meteorological Agency) indicatesthat the configuration of earthquake clusters well coincide with each other with slight differences and it
was useful to understand the outline of the activity in the early stage. Although the manually inspectedcatalogue data is essential for the precise evaluation of a seismic activity, we suppose MFM is one of thepowerful tools for an immediate grasp of the ongoing intense swarm activity.

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*S01-P-19
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

The seismic sequence of the magnitude 5.7 crustal earthquake of 2014 of
Focsani Basin (Romania) – relevant data regarding the stress field in front of
the Southeastern Carpathians bend
Andreea Craiu , * Luminita Angela Ardeleanu , Marius Craiu , Mihail Diaconescu
National Institute for Earth Physics, Bucharest, Romania
The seismic sequence of the crustal earthquake which occurred on November 22, 2014 in Focsani Basin is
the strongest seismic energy release in front of the Southeastern Carpathians bend since 1900. The main
shock with local magnitude 5.7 is the largest instrumentally recorded event in the region. Its aftershock
sequence lasted about 70 days, more than 250 earthquakes with local magnitude > 0.1 were localizedusing the records collected by the Romanian seismic network.
The sequence occurred in the lower crust – the depth of the main shock was 40 km and the majority of theaftershocks had depths greater than 25 km – in the Focsani Basin (part of the Moesian Platform), nearby
the contact point of three important tectonic units: the Scythian Platform, the Moesian Platform and theNorth Dobrogea Promontory. The epicenter distribution – along a NNE-SSW direction – follows theorientation of the Carpathian arc.
We present the detailed space-time evolution of the seismic energy release and determine the focal
mechanism of the largest shocks, for which reliable P-wave polarity data are available – 11 events with local
magnitude > 2.5.
The fault plane solution of the mainshock shows normal faulting with a dominant dip-slip component; thenodal planes are oriented SE-NW. Similar mechanisms are obtained for the strongest aftershocks – 2 eventswith local magnitudes above 4. Although a certain variability of the fault plane solutions of the weaker
events is observed, the normal faulting dominates among the retrieved focal mechanisms.

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*S01-P-20
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Distribution of deep earthquakes in the subducting Pacific slab beneathJapan* Ayako Tsuchiyama 1) , Junichi Nakajima 1) , Toru Matsuzawa 2)
Tokyo Institute of Technology, Tokyo, Japan 1) , Tohoku University, Miyagi, Japan 2)
Generally, the number of earthquakes in slabs decreases with depth. However, the seismicity increases
again in a depth range of 400–500 km. The mechanism of this phenomenon remains poorly understood,
even though many hypotheses for the genesis of deep earthquakes have been proposed, which include
dehydration-embrittlement hypothesis, transformational faulting, and shear instability. In this study, we
analyzed 93 deep earthquakes (M≥3.0) that occurred at depths of >300 km beneath Tokai area in Japan tounderstand factors that control the high seismic activity in the mantle transition zone.
First, we read P-wave polarities and determined focal mechanism solutions of earthquakes. Then, we
picked arrival times of both P and S waves and relocated hypocenters by using double-difference
earthquake relocation algorithm (Waldhauser and Ellsworth, 2000). The relocated hypocenters do not show
a double-planed seismicity as is observed in Iidaka and Furukawa (1994). In the next step, we will relocate
hypocenters with differential travel-time data derived from waveform cross correlations and constrain
hypocenter locations with high accuracy. We will present detailed hypocenter distributions together withfocal mechanism solutions, and discuss a plausible mechanism that facilitates deep earthquakes in the
mantle transition zone.

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*S01-P-21
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

The McAdam, New Brunswick Earthquake Swarms of 2012 and 2015-16:
Extremely Shallow, Natural Events
Allison Bent 1) , Stephen Halchuk 1) , Veronika Peci 1) , Karl Butler 2) , Kenneth Burke 2) , * John Adams 1) ,Nawa Dahal 3) , Sylvia Hayek 1)
Geological Survey of Canada, Ottawa, Canada 1) , Department of Earth Sciences, University of New
Brunswick,Fredericton, Canada 2) , Weston Observatory, Boston College, Weston, United States of America
3)

Beginning in March 2012 people in McAdam, New Brunswick felt and/or heard many earthquakes within a
1x2 km area of the village. The largest events (MN < 2.6) were recorded by regional seismographs (closest
was 65 km away). Public concern combined with the large number of events and their localization led the
Geological Survey of Canada (GSC) to deploy 3 temporary instruments in McAdam. The University of New
Brunswick provided a fourth. The instruments remained in place for several months and were thenremoved, as activity had largely died off by June 2012. There was a short resurgence late in 2015 with 7
felt events occurring 7-9 December. In February 2016, the swarm activity picked up considerably. In lightof the increased activity, which included the largest earthquake of the sequence (MN 3.3 on 9 February2016) the GSC redeployed 4 instruments which remained in place for several months until the activity
again subsided. As of 1 November 2016, 164 earthquakes were located, some by enough stations to allow
precise depth determination by one or more methods. All the earthquakes were extremely shallow, 0.0-1.2
km. The majority of epicenters lie in a WNW-ESE trending ellipse. Focal mechanisms determined for asmall number of events are largely consistent with NE-SW compression and with regional earthquakes.
Sixty-eight of the events were reported as felt, with several of the felt events being of magnitude less than
1.0. A strong motion recorder recorded a PGA of 9%g from an MN 1.7 earthquake at about 0.8 km
hypocentral distance. There was no human activity that could have induced or triggered the swarm, and thecause remains unexplained. McAdam sits on Silurian metasediments intruded by the granitic Pokiok
Batholith exposed just to the NW. No faults are mapped close to McAdam, but the events might haveoccurred on a NW-SE splay of the Fredericton Fault. Swarms like this are probably common in eastern
Canada, but are seldom this well reported or recorded.

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*S01-P-22
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Depth of earthquakes in Greenland* P. H. Voss , T. B. Larsen , T. Dahl-Jensen
Geological Survey of Denmark and Greenland, Copenhagen , Denmark
Even though earthquake monitoring in Greenland has been carried out almost continuously for nearly 90
years, the depth of earthquakes occurring in Greenland are poorly known. For most of the monitoring
period the seismic network in Greenland have included only four or less seismic stations, which is a very
limiting factor in earthquake depth determination, especially taking the size of Greenland (more than 2
million km2) into account. Except for the few earthquakes that has been teleseismicly observed, depth
determination based on the seismic network in Greenland, has been highly uncertain. However, with theinitiation of the GLISN project (Greenland Ice Sheet Monitoring Network) (http://glisn.info/) in 2009, thenumber of seismic stations has increased, so that there today are 21 seismic stations in operation inGreenland all with realtime data connections. GLISN is mainly in operation for the observation of cryoseismic phenomenas, but it provide a significant contribution to the recording of earthquakes. Here we will
present our first results on the depth distribution of earthquakes in Greenland, our focus is mainly on theseven most active regions, identified along the coast areas, but depth of earthquakes occurring below theGreenland ice sheet are also presented.

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*S01-P-23
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S01. Open session

Mw 5.5 Gyeongju Earthquake of 12 September 2016 in Southeastern Korea:
SCR Earthquake Sequence with Moderate Stress Drop
* Won-Young Kim 1) , Yomggyu Ryoo 2)
Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, U.S.A. 1) , Earthquake &Volcano Monitoring Center, Korea Meteorological Administration, Republic of Korea 2)
On 12 September 2016 a Mw 5.5 earthquake occurred about 10 km South-Southwest of the ancient capital
town of Gyeongju on the southeastern Korean peninsula. The mainshock was preceded by a Mw 5.0
foreshock by about 50 minutes and was followed by over 580 earthquakes with magnitude greater than 1.5
within the first 5 months. The 2016 Gyeongju earthquake is the largest instrumentally recorded earthquake
on Korean peninsula. Accurate relocation of the earthquake sequence revealed that earthquakes arealigned along NNE – SSW trending, steeply dipping fault plane (dip=74º) with depth range from 13 to 17
km. Focal mechanism of the foreshock, mainshock and the largest aftershock, vertical strike-slip fault at
depth, suggests that the event represents reactivation of buried high-angle faults in the Precambrianbasement by the contemporary E–ENE trending regional horizontal compressive stress. Strike of the fault
plane(s) of the 2016 Gyeongju earthquake sequence is consistent with the clearly developed NNE–SSW
trending lineaments in southeastern Korea, which were formed at the end of Tertiary during an orogeny
involving opening of East Sea of Korea (Japan Sea) to the east. The mainshock shows a static stress drop of~10 MPa, which is somewhat lower than other similar earthquakes around the area. The Mw 4.6 Odaesan
earthquake in 2007 that occurred about 200 km north of the Gyeongju sequence yielded a stress drop of
20 MPa. Low stress drops of a few MPa are reported for the earthquakes in the Yellow Sea region about
400 km west of the Gyeongju sequence. We compare stress drops of earthquakes in southern Korea withthose of other SCR regions such as Virginia and Oklahoma, USA.

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*S02-1-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Insights into faults, crustal permeability, state of stress and earthquake
physics from induced earthquakes in Oklahoma and southern Kansas* William Ellsworth 1) , Gregory Beroza 1) , Yihe Huang 2) , Cornelius Langenbruch 1) , Martin Schoenball 1) ,Rall Walsh 1) , Matthew Weingarten 1) , Nana Yoshimitsu 1) , Mark D. Zoback 1)
Stanford University, California, USA 1) , University of Michigan, Ann Arbor, Michigan, USA 2)
A large region of north-central Oklahoma and southern Kansas in the central U. S. became seismically
active starting in 2009. The earthquakes followed the initiation of high volume wastewater disposal by deep
injection from newly developed unconventional oil fields and are understood to be primarily aconsequence of disposal. These oil fields produce many times more water than oil, which is uneconomic todispose of except by injection. To date, more than 700 deep disposal wells have injected one billion m3 ofprimarily co-produced water in to the highly permeable Arbuckle formation near the base of thesedimentary section. Owing to its high permeability (~1 Darcy), the pressure perturbation from individual
wells merges into a low-pressure plume (< 1 MPa) spreading across a region that today covers more than
20,000 km2. This relatively small perturbation has activated hundreds of previously unknown basement
faults in more than 1500 M >= 3 earthquakes, including the September 2016 Mw 5.8 Pawnee earthquake.
These earthquakes characteristically occur on strike slip or normal faults that are near-optimally oriented
for failure in the contemporary stress field. Seismicity on each fault characteristically initiates with small
events before the occurrence of the largest in the sequence. Stress drops for the largest events average 10
MPa, releasing tectonic stress in what was previously an almost completely aseismic region. Consequently,
parts of the crust where earthquakes occur must be near a state of failure equilibrium between the strengthof the faults and the stress carried in the North American plate. In response to the seismicity crisis,
regulators have mandated large reductions in fluid injection into the Arbuckle formation beginning in
mid-2016. Seismicity rates are now falling in the region in response to this change; however, it may be
years before the earthquake hazard returns to historic levels.

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*S02-1-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Trigger effects in the development of induced seismicity and the influence ofhuman being over the natural seismicity of Kuzbass and Baikal regions of
Russia* Victor Seleznev 1) 2) , Aleksey Bryksin 2) , Aleksey Emanov 3) , Aleksandr Emanov 3) , Ekaterina Leskova 3) ,Aleksandr Fateev 3)
Geophysical Survey of the Russian Academy of Sciences, Obninsk, Russia 1) , Seismological Branch ofGeophysical Survey of the Russian Academy of Sciences, Novosibirsk, Russia 2) , Altai—Sayan Branch ofGeophysical Survey of the Russian Academy of Sciences, Novosibirsk, Russia 3)
The upgrowth of induced seismicity near excavations and trigger effects of anthropogenic factors impacting
it was studied on the base of experimental data collected by temporary seismological networks placed nearcoal mines. Experiments were conducted near four coal mines in Kuzbass with different geotectonic
conditions. These experiments proved the considerable contribution of powerful mining equipment
vibrational loading to the anthropogenic seismicity process. In all cases while seismological networks wereplaced near excavations with powerful mining equipment, we observed seismic activizations accompanying
the mining process. It would be sufficiently reasonable to state that high-production coal mining equipment
works at the same time as a powerful vibrational source in subsurface and together with changes in fluid
conditions could form pronounced induced seismicity near excavations. The appearance or disappearanceof vibration exert influence on seismic conditions of activated area practically immediately. The qualitative
assessment, based on the data of seismic events catalogue of Altay-Sayan region, of the influence of humanactivity on natural seismicity in designated areas is constructed. Local intervention in natural processes on
examples of carrying out of industrial explosions at open-cast mining in Kuzbas and operation of a site of
the railway along coast of lake Baikal is investigated. Gutenberg-Richter plots (GR-plots) are built forvarious samples of seismic events on time for Kuzbas region and variations of "b-value" are shown, which
depends on time of observation (temporal). Also GR-plots are constructed for various strips along therailway near Baikal lake and the change in 'b-value" is discussed, which depends on offset from the railway(spatial). Finally the experiment with powerful vibration exciter is considered and the hypothesis ofdischarging effect of powerful influences on short distances is setting up.

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*S02-1-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Source parameters of the 2014 M5.5 Orkney earthquake sequence, South
Africa, estimated by using near-field underground seismic arrays in goldmines
* Kazutoshi Imanishi 1) , Hiroshi Ogasawara 2) , Yasuo Yabe 3) , Shigeki Horiuchi 4) , Makoto Okubo 5) ,Osamu Murakami 6)
Geological Survey of Japan, AIST, Tsukuba, Japan 1) , Ritsumeikan University, Kusatsu, Japan 2) , Tohoku
University, Sendai, Japan 3) , Home Seismometer Corporation, Shirakawa, Japan 4) , Kochi University,
Kochi, Japan 5) , Tono Research Institute of Earthquake Science, Association for the Development ofEarthquake Prediction, Mizunami, Japan 6)
The M5.5 Orkney earthquake occurred on August 5, 2014, near Orkney town, South Africa. The mainshock
and aftershocks were recorded by underground arrays in gold mines, which are composed of 46 threecomponent geophones installed at 2-3 km depths. The sampling rate is 6 kHz. The observed waveforms
display high signal-to-noise ratios and contain high frequency components up to at least 1 kHz, providing
us an unprecedented opportunity for precise determination of aftershock distribution and source
parameters. We determined hypocenters of 2000+ earthquakes from 4 August to 31 October 2014 byautomatic earthquake location software from Home Seismometer Corp. (Horiuchi et al., 2011). Aftershocks
distribute at a depth range of 4–7 km and form a 8 km-long near-vertical plane in the NNW-SSE direction.
This distribution agrees with the mainshock focal mechanism (left lateral strike-slip faulting). We also
determined 500+ aftershock focal mechanisms by using P-wave polarity data as well as body wave
amplitudes, where almost all aftershocks could be explained by a double-couple solution. Stress tensor
inversion reveals that strike-slip faulting with a NW-SE compression prevails throughout the region, which
differs from the stress state on the mining levels (e.g., Ogasawara et al., 2012, 2013) but explains theoccurrence of the mainshock. We also found that normal-faulting stress fields prevail around the southernpart of the aftershock distribution, where low stress drop aftershocks are also prominent (Kazuki Sato BSc
thesis, Ritsumei University). We infer that the mainshock terminated at the area where the stress field isdifferent from the mainshock area and the stress level is low.
Acknowledgements. The seismic network developed by Inst. Mine Seismol. Ltd (IMS) used in this study isoperated and maintained by Anglogold Ashanti Ltd (AGA) and Open House Management Solutions Ltd.
The data processing was performed by IMS. The data is owned by AGA.

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*S02-1-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

State of the art in 3D reflection seismic interpretation: New insights into acomplex structural architecture in the vicinity of Orkney M5.5 event, South
Africa* Musa Manzi 1) , Hiroyuki Ogasawara 2) , Raymond Durrheim 1) , Hiroshi Ogasawara 2) , Tullis Onstott 3) ,Artur Cichowicz 4)
University of the Witwatersrand, Johannesburg, South Africa 1) , Ritsumeikan University, Kusatsu, Japan 2) ,Princeton University, New Jersey, USA 3) , CGS, Pretoria, South Africa 4)
In August 2014, the M5.5 earthquake occurred in the Precambrian rocks of the Witwatersrand Basin, South
Africa. The M5.5 mechanism was strike-slip faulting, which is different to a typical mine induced
earthquake with normal-faulting. It is suggested that M5.5 was caused by dyke several hundreds of meters
below the mining horizon. To better understand the structural complexity associated with the M5.5 and its
aftershocks, we have processed and interpreted the high-resolution 3D reflection seismic data that wereacquired in 2012 for gold exploration. A number of aftershocks fall within the 3D seismic volume providing
unique opportunity to directly correlate structures mapped by seismics with the location of the aftershocks.
It is envisioned that good seismic mapping of the shale units (4 - 7 km depths) and their associatedstructures would help to better understand the region's structural framework and to constrain the timing ofactivity of the faults.
The main outcome of the seismic interpretation has been an improved understanding of the complex
structural architecture in the area. In particular, seismics has mapped normal (500 m maximum throw),north-northeast trending major faults and their subordinate structures. Faults are listric in form; dipping
relatively steeply (65 - 70 deg.) at 1.5 - 2.5 km below the surface. At greater depths (4 - 5 km), below mining
horizons, the dip decreases to about 40 to 50 deg. The seismic sections also exhibit the near-verticalfeatures characterized by high amplitude attenuation associated with fault zones. These features crosscut,
but do not displace, the entire stratigraphy of the basin. We interpret these near-vertical features as dykes
with thickness from 1 m to 30 m, which may be possible sources of the M5.5 event.
It is, therefore, important to integrate the reflection seismic interpretation with the seismicity data so as tobetter understand the geometric nature of the structures associated with the M5.5 event.

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*S02-1-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Rupture Process of the 2014 Orkney Earthquake, South Africa* Makoto OKUBO 1) , Artur Cichowicz 2) , Hiroshi Ogasawara 3) 2) , Osamu Murakami 4) 2) , Shigeki Horiuchi
5)

Kochi University, Kochi, Japan 1) , JST-JICA SATREPS, Tokyo, Japan 2) , Ritsumeikan University, Kusatsu,
Japan 3) , Tono Research Institute of Earthquake Science, Association for the Development of Earthquake
Prediction, Mizunami, Japan 4) , Home Seismometer Corporation, Shirakawa, Japan 5)
An earthquake occurred at 10:22:33 UT on 5 August 2014 in the Klerksdorp district, the North Westprovince of South Africa. This epicenter locates beneath Orkney town, which has 10 more than gold mines.
The Council for Geoscience (CGS) in South Africa reported that the magnitude and depth was ML5.5 and4.7 km, respectively. CGS have operated 17 seismic accleration observations on surface, and continuous
acceleration seismograms were obtained at the time of the 2014 Orkney earthquake and following
aftershocks. In this study, we analyzed the main shock rupture processof this earthquake, by using theseaccelation seismograms. First, we analyzed seismograms of mainshocks, found the initial rupture before
main shock. That initial rupture has occured 0.3 sec before mainshock with a magnitude less than 4. By
operating detailed aftershock distribution analysis, we found most of aftershocks occured surrounding
mainshock and a seismic gap between aftershocks and goldmine blastings. Finally, to understand rupture
process of the main shock, we surveyed for strong motion generating area (SMGA) by appling Isochrone
backprojection method (IBM) to the mainshock's waveforms. SMGA distribution will fill the vacant space of
the aftershocks distribution and main shock (initial rupture) hypocenter.

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*S02-2-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Reservoir-Triggered Seismicity in Brazil: characteristics and new cases
Lucas Barros 1) , * Marcelo Assumpcao 2) , Juraci Carvalho 1) , Luiz Ribotta 3)
University of Brasilia, Brasilia, Brazil 1) , University of Sao Paulo - Sao Paulo -SP - Brazil 2) , The Institute ofTechnological Research of the SP State, Sao Paulo, Brazil 3)
We report here 26 cases of reservoir-triggered seismicity (RTS) in Brazil, emphasizing the cases observed in
the last ten years. In worldwide terms Brazil presents a relatively high number of RTS. Nevertheless, if we
consider the Brazilian high number of reservoirs with power to produce RTS this number is not so
expressive. Not differently of the rest of the world, in Brazil the interest for the RTS subject began aroundthe 70s when the first case had been identified (3.7 mb and V-VI(MM).
Studies on RTS in Brazil have been made there about 40 years ago, by the universities of Brasilia, Sao
Paulo, Rio Grande do Norte and the Technological Research Institute of the State of Sao Paulo in
partnership mainly with the national energy companies. In the middle of the 70´s initiated the reservoir
seismographic monitoring and nowadays almost all the largest Brazilian reservoirs have seismic stations
installed around them.
Two magnitudes 4 RTS earthquakes were observed, the biggest 4.2mb intensity (MM) VI-VII. About 80
percent of the RTS cases present initial seismicity, and the rest with delayed response with some cases
having more than one main event. In Brazil, many cases of RTS exhibit a series of common characteristics.
Furthermore, the magnitude of triggered event is not directly proportional to the depth of the water column
or on the total volume of the reservoir, although, the triggered seismic activity has been more common inreservoirs with depth > 100 m (about a half of these reservoirs presented RTS). However, there arereservoirs that are higher than 100 meters that never had presented RTS and others with height less than
50 m with expressive triggered seismicity. Therefore, there is not a direct relationship between the
maximum magnitude of a triggered earthquake and the dam height and the volume of the reservoir.
In this work, we will present the Brazilian RTS cases and discuss its features, highlighting the new cases,
including that one´s not yet reported.

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*S02-2-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Hydrocarbon induced seismicity in Groningen, the Netherlands* Bernard Dost , Elmer Ruigrok , Jesper Spetzler
KNMI, de Bilt, the Netherlands
Since 2003 the dominant source of induced seismicity in the Netherlands is the Groningen gas field, one of
the largest on-shore gas fields in the world. Due to the shallow source depth, at 3 km, even small magnitude
events cause damage to buildings in the region. In 2012 the largest event, Ml 3.6, took place and more than
50000 damage claims were received by the mining company. Since 1995 a regional monitoring network is
in operation, which has recently been extended over the Groningen field. Presently, more than 75 boreholestrings with a maximum depth of 200 m and 90 surface accelerometers are operational. Since 2003 a newmining law is in place in the Netherlands, which requires for each gas field in production a seismic hazard
and risk analysis. At the same time an increase in the activity rate was observed in the Groningen field,
leading to the development of new hazard models and a re-assessment of parameters like the maximum
magnitude. Understanding the earthquake process is essential in taking mitigation measures. Continued
research is focused on reducing the uncertainties in the hazard and risk models. Key issues are thedevelopment of a site specific Ground Motion Model, improving the location accuracy of events, magnitudescaling and construction of a local shallow shear-wave velocity and Q model.

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*S02-2-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Integrated Petrographic, Geomechanical and Seismological studies ofrockmass behaviour during the final phase of ore extraction at Cooke 4 shaft
in South Africa* Siyanda mngadi 1) 6) , Raymond Durrheim 1) 6) , Halil Yilmaz 1) 6) , Musa Manzi 1) , Thabang Kgarume 2) 6) ,Jan Kuijpers 2) , Tony Ward 3) 6) , Dave Roberts 1) 3) 6) , Makoto Naoi 4) 6) , Hiroshi snr Ogasawara 5) 6) ,Akimasa Ishida 5)
The University of the Witwatersrand, Johannesburg, South Africa 1) , CSIR, Johannesburg, South Africa 2) ,Sibanye Gold, Johannesburg, South Africa 3) , Kyoto University, Kyoto, Japan 4) , Ritsumeikan University,
Kyoto, Japan 5) , JST-JICA Science and Technology Research Partnership for Sustainable Development(SATREPS), Pretoria, South Africa 6)
Seismic events, rockbursts and fault instabilities are prime concerns during the final phase of ore extraction
at the deep (>1km) Cooke 4 shaft in the West Rand gold mining district, South Africa. This research aims tounderstand the seismic and mechanical behavior of the rockmass during the shaft pillar extraction
operations by studying petrography, geomechanics and stress model, and to establish correlations with
monitored microseismicity and underground mapping. The composition of the shaft pillar, observed
through underground mapping and core sample analysis, was found to be quartzite, pebbly quartzite,
argillaceous quartzite and conglomerate. Forming the roof of the hangingwall is the Ventersdorp Contact
Reef (VCR) and Ventersdorp lavas, soft lavas. This affects the ore excavation operations and the stability ofthe pillar. Rock mechanical laboratory tests were restricted to rocks forming the shaft pillar, and the tests
showed that quartzite has the strongest uniaxial compressive strength (UCS), followed by pebbly quartzite,
argillaceous quartzite and lastly, meta-conglomerate, making quartzite the preferred rock type in pillars interms of strength. Different lithologies exhibited specific mining-induced fracturing patterns in the
hangingwall, mainly influenced by weak Ventersdorp lavas. Majority of microseismic events were found tobe associated with the mining fronts. These seismic clusters delineated Ortlepp shears forming ahead of thestope owing to the excavation-induced stress field. This interpretation is supported by undergrounddamage observations, stress model and ubiquitous discing in core samples. The acoustic emissions (AEs)were also concentrated in the vicinity of service excavations (tunnels). Some AE clusters were located awayfrom excavations, likely delineating faults. In conclusion, microseismicity is largely influenced by structural
discontinuities, ore extraction operations, and rock geomechanical properties in underground conditions.

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*S02-2-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Very small repeating earthquakes on a geological fault at 1-km depth in agold mine in South Africa* Makoto Naoi 1) , Junya Yamaguchi 1) , Masao Nakatani 2) , Hirokazu Moriya 3) , Toshihiro Igarashi 2) ,Thabang Kgarume 4) , Osamu Murakami 5) , Thabang Masakale 6) , Yasuo Yabe 3) , Kenshiro Otsuki 3) ,Hironori Kawakata 7) , Tsuyoshi Ishida 1) , Luiz Ribeiro 8) , Anthony Ward 8) , Raymond Durrheim 9) , Hiroshi
Ogasawara 7)
Kyoto University 1) , University of Tokyo 2) , Tohoku University 3) , Council for Scientific and Industrial
Research 4) , Tono Research Institute of Earthquake Science 5) , Open House Management Solutions 6) ,Ritsumeikan University 7) , SeismoGen Cc 8) , University of the Witwatersrand 9)
We deployed an Acoustic Emission (AE) monitoring network consisting of 30 very sensitive AE sensors
and 7 accelerometers at 1-km depth in the Cooke 4 gold mine in South Africa, where many earthquakes up
to ~M 3 were induced by stress buildup due to mining. Naoi et al. (2015) analyzed data obtained by the
network during a 2 month period, and found very small repeating earthquakes of –5.1 ≤Mw ≤–3.6 which
occurred in a region of ~100-m extent on a geological fault. When applied to those repeater sequences, theNadeau and Johnson (1998) empirical formula (NJ formula), which relates the amount of backgroundcreep and repeater activity and is well established for plate boundary faults, yielded an impossibly large
estimate of the background creep. This implies that the repeaters were produced more efficiently, for agiven amount of background creep, than predicted by the NJ formula.
In this study, we extended the analysis period to 14 months (from 7 April 2011 to 30 May 2012), andsearched for repeaters among 3735 events that occurred on the fault, on the basis of waveform similarity
and the proximity of their hypocenters relocated by the Double Difference method applied to relative traveltime accurately determined by cross correlation. Out of the 3735 events, 1572 events (42.1%) wereidentified as repeaters, which formed 360 groups. The largest group saw as many as 45 recurrences.
Activities of some groups continued for the whole 14 months, whereas some groups exhibited a decrease inmagnitude and disappeared eventually. We propose that the disappearance of the repeaters represents thedissipation of unstable patches of the fault, resulting from frictional wear of the contacts as fault creep
progresses.

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*S02-2-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Using empirical relationships to predict PPV for surface explosions* Michelle Grobbelaar
Council for Geoscience, Pretoria, South Africa
Demolition sites have always been located in very remote areas, but with the ever increasing number ofdwellings that are migrating towards these sites, monitoring of the ground vibrations has become a priority.
This study monitored explosions from demolition ranges, by recording the ground motions generated,amount of explosive used and the distance from the source to each of the seismograph stations. The peak
particle velocity (PPV) versus scaled distance (SD) values for each explosion and station were plotted and amultiple regression analysis utilized to obtain the equation parameters, or site constants for three predictor
equations; the United States Bureau of Mines (USBM) equation, the Ambraseys-Hendron equation and theLangefors-Kihlstrom equation.
The data obtained is very scattered, but the higher coefficients of determination (R2) indicate that the site
constants obtained using the USBM equation show better fits than for the other relations. In addition, thegeological constants for many of the regions are similar for the USBM equation, thus it would seem that theUSBM is the more reliable predictive equation to use for each of these sites. However, since most of theenergy escapes into the atmosphere during blasting on the surface, one should caution against using thepredictive equations designed for mining and excavation in the bedrock.

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*S02-3-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Artificial Water Reservoir Triggered Earthquakes at Koyna, India* HARSH K GUPTA
National Geophysical Research Institute, Hyderabad, Telangana, India
Koyna, near the west coast of India is the most prominent site of artificial water reservoir triggered
seismicity (RTS). Soon after the impoundment of the Koyna Dam in 1962, RTS was observed. It hascontinued till now. It includes the largest RTS earthquake M 6.3 on December 10, 1967; 22 M≥5.0, andthousands of smaller earthquakes. The entire earthquake activity is limited to an area of about 30 km x 20km, with most focal depths being within 6 km. There is no other earthquake source within 50 km of the
Koyna Dam. An ICDP Workshop held in March 2011 found Koyna to be the most suitable site to investigate
reservoir-triggered seismicity (RTS) through deep drilling. Studies carried out in the preparatory phasesince 2011 include airborne magnetic and gravity-gradient surveys, MT surveys, drilling of 9 boreholes
going to depths of ~ 1500 m and logging, heat flow measurements, seismological investigations including
the deployment of six borehole seismometers, and LiDAR. The Second ICDP Workshop held during 16-18
May 2014, reviewed the progress made and detailed planning of putting the borehole observatory was
discussed. With improved location of earthquakes using the borehole seismic stations, the errors in
hypocentral parameters have been brought down to ± 300m. The site of a 3 km deep pilot borehole wasdebated and among the 5 possible location, based on the seismic activity and logistics the location of thefirst Pilot Borehole has been finalized and the drilling has started.

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*S02-3-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Scientific deep drilling investigations to probe reservoir triggered seismicity
in the Koyna seismogenic zone, western India* Sukanta Roy 1) , Brijesh Bansal 2) , Vyasulu Akkiraju 1) , Surajit Misra 1) , Deepjyoti Goswami 1) , Nagaraju
Podugu 1) , Satrughna Mishra 1) , Pinki Hazarika 1) , Amrita Yadav 1) , Sanjay Tiwari 1) , Harsh Gupta 3) ,Shailesh Nayak 2)
Borehole Geophysics Research Laboratory, Ministry of Earth Sciences, Karad 415 114, India 1) , Ministry of
Earth Sciences, New Delhi 110 003, India 2) , CSIR-National Geophysical Research Institute, Hyderabad
500 007, India 3)
The Koyna region of western India is an outstanding natural laboratory to test hypotheses and model
reservoir triggered seismicity through scientific deep drilling and monitoring in an intraplate tectonic
setting. Persistent seismic activity during the past five decades including the M~6.3 Koyna earthquake, 22
M ≥ 5 earthquakes, 200 M ≥ 4 earthquakes and a few thousands smaller earthquakes define aseismogenic zone covering an area of 20km x 30km. Most earthquakes are located in the depth range 2-7
km. The frequency of earthquakes in the region is modulated by the annual loading and unloading cycles of
the Koyna and Warna reservoirs. A preparatory phase of investigations including drilling at 9 sites up to1522 m depth has uncovered the Precambrian basement granitoids underlying the Deccan basalt in theregion and shed new light on the subsurface geology and structure. Geological studies of basement
granitoids are bringing out new lines of evidence to constrain the deformation mechanisms associated withrecent and ongoing seismicity.
The Ministry of Earth Sciences, Government of India, has undertaken a two-phase scientific deep drillingand investigations plan. During the pilot phase, two boreholes up to 3000m depth are planned next to eachother; one for making repeat measurements of geophysical, mechanical and hydrological parameters aswell as multi-disciplinary laboratory studies on borehole samples, while the other would house a permanent
array of seismometers and piezometers for long-term monitoring. Drilling of the first pilot borehole at a
carefully chosen site is underway. The datasets acquired from this phase will be analysed together with thedata from the existing network of 6 borehole seismometers (up to 1522 m depth) and 20 surface
seismometers in the region, which will facilitate the design and set-up of a fault zone observatory at depthof ~5000m during the next phase.

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*S02-3-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Crustal Configuration beneath Koyna-Warna Seismicity Region, Western
India* VM Tiwari 1) , S Mishra 2) , CP Dubey 3)
CSIR-National Geophysical Research Institute, Hyderabad, India 1) , BGRL- Ministry of Earth Science
Karad, India 2) , ESSO-National Centre for Earth Science Studies, Thiruvananthapuram, India 3)
We present a 3D upper crustal configuration beneath Koyna-Warna region, western India, a site ofcontinued seismicity over five decades in the continental interior. Seismic activities in the region are
considered as a consequence of triggering of critically stressed regime due to artificial reservoirs. In orderto delineate subsurface density and susceptibility models, Airborne Gravity Gradiometer and highsensitivity Magnetic data (AGGM) are jointly inverted with constrained from several boreholes drilled
through basalt exposed in this region. Model suggests an anomalous N-S oriented high density zone boundby low density rocks on either side in the north of Warna reservoir. Other prominent features are NW-SE
oriented high and low density zones, south of Warna reservoir. The densities of sub-basalt rocks vary from2650 to 2800 kg/m3. Interestingly, the majority of earthquakes are located at the contacts between rocks ofcontrasting densities.

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*S02-3-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Electrical image of Koyna-Warna seismic zone, India from large scale
magnetotelluric studies* Prasanta Patro , Ujjal Borah , Kashi Raju , K. Chinna Reddy , Narendra Babu
CSIR-National Geophysical Research Institute, Hyderabad, India
A major scientific drilling program was launched by Ministry of Earth Sciences, Government of India withan intention to obtain an integrated model which can explain the genesis of reservoir triggered seismicity(RTS) at Koyna-Warna region, India. An exploratory phase covering a suit of geophysical investigations
including magnetotelluric studies were carried out preceding to the deep drilling program. More than one
hundred broad band magnetotelluric stations were recorded during 2012-14 field campaigns in the KoynaWarna seismic zone. The apparent resistivity - phase pseudo section along Warna profile delineated a weakzone near Udgiri, coinciding drilling observations. Coast effect and the Dharwarian trend are apparently
visible from the Phase tensor ellipses and the induction vector maps. A quick 2D modeling was carried out
to the MT data along Koyna and Warna profiles using NLCG approach after rotating the impedances to TE
and TM modes. Later, 3D inversion for all the impedance data using WSINV3DMT was carried out for thefrequency range 0.01 to 1 s. Modeling results in conjunction with the tectonic of Koyna-Warna seismiczone is discussed.

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*S02-3-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

The seasonal variation regime of induced seismicity in the Koyna-Warnaregion, western India* Kusumita Arora 1) , Rajender Chadha 1) , Vladimir Smirnov 2) 3) , Srinagesh Davuluri 1) , Alexander
Ponomarev 2) , I.M. Kartashov 2) 3)
CSIR-National Geophysical Research Institute, Hyderabad, India 1) , Schmidt Institute of Physics of the
Earth, RAS, Moscow, Russia 2) , Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia 3)
The five decade earthquake catalogue of the Koyna-Warna reservoirs region in western India was analyzed
to study seasonal variations in seismic activity related to the annual cycle of loading and unloading of thesereservoirs. Earthquakes started occurring in the region during early 1960s coinciding with the constructionof the Koyna dam and subsequent filling of the reservoir in stages. The seismic activity continues till today.
Our study reveals regularities in the seismic structure in time where the activity peaks thrice every year,
viz., in autumn (September), in winter (November-December) and in spring (February-April). The monsoon
season starts during June and ends in September every year. Seasonal seismic activity is the lowest in May
and June when the water level in the reservoirs is minimum. The first peak in autumn is explained as theinstant reaction of reservoir filling during monsoon season which saturates the system and adds anadditional load due to the weight of the water in the reservoirs. The following two peaks in winter andspring follow the draining phase of the reservoir with a delay caused by the diffusion of water to deeper
levels.
It is shown that intensities of both instant and delayed reaction to seasonal variations of water level change
in time, their correlation also changes in time. The possible factors that may influence the intensity changesof seasonal components of induced seismicity are discussed.

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*S02-4-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Borehole seismological studies at Koyna-Warna: A unique example of thestudy of Reservoir Triggered Seismicity (RTS)* Satyanarayana HVS , Shashidhar D , Mallika K , Harsh Kumar Gupta , Purnachandra Rao N , Mahato CR ,Maity BS , Narsinga Rao D , Sarma ANS , Ajay B
NGRI, Hyderabad, India
The Koyna-Warna region located close to the west coast of India is an outstanding example of Reservoir
Triggered Seismicity (RTS), where earthquakes have been occurring in a restricted area of 30x20 sq km
since the impoundment of Koyna reservoir in 1962 and the Warna reservoir in late 1980's. So far theregion experienced 22 earthquakes of M>5 including the largest triggered earthquake of M~6.3 on Dec 10
1967, about 200 earthquakes of M~4, and several thousand smaller earthquakes. The continued seismicity
at shallow depths of 4-7 km in the Koyna-Warna region for the past 49 years was monitored throughsurface seismograph networks installed from time to time and the location accuracies were improved byenhancing the seismic network capabilities by various upgradations.
Recently under a deep drilling program initiated jointly by Ministry of Earth Sciences and CSIR-National
Geophysical Research Institute to understand the earthquake mechanism at Koyna-Warna a very dense
network of 22 surface broadband seismographs and six borehole seismographs up to depths of 1500m wasinstalled forming a unique example to study the Reservior Triggered Seismicity (RTS) of Koyna-Warna. With
the installation of this unique hybrid seismic network the detection capabilities and the accuracies of the
hypo central parameters and the clear recording of the micro-seismic clusters have improved. There has
been a significant improvement in the location of earthquakes and the absolute errors of location havecome down to ± 300 m. All earthquakes of ML ≥ 0.5 are now located, compared to ML ≥1.0 earlier. The
details of the seismic network along with the improvements will be presented here.
Key Words: RTS, Koyna-warna, Borehole Seismographs

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*S02-4-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Seismotectonics of the Koyna region, India: based on focal mechanism
solutions using borehole and surface seismological networks* Dodla Shashidhar , K. Mallika , H.V.S. Satyanarayana , C.R. Mahato , B.S. Maity , N. Purnachandra Rao ,Harsh Gupta
National Geophysical Research Institute, Hyderabad, India
Artificial water reservoir triggered earthquakes have continued to occur at the Koyna region of western
India since the impoundment of the Shivaji Sagar Lake in 1962. The seismicity is confined to a small regionof about 30 km x 20 km. Recently, six borehole seismometers are deployed at depths varying from 981 m to1522 m, surrounding the seismicity and well below the Deccan basalt cover to improve the accuracy oflocations of these triggered earthquakes. Focal depths are estimated using waveform inversion approachand are mostly between 4 and 8 km in the Koyna-Warna region. Well constrained fault plane solutions arederived which provide vital information regarding the orientation of the fault planes. Analysis of the recent
large earthquake of Mw 4.8 that occurred on 14 April 2012 has indicated a N30E oriented left-lateral strikeslip fault along the Donachiwada fault zone, where the largest M 6.3 Koyna earthquake of 10 December
1967 also occurred. For the first time, reliable fault plane solutions for about 50 smaller earthquakes of ML> 1.9 are estimated, that occurred since January 2015 using the sharp onsets on the high quality borehole
seismic records which are complimented by a dense surface seismic network data. Our analysis presents asignificant improvement in the estimation of absolute locations and fault plane solutions of earthquakes at
Koyna.

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*S02-4-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

An overview of an ICDP project to drill into seismogenic zones of M2.0 –M5.5 earthquakes in deep South African gold mines (DSeis)* Hiroshi Ogasawara 1) 2) , Yasuo Yabe 1) 3) , Takatoshi Ito 3) , Gerrie van Aswegen 1) 4) , Artur Cichowicz 1) ,Michelle Grobbelaar 1) 5) , Ray Durrheim 1) 6) , Martin Ziegler 7) , Margaret Boettcher 8) , Tullis C Onstott 9) ,DSeis Team 10)
JST-JICA SATREPS, Tokyo, Japan 1) , Ritsumeikan Univ., Kusatsu, Japan 2) , Tohoku Univ., Sendai, Japan 3) ,Inst. Mine Seismol., Summerset West, South Africa 4) , CGS, Pretoria, South Africa 5) , Univ. Witwatersrand,South Africa 6) , ETH, Zurich, Switzerland 7) , Univ. New Hampshire, USA 8) , Princeton Univ., USA 9) , CrailC
IshidaA OgasawaraHY ManziM KatoH FunatoA MngadiS YasutomiT HoriuchiS MilevA MoyerP EllsworthB
AbeS OkuboM ImanishiK WardT WechslerN LiebenbergB BersetN HuntJP BuciboS MoremaS DightP
KieftT GuptaH JanssenC ShapiroS MukuhiraY SomalaSN 10)
The International Continental Scientific Drilling Program (ICDP) approved our proposal to drill into andaround seismogenic zones where critically-stressed faults initiated ruptures at depth. The drilling targets
include four ruptures equivalent to M2.0, 2.8, 3.5, and 5.5 earthquakes that dynamically and quasi-statically
evolved in 2.9 Ga hard rock in the Witwatersrand basin, South Africa. A major advantage of our proposed
project is the large quantity of high-quality data recorded by existing dense seismic arrays, both on surface
and near-field underground, in three deep gold mines. Additionally, the great depths (1.0 to 3.3 km fromsurface) at which drilling starts reduces costs significantly and allows a larger number of holes to be drilledwith the available budget. Flexibility in the drilling direction will also allow us to minimize damage to theborehole or the drilled cores. With ICDP funds, we will conduct full-core drilling of 16 holes at ranges of 50
to 750 m to recover both solid and fractured material in and around the seismogenic zones. This will befollowed by core and borehole logging. Additional in-hole monitoring of rock deformation, ground motion,hydrology and geomicrobiology will be supported by co-mingled funds. We will also determine the 3D
stress tensor near the collars of the holes using an overcoring technique that has been optimized for thehighly-stressed ground and the working conditions found in deep South African mines. The measurementof the differential stress is based on the assumption that axi-symmetric variation in the diameter of therecovered core is caused by elastic expansion after drilling.
The M5.5 earthquake that took place near Orkney, South Africa on 5 August 2014 offers a special
opportunity to compare models of the spatio-temporal evolution of both the main rupture and theaftershock activity determined by the inversion of ground motion measurements with direct observations.
Drilling will commence in early 2017.

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*S02-4-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Developing an Induced Seismic Mitigation Plan for the Proposed Utah
Frontier Observatory for Research in Geothermal Energy (FORGE)* Kristine Pankow , Stephen Potter , Hao Zhang , Fan-Chi Lin , Joseph Moore
University of Utah, Salt Lake City, Utah
The U.S. Department of Energy is proposing to develop a Frontier Observatory for Research in Geothermal
Energy (FORGE). The goal for this facility is to develop and test new technologies and techniques related toenhanced geothermal systems (EGS). One of two potential locations for this facility (the Utah FORGE site)is the eastern Basin and Range in Utah's west Desert. The site is located directly west of Roosevelt Hot
Springs and the operating Blundell geothermal power plant. One aspect of developing the FORGE facility iscreating, in advance of any development, an induced seismic mitigation plan. In this paper, we present
both completed and ongoing work related to the development of this plan. This work includes: reviewing
the historical earthquake catalog; using the historical catalog to develop templates for subspace detectionin order to lower the earthquake magnitude of completeness for the study area and to identify seismically
active zones; reviewing previous seismic hazard analyses; the creation of deterministic ground-motion
earthquake scenarios; risk analysis for the scenarios; and the analysis of newly collected seismic data. New
seismic data includes data from a local five-station, broadband network, and data from a 96-element threecomponent Nodal seismic experiment that was operated for approximately one month. The new seismic
data is being used for seismic detection and to develop initial seismic velocity images. Taken together thisinformation will be used to develop a mitigation plan, such as a traffic light system, that can be used tomodify production in order to minimize the risk from potential induced earthquakes.

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*S02-4-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Mapping microseismicity induced by hydrofrac experiments in Europe* Torsten Dahm , Simone Cesca , Jose Angel Lopez Comino , Sebastian Heimann , Claus Milkereit , Arno
Zang
GFZ German Research Centre for Geosciences, Potsdam, Germany
Hydraulic fracturing can be performed to increase the rock permeability and enhance the exploitation of
shale gas and has been increasingly applied in recent years on a global level, but remains poorly developedin Europe, partially because of the disputed environmental consequences. Here, we only consider theseismic hazard associated to hydraulic fracturing, and focus the problem from a seismological viewpoint.
Although moderate magnitude events have been attributed to hydrofrac operations, the seismic response to
fracturing is expected as local microseismicity. This poses important challenges to the detection andlocalization of weak events, identification of fracture migration and the spatial mapping of fracture
distribution and permeability. At the same time, large data volumes currently recorded by dense
microseismic networks provide unprecedented information on microseismicity. New tools need to be
automatized so that large datasets can be handled and the data mined. Furthermore, a seismic detector
needs to be quick, so that massive datasets can be processes in a reasonable time, whereas a seismic
locator needs to be accurate, so that the small-scale patterns and migration of rupture processes can be
resolved. We adopt here recently developed tools, designed to detect coincident arrivals of seismic energy
at seismic stations in a local network and locate their source. We discuss two applications to hydraulicfracturing in Europe. The first is a small-scale experiment in a Swedish mine, where thousands ofmicrofractures (acoustic emissions) are detected and located during an hydraulic fracturing experiment.
The second concerns a recently exploited hydraulic fracturing site in Poland, monitored in the frameworkof the EU project SHEER. There, we analyse realistic synthetic data and real data to discuss one of the firstcases in Europe, where an independent seismic monitoring of hydraulic fracturing operations was
performed.

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*S02-5-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

IS-EPOS e- platform of EPOS Thematic Core Service ANTHROPOGENIC
HAZARDS – a virtual laboratory for collaborative research experimentation* Beata Orlecka-Sikora 1) , Stanislaw Lasocki 1) , Konstantinos Leptokaropoulos 1) , Grzegorz Kwiatek 2) , JeanRobert Grasso 3) , Jean Schmittbuhl 4) , Alexander Garcia 5) , Tomasz Szepieniec 6) , Mariusz Sterzel 6) ,Grzegorz Lizurek 1) , Karolina Chodzinska 1)
Institute of Geophysics, Polish Academy of Sciences 1) , GDZ Potsdam 2) , Universite Grenoble Alpes 3) ,L'Ecole et observatoire des sciences de la terre 4) , AMRA 5) , ACC Cyfronet AGH 6)
Thematic Core Service ANTHROPOGENIC HAZARDS (TCS AH) provides virtual access to IS-EPOS eplatform, which integrates a wide-scale and high quality research infrastructure (RI) in the field ofanthropogenic seismicity and other anthropogenic hazards induced by exploitation of geo-resources. The
undertaking is developed in the framework of European Plate Observing System Program (https://tcs.ahepos.eu/, infrastructural projects IS-EPOS, POIG.02.03.00-14-090/13-00 and EPOS IP,
H2020-INFRADEV-1-2015-1). IS-EPOS platform of TCS AH is designed as e-research environment toensure a researcher freedom for experimentation by providing a virtual laboratory with private workspacefacility for processing streams. The integrated RI is used in novel ways with an access to (i) data gatheredin the so-called “episodes", comprehensively describing a geophysical process, induced by humantechnological activity, which can become hazardous for people, infrastructure and the environment, (ii)problem-oriented services, with the particular attention devoted to methods analysing correlations between
technology, geophysical response and resulting hazards, (iii) the intercommunity social functions: project
brokering, common workspace of project shared by the project participants, upload/download data andcodes to the common workspace. The platform serves research projects, e.g. “Shale gas exploration andexploitation induced risks, SHEER" project (Horizon 2020, LCE 16-2014). It allows to manageinterdisciplinary data and data products from own personal or collaborative research as well as increases
visibility of the project. In addition, platform provides expert knowledge and background information to the
public sector and is also used as a teaching tool, e.g. within educational project ERIS-Exploitation of
Research results In School practice, funded within ERASMUS+ Program of European Commission.

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*S02-5-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Picking vs Waveform based detection and location methods for induced
seismicity monitoring* Francesco Grigoli 1) , Maren Boese 1) , Toni Kraft 1) , Bernd Weber 2) , Stefam Wiemer 1) , John Clinton 1)
ETH-Zurich, Swiss Seismological Service, Switzerland 1) , Gempa GmbH, Potsdam, Germany 2)
Microseismic monitoring is common operation in different georesources related industrial activities, suchas oil&gas, mining or geothermal energy exploitation. In microseismic monitoring operations we generally
deal with large datasets requiring robust automated analysis procedures. Such seismic datasets are often
characterized by multiple events with short inter-event times or overlapping events; in this case, correct
phase identification and event association are challenging, and errors can lead to missed detections and/or
reduced location resolution. In the last years, to improve the performance of the current data analysis
procedure various waveform-based methods for the detection and location of microseismicity have been
proposed. These methods exploit the coherence of the waveforms recorded at different stations and do not
require any automated picking procedure. Although this family of methods have been applied to different
induced seismicity datasets, an extensive comparison with sophisticated pick-based detection and location
methods is still lacking. We aim here to perform a systematic comparison in term of performance amongwaveform-based methods and the pick-based detection and location methods (SCAUTOLOC and
SCANLOC) implemented within SeisComP3. SCANLOC is a new detection and location method specificallydesigned for seismic monitoring at local scale and is based on a cluster search algorithm to associate
detections to one or many potential earthquake sources. On the other hand, SCAUTOLOC is a more“conventional" method and is the basic tool for seismic event detection and location in SeisComp3. Thisapproach was specifically designed for regional and teleseismic applications, thus its performance withmicroseismic data might be limited. We analyze the performance of these methodologies for a synthetic
dataset with realistic noise conditions and for induced seismicity data related to geothermal energy
exploitation in St. Gallen (Switzerland).

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*S02-5-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

The Spatio-Temporal Variation of Seismicity in the South African Gold
Mining Region* Vunganai Midzi 1) 2) , Brian Zulu 1) 2) , Denver Birch 1) , Andrzej Kijko 3) , Ansie Smit 3)
Council for Geoscience, Pretoria, South Africa 1) , University of the Witwatersrand, Johannesburg, South
Africa 2) , University of Pretoria, Pretoria, South Africa 3)
The creation of a reliable earthquake catalogue with homogenous magnitude representation (Mw) is an
essential step for the development of a probabilistic seismic hazard model. In preparing to conduct a
seismic hazard of the Gauteng province in South Africa, such a catalogue of seismic events was compiledby combining publicly available earthquake information from the Council for Geoscience datasets. Twomain datasets used in the creation of the catalogue are from the South African National Seismograph
Network and the Gold Mines cluster networks. The SANSN catalogue consists of 49812 records ofearthquakes occurring between May 1905 and December 2014, whilst the Cluster network catalogue has
7828 records between March 2010 and December 2014. Results of preliminary analysis of the data show astrong spatial and temporal variation in the occurrence of seismicity in the region. The seismicity
characteristics of an area are usually described through the seismic hazard recurrence parameters, themean seismic activity rate, λ, the Gutenberg-Richter b-value and the area-characteristic completenessmagnitude, Mc. These parameters were investigated in terms of their temporal variation within the various
mining regions of the Witwatersrand basin, using the ZMAP software package. The region was divided into
four sub-regions, Klerksdorp-Orkney-Stilfontein-Hartbeesfontein (KOSH), West Rand, Central Rand andEast Rand. In some regions mining stopped some years ago, yet seismicity continues to occur. Researchers
linked this seismicity to flooding of the mines. Results of the analysis showed a strong influence of thetemporal distribution of seismograph stations on the observed variation of recurrence parameters.
However, physical processes such as the flooding of mines as well as the occurrence of large events also
influenced the occurrence of events. A recommendation from this investigation was that time dependent
seismic hazard assessment should be conducted for this region.

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*S02-5-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Seismic hazard assessment for induced seismicity in the Middle Urals,
Russia* Ruslan Diagilev
Union Geophysical Service of the Russian Academy of Sciences, Obninsk, Russia
Traditionally common methods of seismic hazard assessment for wide territories including countries orlarge regions take into account only natural tectonic earthquakes. Such approach is obviously correct if thenatural seismicity is dominant. But in some regions the contribution of induced earthquakes as well as
nontectonic seismic events may be comparable to tectonic one or even prevail over it.
We have tried to estimate the contribution of induced earthquakes occurring in the Middle Urals that is theregion of moderate seismic activity, where hundreds of deposits of different mineral types are under
exploration. To obtain reliable result we followed the idea of probabilistic-deterministic forecasting of
dangerous seismic processes according to common methodology offered by V.I. Ulomov. To estimate an
actual seismic hazard for some mining districts, we used the data set of hundreds of natural and induced
earthquakes and macroseismic data for the strongest ones. It was elaborated two prognostic models. The
first one is the model of seismogenerating zones, describing parameters of whole variety of induced andman-made seismic sources that may occur in the region. The second one is the model of the seismic effectgenerated by induced earthquakes. Both models differ sufficiently from ones elaborated earlier only fornatural seismicity by other researchers.
As result, a set of new maps in terms of seismic intensity and peak ground acceleration for the Middle Urals
had been obtained. They show earthquakes only from three mine districts may generate the mostsignificant seismic effect. In two districts there are conditions for generating shallow Mw 4.5 tectonic
events, that caused by stress-strain changes due to deep mining. The third district may generate strong
collapses. Hundreds of other zones are not able to induce events that produce effect greater thanbackground normal level (5 points of MSK-64 scale).

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*S02-5-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Identifying pathways for gas and fluid migration caused by fracking
processes, with the use of criteria defined in equivalent dimension phasespaces* Stanislaw Lasocki 1) , Beata Orlecka-Sikora 1) , Konstantinos Leptokaropoulos 1) , Grzegorz Kwiatek 2) ,Patricia Martinez-Garzon 2) , Paolo Capuano 3) , Simone Cesca 2)
Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland 1) , Helmholtz-Centre Potsdam GFZGerman Research Centre for Geosciences, Potsdam, Germany 2) , AMRA – Analysis and Monitoring ofEnvironmental Risk, Italy 3)
SHale gas Exploration and Exploitation Risks (SHEER, www.sheerproject.eu) project aims at assessing
short and long-term risks associated with groundwater contamination, air pollution and induced seismicity.
The severity of each of these depends strongly on the unexpected enhanced permeability pattern, which
may develop as an unwanted by-product of the fracking processes and may become pathway for gas andfluid migration towards underground water reservoirs or the surface. An important part of SHEER is
devoted to monitor and understand how far this enhanced permeability pattern will develop both in space
and time. Here we present a novel approach for identifying pathways for gas and fluid migration based on
the transformation to equivalent dimensions. The transformation converts a set of any original parametersof seismic events in a set of their equivalent dimensions, which are strictly comparable. The latter set builds
a phase space, whose metrics is Euclidean. These features of equivalent dimensions make it possible tointroduce any complex, multidimensional criteria for selecting seismic events. We present results of theanalysis of an injection induced seismicity data from The Geysers geothermal field, which is used in
SHEER as a proxy of seismicity accompanying shale gas operations. In addition to occurrence time,location and magnitude these seismic events are parameterized by moment tensors and spectral
parameters. This allows to define and apply criteria for possible linking of fractures into gas migration
pathways in a prescribed direction, based on fracture fault planes orientations, on closeness of locations,on sources radii and on angles between the fault planes.
This work was supported within SHEER: "Shale Gas Exploration and Exploitation Induced Risks" project
funded from Horizon 2020 – R&I Framework Programme, call H2020-LCE-2014-1 and within statutory
activities No3841/E-41/S/2017 of Ministry of Science and Higher Education of Poland.

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*S02-6-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Discrimination of induced seismicity component in the seismicity of
Sakhalin offshore hydrocarbon fields* Sergey Turuntaev 1) 2) , Alexey Konovalov 3) , Andrey Stepnov 3) , Elena Slinkova 1) , Anna Gubanova 2)
Institute of Geosphere Dynamics, Russian Academy of Sciences, Moscow, Russia 1) , Moscow Institute ofPhysics and Technology, Moscow, Russia 2) , Institute of Marine Geology & Geophysics of FEB RAS,
Yuzhno-Sakhalinsk, Russia 3)
Sakhalin Island offshore hydrocarbon fields (Russia) are located in the region of high natural seismic
activity. That causes a concern on the possibility to trigger a catastrophic earthquake by the hydrocarbon
field developments in this region. The concern is backed by probably triggering nature of the catastrophic
Neftegorsk earthquake in 1995 (Mw=7.2). That is why a local seismic network was installed along theeastern shore of Northern Sakhalin in 2006 prior to active phase of the offshore hydrocarbon fielddevelopments. The results of analysis of the seismic activity registered by this seismic network areconsidered in comparison with the natural seismicity registered by the regional seismic network in
1950-1990. It was found that while there are no proved sings of the seismic activity increase due to oil andgas production in the controlled region, some changes in the seismic regime take place: b-value became a
bit higher than it was before; the distribution of the time intervals between successive events became of the
Weibull type with the form parameter less than 1; local maximums of the seismic activity spatial
distribution became closer to the boundaries of the developed hydrocarbon fields; the correlation
dimension calculated by Grasberger-Procaccia method became smaller. All these changes are typical for
induced seismicity.

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*S02-6-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

The Results of the Local Seismic Monitoring in the Underground Baksan
Neutrino Observatory* Alexey Malovichko 1) , Denis Shulakov 2) , Zalim Dudarov 1) , Spartak Dolov 1)
Geophysical Survey RAS , Obninsk, Russia 1) , Mining Institute of Ural Branch RAS, Perm, Russia 2)
Underground Baksan neutrino observatory is located on the territory of the North Caucasus, near Tyrnyauz
city. It consists of two horizontal tunnels going deep into the mountains over a distance of 4 km. The depth
from the surface is approximately 2 km at the most remote point of the tunnels. Two neutrino telescope,
low-noise physical laboratories and ancillary equipment are installed in the underground excavations.
Since the Caucasus region is characterized by high geodynamic activity, local seismic array was deployedin the galleries of observatory. The principal aim of the array is to provide data for the assessment andmonitoring of seismic hazard in the observatory. The monitoring system is installed in the most remote andthe deepest part of the tunnel. The array consists of 6 vertical and one 3-component sensor Sercel L4C andhas the aperture of 150 m x 370 m.
The site of observations is characterized by extremely low levels of background seismic noise. The noiselevel almost coincides with NLNM (Peterson, 1993) in the frequency range of 0.1 - 5 Hz. It increases
slightly at higher frequencies, but remains very low. Thanks to so favorable conditions, seismic sensors
detect a large number of local and regional seismic events with hypocentral distances from few hundred
meters to hundreds of km. Seismic events above magnitude ML=-2 are representatively registered within
the distance of 10 km. Due to high sensitivity, the monitoring system daily registers from tens to a few
hundreds of weak seismic events occurring in the neighborhood of the tunnels. These events occur mainly
within the two local areas. One of them is located directly under the tunnels at a depth of 1.5 km, thesecond - at distance from 1.5 to 4 km to northeast from the monitoring system. Most of these events have atectonic nature, but every month registers up to several tens of events that may be associated with theprocesses of the movement of fluids in the rock mass

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*S02-6-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Experiment to Trigger a Moderate-sized Earthquke* James Mori
DPRI, Kyoto University, Kyoto, JapanWe are proposing an experiment to understand the initiation of large earthquakes by inducing seismic
events on a shallow fault with water injection. Increasing the fluid pressure near an active fault will reduce
normal pressure on a fault and bring it closer to failure, according to the classic Coulomb failure criterion.
A study to monitor the water pressure and subsequent triggered earthquakes can help answer somefundamental questions in seismology about the stress levels that cause earthquakes and the physicalconditions that are necessary for a large earthquake to occur.
Possible sites for such an experiment would be transform faults near mid-ocean ridges, such as the East
Pacific Rise. Seismicity in these regions is quite shallow and accessible with ocean boreholes of 2 to 3 km
depth. In such settings, moderate (M5 to M6) earthquakes occur at repeat intervals of 5 to 15 years. We
would like to conduct a water injection experiment at one of these sites a few years before the expectedearthquakes recurrence, to try to trigger an early occurrence of the event. Also, moderate earthquakes inthese regions are usually accompanied by active foreshock sequences.
What is the water pressure needed to trigger an earthquake ? Assuming a recurrence time of about 15
years and a stress drop of about 2 MPa for an M5 earthquake, to trigger an earthquake 2 years early, we
would need to increase the shear stress 0.3 MPa. Using the Coulomb failure criterion, this would
correspond to a decrease of normal stress (or increase of pore pressure) of about 0.5 MPa. This increase isrelatively small, however, the absolute pore pressure at 1 km depth is about 8 MPa. So pumping pressure ofabout 8.5 MPa would be necessary to reduce the normal stress on the fault. Such pumping pressures are
possible using the current riser drilling technology.

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*S02-6-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Possibilities of seismic monitoring in control of equipment and constructionsof hydro-electric power plants condition* Victor Seleznev 1) 2) , Aleksei Liseikin 2)
Geophysical Survey of the Russian Academy of Sciences, Obninsk, Russia 1) , Seismological Branch ofGeophysical Survey of the Russian Academy of Sciences, Novosibirsk, Russia 2)
Hydro-electric power plants of Russia situated in earthquake-prone regions are equipped with systems ofseismometric and seismological investigations. The systems are integrated in one seismological grid which
is maintained by GS RAS so that observations in local zones become more detailed and it let to investigate
the seismicity in regions of hydrotechnical constructions location at a higher level. The investigations showthat oscillations which source is working equipment of hydro-electric power plant, natural oscillations ofdams, hydroacoustic self-oscillations in water conducts are found in microseisms records even at vastdistances. We have developed methods of detection of these oscillations from records. With the usage ofarchived records for 15 years in a row we've analyzed the changes of natural oscillations of SayanoShushenskaya hydro-electric power plant dam – the biggest HPP in Russia. The Analysis of records fromthe seismological grid let us study out the processes happened during the accident at HPP on 17 august
2009 that helped to find out its reasons. Developed method according to continuous records of seismic
stations lets us realize remote monitoring of vibratory condition of working hydroelectric units; monitor
technical condition of dams through changing of natural oscillations of construction; get additional
objective information which is necessary for investigation of reasons of emergency on hydro-electric power
plants.

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*S02-P-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Spatio-temporal variation in seismicity due to periodically alternating rolesof reservoirs in the Koyna-Warna RTS zone, India* Amrita Yadav 1) , Kalpna Gahalaut 2) , N.Purnachandra Rao 2)
Borehole Geophysics Research Laboratory (NCAOR), Karad, India 1) , CSIR-National Geophysical ResearchInstitute, Hyderabad, India 2)
Reservoir triggered seismicity (RTS) is well-accepted phenomenon describing the triggering of earthquakes
through the local stress change due to the reservoir impoundment. Koyna–Warna region (KWR) in India is
one such famous RTS site where earthquakes keep occurring after 50 and 30 years of Koyna(KR) and
Warna reservoirs(WR) impoundment respectively and after the large M6.3 Koyna earthquake. Here weanalysed the role of the reservoir water levels on spatio-temporal distribution of the earthquakes during
1968–2012. First, we analysed the seismicity data during January 2005-June 2012 recorded by seismic
network operated by CSIR-NGRI. We performed a statistical analysis using Singular Spectrum
Analysis(SSA) which shows that water level series has dominance of variance for annual periodicity. For
the earthquake time series, a zone close to the WR, shows predominance of annual frequency, suggesting acompelling relation between seismicity and reservoir water level changes. To see an overall spatio-temporal
effect of the reservoirs on the seismicity of the region, this type of study is required also for the earlier time
period. In continuation of the previous work we divided the 1968-2004(MERI catalogue) earthquakes into
different zones and performed same analysis. We found the effect of both the long-term and annual
variations of the reservoir water level on the seismicity. Also an alternating role of the KR and WR on theseismicity, for the time period 1983-1995 the earthquakes near WR, during 1996-2004 the earthquakes
near KR and during 2005-2012 again the earthquakes near WR, was found to be associated with annual
variations in reservoir water levels. It appears that during the release of stress in region beneath one
reservoir, the region beneath the other reservoir is accumulating stress and once the stress is released fromone region other region is activated.

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*S02-P-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

3D Poroelastic Modelling of Reservoir Triggered Seismicity (RTS) in Koyna
Region, Western India* Pinki Hazarika , Amrita Yadav , Sukanta Roy
Borehole Geophysics Research Laboratory (NCAOR), Karad, India
Reservoir triggered seismicity (RTS) is a well known phenomenon and about 120 sites have been identified
worldwide where earthquakes have been triggered by filling of artificial water reservoirs. The Koyna region
near the west coast of India is one of the globally recognised sites of RTS, where earthquakes have been
occurring in a small area of 20 x 30 km2 since the impoundment of Koyna reservoir in 1962. Till date 22
earthquakes of M>5 have been occured in this region including largest triggered earthquake of M6.3 on 10
December 1967. RTS can be interpreted as a result of stress and pore pressure changes due to poroelastic
response in the rock matrix. Although numerous studies have been carried out to constrain the mechanismof triggered earthquakes, a satisfactory model for this region remains elusive. Based on poroelastic theory
we have used 3D finite element model (FEM) to simulate the development of stress and pore pressure due
to reservoir impoundment. First we develop poroealstic model to investigate the effect of reservoir
impoundment on local seismicity of the region. Preliminary studies suggest that impoundment of Koyna
reservoir altered the pore pressure in the region and formed pore pressure front that propagated up to
seismogenic depth through the crust with fluid diffusion. The change in stress regime of the region by theseasonal fluctuation in water level of the reservoir is found to be associated with the ongoing seismicity.
However, measurements of different properties (Bulk modulus, Young's modulus, Poission's ratio, porosity,
permeability etc.) through the ongoing deep drilling programme in Koyna region would provide a more
realistic model of RTS.

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*S02-P-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Rock strength variations in an active seismogenic zone: evidences fromscientific drilling in Koyna, western India* Deepjyoti Goswami 1) , Vyasulu V. Akkiraju 1) , Surajit Misra 1) , Sukanta Roy 1) 2) , Amalendu Sinha 3) ,Harsh Gupta 2) , Brijesh K. Bansal 4) , Shailesh Nayak 4)
Borehole Geophysics Research Laboratory, Ministry of Earth Sciences, Karad 415 114, India 1) , CSIRNational Geophysical Research Institute, Uppal Road, Hyderabad 500 007, India 2) , CSIR-Central Institutefor Mining and Fuel Research, Dhanbad 826 001, India 3) , Ministry of Earth Sciences, New Delhi 110 003,
India 4)
Reservoir triggered earthquakes have been occurring in the Koyna region of western India since theimpoundment of the Shivaji Sagar reservoir in 1962. The earthquakes are located in the granitic basement
rocks underlying a thick pile of Deccan flood basalt covering the region. Triaxial measurements on cores of
granitic rocks recovered from recent scientific drilling provide unique opportunity to characterize the effectof ongoing seismic activities on rock strength properties. Nine cored boreholes have been drilled up to adepth of 1522 m in the vicinity of the Koyna seismogenic zone. The boreholes penetrated the total
thickness of Deccan flood basalt and passed through a few hundred meters in the underlying granitoids.
Laboratory data include measurements on granite gneiss, granite, migmatitic gneiss and mylonitised
granite gneiss obtained from four boreholes. Salient results are as follows (i) Increase of rock strength withincreasing confining pressure allow determination of the linearized failure envelopes from which thecohesive strength and angle of internal friction are calculated. (ii) Variable differential stress at different
depths are the manifestations of deformation partitioning in close association of fault zone(s) or localised
fracture zones. (iii) Fractures controlled by naturally developed weak planes such as cleavage and fabricdirectly affect the rock strength properties, but the majority of failure planes developed during triaxial tests
is not consistent with the orientations of pre-existing weak planes. The failure planes may, therefore,
represent other planes of weakness induced by ongoing seismic activity. (iv) Stress-strain curves confirm
that axial deformation is controlled by the varying intensity of pre-existing shear in the granitoids. (v)Frequent occurrences of low magnitude earthquakes may be attributed to low and variable rock strength of
the granitoids, which, in turn, is modified by successive seismic events.

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*S02-P-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Deformations in rocks in the Koyna seismogenic zone, western India
obtained through scientific deep drilling* SURAJIT MISRA , SUKANTA ROY
BGRL-Ministry of Earth Sciences, Karad, India
The Koyna region, located in the Deccan Flood Basalt Province of western peninsular India has been
experiencing reservoir triggered seismicity since the impoundment of the Shivajisagar water reservoir in
1962. The 1967 M6.3 Koyna earthquake, 22 earthquakes of M greater than equal to 5, more than 200
earthquakes of M greater than equal to 4 and several thousand smaller earthquakes have occurred in thedepth range 2-10 km and over a restricted area of approximately 20km x 30km. Scientific drilling carriedout recently up to a depth of 1522 m in the vicinity of the seismogenic zone exposed the cratonic
granitoids underlying the Deccan flood basalt and provided a unique opportunity to study the deformation
features in an area of active seismicity. The salient results are as follows. (1) The basement rocks are
dominantly composed of granite, granite-gneiss and migmatitic gneiss, typical of the Dharwar craton of
peninsular India. (2) The intensity of shear fabric in the basement rocks indicate the presence of a highly
strained shear zone. (3) The granitoids have been affected by later brittle deformation. (4) Occurrences offaults and fractures associated with fault breccias, fault gouge and pseudotachylite veins injected along
tensile fractures are the direct evidences of seismic activity. (5) Prominent slickenlines with slickensides on
fault surface, granular flow of crushed material within fault zone and intensive shattering of rocks observed
without abundant alteration are related with the recent seismic activity. (6) Fracture density varies within
and away from the fault zone which are frequently filled up with ferruginous secondary precipitation,
signifying water channelization at depth.

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*S02-P-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Geological and velocity structures of the Orkney M5.5 fault, South Africa* Hiroyuki Ogasawara 1) , Musa Manzi 2) , Ray Durrheim 2) , Hiroshi Ogasawara 2) , Artur Cichowicz 3) ,Akimasa Ishida 1) , Tatsunari Yasutomi 4)
Ritsumeikan University, Kusatsu, Japan 1) , University of the Witwatersrand, Johannesburg, South Africa 2) ,Council for Geoscience, Pretoria, South Africa 3) , Kyoto University, Uji, Japan 4)
In August 2014, the largest seismic event (M5.5) in a South African gold mining district took place near
Orkney. It has been a question whether the M5.5 event was natural or mineinduced, and what geologicalstructure was re-activated to cause the event.
It is also known that this earthquake occurred below the mining horizons in anarea characterized bycomplexgeological structures. However due to no economic interests at these depths, very little geologicalinformation is known. To better understand the structural complexity of the area, we have interpred the 2D
and 3D reflection seismic data, which were acquired for gold exploration. The 2D/3D reflection seismic
data are characterized by strong seismic reflectors, for example, at a dolomite-lava boundary, a lavaquartzite boundary, and quartzite-shale boundary. On the mining horizons from 2 to 3 km depth, the data
show high optimum mapping of major fault zones, which correlate well with structures mapped
underground. Interestingly, there is less disturbance at the depth of the M5.5 rupture (at least 5 km longhorizontally and 3 km wide in the dip direction). It is suggested that a dyke hosted the M5.5 event. The
near vertical dyke has been identified by underground mapping, however it is not visible on the seismic
data probably due to its thickness being below the seismic detection limit.
It is also very important to calibrate the velocity field below the mining horizons in order to have moreaccurate absolute locations of targets of scientific interest of the M5.5 fault. To achieve this, we will convert
our 3D seismic volume from two-way-travel times to depth using the stacking velocities obtained from thedata processing. Subsequently, we will constrain our P-wave seismic velocity calibration using the stacking
velocities and exploration borehole data. Following the calibration, the geological structure will becompared with the aftershocks and the mainshock fault slip distribution.

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*S02-P-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Searching significant displacement zones of a M5.5 earthquake fault by
forward and inversion analyses of strainmeter data at depth at a very close
distance* Tatsunari Yasutomi 1) , Hiroshi Ogasawara 2) , Akimasa Ishida 2) , Hiroyuki Ogasawara 2) , Durrheim
Raymond 3) , Alex Milev 4) , Makoto Okubo 5) , Teruhiro Yamaguchi 6) , James Mori 1)
Kyoto University, Kyoto, Japan 1) , Ritsumeikan University 2) , Witwatarsrand University, South Africa 3) ,CSIR, South Africa 4) , Kochi University 5) , Hokkaido University 6)
The largest event recorded in a South African gold mining region, a M5.5 earthquake, took place near
Orkney, South Africa on 5 August 2014. It is an unusually well-recorded events: e the main- and aftershocks were recorded by 46 geophones and 3 Ishii borehole strain meters at 2 - 3 km depths withepicentral distances, delta < several km, and 17 surface strong motion meters with delta < 20 km. The
upper edge of the planar aftershock activity dipping almost vertically was only some hundred meters below
the sites where the strainmeters were installed. As the M5.5 seismic rupture is located within a distancethat is drillable from the deep gold mine workings, ICDP approved a project to drill into the seismogenic
zones. Moyer et al. (2016 SCEC) inverted the surface strong motion data, suggesting that there wassignificant fault slip, even at the mining horizon. However, no seismic rupture was mapped in the mineworkings. So, the three strainmeters can constrain the configuration of the seismic rupture. As the
population of the aftershocks varies significantly in space, we will discuss the relationship the fault slip andthe aftershocks.
These strainmeters were only about 150 m o apart. However, their strain changes had different polarities
while the other M4 strain changes with a similar hypocentral distance was the same. So, this information
can place critical constraints on the location and configuration of the M5.5 fault.
First, we conducted a forward analysis by assuming a point source with the mechanism same as
macroscopic one of the M5.5 faultingat a distance of a few km. However, no difference in the polarity ofstrain change was seen, suggesting that the effect of a finite size of the source with an edge much nearer
than the point source had to be taken into account. We are attempting to invert the slip distribution on asource with a finite size together with surface strong motion data. We will report on the results at themeeting.

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*S02-P-07
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

An integrated estimation of the stress field in seismogenic zones in South
African gold mines* Akimasa Ishida 1) , Hiroshi Ogasawara 1) 9) , Yasuo Yabe 2) 9) , Akio Funato 3) , Takatoshi Ito 2) , Shuhei Abe
2), Raymond Durrheim 4) 9) , Siyanda Mngadi 4) 9) , Gerhard Hofmann 7) 9) , Dave Roberts 5) 9) , Harumi Kato
6)

, Alexander Milev 6) 9) , Makoto Naoi 8) 9)
Ritsumeikan University, Shiga, Japan 1) , Tohoku University, Miyagi, Japan 2) , Fukada Geologcal Institute,Tokyo, Japan 3) , University of the Witwatersrand, Johannesburg, South Africa 4) , CSIR, Johannesburg,
South Africa 5) , 3D Geoscience., Tokyo, Japan 6) , Anglogold Ashanti ltd, Johannesburg, South Africa 7) ,Kyoto University., Kyoto, Japan 8) , JST-JICA Science and Technology Research Partnership for Sustainable
Development, Tokyo, Japan 9)
Although it is very important to know the details of the stress state in seismogenic zones for bothseismology and safety in deep South African gold mines, it has not been feasible due to technicaldifficulties.
The Diametrical Core Deformation Analysis (DCDA) technique, proposed by T. Ito and A. Funato, uses aneasy-to-make laboratory measurement of the diameters of drilled core, to estimate the differential stress ona plane normal to the borehole axis, which is calculated assuming that variations in core diameter arecaused by axi-symmetric elastic expansion during drilling. We carried out DCDA for a total of 90 cores
drilled from eighteen boreholes at three seismogenic zones in three deep-level South African gold mines inorder to evaluate the reliability of the DCDA method and to clarify technical problems. Our measured cores
included those from a high-stress-concentration area at 1.0 km depth in a shaft pillar where quasi-static
growth of ruptures was elucidated by the SATREPS's acoustic emission observation, and from a M3.5 fault
area at 3.3 km depth. We also conducted DCDA with cores that were recovered from over-coring stressmeasurements, and compared these results. It was observed that drilling quality sometimes affects DCDA
results, as South African geological drilling crews don't care about the smoothness of the core surface
because the main purpose of geological exploration drilling is to identify the lithology. However, if we
scrutinize cores that are straight and smooth enough for DCDA, the DCDA results were in coherence withthe results of the overcoring stress measurements. If we instruct drilling companies to use a stabilizer tostraighten the drilling operation, we will be able to obtain more cores suitable for DCDA to elucidate stressvariations along a borehole. We are currently developing a procedure to effectively select reliable DCDA
results. At IAG-IASPEI 2017, we are going to make a follow-up report.

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*S02-P-08
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Experimental measurements of seismic velocities on core samples and theirdependence on mineralogy and stress, Witwatersrand Basin (South Africa)* Nomqhele Nkosi , Musa Manzi
University of the Witwatersand, Johannesburg, South Africa
The measurement of seismic velocities, especially at great depths (~2 km-3 km) under high stressconditions (~65 MPa-70 MPa), are crucial for proper interpretation of reflection seismic data, and therefore,
for understanding the seismic reflective nature of lithological boundaries. The integration of geological andgeophysical concepts has enabled us to better understand the nature of the seismic reflectivity of theworld's deepest gold-bearing reef, the Carbon Leader Reef (CLR). This was done by measuring theultrasonic velocities and bulk densities as well as conducting mineralogical analyses on drill-core samples.
The results show that the quartzite samples overlying and underlying the CLR exhibit similar velocities (~5028 m/s-5480 m/s and ~ 4777 m/s-5211 m/s, respectively) and bulk densities (~ 2.68 g/cm3 and 2.66
g/cm3). This is due to similar mineralogy and chemical compositions observed within the units. However,
the CLR has slightly higher velocity (~ 5070 m/s-5468 m/s) and bulk density (~ 2.78 g/cm3) than thesurrounding quartzite units probably due to higher pyrite content in the reef. In the data set it is found thatseismic velocities increase with (1) decreasing silica content, (2) increasing iron and pyrite content and (3)decreasing grain size. Reflection coefficients calculated using the seismic velocities and densities at theboundaries between the CLR and its hangingwall and footwall units range between ~0.02 and 0.05, which
is below the suggested minimum of 0.06 required to produce a strong reflection between two lithologicalunits. This suggests that reflection seismic methods might not be able to directly image the CLR as aprominent reflector, as observed from the seismic data.Samples were also subjected to stresses of up to 65
MPa to investigate the dependence of ultrasonic velocities on stresses. Velocities increase with progressive
loading, but at different rates in shale and quartzite rocks as a result of the presence of micro-defects.

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*S02-P-09
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Estimate of the stress state in a close proximity to an earthquake source in aSouth African deep gold mine
* Shuhei Abe 1) , Yasuo Yabe 1) , Takatoshi Ito 2) , Masao Nakatani 3) , Gerhard Hofmann 4) , Hiroshi
Ogasawara 5)
Graduate School of Science, Tohoku University, Sendai, Japan 1) , Institute of Fluid Science, Tohoku
University, Sendai, Japan 2) , Earthquake Research Institute, the University of Tokyo, Tokyo, Japan 3) ,ANGLO GOLD ASHANTI, Johannesburg, South Africa 4) , Faculty of Science and Engineering, Ritsumeikan
University, Kusatsu, Japan 5)
An earthquake of Mw2.2 (mainshock, hereafter) occurred at 3.3km depth in Mponeng mine, a deep gold
mine in South Africa. A rupture plane of the mainshock diagonally cut a 30-m-thick gabbroic dyke. Yabe etal. (2013) drilled a borehole passing a source fault of the mainshock ~1.5 years afterward. They constrained
possible ranges of stress magnitudes and the principal directions based on criteria of borehole breakout(BB) and core discing (CD) and a slip direction of the mainshock. In this study, we estimate the stress state
in a close proximity to the source fault more tightly than Yabe et al. (2013) by using DCDA and DRA, in
addition to information taken into account in Yabe et al. (2013). Considering that the mainshock occurredin the dyke, we divided the study are into three; host rock (quartzite), footwall dyke and hanging-wall dyke.
The principal directions of stress in the host rock and the hanging-wall dyke were normal faulting one,being consistent with the CMT solution of the mainshock. But, the principal direction in the footwall dyke,
where no borehole breakout or core discing was observed is reverse faulting one. To improve theestimation in the footwall dyke, we will measure stress magnitudes by DRA and compare with 3D model
simulation.

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*S02-P-10
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Evaluation of the induced risks caused by shale gas exploration andexploitation
Paolo Capuano 1) 2) , Beata Orlecka-Sikora 3) , * Stanislaw Lasocki 3) , Simone Cesca 4) , Andrew Gunning 5) ,Janusz Jaroslawsky 3) , Alexander Garcia-Aristizabal 2) , Rachel Westwood 6) , Paolo Gasparini 2)
The University of Salerno, Fisciano (SA), Italy 1) , Center for the Analysis and Monitoring of Environmental
Risk (AMRA), Napoli, Italy 2) , Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland 3) , GFZ
German Research Centre for Geosciences, Potsdam, Germany 4) , RSKW Ltd, United Kingdom 5) , The
University of Keele, Keele, United Kingdom 6)
Shale gas operations may affect the quality of air, water and landscapes; furthermore, it can induce seismic
activity, with the possible impacts on the surrounding infrastructure. SHEER (SHale gas Exploration and
Exploitation induced Risks) project aims at setting up a probabilistic methodology to assess and mitigate
the short and the long term environmental risks connected to the exploration and exploitation of shale gas.
A test site located in Poland has been monitored before, during and after the fracking operations with theaim of assessing environmental risks connected with groundwater contamination, air pollution andearthquakes induced by fracking and injection of waste water. The severity of each of these hazards
depends strongly on the unexpected enhanced permeability pattern, which may develop as an unwanted
by-product of the fracking processes. The considered hazards may be partially inter-related as they all
depend on this enhanced permeability pattern. Therefore they are being approached from a multi-hazard,
multi parameter perspective. Methodologies have been developed to model fracture evolution around shale
gas exploitation sites and a robust statistically based, multi-parameter methodology to assess environmental
impacts and risks across the operational lifecycle of shale gas has been defined. All the developed
methodologies are applied and tested on a comprehensive database consisting of seismicity, changes of thequality of ground-waters and air, ground deformations, and operational data collected from the ongoing
monitoring episode (Wysin, Poland) and past episodes. Best practices to be applied in Europe to monitor
and minimize any environmental impacts will be worked out with the involvement of governmental
decisional bodies, private industries and experts
This work was supported under SHEER: "Shale Gas Exploration and Exploitation Induced Risks" projectn.640896, funded from Horizon 2020 - R&I Framework Programme, call H2020-LCE-2014-1

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*S02-P-11
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Induced seismicity in the region of the geothermal power plant at Insheim(central Upper Rhine Graben, SW Germany)
Andrea Bruestle 1) , Margarete Pilger 1) , Thomas Plenefisch 2) , * Ulrich Wegler 3) , Bernd Schmidt 4)
Germany 1) , BGR, Hannover, Germany 2) , Universitaet Jena, Germany 3) , Geological Survey of RhinelandPalatinate, Mainz, Germany 4)
The Upper Rhine Graben is the region with the highest temperature gradient in Germany. Since 2012 at
Insheim a geothermal power plant is running in the central Upper Rhine Graben. It is accompanied bysmall to moderate induced seismicity. Before starting regular operation, hydraulic stimulation in April 2010
caused two seismic events of ML 2.2 and 2.4, which were felt by inhabitants. As a consequence the local
seismic monitoring network of the company was improved by an additional scientific network within the
research-projects MAGS and MAGS2. The densified seismic network of up to 14 surface stations is
operated by the Federal Institute for Geosciences and Natural Resources BGR. The network was completed
over time by 4 borehole stations, operated by the Local Seismological Survey of Rhineland Palatine LER
and industrial partner. The event detection was done by a real-time cross correlation detector, which wasdeveloped as a SeisComP3-plugin. The network extension of less than 20 km made a standard
determination of the local magnitude impossible. Therefore a relative magnitude was determined from theamplitude of master and detected events. The local 1D-velocity model was improved using VELEST.
Corresponding station corrections are in accordance to the tectonic situation in the graben structure. Since
the commissioning of the power plant in October 2012 about 810 events were identified and analyzed. As
the area is densely populated the seismic background noise varies strongly resulting in a magnitude ofcompleteness of 0.0 during the day and -0.4 during nighttimes. No seismicity is observed when the power
plant is offline during maintenance periods. After recommissioning seismic activity is temporarily increased
followed by a continuous decrease to a low activity level. Seismicity is located within the crystalline
basement, which underlies the sedimentary graben fill. Focal mechanisms show the same major strikedirection as the local tectonic situation.

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*S02-P-12
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Analysis of static stress transfer in the 2013 Valencia Gulf (NE Spain)
seismic sequence
Lluis Salo 1) 2) , Tanit Frontera 1) , Xavier Goula 1) , Lluis Pujades 2) , Alberto Ledesma 2) , * Josep Batllo 1) ,Jose Antonio Jara 1)
Institut Cartografic i Geologic de Catalunya (ICGC) 1) , Universitat Politecnica de Catalunya (UPC) 2)
The role of static stress transfer as an earthquake triggering mechanism is evaluated in the seismic
sequence that took place in Spain's Valencia Gulf during September and October 2013. Earthquakes
occurred in spatiotemporal correlation with injection activities conducted at the Castor Underground Gas
Storage.
Coulomb Stress Changes (CSC) are quantified using the Coulomb Failure Function, which considers
positive values as those promoting failure on the objective fault plane. Focal Mechanism (FM) solutions forthe 8 strongest events in the sequence (M_L 3.5 - 4.3) are computed from full waveform inversion, and arethen used to place the earthquake sources. A geometrical model containing both the FM-derived faults andthe previously mapped structures in the area is built; CSC are then quantified along the sequence on all
those faults.
We first assess whether the earthquakes can be explained based on static stress transfer on its own, andwhich of the previously mapped structures in the area is most likely to have slipped. The shortening on theMain Fault's characteristic earthquake cycle as a result of the experienced seismicity is also evaluated.

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*S02-P-13
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Spectral Characteristics of the 2006 Quarry Blasts in the Tehran Region
based on the TDMMO Network* Jamileh Vasheghani Farahani 1) , Hiroe Miyake 2)
Institute of Geophysics, University of Tehran, Tehran, Iran 1) , The University of Tokyo, Tokyo, Japan 2)Tehran, the capital city of Iran, is located between the Alborz and Central Iranian tectonic zones. The
Tehran region has several active mines in the south and southeast of Tehran. They produce quarry blasts
with small magnitudes. In this research, spectral characteristics were computed for data from the Tehran
Disaster Mitigation and Management Organization (TDMMO) network in the Tehran region. Data catalog
was selected from previous studies from discrimination between microearthquakes and quarry blasts in2012 by adaptive neuro-fuzzy inference systems method. Data was selected and analyzed for one year
duration from Jan to Dec 2006. A total of 42 events quarry blasts data was extracted from the quarry blast
catalog. The Brune's model is used to estimate source parameters like corner frequency and fmax. We
obtained spectral characteristics for stations with a criterion for the signal to noise ratio; where signal tonoise ratio was larger than 2. Magnitude (Mw) for the quarry blasts was calculated from 1.1 to 2.4 atepicentral distances between 8.81 and 43.90 km. Mean of moment magnitude for all signals and stations
from 42 events has been evaluated to be Mw=1.6, and also mean of seismic moment obtained; M0=4.4E+11 Nm. Maximum and minimum seismic moment for events are calculated to be 3.80E+12 and5.10E+10 Nm, respectively. Other parameters like mean of corner frequency and fmax for this research for
all signals obtained 1.7 and 4.8 Hz, respectively. Moreover, the average stress drop by the quarry blasts in
the Tehran region obtained about 2.4 MPa. Comparison between the previous studies for a crustal
earthquake in the Tehran region in 2009 and this study showed that stress drop for quarry blasts (2.4 MPa)
are a bit smaller than the crustal earthquake (3.3 MPa). Results for this research can be used for bothseismological and engineering purposes.

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*S02-P-14
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

Analysis of ambient seismic noise levels for the SATREPS stations and theirtechnical aspects* Jorge Real , Vladimir Kostoglodov , Allen Husker
Universidad Nacional Autonoma de Mexico, IGEOF, Mexico
The joint research project between Japan and Mexico entitled "Evaluacion del peligro asociado a grandes
terremotos y tsunamis en las costas del Pacifico mexicano para la mitigacion de desastres" under the"Science and Technology Research Partnership for Sustainable Development" (SATREPS) program,contemplates the installation of 7 broadband seismological stations in the state of Guerrero, Mex. It is
important to know the levels of environmental seismic noise, so in this work we present the seismic andbackground noise curves and compare the maximum admissible noise (HNM) and minimum (LNM) curves
defined by Peterson (1993) to evaluate characteristics and design of the site of the seismic station, in
addition to showing the technical aspects of the installation.

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*S02-P-15
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

The features of deep seismic structure of the area of junction of theEurasian, Okhotsk and North American plates in Eastern Russia* Victor Seleznev 1) 2) , Aleksei Liseikin 2) , Victor Solovyev 3) , Aleksandr Salnikov 4) , Sergey Shibaev 5)
Geophysical Survey of the Russian Academy of Sciences, Obninsk, Russia 1) , Seismological Branch ofGeophysical Survey of the Russian Academy of Sciences, Novosibirsk, Russia 2) , Altai—Sayan Branch ofGeophysical Survey of the Russian Academy of Sciences, Novosibirsk, Russia 3) , Siberian ResearchInstitute of Geology, Geophysics and Mineral Raw Materials, Novosibirsk, Russia 4) , Yakutian Branch ofGeophysical Survey of the Russian Academy of Sciences, Novosibirsk, Russsia 5)
We compared the results of seismological studies and DSS with the known geodynamic reconstructions in
the area of junction of the Eurasian, Okhotsk and North American plates. Comprehensive analysis of thematerials of DSS and seismology represents a significant manifestation of this area of triple junction of theplates in the deep structures of the Earth's crust and in the Moho. Abnormal of seismicity and deep
structure of the zone in the alignment of the profile of the DSS is a few hundred kilometers. In the seismic
section it is marked by thin (37–42 km) crust (compared with the depths to the boundary M (57 km) in theadjacent northwestern area), low boundary velocities along the Moho (7.85 to 8.0 km/s), and low average(effective) velocities of P waves in the Earth's crust (~6.3 km/s). In the plate junction area, the waves
refracted from the Moho are weakly expressed in the wavefields. In the deep seismotomographic profile,
this zone is marked by an extremely inhomogeneous medium crust and less contrasting reflections in thelower crust and Moho section (from the CDP data). In the wide plate junction area we have established low
ratios of the velocities of P and S waves in the Earth's crust (≤1.6–1.7) and low Poisson's ratio (≤0.20),
which might indicate a strong fragmentation of the crust. Position the main border between the Eurasianand Okhotsk plates specified, it passes approximately along the 144 meridian. This is confirmed by most ofseismological and DSS data: the maximum number of earthquakes, maximum total released energy, major
earthquakes, minimum depth of the hypocenters, local rise of the Moho and intracrustal boundary, lowest Pwave velocities in the crust, and low velocities along the boundary M. A joint border of Okhotsk and theNorth American plates that run along the fault Ulakhan is also contrasting on the seismic structure.

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*S02-P-16
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S02. Anthropogenic seismicity

A physical seismic modeling study of multi-azimuth seismic refraction for ahorizontal transverse isotropic medium* Young-Fo Chang 1) , Cheng-Wei Tseng 2) , Jia-Wei Liu 1) , Chao-Ming Lin 3)
National Chung Cheng University, Taiwan 1) , Industrial Technology Research Institute, Taiwan 2) , Hsiuping
Institute of Technology, Taiwan 3)
In order to investigate the characteristics of anisotropic strata, a multi-azimuth seismic refraction technique
is proposed in this study. To simplify the problem, a two-layer (isotropy-horizontal transverse isotropy(HTI)) model is considered. A new travel time equation of the refracted P-wave propagation in the isotropyHTI medium is derived, which is the function of the phase and group velocities of the HTI medium. The
head wave velocity measured in the physical model experiment is the group velocity. The isotropicintercept time equation of a refraction wave can be directly used to estimate the thickness of the top(isotropic) layer of an isotropy-HTI medium, because the contrast between the phase and group velocitiesof the HTI medium is seldom greater than 10 percent in the earth. In addition, under an assumption, thecontrast between the phase and group velocities of an anisotropic medium is small, the approximatedtravel time equation of a refraction wave is obtained. This equation is only dependent on the group velocityof the HTI medium. The elastic constants A11, A13 and A33 and the Thomsen anisotropic parameter(Epsilon) of the HTI medium can be estimated using the multi-azimuth seismic refraction technique.

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*S03-1-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseEnvelopes of scalar plane wavelets propagating through 2-D random media
with power-law spectra
Yuji Tomiyama 1) , * Jun Kawahara 1) , Kentaro Emoto 2)
Ibaraki University, Japan 1) , Tohoku University, Japan 2)
The envelope broadening and the peak delay of the high-frequency S wavelets from regional earthquakes
are caused by scattering due to random velocity inhomogeneities in the earth. Several stochastic models
have been proposed so far to describe these phenomena, such as the radiative transfer theory, the diffusion
approximation, and the Markov approximation. Recently, Sato (2016, Geophys. J. Int.) proposed a newstochastic model to synthesize the envelope of a scalar wavelet radiated from a point source in a 3-D von
Karman-type random medium having a power-law spectrum. The point is to split the spectrum into two
components using the center wavenumber of the wavelet; the long-scale component produces the envelope
broadening and the peak delay by multiple forward scattering, and the short-scale component causes
amplitude attenuation by wide-angle scattering. The former and latter phenomena are evaluated by theMarkov and Born approximations, respectively. Later, Sato and Fehler (2016, Geophys. J. Int.) extended
Sato's theory into the case of a wavelet from a point source in a 2-D random medium. They showed that thesynthetic envelopes, except for coda, match well the results of finite difference (FD) simulations. Emoto andSato (2016a, Abstr. JpGU Meet.; 2016b, Abstr. Seism. Soc. Jpn. Fall Meet.) performed 3-D FD simulations
and obtained the results consistent to the theory. In this study, we conducted FD simulations of scalar
plane wavelets propagating through 2-D von Karman-type random media. We followed Sato and Fehler(2016) concerning the choice of the model parameters. We produced 15 media with different random
seeds, and set 7 receivers at each propagation distance in every medium. The simulated seismograms weresquared and stacked to obtain FD envelopes. We found they totally agree well with the present theory of aplane-wavelet version, except for the small von Karman order and the low center wavenumber of the
wavelets.

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*S03-1-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseStatistical characteristics of scattered waves in random media based on 3D
finite difference simulations* Kentaro Emoto , Haruo Sato
Tohoku University, Sendai, Japan
Short-period seismograms show complex waveforms due to the scattering by the small-scale
heterogeneities widely distributed in the solid Earth. The scattering causes the broadening of seismogramenvelope, the attenuation of the peak amplitude with travel distance increasing, and the excitation of long
lasting coda waves. In this study, we conduct the 3D finite difference (FD) simulation of the scalar wavelet
propagation in the random heterogeneous media by using the Earth Simulator, a vector supercomputer
managed by JAMSTEC. We analyze the characteristics of the scattered waves and compare them with thedirect envelope synthesis methods, such as the radiative transfer equation with the Born approximationand the improved Markov approximation based on the parabolic approximation (Sato, 2016).
We confirmed that Born envelopes adequately fit with FD envelopes in the whole lapse time range, but
improved Markov envelopes fail to model even at the peak of the envelopes for the case of a shortcorrelation distance. On the other hand, improved Markov envelopes well model FD envelopes around thepeak for the case of a large correlation distance. In this case, although the Born envelopes can't model the
peaks of FD envelopes, late coda part of the envelopes are well reproduced. We also investigate the
distribution of the squared amplitudes of FD traces. We find that the distribution varies as lapse timeincreases from the log normal distribution at onset to the exponential distribution at the coda. For the caseof a short correlation distance, squared amplitudes obey the exponential distribution soon after the onset.
This means that the random scattered waves are dominant from the early lapse time, since wide angle
scattered waves are dominant. According to the FK analysis of the FD traces, squared amplitudes obey the
exponential distribution before the energy fluxes of the scatted waves become isotropic.

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*S03-1-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noise

Propagation of a Scalar Wavelet through von Karman-type Random Media* Haruo Sato , Kentaro Emoto
Tohoku University, Sendai, Japan
Short-period seismograms of small earthquakes show envelope broadening of an S-wavelet with travel
distance increasing and excitation of long lasting coda waves. Their durations are much larger than thesource duration. We may interpret the collapse of a seismic wavelet as result of scattering by earth medium
heterogeneities. As a mathematical model, we study the propagation of a scalar wavelet through vonKarman-type random media. When the center wavenumber of the wavelet is lower than the corner
wavenumber, the radiative transfer equation with the Born approximation is useful for the synthesis ofwavelet intensity. When the center wavenumber is in the power-law spectral range higher than the corner
wavenumber, the Markov approximation method based on the parabolic approximation is useful for thesynthesis of wavelet intensity; however, this approximation fails to synthesize coda excitation. In this case,
we propose the following method for the synthesis of intensity time trace from the onset through the peak
until coda for an impulsive radiation from a point source. Taking the center wavenumber of the wavelet as areference, we divide the random medium spectrum into high– and low-wavenumber spectral components.
Applying the Born approximation to the high–wavenumber component, we calculate the scattering
coefficient, which is used in the radiative transfer equation for the calculation of intensity. Applying theMarkov approximation to the low–wavenumber component, we calculate the envelope broadening andwandering factors. Convolution of these factors with the intensity calculated in the previous step leads to
the Green function in the random media. By comparing the synthesized intensity time traces with FD
simulations, we have confirmed the usefulness of the proposed synthesis from the onset through the peak
until early coda.

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*S03-1-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseRole of localized heterogeneities on distortion of the apparent radiation
patters: aftershock sequence of the 2016 Kumamoto earthquake* Shunsuke Takemura , Tatsuhiko Saito , Hisahiko Kubo , Katsuhiko Shiomi
National Research Institute for Earth Science and Disaster Resilience, Tsukuba, JapanThe azimuthal variations of observed maximum amplitudes during local earthquakes (called the “apparent
radiation patterns") are gradually distorted from the expected four-lobe patterns of a double-couple point
source with increasing frequency and distance (e.g., Liu and Helmberger, 1985; Takemura et al., 2009,2016). In this study, we examine the frequency- and distance-dependent characteristics of the apparent
radiation patterns for P and S waves using NIED Hi-net waveforms of 30 aftershocks of the 2016 Mw 7.1
Kumamoto earthquake. Analyzed aftershocks are concentrated around two regions: the fault zone of the2016 Kumamoto earthquake and Aso volcano area. Thus, we separately analyze the aftershocks in the fault
zone (region A) and the volcanic area (region B). To quantify distortion from the four-lobe pattern, we
calculate cross-correlation coefficients (CCCs) between observed and theoretical apparent radiation
patterns as a function of normalized hypocentral distance kL, where k is wavenumber and L is hypocentral
distance. Focal mechanisms are referred from the NIED F-net moment tensor catalog.
In the Chugoku region, CCCs show linear decay from 0.75 to 0.25 with increasing log(kL) from 1.64 to 2.85
and no significant difference of decay rate between P and S waves (Takemura et al., 2016). However, CCCs
in this study show different characteristics from ones in Chugoku region. In region A, CCCs for P and S
waves linearly decay in the same log(kL) range, but values are smaller (0.45-0.2) than Chugoku region,
indicating that crustal heterogeneity in region A is stronger than Chugoku region. On the other hand, inregion B, CCCs for S wave are very small (=0.15-0.2) even for small log(kL), but ones for P wave well agrees
with Chugoku region, suggesting that around the volcanic area S-wave velocity structure has relatively
strong heterogeneous nature compared to P-wave one.

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*S03-1-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseModeling waveform anomaly across central Japan with scattered seismic
waves as inferred from high-frequency simulations* Simanchal PADHY 1) 2) , Takashi FURUMURA 1)
Earthquake Research Institute, The University of Tokyo 1) , CSIR-National Geophysical Research Institute,
Hyderabad 2)
We model significant waveform attenuation anomaly observed in central Japan for intermediate to deepfocus (>190 km) earthquakes in subduting Pacific (PAC) plate. Analyses of Hi-net waveform data from themoderate sized (M 4-6) PAC plate events show differences in amplitude and duration of the high-frequency
coda of P- and S-waves and their frequency content between the events occurring on northern andsouthern ends of the PAC plate. The northern events experience abnormally high attenuation of highfrequency (>1 Hz) seismic waves giving rise to spindle-shaped seismograms with strong converted phases
and extended coda with very slow decay at the eastern stations. We investigate the cause of such waveform
anomaly using the finite difference method (FDM) simulation of wave propagation through the subduction
zone. Results of simulation carried out for a suite of plate models with key subduction zone elements showthat the waveform anomaly is primarily explained by strong attenuation and defocusing of seismic waves by
the localized highly heterogeneous low-wave speed anomaly, representing partial melting of the upper
mantle. The data are secondarily explained by partial melting of the Philippine Sea (PHS) plate, mainly thehydrated basaltic oceanic crust, causing strong scattering of high-frequency seismic waves. The findings ofthis study have wide geodynamic implications such as the magma genesis and mechanism of intermediate
earthquakes in young (<25 Ma) and warm subduction zones of central Japan.

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*S03-1-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseElastic vs. Acoustic Radiative Transfer Theory - Estimation of Seismic
Attenuation Parameters in GermanyPeter J. Gaebler 1) , Tom Eulenfeld 1) 2) , * Ulrich Wegler 2)
BGR, Hannover, Germany 1) , Universitaet Jena 2)
In a first step a local data set is used to compare the outcomes of elastic and acoustic radiative transfer
theory simulations. Frequency-dependent scattering and intrinsic attenuation parameters are estimated forthe crustal structure beneath the W-Bohemia/Vogtland swarm earthquake region close to the border ofCzech Republic and Germany using the two different modeling approaches. The parameter estimations are
based on fitting synthetic envelopes to observed seismogram envelopes from shallow local events. The twodifferent methods yield a very similar S-wave scattering and intrinsic attenuation model for the crustal
structure in the Vogtland region with intrinsic attenuation being the dominant source of seismic
attenuation. The similarity of the results indicates that for a simple half space setup, isotropic scattering andonly modeling S-wave propagation, the acoustic approach suffices to obtain basic parameters about theattenuation properties of the medium. This is especially attractive, as analytic solutions to this approach
exist, which can be computed efficiently and deliver results with only minor computational costs.
In a second step over 20 years of earthquake data from the German Central Seismological Observatory
data archive is used to estimate the spatial dependent distribution of seismic intrinsic and scattering
attenuation of S-waves for frequencies between 0.5 and 20 Hz in Germany using acoustic radiative transfer
theory. We present preliminary results of the spatial distribution of intrinsic attenuation represented by theabsorption path length, as well as of scattering attenuation in terms of the mean free path and compare theoutcomes to results from previous studies. Furthermore catalog magnitudes are compared to moment
magnitudes estimated during the inversion process.

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*S03-2-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseTrans-dimensional imaging of scattering and intrinsic Q structures* Tsutomu Takahashi
Japan Agency for Marine-Earth Science and Technology
Precise imaging of scattering and intrinsic Q structures is essential to describe wave propagation processesof high frequency seismic waves (>1Hz). The multiple lapse time window analysis (MLTWA) has been used
to estimate these Q values by assuming constant Q in a study area (e.g., Hoshiba 1993). This study
generalizes this MLTWA for a stable estimation of 2-D Q structures under the Bayesian framework in
dimension variable space. Study area is partitioned into small areas by means of the Voronoi tessellation.
Scattering and intrinsic Q in each small area are constant. We define a misfit function for spatiotemporalvariations of wave energy as with the original MLTWA, and maximize the posterior probability withchanging not only Q values but the number and spatial layout of the Voronoi cells. This maximization isconducted by using the reversible jump Markov chain Monte Carlo (rjMCMC) (Green 1995) since thedimension of posterior probability is variable. After a convergence to the maximum posterior, we estimate
Q structures from the ensemble averages of MCMC samples around the maximum posterior probability.
Synthetic tests showed stable reconstructions of input structures with reasonable error distributions. We
applied this method for seismic waveform data of ocean bottom seismograms at the outer-rise area off
Tohoku, and estimated Q values at 4-8Hz, 8-16Hz and 16-32Hz. Intrinsic Q are spatially uniform at all
frequency bands, and scattering Q shows two distinct strong scattering regions at petit spot area and highseismicity area. These strong scattering are probably related to magma inclusions and fractured structure,
respectively. While our generalization of MLTWA is still based on a classical waveform modeling inconstant Q medium, this method can be a fundamental basis for tomographic imaging of Q structures in thecrust.

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*S03-2-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseScattering and attenuation structures beneath volcanoes inferred fromenvelope widths of volcano-seismic events* Hiroyuki Kumagai 1) , Cristian Lopez 2) , John Londono 2) , Yuta Maeda 1) , Rudy Lacson 3)
Nagoya University, Nagoya, Japan 1) , Colombian Geological Survey, Manizales, Colombia 2) , Philippine
Institute for Volcanology and Seismology, Quezon, Philippines 3)
It has been known that volcanoes exhibit highly heterogeneous structures with strong attenuation.
Investigating scattering and attenuation structures is important to understand magma and hydrothermal
systems beneath active volcanoes. In previous studies, the transport mean free paths (lm) and quality
factors (Q) at volcanoes have been estimated by using seismic waveform data acquired by seismic
experiments using artificial explosions, in which envelope waveforms (Wegler, JVGR, 2003) and spatiotemporal seismic energy distributions (Yamamoto and Sato, JGR, 2010) were analyzed. In this study, we
propose a new approach using envelope widths of volcano-seismic events. The envelope width (p) is
defined by the ratio of the cumulative amplitude (I) to the peak amplitude (A) of an envelope waveform of a
volcano-seismic event in a 5-10 Hz band at each station. We used the analytical equation of Paasschens(Phys. Rev. E, 1997) for the radiative transfer theory in 3D isotropic scattering medium to derive therelationship of p with lm and Q. The estimated relationship indicated that p increases with decreasing lm
and Q at a constant source-station distance, and p also increases with the source-station distance. We
estimated p values for volcano-tectonic events at Taal volcano, Philippines, and at Nevado del Ruiz volcano,
Colombia. Our estimated p values ranged up to 5 s and increased with increasing source-station distance.
Our estimated relations between p and source distances at both the volcanoes were not explained by
uniform lm and Q structures. We used the Monte Carlo simulation method of Yoshimoto et al. (JGR, 2000)
to interpret the estimated relations. Our results indicated that the relations can be explained by depth
dependent lm and Q structures: lm and Q are 500 m and 50, respectively, down to a depth of 1000 m,
below which lm and Q are 10000 m and 100. The pulse width may be used as a new measure to investigate
scattering and attenuation structures at volcanoes.

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*S03-2-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseIntrinsic Attenuations in the Oceanic Lithosphere and Asthenosphere
Constrained by Seismogram Envelopes* Nozomu Takeuchi 1) , NOMan Project Team 2)
University of Tokyo, Tokyo, Japan 1) , Various Institutions, Japan 2)
It is widely accepted that the oceanic lithosphere and asthenosphere have high-Q and low-Q, respectively,
however, it is not very clear to which extent such attenuations are affected by seismic wave scattering (e.g.,
Shito et al. 2015, JGR; Kennett and Furumura 2013, GJI). To distinguish the intrinsic and scattering
attenuations, analyzing seismogram envelopes is known to be effective. We deployed broadband ocean
bottom seismometers on the old Pacific seafloor between 2010-2014 (NOMan Project, http://www.eri.utokyo.ac.jp/yesman/). We had quite large number of aftershocks of 2011 Great Tohoku Earthquake andsucceeded in obtaining envelopes of Po/So and T-phase at various distances. The data purely sample theold ocean, which should provide unique opportunities to quantitatively constrain the attenuations in theocean. We applied our envelope simulation method (Takeuchi 2016, JGR) and obtained the attenuation
model by grid-searching the best structural parameters to explain the observations.
One of the most unique features of Po/So is that spatial attenuation (i.e., energy loss rate per unit
propagating distance) is independent from wave type (P- or S-wave) and frequency (Butler 1987, JGR).
Several previous studies (e.g, Sereno & Orcutt 1987, JGR; Mallick & Frazer 1990, GJI) explained suchfeatures by slightly ad-hoc attenuation models (strong frequency dependency; larger P attenuations than S).
In contrast, we tried to explain the observations without such assumptions and succeeded in explaining
most of the observed features. The results suggest that the saturation of backscattering coefficients at
higher wavenumbers is primarily responsible for the constant spatial attenuation.

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*S03-2-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noise3D Diffraction Imaging of Fault Zones* Vladimir Cheverda 1) 2) , Galina Reshetova 1) 2) 3) , Maksim Protasov 1) 2)
Institute of Petroleum Geology and Geophysics, Novosibirsk, Russia 1) , Novosibirsk State University,
Novosibirsk, Russia 2) , Institute of Computational Mathematics and Mathemmatical Geophysics,
Novosibirsk, Russia 3)
Presented research focusses on seismic analysis of fault damage zones. The statistical modelused based onusing fault facies technique. The statistical ensembles of facies spatial distribution are sampled for different
values of model parameters. Seismic forward modeling and imaging is performed for each realization. The
comparative statistical analysis of original models and the corresponding seismic images is carried out. Our
study allows to estimate the potential ability of using seismic methods to analyze the detailed geologicalstructures of subsurface fault zone.
Characterization of faults is a prerequisite for providing reliable assessments of expected flow patterns andtrap-integrity in subsurface reservoirs. Fault characterization in specific reservoirs remains highly
challenging, as reflected by the substantial literature addressing data handling and modelling of faultrelated parameters aimed at capturing and forecasting the impact of faults on fluid flow. The complexity offault characterization relates both to the nature of the input data available for description as well as thetools and methods used to process this information into models of actual faults.
Faults can be considered as volumetric entities consisting of deformed host rock generated during thefaulting process. The products of this process are closely linked to a wide range of parameters, such as
tectonic regime, magnitude of fault displacement and mechanical properties of the host rock.
Direct observational data from any individual fault in a subsurface reservoir is either very scarce (i.e. rare
cores and well logs through faults), or offers only limited resolution (i.e. physical constrains to seismic
acquisition). Thus, characterization of fault properties in sub-surface reservoirs, apart from seismicallyresolvable geometric relations, is extensively governed by concepts derived from a combination oftheoretical considerations and outcrop and laboratory studies.

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*S03-2-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noise

Joint inversion for shallow crustal discontinuities from high-frequency
waveforms of microearthquakes* Pavla Hrubcova , Vaclav Vavrycuk
Institute of Geophysics, Academy of Sciences, Prague, Czech Republic
The waveforms of microearthquakes are of high frequency and complicated. They contain many phases
secondarily generated at crustal interfaces and at small-scale inhomogeneities. They are highly sensitive to
focal mechanisms and thus very different for each station of local networks. However, with a large numberof clustered microearthquakes, the reflected/converted waves in waveforms can serve for detecting
prominent discontinuities within the crust. With a dense network of sensitive seismic stations and a goodazimuthal distribution, it is possible to retrieve a depth of these discontinuities and map their lateralvariations. The standard microseismic monitoring is routinely investigated for source parameters; however,an analysis of shallow crustal structure is often missing.
The structure studies based on microseismic data are specific. The depth of discontinuities is modelledusing several independent tools provided by refraction and reflections seismics combined with theearthquake source analysis. This includes ray tracing for calculating traveltimes of converted and/orreflected phases, analysis of focal mechanisms and radiation patterns for converted/reflected phases, fullwaveform modelling using discrete wavenumber method for comparing synthetics with observed data,alignment of traces and their stacking for amplifying studied phases, and grid search for the inversion. Jointinterpretation of more phases converted/reflected from the same interface increases the stability of
retrieved results and enhances the robustness of the inversion. A novel concept for extracting crustal
structure from high-frequency waveforms of local microearthquakes is demonstrated on natural seismicity
in the West Bohemia swarm region, the Czech Republic. Clustered seismicity in West Bohemia indicates astrong-contrast interface at depths of 3.5-6.0 km, which is in agreement with previous profiling and might
be related to trapping of fluids ascending from the mantle.

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*S03-3-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseBias in velocity measurements from ambient noise due to anisotropic source
distributions* Olafur Gudmundsson , Hamzeh Sadeghisorkhani , Roland Roberts , Ari Tryggvason
Uppsala University, Uppsala, Sweden
Secondary microseismic sources are strong off the Atlantic coast of Norway and dominate ambient noise
recorded in Scandinavia. At the same time, the source distribution is quite heterogeneous andsources from the south and east (Baltic Sea) are weak or absent. This source heterogeneity causes
significant bias in measurements of velocity of surface waves extracted from ambient noise by correlation.
We study this bias effect synthetically and characterize it in terms of Weaver's asymptotic formula at large
inter-station distance, r, or short wavelength, L, and in terms of Fresnel angles at short inter-station distanceor large wavelength. We find that the bias of group-velocity measurements is significantly higher than thatof phase velocity. We find that Weaver's formula applies to within several percent when the ratio r/L > 10
and when the local anomaly angular width exceeds the width of the Fresnel angle. When the source
distribution varies on a small angular scale and inter-station distances are relatively short the phasevelocity bias can be as large as several percent. We quantify the bias effects of the mapped source
distribution around Scandinavia and find that in this region of relatively weak crustal heterogeneity (3%)
the bias often exceeds the heterogeneity level, particularly for group velocity. This highlights the need for
careful study of the effective source distribution of microseisms and its potential bias effects in regions of
weak heterogeneity before inverting dispersion measurements for 3D velocity structure. Phase velocity is tobe preferred over group velocity and careful data selection based on the ratio r/L and the azimuthal
distribution of the source is vital.

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*S03-3-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseApproximate vector sensitivity kernels of coda waves to seismic velocitychanges based on the scalar single isotropic scattering model* Hisashi Nakahara , Kentaro Emoto
Tohoku University, Sendai, Japan
Coda-wave interferometry has been used to detect velocity changes in association with large earthquakes
or volcanic eruptions. Sensitivity kernels of travel times of coda waves are necessary to determine theregion of velocity changes correctly. These sensitivity kernels have been formulated so far for scalar waves
based on different assumptions of two-dimensional single scattering or multiple scattering, threedimensional single scattering or multiple scattering, or diffusion. However, no formulation has been madefor vector waves as far as we know. Hence, we tackle this formulation and derive analytical approximate
expressions for two-dimensional and three-dimensional cases. The key point in our simple extension tovector waves is the projection of seismic phonon energy into horizontal and vertical components by using
the square of the direction cosine of the polarization direction. Thanks to this simple idea, we can derive
analytical expressions of the approximate vector sensitivity kernels by using the single isotropic scatteringmodel for scalar waves, though we can treat either P waves or S waves at a time. Our results show that thesensitivity kernels are different for different components, and accordingly different components show
different travel time changes with respect to lapse time. These are theoretically shown for the first time bythis study. The approximate vector sensitivity kernels have two clear peaks at a source and a receiver
which are different from different components. Comparing with finite difference simulations of vector wave
propagation, we find that our approximate vector sensitivity kernels are very good for two-dimensional
cases, but are worse for three-dimensional cases. So far the reason is not clear yet. However, ourapproximate vector kernels are helpful to consider how to use seismograms of the different components
simultaneously in coda-wave interferometry.

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*S03-3-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseLand-atmosphere coupling and source of low-frequency seismic noise fromthe analysis of co-located barometers and seismometers* Toshiro Tanimoto , Jiong Wang , Anne Valovcin
University of California, Santa Barbara, USA
We studied the nature of coupling between atmosphere and solid Earth by examining co-locatedseismometers and barometers that are available from many arrays. We summarize a few characteristicfeatures from our analysis of Pinon Flat array in Southern California and Earthscope Transportable Array(TA).
First, we can establish from data that atmospheric pressure at Earth's surface is closely related to winds,
basically proportional to square of wind speeds. This pressure in turn causes vertical and horizontal
motions in solid Earth. Correlation between pressure and vertical motion is high (correlation coefficient ~0.8 or higher), especially for frequencies below 0.05 Hz. This high correlation occurs only above a certain
threshold pressure, however (Tanimoto and Valovcin, GRL, 43, 2016). Below this pressure, verticalamplitudes show no correlation with atmospheric pressure. Above this pressure the local atmospherepressure directly controls vertical motions, showing almost perfect phase-to-phase match in waveforms.
Above 0.05 Hz, this correlation starts to become smaller as ocean waves become the dominant source ofseismic ground motions.
Horizontal ground motions show quite different behaviors. Horizontal seismic amplitudes change with local
atmospheric pressure for the entire range of pressure that barometers can measure. It indicates that groundtilt is the dominant cause of horizontal noise. It is noteworthy that tilt effects on horizontal motions are
significant even at low pressure.
Pressure vs. horizontal amplitudes show different (bifurcating) behaviors for many stations between
summer and winter. In winter, noise level is always high and is constant in pressure-amplitude plots,
meaning local atmospheric pressure is not responsible for seismic motions. But in summer, horizontal
amplitudes show good correlation with local pressure changes and show wide variations in amplitudes aspressure changes significantly with time.

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*S03-3-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noise

Dominant source locations of secondary microseisms in Japan estimated by
Hi-net data
* Ryota Takagi 1) , Kiwamu Nishida 2)
Graduate School of Science, Tohoku University 1) , Earthquake Research Institute, The University of Tokyo
2)

Microseisms are energetic ambient seismic wavefield generated by ocean swells, which are categorized
into primary (10-14 s) and secondary microseisms (5-7 s). Although source locations are crucial
for understanding the excitation mechanisms of microseisms, source locations of secondary microseisms
still remain uncertain. Moreover, understanding microseism wavefield is important to correctly interpret
results of seismic interferometry. In the present study, we estimate dominant source locations of Rayleighwaves in secondary microseisms observed in the Japan islands using Hi-net data. We first estimate backazimuths of Rayleigh waves in the period of 4-8 s based on polarization analysis. Since fundamental
Rayleigh waves, dominating secondary microseisms, generally show retrograde particle motions, backazimuth of Rayleigh waves can be determined from three component records at single stations. We thensearch locations explaining the back azimuth distributions within subarrays in the Japan island. The
estimated sources of Rayleigh waves distribute in specific regions. Dominant locations are 100-200 km off
the coast of Fukushima and Miyagi in the Pacific, off Tottori in the Sea of Japan, and off the the Shonai
Plain. The off Tottori sources show a clear seasonal variation, detected only in the winter season, which isconsistent with ocean wave activity in the Japan Sea predicted by an ocean action model WAVEWATCH
III. The off Tottori and off Fukushima-Miyagi sources are located at an ocean basin with the depth of
1000-2500 m and at shelf slope with the ocean depth of 2000-6000 m, respectively. The ocean depths areclose to the resonance depth for the period of 4-8 s. The off Shonai sources are located in the regions inshallower ocean depth. We consider investigating frequency dependence of source locations may deepen
our understanding of mechanism of microseisms.

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*S03-3-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseComparison of microseismic Rayleigh and Love waves sources around
Scandinavia
Hamzeh Sadeghisorkhani , * Olafur Gudmundsson , Roland Roberts , Ari Tryggvason
Uppsala University, Uppsala, Sweden
Use of the ambient noise wave field to image Earth structure has extensively increased during the past
decade. Information about noise-source locations and their excitation process can be useful for theapplication of the ambient-noise method and interpretation of its results. The source locations andmechanism of microseismic Rayleigh waves have been studied in many areas. However, few studies havebeen published about the source distributions and processes of microseismic Love waves. The lack of
information about Love wave source locations and their excitation mechanism applies in particular to thesecondary microseisms.
An inversion of cross-correlation envelopes over one year (2012) in five sub-arrays of the Swedish National
Seismic Network (SNSN) is used to map and compare the azimuthal source distributions of Rayleigh andLove waves within the primary and secondary microseisms around Scandinavia. The results from all sub
arrays can be combined to map the potential source locations of the Rayleigh and Love waves. Comparisonof the source locations of the two waves types indicates that Rayleigh and Love waves within the primary
microseismic band arrive from similar directions, whereas in the secondary microseismic band the source
locations are not always co-located. Our results suggest that most of the energy of the secondary
microseisms originates in near-coastal areas (mainly along the western coast of Norway), and could be
related to channel-shaped features in the ocean bottom bathymetry. Also, the dominant source locations ofdifferent period ranges of the secondary microseisms varies, especially for the Love wave.

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*S03-3-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseGlobal source location of P-wave microseisms using Hi-net data from 2005
to 2011* Kiwamu Nishida 1) , Ryota Takagi 2)
The University of Tokyo, Tokyo, Japan 1) , Tohoku University, Sendai, Japan 2)
Source locations by a back projection method is feasible for understanding the excitation mechanism of
secondary microseisms. However, complex wave propagations of surface waves caused by strong shallow,
lateral heterogeneities prevent from the precise location of the sources. In contrast, body wave microseisms
are less scattered than the surface-wave microseisms. Although the amplitudes of body wave microseisms
are smaller than surface wave amplitudes, recent developments in source location based on body-wave
microseisms enable us to estimate precise locations of forcing and the amplitudes quantitatively [e.g.
Nishida and Takagi, 2016]. In this study, we made a catalogue of P-wave microseisms by array analysis
using the Hi-net operated by NIED from 2005 to 2011. We analyzed vertical-component velocity-meterswith a natural frequency of 1 Hz at 202 stations in Chugoku district. The instrumental response wasdeconvolved by using an inverse filtering technique after reduction of common logger noise. The records
were divided into segments of 1024 s. After exclusion of segments which include transients, the frequencyslowness spectra were calculated. The spectra at 0.15 Hz show that clear teleseismic P-wave microseisms
on seismically quiet days when local swell activities were calm. The local maxima of the spectra were
picked up. The centroids of the sources were located by backprojecting the corresponding slowness. The
source locations show clear seasonal variations. In winter months, they were located in the northwestern
Pacific, and in the summer months they were located in the southern Indian ocean. Through the years,
centroids stayed in the north Atlantic ocean, although they show a weaker seasonal variation with the
maximum in winter. The locations can be explained by an ocean action model (WAVEWATCKIII: Ardhuin
et al. 2011). In further studies, we will calculate the equivalent vertical single force for quantitative
discussions.

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*S03-4-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseQuantifying the body-wave information retrieved from global earthquake
coda correlation* Hsin-Hua Huang 1) 2) 3) , Victor Tsai 2) , Fan-Chi Lin 3) , Weitao Wang 4) , Julien Chaput 5)
Institute of Earth Sciences, Academia Sinica, Taiwan 1) , Seismological Laboratory, California Institute ofTechnology, U.S.A. 2) , Department of Geology and Geophysics, University of Utah, U.S.A. 3) , Key
Laboratory of Seismic Observation and Geophysical Imaging, Institute of Geophysics, China Earthquake
Administration, China 4) , Department of Mathematics, Colorado State University, U.S.A. 5)
Body wave retrieval from noise or coda correlations provides sampling at greater depths and has advanced
our ability to probe and monitor the deep Earth. However, to date the identification of body waves incorrelations relies mainly qualitatively on the signal-to-noise ratio of phases and the matching of theoreticaltravel times and lacks a quantitative validation of their travel-time accuracy and spatial sensitivity. Based onrecent observations that the late coda of large earthquakes is not diffuse and that the source locations of
the large earthquakes used in coda correlations are well known, it becomes viable to approach the question
through numerical simulation with spherically symmetric Earth models (no scattering) for coda correlation.
By varying numerous parameters such as source duration, source distribution, and velocity/Q structure,
143 global large earthquakes (Mw7) and USArray stations are used to compare with and to validate theobservations of recently-reported core phases (e.g. P'P') from coda correlations (Huang et al., 2015).
Simulation results show that using only reverberations can replicate most of the features of the body-wave
signals observed in correlation functions. The travel time bias present in the (zero-offset) autocorrelation
functions is insignificant (within 0.5 s) as long as the selected coda windows are sufficiently late (after~10000 s) while the bias in cross-correlation functions shows a systematic trend that increases with station
separation regardless of source distribution. With the aid of ray-based modeling, we explore the mechanismof such bias, the emergence of spurious phases, and distinct frequency content between coda and noisecorrelation. Gaining a better understanding of such body-wave information improves our ability to use andvalidate correlation-based data, making it possible to reliably integrate such measurements with earthquakebased data in future applications.

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*S03-4-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseIlluminating the Cascadia forearc and Mendocino Triple Junction systemfrom seismic interferometry* Benoit TAUZIN 1) , Thanh Son Pham 2) , Hrvoje Tkalcic 2)
Laboratoire de Geologie de Lyon : Terre, Planetes, Environnement, Universite de Lyon 1) , Research Schoolof Earth Sciences, Australian National University 2)
We use autocorrelation to extract the reflection response from the coda of transmitted P-waves from distantearthquakes recorded at dense seismic arrays in the western US (Cascadia 93 and FAME Mendocino
experiments). This results in two 300 km-long reflectivity profiles across the forearc and arc of the Cascadia
subduction zone in Oregon and northern California. The results show good agreement with priorknowledge of the forearc based on inverse scattering and multi-mode conversion imaging, including thepresence of a dipping low-velocity zone (LVZ) from 20 to 40 km depth near the plate interface. Fromobserved data and numerical modeling with spectral element methods, we investigate how the quality of
the reflection response obtained from P-coda autocorrelation is influenced by the distribution ofearthquakes and the complexity of the transmitted wavefields. We also illuminate more precisely theuppermost 100 km of the mantle in the transitional domain from subduction to transform regimes in the
Mendocino Triple Junction system. We find that the LVZ extends from the subduction regime at North tothe transform regime at South as far as the Clear Lake volcanic field (38.97 degree North; 122.77 degreeWest). We speculate the existence of a portion of the Gorda plate near 60 km depth in the transformdomain below this same volcanic field. Our results raise questions on the nature of the LVZs, theirrelationship to non-volcanic tremors in the subduction and transform regimes of the Mendocino and San
Andreas regions, and on the presence of remnants of fossil slabs attached to the Pacific plate underneaththe edge of the North American plate.

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*S03-4-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseRetrieval of tsunamis by the interferometry of deep ocean pressure records* Shingo Watada , Lisa Kaneko , Yuchen Wang , Kenji Satake
The University of Tokyo, Tokyo, Japan
Ocean surface waves are ubiquitous and incessant. We applied the waveform interferometry to the records
from deep ocean pressure gauges to retrieve tsunami waveforms without tsunami sources.
Continuous pressure records for the year 2011-2015 from three tsunami-meters operated by NOAA,
located along the western boundary of the Pacific at the depth of 5500-5900 m were used for the tsunami
interferometry. Distance between stations ranges from 956 to 2265 km. De-tided data were processed toenhance the cross-correlations. The stacked waveform showed gradual amplitude increase toward thearrival time of virtual tsunami propagating between two stations. A sharp transition from positive tonegative amplitude was observed at the expected arrival time.
This characteristic waveform reflects the fact that the long-wave tsunami at the deep ocean is nearly nondispersive for a broad wave-period range. In theory the cross-correlation of 2D isotropic non-dispersive
wavefield coming from large distance shows a gradual increase of amplitude before the expected arrival
time of the virtual waves traveling between two points. No plane wave arrives at two points with a time laglarger than the traveltime between the two points, corresponding to the abrupt amplitude decrease of crosscorrelated waveforms. In reality dispersive surface gravity waves propagate at speeds slower than longwaves and appear later than the virtual tsunami.
The extracted virtual tsunami waveforms were then analyzed for the phase velocities of tsunamis between
two points. Subtracting the initial phase from the measured phase by assuming cylindrical 2D waves, we
succeeded in measuring the phase velocity of virtual tsunamis for the period range from 300 to 3000 s. The
measurements were in good agreement with the tsunami phase velocities expected from the ocean depth.
A clear reduction of phase velocity from long-wave speed, as predicted from the surface gravity wave
theory, was detected for wave periods near 300 s.

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*S03-4-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseHV Spectral Ratio (HVSR) for preliminary seismic characterization of Sun
Pyramid in Teotihuacan, Mexico.
Jose Pina-Flores 1) 2) , Shinichi Matsushima 3) , * Francisco J Sanchez-Sesma 1) , Juan C Molina-Villegas 4) ,Jesus Morales-Valdez 1) , Mario A Saenz-Castillo 5) , Cesar A Sierra-Alvarez 5) , Hiroshi Kawase 3)
Instituto de Ingenieria, Universidad Nacional Autonoma de Mexico, Mexico 1) , Facultad de Ingenieria,
Universidad Nacional Autonoma de Mexico, Mexico 2) , Disaster Prevention Research Institute, Kyoto
University, Uji, Japan 3) , Facultad de Ingenieria,Universidad de Medellin, Colombia 4) , EAFIT University ofMedellin, Colombia 5)
Currently Teotihuacan is one of the most important archaeological sites in Mexico and it is the mostrepresentative city of the classic period in the central Mexican anti-plane. In the center of Teotihuacan twomonumental structures stand out: The Moon and the Sun pyramids. The latter is the largest structure. With
the purpose of knowing its seismic characteristics and constructive processes of the Sun Pyramid, we
carried out a campaign of environmental seismic noise measurements with 16 sensors distributed in the
different locations and levels of the pyramid. In this work we show some preliminary results of the HVSpectral Ratios (HVSRs) which show a clear effect of amplification in different frequencies for the different
levels produced by the existence of irregular geometry. Also, we will focus on the directionality of HVSRs inorder to understand the topological effect and the heterogeneity within the pyramid.

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*S03-4-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseCrustal Structure of South Yogyakarta Area Revealed By Spatial Auto
Correlation and Ambient Noise Tomography* Wiwit Suryanto 1) , Jean-Philippe Metaxian 2) , Ade Anggraini 1) , Fittra Irwandhono 1) , Francois Beauducel
3)

Universitas Gadjah Mada, Yogyakarta, Indonesia 1) , Universite de Savoie, Le Bourget du Lac, France 2) ,Institut de physique du globe de Paris, France. 3)
The 2006 Yogyakarta earthquake struck the Indonesian island of Java with Mw 6.3 on May 26, 2006 thatcaused major damage and thousands of deaths in the area of Yogyakarta and Central Java province.Basedon the aftershocks recorded by temporary seismic network deployed shortly after the earthquake disaster,
the source of the 2006 earthquake was located about 20 km east of Opak fault. However, detail structure of2006 earthquake's fault remains unclear. Its vicinity to highly populated Yogyakarta brings a reasonable
motivation to investigate this geology structure and its potential hazard further. Until 2016, several weaker
earthquakes were still felt by residents living around Opak fault and 2006 fault zone. To follow up this case,Gadjah Mada University and the Institut de Recherche pour le Developpement (IRD) conducted a seismic
measurement around the faults area from October 2015 to May 2016. The purposes of this measurement
were to determine the detail structure of the fault and to obtain velocity model of subsurface ( YOG ver 1.0)
using Spatial Auto Correlation (SPAC) and Ambient Noise Tomography (ANT) method. Data acquisitions
were carried out on the west side and the east side of the fault zone to map lateral velocity variation. Shearwave velocity, Vs contrast obtained by this measurement clearly indicates Opak Fault and 2006's fault
zones which also reflects different types of lithology. This result improves the accuracy of local earthquake
relocations and provides better images of local structures in Yogyakarta area. Through this research a
processing software for Ambient Noise Tomography (GAMANT) also has been developed. As themeasurement around Opak fault and 2006 fault zone shows very promising results, another experiment in
Merapi will also be conducted this year to investigate the possible relation between crustal fault andvolcanic activities.

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*S03-4-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseSurface wave tomography of Java Island from ambient seismic noise* Sri Widiyantoro 1) , Zulfakriza Zulhan 1) , Agustya Martha 1) 2) , Phil Cummins 3) , Erdinc Saygin 4) , Tedi
Yudistira 1) , Andri Nugraha 1) , Bayu Pranata 1) 2) , Shindy Rosalia 1)
Insitut Teknologi Bandung, Bandung, Indonesia 1) , BMKG, Jakarta, Indonesia 2) , Australian National
University, Canberra, Australia 3) , University of Western Australia, Perth, Australia 4)
P- and S-wave velocity structures beneath the Sunda Arc, including Java Island, were successfully imaged
in our previous studies using a global data set and a nested regional-global tomographic method. To obtain
detailed crustal structure information of the region beneath Java, we have since employed the Ambient
Noise Tomography (ANT) method. In this study, we have used seismic waveform data from MErapi
AMphibious EXperiment (MERAMEX) in central Java and those recorded by BMKG stationary
seismographic stations in Java and 25 portable seismographs, which were installed for 2 to 8 weeks ineastern and western Java. The data have been processed to obtain waveforms of cross-correlated noise
between pairs of seismographic stations. Our preliminary results, for example, indicate that the Kendeng
Zone, an area of low gravity anomaly extending from central to east Java, is associated with significantly
lower seismic velocity than average. On the other hand, the southern mountain range, with a high gravity
anomaly, is related to a high seismic velocity anomaly. We are now in the process of finishing dataacquisition in western Java. The expected ANT imaging results of the whole of Java Island will bepresented in the meeting. For future work, we will combine the ANT result with the mantle velocity models
using body wave tomography to obtain accurate locations of earthquake hypocenters and to constructregional tectonic structures in unprecedented detail. Both of these are vital for understanding seismic
hazards in Java, which is one of the most densely populated islands in the world.

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*S03-5-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseDepth dependence of stress sensitivity of seismic velocity changes as
inferred from noise correlation analyses at Izu-Oshima volcano, Japan* Tomoya Takano , Takeshi Nishimura , Hisashi Nakahara
Department of Geophysics, graduate School of Science, Tohoku University
We determine stress sensitivity of seismic velocity changes at Izu-Oshima in Japan based on a seismic
interferometry method. Ambient noises recorded at four seismic stations deployed on the small volcano
island for 4 years from January 2012 to December 2015 are used to calculate cross correlation functions.
Cross correlation functions are estimated at frequency bands of 0.5-1Hz, 1-2Hz, and 2-4Hz. Applying amoving window time analysis to the cross correlation functions, we estimate daily seismic velocity changes.
Decrease and increase of seismic velocity changes are well associated with the areal strain changes
observed by GNSS network. Comparing the areal strain changes with seismic velocity changes, we
calculate the stress sensitivity of seismic velocity changes to be (7.1+/-1.3)x10-8 Pa-1 at the frequency
band of 0.5-1Hz, (1.4+/-0.1)x10-7 Pa-1 at 1-2Hz, and (1.3+/-0.1)x10-7 Pa-1 at 2-4Hz, respectively. The
stress sensitivity of seismic velocity at 0.5-1Hz is lower than those at the higher frequencies. The observed
seismic velocity changes are located in the upper 1 km by assuming the wave length of Rayleigh-wave. The
result at Izu-Oshima is consistent with the stress sensitivity of seismic velocity changes by previous studies.
We conclude, therefore, that the stress sensitivity of seismic velocity changes decreases with depth down toa few kilo meters, which is probably due to the increase of confining pressure.

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*S03-5-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseObservation of coseismic and postseismic velocity changes for deep
borehole seismic stations in the Kanto area
* Manuel Hobiger 1) 2) , Ulrich Wegler 2) 3) , Katsuhiko Shiomi 4) , Hisashi Nakahara 5) , Kazuo Yoshimoto 6)
Swiss Seismological Service (SED), ETH Zurich, Zurich, Switzerland 1) , Federal Institute for Geosciences
and Natural Resources (BGR), Hanover, Germany 2) , Institute of Geosciences, University Jena, Jena,
Germany 3) , National Research Institute for Earth Science and Disaster Resilience (NIED), Tsukuba, Japan4), Department of Geophysics, Graduate School of Science, Tohoku University, Sendai, Japan 5) ,Earthquake Research Center, Yokohama City University, Yokohama, Japan 6)
Using Passive Image Interferometry (PII), we analyze long time series of seismic noise data from Hi-net
seismometers in the Kanto Basin in and around Tokyo. The 17 deep borehole seismometers used in thisstudy are located in depths between 1200 and 3500 m below the Earth's surface. The analyzed time series
span 9.5 years (January 2003 to June 2012) and include the recordings of the MW 9.0 Tohoku-oki
earthquake on 2011 March 11 and also an M 5.7 earthquake in Southern Ibaraki prefecture on 2004
October 6.
Single-station cross-correlations and cross-correlations were calculated for the different stations and station
pairs, respectively, in frequency ranges between 0.125 and 4.0 Hz. Significant coseismic velocity drops areobserved, followed by postseismic recovery that can be modeled by an exponential function. Using thefrequency-dependence of the velocity changes, we can constrain the depth range of the observed velocitychanges. Furthermore, we correlate the observed velocity changes with the pga and pgv values at therespective sites.
As this study uses very deep sensors compared with previous studies, we anticipate that the observed noise
field differs from the one observed at surface stations. Consequently, the depth range of the observed
coseismic velocity changes can be constrained more precisely combining the results of this study withprevious results.

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*S03-5-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseMonitoring volcanic and geothermal fields using seismic noise: the casestudy of the Las Tres Virgenes geothermal field (Mexico).
* Marco Calo , Erik Alberto Lopez Mazariegos , Valente Ramos Avila , Javier Francisco Lermo Samaniego
National Autonomus University of Mexico (UNAM)
Volcanoes are known to be dynamic systems where physical properties change over the time because of
the magma ascending into de main and secondary conduits that produce variations of stress on the edifice
and in the crust. Geothermal systems under exploitations are often compared to volcanoes because reinjection of fluids in depth through wells may create small perturbations of the field that can also generate
induced seismicity.
In the last decade the analysis of large records of seismic noise allowed to retrieve useful information about
the non-stationary condition of the physical properties of volcanoes with the aim to develop efficient
forecasting eruption models. First attempts to detect seismic velocity variations during injections also
showed that the seismic noise monitoring might be use to observe and describe such variations over thetime.
In this work we show how the seismic noise correlation technique can be applied to monitor changes onseismic velocities into a geothermal field operating in a volcanic region, and which are the observables
originated by the power plant activities and those related to the natural activity of the area.

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*S03-5-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseAnisotropic S-wave velocity change in the shallow subsurface associatedwith the 2016 Kumamoto earthquakes* Kaoru Sawazaki , Tatsuhiko Saito , Tomotake Ueno , Katsuhiko Shiomi
National Researh Institute for Earth Science and Disaster Resilience, Tsukuba, Japan
In this study we focus on anisotropic S-wave velocity change at KiK-net station KMMH16, where PGV
exceeding 100 cm/s was recorded when the 2016 Kumamoto earthquake, Japan, occurred. We use 217
earthquake waveforms registered by station KMMH16, where S-wave coda is used to avoid apparent
velocity change due to difference in incident angles. After correcting azimuthal bias, we rotate twohorizontal components every 10 degree for both surface and borehole bottom (255 m depth) records tocompute polarized waveform pairs. Then we deconvolve the polarized waveform on the ground surface bythat at the borehole bottom to extract Green's function between the two sensors. After applying 4-20 Hz
bandpass filter to the deconvolved waveform, we apply the stretching technique using lag-times of 0.2-0.9 s
to extract relative velocity change before and after the Kumamoto earthquake for each polarization
direction.
In the period within 7 minutes to 26 hours after the MJ6.5 foreshock on April 14, we find the maximum
velocity change of -7.0% for N50E polarization direction, while the minimum velocity change is -3.6% for
N10W direction. The N50E direction is close to the along-strike direction of the Futagawa-Hinagu fault
system. Within 53 minutes to 14 hours after the MJ7.3 mainshock on April 16, the velocity further reduceto -7.4% for N50E direction. The velocity recovers to -4.8% by two months after the mainshock, while nofurther recovery is found within 2-9 months after the mainshock.

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*S03-5-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseSpatio-temporal changes of seismic scattering properties associated with thedike intrusion on 15 August 2015 at Sakurajima volcano, Japan, detected byseismic interferometry* Takashi Hirose , Hisashi Nakahara , Takeshi Nishimura
Department of Geophysics, Graduate School of Science, Tohoku University
Seismic interferometry has been used to detect spatio-temporal changes of seismic scattering properties(e.g. Obermann et al. 2013a). At Sakurajima, one of the most active volcanoes in Japan, a dike intrusion
took place on 15 August 2015, and large ground deformation was observed (e.g. Hotta et al. 2016). Such adike may work as a new scatterer for seismic waves. Therefore, we applied seismic interferometry to detectchanges in seismic scattering properties associated with this event. We used the vertical components ofambient seismic noise data at 1 – 2 Hz recorded at 6 JMA stations from 1 January 2012 to 31 August 2015.
We calculated coherences between reference CCFs (stacked over 2012 and 2013) and daily CCFs, andfound that all station pairs showed significant decreases of coherences before and after the dike intrusion.
To locate the region where the seismic scattering properties changed, we used sensitivity kernels
calculated from 2D radiative transfer model. Parameters of scattering and intrinsic absorption that areneeded to calculate sensitivity kernels were estimated by modeling the space-time distribution of energy
density of active shot records. The best-fit parameters were as follows: Mean free path of Rayleigh waves
was 1.2 km at 1 – 2 Hz, and intrinsic absorption Q was 62.8f (f is the frequency). Then, we calculated thedifferences between mean values of coherence in 2014 and those of from 16 August 2015 to 31 August
2015 (hereafter ΔC). Assuming that one seismic scatterer appeared on the surface projection of the dike,
we searched the best location of the scatterer to explain observed ΔC. That was located at the same placeas the dike determined by using geodetic data (Hotta et al. 2016) with an accuracy of about a few km, andthe change of scattering coefficient (Δg) was estimated as 1.4 km-1. Acknowledgements: We usedseismograms recorded by JMA. Active seismic experiments were conducted by DPRI, Kyoto University,
other 8 universities, and JMA.

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*S03-5-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseCharacterization and monitoring of ambient vibrations of a rock slope close
to collapse* Jan Burjanek 1) , Donat Faeh 2)
Institute of Geophysics of the CAS, Prague, Czech Republic 1) , Swiss Seismological Service, ETH Zurich,
Zurich, Switzerland 2)
We present the ambient vibration study of Alpe di Roscioro, a developing rock slope failure located above
the village Preonzo in southern Switzerland. Following a major failure in May 2012 (volume ~210,000 m3),
the remaining unstable rock mass (~140,000 m3) remains highly fractured and disrupted, and has been thesubject of intensive monitoring. A small-aperture seismic array was deployed at the site shortly after the2012 failure. The measured seismic response exhibited strong directional amplification (factors up to 35 at
3.5 Hz), higher than previously recorded on rock slopes. The dominant direction of ground motion was
found to be parallel to the primary direction of deformation and perpendicular to open fractures, reflecting
subsurface structure of the slope. The site has been later equipped with two semi-permanent seismic
stations to monitor changes of the seismic response due to internal damage that may precede subsequent
failure. Although failure has not yet occurred, our data reveal significant variations in the seismic response.
Resonant frequencies exhibit seasonal trends related (both directly and inversely) to temperature changes,
and are sensitive to freezing periods (resonant frequencies increase with temperature and during freezing).

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*S03-P-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseSeparation of intrinsic attenution and scattering loss for the contiguous US
Tom Eulenfeld 1) 2) , * Ulrich Wegler 2)
BGR, Hannover, Germany 1) , Universitaet Jena 2)
We invert 10 years of earthquake envelopes registered by the USArray to construct maps of S-wave
intrinsic and scattering attenuation of the crust beneath the contiguous US in the frequency range 1 Hz to
20 Hz. We also report site amplification factors and a comparison of estimated moment magnitudes with
Richter magnitudes determined by the Array Network Facility (ANF). We observe a distinct west-east
decline of intrinsic attenuation for high frequencies corresponding to the west-east transition from young,hot rocks to old and cold rocks. Scattering loss on the other hand depicts a raising west-east trend, but
generally has a higher spatial variation than intrinsic attenuation. The crust in the western part of theUnited States appears to be more homogeneous on the relevant length scales than the crust in the eastern
part.

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*S03-P-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseSpatial variations of intrinsic absorption and scattering loss in Taiwan basedon a Multiple Lapse Time Window Analysis* Kevin Gillet 1) , Ludovic Margerin 1) , Shu-Huei Hung 2) , Marie Calvet 1)
IRAP - University of Toulouse, Toulouse, France 1) , Department of Geosciences, National Taiwan
University, Taipei, Taiwan 2)
We use seismic recordings from 2012 to 2015 to estimate intrinsic absorption and scattering loss in
Taiwan. Signals were recorded by a network of about 150 stations. About 400 events of magnitude between
3.5 and 6.5 and 4000 events of magnitude between 1.8 and 3.5 were recorded per year. We use theMultiple Lapse Time Window Analysis introduced by Fehler et al. (1992) to measure integrals of energy indifferent windows in the coda of the signals, selecting events with hypocentral distances below 100 km andsources less than 40 km deep. These measurements, which represent the temporal distribution of theenergy in the coda, can be used to separate the two components of attenuation, absorption and scattering.
An inversion using a Levenberg-Marquardt algorithm is performed to find estimates of the absorption andscattering quality factors Qi-1 and Qsc-1, for each station considered. We find that Taiwan is one the mosthighly attenuating regions in the world, with an average of Qsc-1 = 1e-2 and Qi-1 = 7e-3 at 1-2 Hz. Anotherimportant feature is that attenuation varies widely across Taiwan, by a factor of 3 for total attenuation. We
find that the eastern Coastal Range and parts of the western Coastal Plain are the most highly attenuating
regions of Taiwan. However, the region surrounding the Peikang Basement High and parts of northern
Taiwan are more weakly attenuating, which increases risk for the cities in this region. Overall, intrinsic
absorption is more uniform than scattering loss. The Coastal Plain shows strong scattering. The Coastal
Range shows strong scattering and absorption, consistent with the volcanic origin of the structures.
Scattering in the Central Range seems weaker than in these two regions. Our study shows that attenuation
should be taken into account for seismic studies and monitoring in Taiwan, given the importance andlateral variability of the mechanism.

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*S03-P-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseSignificant anomalies in high-frequency seismograms for intra-slab
earthquakes observed in Kanto area, Japan: Importance of mode-conversion
scattering* Nozomi Kanaya , Takuto Maeda , Kazushige Obara , Akiko Takeo
Earthquake Research Institute, the University of Tokyo, JapanIn Kanto-Tokai area in Japan, very complicated high frequency seismograms are frequently observed as it
is located above a complex subducting zone. In this study, we found characteristic high-frequency
seismogram anomalies potentially being related to characteristic inhomogeneity in this area.
We analyzed Hi-net (NIED) records in Kanto-Tokai area for 20 intra-slab earthquakes (M4.4−6.9) occurred
within the Pacific slab from October 2004 to April 2016, 227−453 km in depth. After applying bandpass
filters of octave bandwidth of 1−16 Hz, characteristic wave packets were identified from root mean squared(RMS) envelope seismograms. At a frequency range of 8−16 Hz in Kanto area, we found wave packets
preceding the arrival of S waves by about 10 s. At lower frequency of 1−2 Hz, we did not find similar
packets. The amplitude of the packet was always predominant in the vertical component. No strong
polarization in the horizontal component RMS envelopes is observed.
Complicated-shape wave packets lasting about 10 s, without significant pulse of boundary conversion,suggest that scattered wave packets are generated by the small-scale inhomogeneities. In addition, thiscannot be explained by a simple S-to-S scattering because of its arrival time. Based on the systematic
detection, we found that the wave packet propagated almost along the radial direction from the epicenterwith the same apparent velocity as that of the S waves. Considering the wave packets arrived earlier than S
waves, they are expected to involve mode-conversion such as P-to-S or S-to-P scattering generated bycharacteristic inhomogeneity between the epicenter and seismic stations.
Preliminary numerical simulations of seismic wave propagation in this area with superimposed onto a smallscale stochastic velocity fluctuation did not explain these peculiar wave packets. Considerable updates
especially for small-scale inhomogeneities are expected to contribute to further understandings of the
subduction zone.

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*S03-P-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseAmplitude fluctuation of seismic waves in the crust* Kazuo Yoshimoto 1) , Shunsuke Takemura 2) , Manabu Kobayashi 1)
Yokohama City University, Yokohama, Japan 1) , NIED, Tsukuba, Japan 2)
The amplitudes of high-frequency P- and S-waves generated by local earthquakes vary from site to site,even at similar hypocentral distances. It had been suggested that, in addition to non-isotropic source
radiation and local site effects, complex wave propagation in inhomogeneous crust is responsible for thisobservation. To quantitatively investigate this effect, we performed observational and numerical studies on
the amplitude fluctuation of P- and S-waves in inhomogeneous crust. Using seismic data from 31 small-tomoderate crustal earthquakes that occurred in western Honshu, Japan, we measured the fluctuation inmaximum velocity amplitudes observed by the borehole seismometers of the NIED Hi-net. Observed
maximum velocity amplitudes of P- and S-waves in the frequency bands of 1–2 and 2–4 Hz werenormalized on the basis of the coda normalization method. Other technical details are same as in
Yoshimoto et al. (2015). Our observations of P- and S-wave amplitudes (coda-normalized maximum velocity
amplitudes) revealed that fluctuations in P- and S-wave amplitude increase with increasing frequency andhypocentral distance, with large fluctuations showing up to ten-times difference between the largest andthe smallest amplitudes. It was found that the standard deviation of amplitude fluctuation of P- and S-waves
increases monotonically in small hypocentral distances; however, the increase tends to become saturated
at a hypocentral distance of tens of kilometers. Our numerical simulation via finite-difference method
indicated that the observed characteristics of amplitude fluctuation can be explained by crustal
inhomogeneity stochastically characterized by an exponential random model with a correlation length ofabout one kilometer and standard deviation in seismic velocity of a few percent.

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*S03-P-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noise

Shallow S-Wave Velocity Structures of the Northern Taichung Area, Taiwan,
Using Microtremor Array Data
* Huey-Chu Huang , Tien-Han Shih , Cheng-Feng Wu
National Chung Cheng University, Chia-Yi, Taiwan
Shallow S-wave velocities have widely been used for earthquake ground-motion site characterization. We
investigate the shallow S-wave velocity structures at the northern Taichung area, Taiwan by using the arrayrecords of microtremors at 24 sites. The dispersion curves at these sites are calculated using the F-K
method (Capon, 1969); then, their S wave velocity structures are estimated by employing the surface wave
inversion technique (Herrmann, 1991). At most sites, the observed phase velocities are almost flat with thephase velocity of about 1000 m/sec in the frequency range from 0.5 to 2 Hz. This suggests that a thickness
layer with an S-wave velocity of about 1100~1400 m/sec was deposited. If the S-wave velocity of the
Tertiary bedrock is assumed to be 1500 m/sec, the depths of the alluvium at the northern Taichung area
are between 270 m and 1400 m. The depth of the alluvium gradually increases from east to west. The Swave velocity decreases from east to west while the depth is larger than 400 m at the area.

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*S03-P-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseComparison three applications of microtremor analysis for investigating
shallow S-wave velocity structure in the Western plain of Taiwan* CHUN-TE CHEN 1) , KUO-LIANG WEN 2)
Academia Sinica, Taipei, Taiwan 1) , National Central University, Chungli, Taiwan 2)
We had conducted forty-five array measurements of microtremors and applied GA-Haskell calculation for
more than one thousand microtremors H/V measurements in order to investigate the shallow S-wave
velocity structure in the Western plain of Taiwan. The microtremor array measurements are reliable toobtain shallow velocity S-wave structure. However, the interval of measurement is about 15 km due to thelimitation of economic and manpower issue. GA-Haskell method applies for one thousand microtremors
H/V measurements so as to improve the survey interval to about 2 km. Nevertheless, the velocity structure
calculated by GA-Haskell method is difficult to quantify the misfit. Hence, we utilize the H/V inversion
approach to the same sites of microtremors measurements. The objective of this study is to compare threedifferent methods and figure out the skill of three methods in estimate the shallow velocity. The suspension
PS-logging profiles are using to validate our calculations. After the verification, the Horizontal-to-vertical
spectral ratios of microtremors (MHVRs) are hence applying to investigate the shallow S-wave velocity
structure in Taiwan.

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*S03-P-07
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseElastic Velocity Change associated with the 2016 Kumamoto Earthquakes,
Japan* Tomotake Ueno , Tatsuhiko Saito , Kaoru Sawazaki , Katsuhiko Shiomi
NIED, Tsukuba, Japan
A seismic interferometry analysis of the Hi-net seismograms found temporal change of subsurface velocity
structure after the 2016 Kumamoto earthquakes. Significant velocity decreases (-6.0 - -0.5 %) were detected
near the main shock fault by the analysis of ambient noise auto correlation function (ACF) with the lag timeof 4-15 s. The large ground acceleration (> ~100 cm/s/s) and the large volumetric strain (> ~-5x10^-6) wereobserved at these stations where the velocity decreases were found. We also analyzed the ACFs with thelag time of 1-5 s and found velocity increase and decrease around the fault. A station N.MSIH near the fault
shows velocity increase. Fukuyama and Suzuki (2016) estimated large compressional strain at the N.MSIH
station by analyzing permanent vertical displacements recorded at two acceleration sensors deployed
different depths. The compressional strain change may cause the velocity increase of N.MSIH. On the other
hand, when we analyzed the ACF at the lag time of 4-15 s, velocity change was not recognized due tounstable behavior of the ACFs. The dependence of the velocity change on the lag time suggests that thevelocity change considerably varied in space. The velocity increase associated with the earthquakes may
reflect localized strain change near the main rupture. High-density observation around the focal area
enabled us to detect the localized velocity increase after large earthquakes.

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*S03-P-08
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseA temporal and spatial change in seismic velocity caused by the 2016
Kumamoto earthquake using cross-correlations of ambient seismic noise.
* Hiro Nimiya 1) , Tatsunori Ikeda 2) , Takeshi Tsuji 1) 2)
Earth Resources Engineering, Kyushu University, Fukuoka, Japan 1) , WPI-I2CNER, Kyushu University,
Fukuoka, Japan 2)
Revealing the damage of seismogenic faults caused by earthquakes is important to understand thecondition of the seismogenic faults and to predict the seismogenic fault behavior.In recent years, someresearches demonstrate that the seismic velocity change at the large earthquake is associated withvariation of subsurface stress and crust damage.To estimate temporal variation of the subsurface associatedwith the 16 April 2016 Mw 7.1 Kumamoto earthquake, we estimated spatial and temporal variation ofseismic velocity by using ambient seismic noise recorded by a high-sensitivity seismograph network (Hinet) for a year of December 2015 to November 2016. We computed cross-correlations of ambient seismic
noise records to retrieve virtual seismogram propagating between the pair of stations, and applied thestretching interpolation technique to estimate the temporal change in seismic velocity. Our results showthat the seismic velocity near the Futagawa-Hinagu fault zone and volcanic regions clearly decreased at the
Kumamoto earthquake. The velocity reduction near the fault zone (~0.4%) could be occurred due to thedamage of the fault. The largest seismic velocity reduction observed around Mount Aso (~0.8%) might becaused by pressurized volcanic fluids. Furthermore, the decrease in seismic velocity gradually returned tothe pre-earthquake value, suggesting gradual healing of the damage caused by the earthquake.

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*S03-P-09
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseTemporal change of subsurface structure near Mt. Aso inferred from seismic
interferometry using V-net vertical array data
* Yuta Mizutani 1) , Kiwamu Nishida 2) , Yosuke Aoki 2)
The University of Tokyo, Tokyo, Japan 1) , Earthquake Research Institute, The University of Tokyo, Tokyo,
Japan 2)
It is important to monitor the temporal change of the seismic velocity related to the volcanic event. In thisstudy, we estimated the temporal change of subsurface structure in the Aso region with seismic
interferometry (SI). In this study, we analyzed the data recorded from Jan. 1, 2015, to Oct. 31, 2016, at 4 Vnet stations deployed by National Research Institute for Earth Science and Disaster Resilience (NIED)
around Mt. Aso. Each station is composed of a broadband seismometer at the surface and a high-frequency
seismometer (1 Hz) at the bottom of a borehole (depth ~200 m). First, the records were bandpass-filteredfrom 2 to 8 Hz. After 1-bit normalization and spectral whitening, a daily CCF between the same componentof the bottom and surface sensors was calculated. Then, we made a reference CCF to stack CCFs from Oct.
25 to 31, 2016. Second, we measured the delay times in time windows of 2.56 s whose center time wasincreased from -5 s to 5 s every 0.2 s. When the temporal change is homogeneous, the slope characterizes
the bulk velocity change within a spatial scale of about 2 km, and the intercept characterizes the localized
velocity change between the sensor pair (~200 m). After the 2016 Kumamoto Earthquake, in the NScomponent at Takamori station and the ES station at other stations, the estimated slope showed thevelocity reduction of approximately 0.2 %. On the local velocity change in the borehole, nearly 5-8 %velocity drop was observed at 3 stations except for Nagakusa station. Otherwise, there was an
approximately 20 % drop at Nagakusa station. This could attribute the serious damage on the station of thesubsurface structure by the earthquake. At Ichinomiya station, the velocity change with the time scale of a
few weeks was detected. This change was well agreed with a simple model of the ground water level
inferred from the data, and could be localized near the borehole because the station is in a volcanic alluvial
fan.

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*S03-P-10
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseSeismic velocity variation within the Tatun Volcano Group, Northern
Taiwan, from ambient noise analysis* Ya-Chuan Lai 1) 2) , Cheng-Horng Lin 1) 2) , Hsiao-Fen Lee 1) 2) , TVO Team 1) 2)
Institute of Earth Sciences, Academia Sinica, Taiwan 1) , Taiwan Volcano Observatory at Tatun 2)
The Tatun Volcano Group (TVG) locates in the north part of Taiwan, where is only 15 km away from thedowntown Taipei. Thus, the monitoring for the potential activity of volcano is required for geohazard
assessment. Up to now, more than forty broadband seismic stations have been installed in the TGV area tomonitor the micro-earthquakes and the specific singles related to hydrothermal system. Such dense seismic
network with long-term continuous seismic data would provide the information to study the temporal or
spatial change of properties of the TGV. In the study, we use correlation of ambient noise between stations
to determine the temporal variation among 2013 to 2015. The seismic velocity variations show comparable
pattern with the anomalies of geochemical observations related to ML 4.0 Shilin earthquake. Significant
velocity reduction was observed by the nearby interstation path and HCl concentration rapidly increased.
Additionally, we also compared the temporal/spatial seismicity with the velocity variation.

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*S03-P-11
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseStudy of repeating events in the Jalisco subduction zone, Mexico* Guillermo Gonzalez 1) , Allen Husker 1) , William Frank 2) , Leticia Avila 1)
Universidad Nacional Autonoma de Mexico 1) , Massachusetts Institute of Technology 2)
Low Frequency earthquakes (LFEs) as well as repeating low amplitude regular earthquakes are bothobserved in the Jalisco subduction zone, Mexico. We use the “Mapping the Rivera Subduction Zone"(MARS) seismic array, which is a large array of 51 stations located in Jalisco, Colima and part ofMichoacan, to detect and locate them. This is done in both cases with a matched filter search (Frank et al.,2014). The templates for the repeating earthquakes are found by stepping through 10s windows and crosscorrelating those with the rest of the data stream on a single station. High correlation coefficients thatmatch in time with other stations are found to be events/templates. These templates are then used in thematched filter over the array spanning at least eight months. The LFEs are much smaller than the regularearthquakes. In order to find them, specific move-outs are used by grid searching in zones where tectonic
tremor (TT) has previously been found. Nonetheless, the detection of LFE's has been difficult and do notmatch TT activity in the zone so far. The main reason for this is that few LFE templates above the TT
background signal have been observed.

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*S03-P-12
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S03. Imaging of heterogeneities in the Earth with seismic scattered waves and ambien
t noiseThe study of the high-frequency microseismic noise at the Russian Platform* Alina Besedina , Ivan Batukhtin , Alexey Ostapchuk
Institute of Geosphere Dynamics, Russian Academy of Sciences, Moscow, Russian Federation
Passive seismic imaging is based on coherent signal allocation in the measurement results of seismic noiseof two receiver stations. Numerous theoretical studies and numerical simulations have shown that the crosscorrelation of seismic noise determines the source function (Green's function), which describes the
propagation of surface waves between two receiver-stations. Rayleigh surface waves with weak damping is
widely used by researchers to construct the deep structure of the geological environment with the help of
the cross-correlation techniques. Studies show that body waves give a substantial contribution for highfrequencies. However, the contribution of energy and the distribution of noise sources define frequency
range and conditions of the measurement, which is especially important for high-frequency seismic noisein the area for which the noise is largely man-made. The paper studied the composition of seismic noise in
the range of high frequencies at the Russian Platform, which is characterized by thick deposits of loose
sediment, as well as a high level of anthropogenic interference. This work was supported by the RussianFederation Presidential Program for State Support of Young Scientists (project no. MK-2698.2017.5).

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*S04-1-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Revision of the world's best-known recurrence pattern of historicalsubduction earthquakes along the Nankai trough off southwest Japan andtheir relationship with large inland earthquakes* Katsuhiko Ishibashi
Professor Emeritus, Kobe University, Kobe, Japan
Nine series of M 8-class interplate earthquakes, whose recurrence is a nationwide concern, have beenrecognized along the Nankai trough off SW Japan; in 684, 887, 1096/99, 1361, 1498, 1605, 1707, 1854
and 1944/46. For deeper understanding of their recurrence nature I reevaluated their space-time pattern
in a careful historiographical manner. Some examples of discussions are as follows. On the 684-887
interval, a historian supposed an earthquake in 794 based on an ancient document. But, by critical readingof the document I strongly suggest that this event was a thunderstorm. As for the 1096/99 series it has
been considered that the 1096 event occurred in the east and the 1099 one followed in the west. The latter,
however, has no evidence of a great earthquake except for an inferred coseismic subsidence in Shikoku,
while the former has various evidence of a great earthquake. I examined the only material referring to thesubsidence in Shikoku, and clarified that it had originally been written about 80 years after the earthquake
and probably duplicated around 100 years later, suggesting unreliability of the 1099 subsidence. I interpretthat the 1099 event was an inland earthquake and the 1096 event was an “entire-Nankai trough"earthquake. Regarding the 1605 event, though I had once proposed an idea that it had been a greattsunami quake along the Nankai trough, which has been widely accepted, I reexamined historical
documents in the early 17th century thoroughly and propose a new view that the 1605 event was a greatearthquake along the Izu-Bonin trench, referring to the 2010 off-Bonin earthquake, and that the Nankai
trough earthquake of this series was the 1614 event so far commonly regarded as an inland earthquake. I
also discuss remaining problems and the relationship between Nankai trough earthquakes and large inland
earthquakes, and propose a seismotectonic model attaching importance to the Amur plate motion in
addition to the Philippine Sea plate subduction.

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*S04-1-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

A possible tsunami caused by a submarine landslide in 1512 at the Nankai
trough, Japan* Toshitaka Baba 1) , Taiki Okada 2) , Juichiro Ashi 3) , Toshiya Kanamatsu 4)
Graduate School of Science and Technology, Tokushima University 1) , Faculty of Engineering, Tokushima
University 2) , Atmosphere and Ocean Research Institute, The University of Tokyo 3) , Japan Agency for
Marine-Earth Science and Technology 4)“SHINCHO-KI" is an ancient document that records tsunami damages caused by the 1512 Eisho
earthquake, the 1605 Keicho earthquake, the 1707 Hoei earthquake and the 1854 Ansei-Nankai
earthquake at Shishikui region in Tokushima, where is located along the coast of the southeastern part of
Shikoku, facing to the Nankai trough. According to SHINCHO-KI, 3700 people were dead at Shishikui by
the tsunami during the 1512 Eisho earthquake. However, no evidence was found for the occurrence of1512 Eisho earthquake except for SHINCHO-KI, while the other earthquakes were recorded in many
ancient documents in the southwestern Japan.
To investigate the source mechanism of the 1512 Eisho earthquake, we carefully read a bathymetric chart
and found a scarp with height of about 400 m and width of about 6000 m at a position about 24 km
offshore in the southeastern direction from Shishikui. We also carried out a survey by using a deep-towed
sub-bottom profiler (SBP) on ROV NSS during the R/V Hakuho-maru KH-16-5 cruise. The result showsdetailed structures possibly caused by a recent landslide. The vertical displacement of the strata wasmeasured to be about 50 m. By considering these results, we simulated the 1512 Eisho tsunami generated
by a submarine landslide. The topographic data in Shishikui which is needed in the calculation was madefrom the present data. But we removed the artificial structures such as wave breakers and altered costallines by referring to old map images. The numerical simulations indicated that the tsunami flow depths
during the 1512 Eisho tsunami described in SHINCHO-KI could be simulated by the assumed submarine
landslide. The maximum tsunami height of 9 m was calculated at Shishikui, while it was 3 m along the Kii
Peninsula located at the opposite side of the Kii Channel.

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*S04-1-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Hot Spring Anomalies Observed in Kumamoto Prefecture Associated withthe 1946 Nankai Earthquake* Yasuyuki Kano
Kyoto University, Kyoto, Japan
Kumamoto-Ken Saii-shi (Record of natural disasters in Kumamoto Prefecture) published by the Kumamoto
meteorological station in 1952 describes the 1946 Nankai earthquake in the chapter for earthquakes, "No.
242, December 21, Showa-21: Great earthquake in the Nankai area. The hypocenter is south of Kii(Wakayama Prefecture). There are anomalies in groundwater at many hot springs." (Only related
descriptions are extracted and translated here). The anomalies are summarized in a table. The hot springs
where anomalies are observed are located in the areas corresponding to Hitoyoshi, Kumamoto, Amakusa,
Yatsushiro, Tamana, Minamata and Oguni, using the present location names. The conditions or changes inflow rate, color, and temperature are listed for 15 hot springs. The times of the changes at the hot springs
varies from December 23, 1946 to January 6, 1947. The observation periods are from several days to about
a half month. The changes in flow rate, both increases and decreases, began on the day of the earthquake
and continued over 10 days for most hot springs. The color changes were observed for 10 hot springs. The
color changed to light brown, milky white, rust color, clay red, or black at the time of or after theearthquake.
Groundwater anomalies are generally explained by static strain steps or dynamic strain oscillations i.e.
seismic waves. Static volumetric strain steps calculated assuming the model of Sagiya and Thatcher (1999)
are extension with order of 100 nano strain, which will produce at most 50 cm of ground water level
decrease for usual poroelastic materials. Although the ground water level decrease should produce
decrease in flow rate, both increases and decreases in flow rate are reported in the Kumamoto-Ken Saii-shi.
It is difficult to explain the anomalies solely by static strain steps and poroelastic effects. Local permeabilitychanges caused by dynamic strain or shaking may cause some of the reported anomalies.

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*S04-1-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Earthquakes before 6 April 1667 in southern Dalmatia and Montenegro* Paola Albini , Andrea Rovida
INGV, Milano, Italy
Although the area of southern Dalmatia (Croatia) and coastal Montenegro is known to be prone to large
earthquakes, and characterised by high seismic hazard, the actual knowledge of its pre-instrumental
seismicity, as described by catalogues and published studies, is still largely imperfect. The only exception is
the recently reappraised M 6.4 earthquake of 6 April 1667, Dalmatia. With the scope of getting to a revised
scenario of the seismicity of the region before the large 1667 earthquake, the echo of which for sure had
cast a shadow over the information on previous events, a systematic survey was performed. Historicalsources for the 14th to 17th centuries were searched for, and successfully retrieved, focusing on those not
yet taken into account by previous seismological studies, and complementing an earlier survey carried out
more than ten years ago. Before the reinterpretation of the historical records here proposed, the earliest
earthquake to appear in current catalogues was dated to 1472. This informative gap was thus partiallyamended with a handful of new, though unfortunately isolated, records of 14th century earthquakes, andwith a critical reappraisal of a set of large and moderate earthquakes along the following 250 years. The
increase in type, number, and accuracy of testimonies and earthquake records made it possible to extend
more than one century backwards the availability of robust sets of macroseismic intensity data, and toassess new earthquake parameters. The newly obtained data contribute to putting into a substantiallydifferent perspective the pre-1667 seismicity of southern Dalmatia and Montenegro.

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*S04-1-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

The 1895 Ljubljana earthquake: can the intensity data points discriminate
which one of the nearby faults was the causative one?
* Lara Tiberi 1) , Giovanni Costa 1) , Petra Jamsek Rupnik 2) , Ina Cecic 3) , Peter Suhadolc 4)
Department of Mathematics and Geosciences, University of Trieste, Trieste, Italy 1) , Geological Survey ofSlovenia, Dimiceva ul. 14, SI-1000 Ljubljana, Slovenia 2) , Agencija RS za okolje, ARSO, Ljubljana, Slovenia.
3), Department of Mathematics and Geosciences, University of Trieste, Trieste, Italy, retired 4)
The earthquake (Mw 6) that occurred in the central part of Slovenia on the 14th of April, 1895, affected abroad region, causing deaths, injuries and destruction. This event was much studied but not fully explained,
in particular its causative source model.
The aim of this work is to contribute to the identification of the seismogenetic source of this destructive
event, estimating peak ground parameters through the use of different GMPEs and computing a series ofground motion scenarios based on various fault models and nucleation points in the surroundings of
Ljubljana: Vic, Zelimlje, Borovnica, Vodice, Ortnek, Misjedolski, Dobrepolje faults. The synthetic
seismograms, at the basis of our computations, are calculated using the multi-modal summation techniqueand a kinematic approach for extended sources. In particular, we compute the maximum peak ground
velocity value at 1 Hz because at high frequencies seismograms are strongly influenced by the shortwavelength complexities of the medium.
The qualitative and quantitative comparison of these simulations with the intensity field allows us todiscriminate between various sources and configurations. The quantitative validation of the seismic source
is done using an appropriate regression law, expressly calculated for this study. The main strong
earthquakes used for this calculation are the two Bovec earthquakes (1998, 2004), the Aquila event of2009, the two Emilia ones of 20th and 29th of May, 2012 ant the last Amatrice event of 24th of August
2016.
This study allows us to identify the most probable causative source model of this event, contributing to theimprovement of the seismotectonic knowledge of this region.

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*S04-2-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

The Innsbruck earthquake of 22nd December 1689
* Christa Hammerl
ZAMG, Vienna, Austria
Knowledge of historical earthquakes has become more important in recent years. Complete and accurate
information is necessary in order to carry out a coherent seismic hazard assessment of a specific area. In
particular, since the introduction of Eurocode-8, the building code for the construction of earthquakeresistant buildings in Europe, the importance of new assessments of historical earthquakes due to the stateof the art has increased. For seismic hazard assessment, earthquakes that occurred prior to the
instrumental period must be considered. Due to the relatively long "return periods" of stronger earthquakes
in Austria, the interpretation of historical earthquakes is of great importance.
The historical seismicity in Tyrol is characterized by a moderate activity and is one of the most seismic
active areas of Austria.
The information on the quake of 22nd December 1689 shows that the damage in Innsbruck and Hall in
Tyrol was similar to the damage resulting from the quake in 1670 (epicentre Hall, epicentral intensity=8
EMS-98). The 1689 quake caused fatalities in Hall and in Innsbruck.
The epicentral intensity was estimated with 7-8 EMS-98.
Several new sources have been found in the archives for the earthquake of 1689. A contemporary sourcefrom the city archive in Hall in Tyrol contained unknown information for this quake. The source describes
the damage of the earthquake of 1689 in Hall, which leads to much more detailed knowledge of its impact
on the city.
Although the event discussed occur rarely, earthquakes of such intensity can cause personal
suffering and huge economic losses. It is therefore important to investigate the effects of historicalearthquakes according to the state of the art.
Reports about this earthquake are known from the following cities: Augsburg, Hall in Tyrol (with St.
Magdalena in Halltal), Innsbruck (Allerheiligen, Arzl, Hoetting and Muehlau) and Schwaz.

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*S04-2-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

A New Approach to Comprehend Historical Tsunami Source* Ritsuko S. Matsu'ura 1) , Yuta Mitsuhashi 2) , Yukitoshi Fukahata 3)
Earthquake Research Center, ADEP, Tokyo, Japan 1) , Kozo Keikaku Engineering Inc., Tokyo, Japan 2) ,Kyoto University, Uji, Japan 3)
For decades, the initial wave height for a tsunami simulation has been acquired from the crustal
deformation of one rectangular fault with a uniform slip in a semi-infinite media, or summation of manysmall rectangular faults. However, the inevitable singularity around the rectangular edge, especially nearcorners of a uniform slip rectangular fault is often harmful for tsunami simulations, when the source isclose to the target land area. Recently, we made a new easy to use program for calculating surface
deformation due to a fault of arbitrary shape with arbitrary slip distributions in a horizontal multi-layered
media. We used this program for the forward modeling of some historical tsunamis in Japan, such as 1707
Hoei Earthquake, and 1611 Keicho Sanriku Earthquake. We only know rough tsunami heights for several
ten points, and approximative arrival times of tsunami for some places for those historical events. However,some historical materials and paleoseismological surveys allow us to infer inundated area and its status. We
show some physically plausible but rather simple models for those examples. We examined only ellipsoidal
shape faults with the smoothly tapered slip amount from the center to ellipse. We also show the differencesof tsunamis generated by traditional rectangular sources with uniform slip from tsunami generated by ourmodels.
Another fatal problem frequently observed for the tsunami simulation is to confound the crustal
deformation with the dynamic solution of the elastic equation, intending to include the rupture process into
the tsunami calculation. Since the crustal deformation is nothing but the static solution, it only gives the
final deformation after the whole source rupture movement has ceased. If the source is divided into small
rectangles and the crustal deformation of each rectangle is used as the initial wave height at a certain time
window, that tsunami simulation is invalid.

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*S04-2-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Is the survival rate a clue to estimate the location of epicenter of historicalearthquakes?
* Taku Komatsubara
Geological Survey of Japan, AIST, Tsukuba, Japan
1 Introduction
I took reflectively refuge during the preliminary tremors of the 2011 off the Pacific coast of Tohoku
Earthquake. This experience suggested the human beings attempt to escape from house collapsing during
the preliminary tremors, and duration of preliminary tremors (i.e. epicentral distance) and survival ratewould have close relationship. I try to estimate the epicenter of inland earthquakes from mortality.
2 Case of the 1858 Hietsu Eq.
This earthquake occurred midnight, was double earthquake. Local governments described victims andpopulation, number of fallen and total houses in each village. The mortality is high along the western part of
the Atotsugawa fault, and nobody injured in the Shogawa valley. The ratio of fallen houses is almost
homogeneous along the Atotsugawa fault and in the Shogawa valley. These facts can be interpreted that theepicenter was at the western part of the Atotsugawa fault, and later shock occurred in the Shogawa valley.
The reason why is the residents in the Shogawa valley escaped from houses at the first event, thereafter thelater event caused collapse of houses, and many people had enough time to escape from collapsing houses
along the eastern part of the 70 km long Atotsugawa fault.
3 Case of the 1995 Hyogo-ken Nanbu Eq. This present earthquake hit a megalopolis. The mortality wasclosely similar distribution of the fallen buildings rate, and victims concentrated along the basin edge. The
mortality has a little relationship with the epicentral distance. This fact would reflect following situations. 1)
Many people could not escape from two-storied low resistant houses. 2) Many people were killed bycollapsing buildings which blocked vacant grounds. 3) People have studied “Crawl under desks while
shaking". The factor 2) is common in urban area in historical age. It must be cautious to make use ofsurvival rate to be an indicator of epicentral distance for historical earthquake in urban area.

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*S04-2-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Value of macroseismic information in earthquake studies in XX century: twocase studies* Ruben Tatevossian , Nina Mokrushina
Institute of Physics of the Earth, Moscow, Russia
It is generally accepted that the instrumental era in seismology had started from the beginning of XX
century. In most international and national projects related to earthquake cataloging two time-periods are
explicitly distinguished: historical and instrumental with time-boundary at 1900. It is commonly shared
opinion that instrumental determinations of earthquake parameters are much more precise and reliable. Of
course, seismologists are aware that the location accuracy and magnitude assessment can be rather poor inearly-instrumental period, but some problems, specific for historical earthquakes, such as duplications, do
not exist. In the presentation, on the base of Altai region catalogue for 1914, it is shown that this opinion is
too optimistic. Another problem is location accuracy. It is shown that there is a gross error in hypocenter
location of 1978 off-shore earthquake in the Black Sea. The error is evident from macroseimic data spatial
distribution. It is a serious problem because the Mw=5.7 earthquake is the largest near the Russian coast ofBlack Sea.

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*S04-2-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

From historical seismology to seismogenic source models, 20 years on:
results and challenges* Gianluca Valensise , Pierfrancesco Burrato , Umberto Fracassi , Paola Vannoli
Istituto Nazionale di Geofisica e Vulcanologia
Over the past 20 years historical seismology has gone through a silent revolution that turned it from purely
descriptive to fully quantitative, transformed its outcomes from vaguely subjective to solidly reproducible,and – unbeknown to many – greatly increased its relevance far beyond the mere computation of “activity
rates" in the modern SHA practice.
In Italy the main aspect of this revolution was spawned by the creation of “new generation catalogues",
large databases providing for each earthquake all felt intensities along with precise identification of thereported sites and even a description of the earthquake effects. These catalogues allowed automatic
processing of intensity data to derive the epicentral parameters, an equivalent magnitude and thegeometric parameters of the prospective causative fault through a Fortran code termed Boxer (Gasperini etal., BSSA, 1999).
Increased data resolution and manageability allowed large Italian earthquakes sequences to be explored in
depth, often revealing an unexpected source complexity and setting new constraints on the location andmagnitude of the most significant shocks (e.g Fracassi & Valensise, BSSA, 2007; Burrato & Valensise,
BSSA, 2008). This evidence contributed to unraveling the arrangement and behavior of large seismogenic
fault systems, greatly supporting seismotectonic interpretations in areas dominated by large tectonic
complexity and by blind faulting (Basili et al., Tectonophysics, 2008; Kastelic et al., MPG, 2013; Vannoli etal., Pageoph, 2015).
More recently historical data have been used to calculate earthquake budgets to be compared withgeodetic evidence for ongoing strain and fault slip rates, thus strengthening earthquake recurrence models
devised for seismic hazard assessment (Carafa et al., GJI, 2017).
Little of this would have been possible without historical seismology data, an often overlooked wealth of
information that still awaits to be exploited in many seismogenic areas worldwide.

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*S04-3-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

A STRUCTURED AND HIERARCHICAL DATABASE OF MEXICANHISTORICAL EARTHQUAKES: 1469 TO 1912
* GERARDO SUAREZ 1) , CARLOS CHICO 2) , DANIEL RUIZ 2)
INSTITUTO DE GEOFISICA, UNAM 1) , FACULTAD DE INGENIERIA, UNAM 2)
A structured and hierarchical database of historical earthquakes in Mexico during the last 450 years was
designed and developed. The macroseismic data were located using the official Mexican almanac and to all
identified locations a value of intensity on the Modified Mercalli Intensity (MMI) value was assigned. In
total, 328 earthquakes were identified from 1469 to 1912. The earthquakes were classified according totheir tectonic origin. The database may be queried by date, date range, seismic region or locality. Specificqueries may also be made for buildings reportedly damage or associated phenomena to earthquake. The
full verbatim macroseismic information may also be accessed from the database so the user can make theirdecision regarding the interpretation. When sufficient data were available, the epicenter and magnitude ofthe earthquakes was estimated following the inversion method of macroseismic data points proposed by
Bakun and Wentworth (1997). For this purpose, attenuation curves of attenuation versus moment
magnitude were constructed for three general categories of earthquakes in Mexico: subduction zone, inslab earthquakes in the subducted Cocos plate and crustal earthquakes. As a first example, the resulting
catalog has been used to study the seismicity of the Trans Mexican Volcanic Belt (TMVB). This region iswhere the largest concentration of the population of Mexico lives. As a result, several crustal earthquakes
on the TMVB were identified, which were previously unknown. The database is open and available to any
interested user at http://sismoshistoricos.org/.

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*S04-3-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Dynamic Rupture Modeling of Historic, Pre-Instrumental Earthquakes on the
San Andreas and San Jacinto Faults, Southern California* Julian Lozos
California State University, Northridge, Northridge, California, USA
Southern California has an active record of instrumentally-recorded earthquakes, but its pre-instrumental
historic record of damaging earthquakes is also extensive. Paleoseismic studies, and analysis of firsthanddescriptions of ground motion and damage have attributed some of these events to specific fault sections.
However, with the density of active faults in southern California, many of these interpretations are nonunique. Dynamic rupture modeling can be a helpful tool for further interpretation of these observational
datasets. This type of modeling allows for physics-based assessment of plausible rupture paths andprocesses within complex fault systems. The models can take observation-based fault geometry, stresses,
and surrounding geological setting as site-specific initial conditions; the calculated slip and ground motion
patterns can then be compared to historic and paleoseismic records to determine the best match. Here, I
discuss how I have used dynamic modeling to examine, and in some cases reevaluate, several historic
earthquakes traditionally associated with the San Andreas and San Jacinto faults in inland southern
California. A similar approach would likely also be helpful in examining source faults and processes inother regions with long historic pre-instrumental earthquake records.

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*S04-3-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

THE 7TH JULY, 1923, CANAL DE BERDUN EARTHQUAKE, IN THE
PYRENEES. ITS MACROSEISMIC FIELD FROM CONTEMPORARY
RECORDS* Josep Batllo 1) , Jose Manuel Martinez Solares 2)
Institut Cartografic i Geologic de Catalunya, Barcelona, Spain 1) , Instituto Geografico Nacional, Madrid,
Spain 2)
Seismicity rate in the Pyrenees can be considered moderate. Nevertheless, damaging earthquakes occurs
as it is well known from their historical seismicity records. Among them, the 7th July, 1923, known as Canalde Berdun earthquake, is one of the biggest events (maybe the largest one) occurred during the
instrumental period in this region. As it occurred in a sector with low population density, and the produced
damage was, consequently, moderate, not much attention has been paid to it.
Its size, recently re-estimated from waveform inversion of contemporary seismograms, on the order of Mw
5.4, and unique location among the large earthquakes in the Pyrenees, in the central, south part of thechain, make this event of great interest for a better definition of the regional seismicity. For this reason we
decided to study a new its source from the analysis of the available contemporary macroseismic records
and related documents.
Observatory Fabra, in Barcelona, preserves a large collection of macroseismic records of earthquakes
occurred in the North and East of Spain during the XX Century. Among them, the whole documentation of
the survey on occasion of the 7th July 1923 earthquake in the Pyrenees. A detailed reanalysis of theserecords, complemented with information published in the contemporary press and studies allowed areconstruction of the macroseismic field in the Spanish side of the Pyrenees. From it macroseismic
estimates of the epicentral location and magnitude, in very good agreement with the instrumental ones, areobtained. We present the different steps of the undertaken research, some of the obtained results and its
consequences for the regional seismicity and we compare them with present earthquakes occurred in thesame region.

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*S04-3-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

The newly discovered 1885 earthquake in the French Guiana - Brazil border,
6.0 mb, the largest historical mid-plate event in South America.
* Marcelo Assumpcao 1) , Alberto Veloso 2)
University of Sao Paulo, Sao Paulo, Brazil 1) , University of Brasilia, Brasilia, Brazil 2)
On August 4, 1885, a strong tremor was felt along 1400 km of the Amazon river, from Belem near the coast
to Urucurituba near Manaus, with intensities reaching IV-V MM, as reported by all newspapers of Belemand Monte Alegre, Parah state. The French Seismic catalogue (http://www.sisfrance.net/Antilles/) reports astrong shaking (intensities V to VI MM) in Cayenne and Guisanbourgh, French Guiana. Other, independentaccounts of this earthquake were reported by newspapers in Surinam (V in Paramaribo) and Guyana (IV in
Georgetown). A survey of all available macroseismic data indicates the event was felt up to 1200km
distance. We used an intensity = f (magnitude, distance) attenuation relation for Brazilian intraplate
earthquakes to locate the best epicenter and magnitude of the 1885 earthquake. The epicenter was locatedin the border between French Guyana and Brazil and a magnitude of 6.0 (+- 0.3) mb was estimated. This
event is one of the largest to have occurred in mid-plate South America. Previously known large events innorthern Brazil were 1955.01.31 in Mato Grosso state (6.2 mb) with an average felt radius of about 600 km,
and the 1985.08.03 Amazonas (5.5 mb) felt up to 420 km, on average. Other historical accounts ofearthquakes felt near the border between French Guiana and Brazil (1949, ~5.3 mb; 1951, ~4.8 mb) as wellas the recent 2006, 5.2 mb, event near Caienne, suggest that this region could be regarded as a seismic
zone, not previously considered in seismotectonic studies in South America.

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*S04-3-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

An intensity database for earthquakes on the Highveld of South Africa from1840 to 1950
* Nicolette S. Flint
Council for Geoscience, Cape Town, South Africa
A database of macroseismic observations from historical earthquakes on the Highveld of South Africa wascompiled as a contribution to the seismic microzonation of Johannesburg and the Witwatersrand Basin.
The database contains over 3,000 intensity data points (IDPs) that have been assigned from macroseismic
observations retrieved from questionnaires, newspaper reports, Observatory log books, Government reports
and published seismic compilations. The database includes IDPs from 199 tectonic earthquakes felt in andaround Johannesburg between 1840 and 1950. IDPs from over 700 mining-related earth tremors between
1907 and 1950 are also included. Seventeen tectonic events and 28 mining-related tremors have 10 ormore IDPs each. Both datasets are comprised of relatively low intensity values mostly determined fromhuman perception of shaking, largely indoors, rather than structural damage. However, 102 and 76 of IDPs
from each dataset respectively have intensity values of V MMI-56 or higher. The occasional strong
earthquake is consistent with the tectonic setting of the Highveld. The moderate magnitude mining related
tremors are shown to increase in frequency, intensity and magnitude as the gold mines progress deeper.
This database represents a thorough review of all the available sources of information and correction oftransposed digits and other errors in previous compilations. This review also reveals the benefits of using
additional contemporary resources from different languages, governments and disciplines in thecompilation of IDP datasets. The database led to the development of a seismic history for the Highveld andthe gold mines, considering the broader geo-political context of the rise of the independent Boer republics,
the “mineral revolution" and the establishment of Johannesburg, and the course of colonial rule insouthern Africa.

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*S04-4-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Methodology to Determine the Parameters of Historical Earthquakes in
China* Jian WANG 1) , Guoliang LIN 2) , Zhe ZHANG 1)
Institute of Geophysics, China Earthquake Administration, Beijing, China 1) , Yunnan Seismological Bureau,
China Earthquake Administration, Kunming, China 2)
China is one of the countries with longest culture history. Meanwhile China has been suffered very heavy
earthquake disaster, so abundant earthquake recordings remained. In this paper, we try to outline somebasic information about China historical sources of earthquakes and the achievements of research. There
were two large-scale collections of historical earthquake archives in China. We also introduce China
intensity scale and the editions of historical earthquake catalogues. Total four formal editions of “The
Catalogue of Chinese Earthquake" were compiled. Spatial-temporal and magnitude distribution of historicalearthquake are analyzed briefly. The practice procedures of tradition methods were illustrated. Generally,
the parameters of an historical earthquake were determined according to the relation between theparameters and intensity data. Several such relations were listed which often used in China. Owing to rely
heavily on the historical earthquake archives, the traditional method has its limitation.
Besides traditional methods, we also illustrate a new approach to amend the parameters of historicalearthquakes or even identify candidate zones for large historical or palaeo-seismic earthquakes. In the new
method, a relationship between instrumental recorded small earthquakes and strong historical earthquakes
is built up. Geophysics implication of new method was analyzed. The modern-day seismicity can point out
the locations of persistent weaknesses in the lithosphere. Such persistent has also been observed on amuch smaller scale in the location of acoustic emissions (AE) during cyclic loading in laboratory rockdeformation tests. From view of fracture mechanics, the occurrence of a strong earthquake means that the
local crust medium has been experienced a process of changing. The new method might help us to judge
historical earthquake parameters and amend them, even find a new candidate site.

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*S04-4-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Document database for historical earthquakes around Tokyo area
* Kenji Satake 1) , Jun Muragishi 1) , Akihito Nishiyama 1) , Masaharu Ebara 2) , Toshifumi Yata 3) , Takeo
Ishibe 4)
Earthquake Research Institute, University of Tokyo, Japan 1) , Historiographical Institute, University ofTokyo, Japan 2) , Faculty of Humanities, Niigata University, Japan 3) , Association for the Development ofEarthquake Prediction, Tokyo, Japan 4)
The Tokyo metropolitan area has suffered many damaging earthquakes, since the beginning of shogunate
capital in Edo (former name of Tokyo) in 1603. During the Edo period (1603-1867), the 1703 Genroku
Kanto earthquake and the 1855 Ansei Edo earthquake caused the severest damage; the casualties were
estimated as 10,000 for each event. The 1703 earthquake is considered to be an M~8 plate-boundary
earthquake, similar to the 1923 Kanto earthquake which caused the worst disaster in Japan, and thedamage was documented in wide area. The 1855 earthquake (M~7) seems to have occurred just beneath
Tokyo, because the damage was mostly limited in Edo city.
We constructed the full-text digital document database for these earthquakes, as well as other smaller
earthquakes that caused damage in Edo and suburbs. For the 1703 earthquake, the total number of records
is 378, including memorial monuments of tsunami victims in Boso peninsula. For the 1855 earthquake,numerous documents including caricature were published, and only a part of them has been included in
the database. The database contains about 1200 records from other 35 earthquakes in and around Tokyo
area in the Edo period. For about a half of them, historians emended the descriptions and assigned thereliability of documents.
The database has similar format as the Online Database of Historical Documents in Japanese Earthquakes
and Eruptions in the Ancient and Medieval Ages (Ishibashi, 2009) which covers the earthquakes between
416 and 1607 with about 3000 records.

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*S04-4-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Estimation of source regions of large earthquakes from felt reports of JMA
seismic intensity database - Evaluation of applicability to historical large
earthquakes * Takeo Ishibe 1) , Ritsuko, S. Matsu'ura 1) , Koji Iwasa 1) , Ryoichi Nakamura 2) , Kenji Satake 3)
Association for the Development of Earthquake Prediction, Tokyo, Japan 1) , Tokyo Electric Power Services
Co., Ltd., Tokyo, Japan 2) , Earthquake Research Institute, the University of Tokyo, Tokyo, Japan 3)
Can felt reports of historical documents be used to estimate the source of large earthquakes? Before
establishing a new methodology, we show that the source area of recent three large earthquakes (2004
Niigata-Ken Chuetsu, 2008 Iwate-Miyagi, and 2011 Fukushima-Hamadori earthquakes) can be imaged fromthe spatial distribution of felt reports by using the JMA seismic intensity database. Our preliminary results
imply the possibility that the large earthquake source can be constrained from spatial and temporal
distribution of felt reports.
For the case of the 2004 and 2008 earthquakes, number of aftershocks with felt reports decreases withincreasing distances at epicentral distance <100 km from the mainshock, while they fluctuate at epicentral
distance >100 km, probably due to site condition and/or attenuation structure. This indicates that theeffects of site amplification near surface and heterogeneous attenuation structure should be properly taken
into consideration in a new methodology to estimate source of historical earthquakes. For the case of the2011 earthquake, the number of aftershocks with felt reports fluctuated even within 100 km from themainshock, because of the aftershocks following the 2011 Tohoku-oki earthquake.
Source of a historical large earthquake has been traditionally estimated from distribution of or casualties
recorded in historical literature. However, the damage was caused by not only a ground shaking but also
tsunami, massive fire and/or landslide. In addition, the distribution of building damage is strongly
controlled by the population density and elapsed years since constructed. In some historical literature,earthquakes that were felt without any damage are also reported as well as damage description from major
earthquakes, whereas these were not fully utilized except for several previous studies (e.g., Matsui andOike, 1997; Satake, 2002; Matsu'ura and Tsuji, 2010).

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*S04-4-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Historical Earthquake of Georgia* Nino Tsereteli , Otar Varazanashvili
Institute of Geophysics of I. Javakhishvili State University, Tbilisi, Georgia
This work discusses the historical earthquakes that occurred in Georgia during the period between 1250
BC and 1900, and the problems associated with their study. Many monuments of cultural heritage andarchitectural buildings have the signs of seismic effects. Despite the wide range of analytical work done incompiling historical earthquake catalogues some arguable interpretation of the data on certain historicalearthquakes, inaccuracies in determining the parameters were still preserved in these fundamental studies.
In addition, significant information existent in numerous original sources has remained undeveloped. They
can provide important data for the quantitative parameterization for the newly discovered historicalearthquakes Georgia. It is noteworthy that only a little quantity of geologic, geomorphologic andarchaeological data was used for the parameterization of historical earthquakes in Georgia in each of theabove mentioned catalogues. Methodology for creating a catalogue of historical earthquakes is based ontransformation of descriptive data of damage in terms of macroseismic intensity range, as well as on
determination of its location, magnitude, focal depth and their errors. This parameterized catalogue
represents the full database of historical earthquakes that affect the territory of Georgia. The summarized
map of the distribution of maximum damage in the historical period (before 1900) on the territory ofGeorgia clearly shows the main features of the seismic field during this period. In particular, in the axial
part and the southern slope of the Greater Caucasus there is a seismic gap, which was filled in 1991 by thestrongest earthquake and its aftershocks in Racha. In addition, it is also obvious that very high seismic
activity in the central and eastern parts of the Javakheti highland is not described in historical materials
and this fact requires further searches of various kinds of sources that contain data about historicalearthquakes.

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*S04-4-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

How to Cope with Earthquakes in Himalaya?
* HARSH K GUPTA
National Geophysical Research Institute, Hyderabad, Telangana, India
Earthquakes are one of the worst natural calamities. The Himalayan seismic belt extending from Kashmir to
Arunachal Pradesh has been seismically one of the most active intra-continental regions. The Gorkha
earthquake of Mw 7.8 on April 25, 2015 broke a long seismic quiescence in the central Himalayan region.
Many studies indicate that enough strains have accumulated to generate Mw 8 and larger earthquakes in
the region. It is also argued that the Gorkha earthquake may not have released the accumulated strains andlarger earthquake(s) should occur sooner or later. As short time earthquake forecast is not possible (though
there are some success in medium term forecasts), and earthquake shall continue to occur. We need todevelop earthquake resilient society. Developing earthquake scenarios as what would happen if one of theearlier earthquakes repeats today, and sharing it with the concerned state governments and public is
extremely helpful. A couple of very successful exercises were conducted by the National Disaster
Management Authority, Government of India, for a repeat of the 1905 Kangra earthquake and the 1897
Shillong earthquake during the years 2013 and 2014. The 1905 Kangra earthquake had claimed ~ 19,000
human lives. For a hypothetical earthquake of Mw 8, occurring near Mandi in Himachal Pradesh, ascenario was developed taking into account the estimated intensities, population density, typology of thehouses. It was inferred that the human lives lost would be several folds higher than ~19,000 lost during the1905 Kangra earthquake. Detailed preparations were undertaken before the mock drill conducted on the
13th February 2013 involving the states of Punjab, Haryana, Himachal Pradesh and the Union Territory of
Chandigarh. A similar exercise was conducted for the eight north-east Indian states for the repeat of the
Shillong earthquake of 1897 during 2014. Several short- comings in preparedness were identified. The best
part was public awareness generation.

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*S04-P-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Development of historical earthquake and volcanic activity database using
historical diaries* Akihito Nishiyama 1) , Masaharu Ebara 2) , Akihiko Katagiri 1) , Yusuke Oishi 3) 1) , Kenji Satake 1)
Earthquake Research Institute, The University of Tokyo, Tokyo, Japan 1) , Historiographical Institute, The
University of Tokyo, Tokyo, Japan 2) , Fujitsu Laboratories Ltd., Kawasaki, Japan 3)
Japan is exposed to frequent disaster risks of earthquakes and volcanic eruptions. Descriptions on thesenatural disasters can be found in a large amount of historical diaries that were written by officials of local
governments before the middle of AD 19C. These historical diaries were often used as official records of
local governments and contain descriptions about natural phenomena such as daily weather, earthquake
ground shaking or volcanic smoke. Since these descriptions were made on the same day as thosephenomena occurred, they are highly credible. Furthermore, the place where the diaries were written canbe precisely specified. Since the same person kept the diary for several decades, continuous and stable
information can be obtained. In Kinki district, especially around the ancient capitals, Kyoto and Nara, thehistorical diaries have been existed from the ancient and medieval (AD 10-16C) eras providing thecontinuous records of about 900 years. From the modern times (AD 17-19C), the historical diaries can befound nationwide. Therefore, it is possible to analyze seismic and volcanic activities of the historical era by
utilizing the historical diaries before observations of modern instruments began.
In this research, we analyze the historical diaries and extract the high-quality records of natural phenomena
such as sensible earthquakes and volcanic smoke to create a database. In addition, we will create ageographic information system based on this database to show spatio-temporal distributions of felt
earthquakes and volcanic activities of the historical era. By combining the present analysis with earthquakeand volcanic researches based on modern instrument observations, we aim to elucidate the long-term
nationwide earthquake and volcanic activities in Japan from the historical era to the present day.

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*S04-P-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Source area and magnitude of an aftershock following the 1854 AnseiNankai earthquake* Haruo Horikawa 1) , Ichiro Nakanishi 2)
National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan 1) , Kyoto University,
Kyoto, Japan 2)
Great earthquakes repeatedly occur along the Nankai trough, where the Philippine Sea plate is subducting
beneath the Eurasian (or Amurian) plate. The 1854 Ansei sequence have two great earthquakes: theeastern part (Tokai region) ruptured first and the western part (Nankai region) ruptured about 32 hours
later. Historical documents show that the Ansei Nankai earthquake associated several aftershocks withstrong shakings. The source region and magnitude of the aftershocks have been inferred from thedescriptions of historical documents, but an exception is an aftershock that occurred on the New Year's eve
on a Japanese classical calendar, which strongly shook Kochi, close to the plate boundary. In this study, we
try to quantitatively estimate the magnitude and source region of this aftershock. Firstly, we inferred theseismic intensity from historical documents. The historical documents show that the ground motions wereprolonged and suggest that the ground motions were rich in long-period components. Next, we estimate thesource region and magnitude from the seismic intensity data, evaluating the residuals between theobserved (interpreted) seismic intensities and the calculated ones with the aid of the Bayesian statistics.
The seismic intensities were calculated with an empirical attenuation relationship, in which a finite fault
was assumed. It is highly probable that the magnitude was larger than seven, and we found that the source
region would be located to the southeast from Kochi. However, the inferred source location is notconsistent with the historical descriptions that the number of felt earthquakes around Kochi greatly
increased after this event, which suggests that seismicity increased around the region. Our inferred location
is not closely located to Kochi. This inconsistency might be responsible for the effect of rupture directivity,
which is not taken into consideration in the attenuation relationship used in this study.

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*S04-P-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

What age distributions of stone lanterns tell about historical earthquakes?:case studies at three sites in Japan* Mamoru Kato , Jun Hioka
Kyoto University, Kyoto, Japan
Strong ground motion often topples stone lanterns, small stone objects standing in precincts of Japanese
temples and shrines, which are observed in recent large earthquakes in Japan. Topple of stone lanterns
occurs when the ground shaking is equal to or larger than JMA Intensity 5, which is roughly equivalent to
MM Intensity 7. Descriptions of similar damage are found in historical documents, and have been used toestimate seismic intensities of historic ground motion. Design and size of old stone lanterns are similar to
those of modern ones, which makes them practical sensors of ground motion at least for last 500 years. It isa customary practice to engrave the date of dedication in the stone lantern and we can identify stonelanterns which have experienced major historical earthquakes. This means stone lanterns as a group arerecords of historical earthquakes and in this study we explore what we can learn from such non-textual
materials. Increase/decrease of stone lanterns frequently occur by anthropogenic or religious reasons, andquality of data is essential in identifying effects of earthquakes. We surveyed stone lanterns at three sites:
Kitano-Tanmangu Shrine, Kyoto, Iwashimizu-Hachimangu Shrine, Yawata, and Zenkoji Temple, Nagano.
These three sites are known for historical large earthquakes and a large numbers of stone lanterns in theirsmall precincts. We are able to identify that historical earthquakes has weak effects on age distributions ofstone lanterns. Among our findings are that very large earthquakes apparently wiped out stone lanterns inearly years, and that dedication of stone lanterns apparently increases a few years after the earthquake, anindication of recovery from the disaster. It is difficult to estimate severity of historical ground shaking fromstone lanterns.

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*S04-P-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

The Japan GIS Database of the Historical Disaster using research data ofArcheological excavation, Geological survey and Historical documents.
* Taisuke Murata , Nobuhiko Koike
Nara National Research Institute for Cultural Properties, Nara, Japan
Nara National Research Institute for Cultural Properties has started this project since 2014, supported by
the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, under its Earthquake
and Volcano Hazards Observation and Research Program. The purpose of this project are to 1) collect all
historical evidence of natural disaster in Japan based on research data of archaeological excavation,
geological survey, and historical documents, 2) build a GIS database that can make easily to study,
simulate, and develop several disaster mitigation systems, programs, and methods, and 3) open to the
public for area studies of hazards. In this session, I would like to present a new result of this GIS model.

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*S04-P-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Numerical reconstruction of the source rupture and strong ground motionsof the 1935 Hsinchu-Taichung Earthquake, Taiwan from historicaltriangulation data
* Ming-Hsuan Yen 1) , Shiann-Jong Lee 2) , Kuo-Fong Ma 1)
Department of Earth Sciences, National Central University, Taiwan 1) , Institute of Earth Sciences,
Academia Sinica, Taipei, Taiwan 2)
On 21 April 1935, a large earthquake with a local magnitude of 7.1 struck central Taiwan, named theHsinchu-Taichung earthquake. It was the most destructive earthquakes in Taiwan history since 1600. This
event was associated with two major faults: the northern one as the Shihtan reverse fault, and the southern
one as the Tuntzuchiao right-lateral strike-slip fault. To understand its possible rupture history of theassociated faults, and its potential impact to Taiwan of a destructive earthquake of this kind, wereconstructed the possible source characteristics and the strong ground motions of the 1935 HsinchuTaichung earthquake using historical triangulation data as the reference. There are three main types of fault
model for this event, as two previously proposed fault models and a combined model. We investigated thespatial slip distribution based on these models from source inversion by using the triangulation data that isin the time of 1917-1937. In comparison to about 60 stations of the triangulation data, we chose a bestmodel for a scenario for ground motion simulation by Spectral-Element Method (SEM). The preferred (bestfit) inversion result suggested that this earthquake was composed of four fault-segments, as two observed
surface rupture faults to the north by reverse faulting and to the south by strike-slip motion, and with two
blind faults without surface rupture in between. We also compared the spatial slip distribution, thesynthetic ShakeMap, and the historical intensity distribution for various scenarios to examine the possible
hazard from the reconstructed source model. Results from this study suggested that the multiple faultsegments might rupture from adjacent fault segments with different styles of faulting.

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*S04-P-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

The large Hyuga-nada earthquake on June 30th, 1498 is a fake earthquake−Examination of the damage descriptions in Kyushu in the war chronicle"Kyusyu-gunki"−* Tomoya Harada , Akihito Nishiyama , Kenji Satake , Takashi Furumura
Earthquake Research Institute, The University of Tokyo, Tokyo, Japan
A large earthquake in Hyuga-nada Sea on the east side of Kyushu Island, Japan along Nankai Trough in "Mino-koku" (9-11 a.m.) on June 30th, 1498 on Julian calender, which was based on the descriptions about
serious damage due to a large earthquake in Kyushu in the war chronicle "Kyushu-gunki", has been
accepted by many seismologists as the 1498 Meio Hyuga-nada earthquake. "Kyushu-gunki" is one of the
popular novels which was written more than 100 years after the 1498 event. The damage descriptions havebeen used to estimate the location of this earthquake without evaluating the reliability. In this study, inorder to assess credibility of the description, we carefully examined writing process of "Kyushu-gunki" anddamage descriptions in this war chronicle. Our findings are summarized as follows: (1) "Kyushu-gunki" wascompleted in Kyushu in 1607, hence the writers' experience of the contemporary 1596 destructive
earthquake in Kyushu might have influenced the description of the damage of 1498 earthquake; (2)Damage descriptions of "Kyushu-gunki" were generic without location information and most of them arecited from descriptions of damage in Kyoto due to the 1185 large earthquake in the war chronicle "Gempeijosui-ki"; (3) Origin time ("Mi-no-koku") of this event is described only in "Kyushu-gunki" and it is close tothat of the 1498 great Tokai earthquake ("Tatsu-no-koku": 7-9 a.m.); (4) The chapter of the earthquake
damage also includes serious famine in Kyushu in 1503 and pains of people by many disasters, making thischapter a stage setting for later stories. To make a story of the war chronicle more interesting, writers seemto have created fictitious story of serious damage due to a large earthquake in Kyushu based on old war
chronicles and some records of the 1498 Tokai earthquake. Therefore, it can be concluded that the 1498
Meio Hyuga-naga earthquake is a fake earthquake and it should be deleted from Japanese historicalearthquake catalog.

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*S04-P-07
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S04. Historical and macroseismic studies of earthquakes

Revisiting source parameters of the 1906 Meishan, Taiwan earthquake fromfull-waveform measurements of historical records* Yiwun Liao 1) , Ming-Che Hsieh 2) , Kuo-Fong Ma 1)
Department of Earth Sciences, National Central University, Taiwan 1) , Sinotech Engineering Consultants,
INC, Taiwan 2)
The 1906 Meishan earthquake (M7.1) was one of the largest damaging earthquakes in Taiwan in the early
20th century. Historical literatures and recent studies showed that the Meishan earthquake was related to
the Meishan Fault and had a right-lateral faulting mechanism striking in east-west direction. With thehistorical Omori records at station Taipei, Taichung and Tainan, we carried out a waveform simulation of
the 1906 Meishan earthquake for understanding source rupture properties of the 1906 Meishanearthquake and the yielding predicting ground-motion in the region. A two-step waveform simulation basedon SGT (strain Green's tensor) is carried out for this attempt. In the first step, possible fault models of the1906 Meishan earthquake from geological survey and recent studies are compiled for simulation. As thepreliminary results, with an east-west strike faulting mechanism as Meishan fault, the synthetic waveforms
and intensity maps were not well explained. We, thus, further carried out a grid-search in focal mechanismby fitting first-motion and shear-wave polarities of historical records and synthetics to evaluate possible
focal mechanism. By comparing the simulated intensity distribution maps with the historical records, theMeishan earthquake is suggested to be associated with a north-south striking thrust faulting mechanism.
Also by comparing the converted waveforms from the 1999 Chiayi earthquake to the Gray-Milne
seismograms recorded at the ancient station Penghu and Tainan, the similarity of the waveforms also
convinces that the Meishan earthquake might have a similar focal mechanism of a north-south striking
thrust fault with the 1999 Chiayi earthquake. According to our results and the distribution of theaftershocks, the surface rupture of the Meishan fault might be a transfer fault between two thrust faulting
systems in the western coastal plain of Taiwan.

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*S05-1-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

On guidelines for preservation and usage of analog seismogram archives* Paul Richards
Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, United States
Seismology is an observational science, and seismograms routinely exhibit features that are not yet fully
understood.
The time-scale of earthquake occurrence requires examination of ground motions recorded over periods far
longer than the three decades now available from the era of digital recording. Most underground nuclear
test explosions, and almost all atmospheric nuclear tests, took place during the era of analog recording.
Different countries have taken different approaches to making analog seismograms usable in the modern
era. There is much to be learned from shared experience. Can we develop consensus on those analog
records that must be rescued, and preserved with metadata, for use by future generations? We can hope tolearn from advanced programs of data rescue, applying successful methods to unexplored archives.
About fifteen different United States institutions hold substantial archives of analog seismograms,
containing information needed by future generations of researchers. Consensus is needed on selection ofdatasets that should be converted from analog to digital form, for use by younger generations who often
expect data centers to provide digital data from well-characterized instruments. Such selection of suitabledatasets, can be informed by circulating practical information on the level of effort needed—informationthat has been acquired by countries that have engaged in this type of work for decades.
The Lamont Geological Observatory of Columbia University deployed a sparse global network of PressEwing instruments in the mid-1950s, preceding the WWSSN deployment by several years. I give examples
of analog recordings of large atmospheric explosions that exhibit phenomena not recorded via digital
media---including, from the 1950s: high-altitude explosions above the Pacific recorded teleseismically; andmulti-megaton explosions in the atmosphere recorded on vertical component seismometers via the effect ofdensity variations in the air.

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*S05-1-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

Twenty-five years of activity of the ESC Working groups devoted to thepreservation of the tangible and intangible heritage of Euro-Mediterranean
seismology* Graziano Ferrari
Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
At the beginning of 1990 the Istituto Nazionale di Geofisica started promoting the TROMOS project
devoted to the research, recovery, restoration and enhancement of the historical heritage of seismology in
Italy. The project was not confined to strictly seismological disciplines, embracing as the history of science,scientific instruments and technology.
In 1992, with the establishment of the ESC WG “History of seismometry" (HoS) the experience of Tromos
was extended to the whole European area. The activity of the WG has increased the awareness of theimportance of the tangible heritage of instrumental seismology (seismograms, bulletins, manuscripts, etc);
as a consequence, in 1997 a first census of Euro-Mediterranean historical seismic stations and the relevant
instruments, was published.
As an evolution of the HoS, in 2002 a new ESC WG “History and data of instrumental seismology" (HDIS)
was established, and a collaborative project EuroSeismos was launched in the WG's framework.
The experience and the technologies of SISMOS of INGV in Rome have allowed to broaden the “userbase" of the project to the whole Euro-Mediterranean area. During the period 2003-2010 around 30,000
historical seismograms from 34 Euro-Mediterranean countries have been scanned at Sismos and now are
freely shared online to the whole seismological community (seismogramrequest.rm.ingv.it).
Finally, at the ESC General Assembly in Moscow on 2012 a new ESC WG “Methods and data for the studyof earthquakes recorded on pre-WWSSN historical seismograms" took the place of HDIS. The aim of this
WG is to investigate earthquakes in the Euro-Mediterranean area, using seismograms of the pre-WWSSN
era and other data.
During 25 years, the activity of these ESC WGs involved tens of members, produced tens of papers andmore then hundred of presentations in seismological and history of science meetings enhancing thescientific and cultural value of the tangible and intangible heritage of Euro-Med seismology.

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*S05-1-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

The contribution of the Sismos project to the preservation, disseminationand scientific usage of the material heritage of instrumental seismology ofEuro-Mediterranean area
* Graziano Ferrari
Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
In view of the long Italian tradition in instrumental earthquake observation, on 2001 INGV officially started
the Sismos project for the research, recovery, high resolution scanning and dissemination of seismograms
recorded in Italian and Euro-Mediterranean area observatories during the period 1895 -1984(sismos.rm.ingv.it/en/). The Sismos High resolution scanning laboratory is equipped with 3 flat bed A0format scanners, and the seismograms are scanned at 1016 dpi grey scale.
A major effort was made to intervene in the different sectors (scientific, historical, cultural and popular
dissemination) with the disciplinary rigour of the different disciplines and synergies involved as comparedwith analogous initiatives at the national and the international level.
During the period 2006-2010 SISMOS was part of the facilities of the European project NERIES, from 2010
and 2012 participated to the GEM project, and is also a seismological infrastructure (History and data of
instrumental seismology) of the European Plate Observing System (EPOS).
SISMOS pays also particular attention to the recovery, restoration and conservation of historical materials
relating to Italian and international seismology with scientific as well as cultural aims.
Since 2008, two restoration laboratories have been set up at Sismos, one for historical papers (i.e.
seismograms, bulletins, etc.) and one for historical instruments.
Since 2005, SISMOS has developed a specific software for the viewing and processing of raster images ofhistorical seismograms into a vectoral form: Teseo2 - Vectorizer of historical seismograms(teseo.rm.ingv.it/). The program has been extensively used by SISMOS researchers and foreign colleagues.
A new database and a new interface of the SISMOS portal make more efficient the request and download ofsome of the over 200,000 seismograms' raster images (seismogramrequest.rm.ingv.it) and relevant
instrument's constants (over 20,000) and station bulletins (over 500,000 pp).

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*S05-1-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

A brief introduction to the analog seismograms storage in China* Ruifeng Liu , Leiyu Mou
Institute of Geophysics, China Earthquake Administration, Beijing, China
From 1950 to 1980, China Earthquake Administration(CEA) finished the construction of National Seismic
Network with 86 stations, among them 24 stations equipped with short period seismograph, broad bandseismograph and long period seismograph, and 62 stations equipped with short period seismograph. From
1996, supported by the central government and local governments, CEA launched national projects of
updating the seismological observation facilities into digital seismological observation systems. By the endof 2007, CEA had accomplished analog to digital conversion of the then existing seismological observation
systems and set up 1007 digital seismic stations. This indicates full digitization of seismological observationin China.
From 1950 to 2007, CEA accumulated a huge mass of analog seismograms, some seismographs are stored
in Institute of Geophysics, and some seismographs are stored in provincial seismological earthquake
administration. Due to storage in different regions, some seismograms have been damaged or lost. We mustsort through these valuable historical seismograms and input to computer timely for proper record.
CEA pay more attention to analog seismograph rescure, we scanned about 40,000 seismographs with 600
dpi in jpg format in 2015. With the helps of Prof. Paul Richards and Dr. Won-Young Kim, we installed theanalog seismograph digital software SeisDig and digitized some seismographs in 2016. SeisDig is a
Graphical User Interface (GUI) based interactive digitizing tool, digitizing operations are mouse selected.

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*S05-1-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

Analog Seismogram Archives at Earthquake Research Institute, theUniversity of Tokyo* Kenji Satake 1) , Hiroshi Tsuruoka 1) , Satoko Murotani 2) 1)
Earthquake Research Institute, University of TokyoTokyo, Japan 1) , National Museum of Nature andScience, Japan 2)
Earthquake Research Institute of the University of Tokyo has several kinds of archives of analog
seismograms and mareograms. First one is Historical Seismogram Collection, which includes seismograms
recorded at Tokyo (at various locations and instruments around Hongo with a total of 213,579 records from1887 to 1986), Tsukuba (10,769 records for 1922-1962), and Wakayama (12.650 records for 1922-1968).
Seismograms at particular locations and dates can be searched at the website: http://wwweic.eri.utokyo.ac.jp/susu/en/. The oldest record from large earthquake is from the 1891 Nobi earthquake recordedat Hongo on a circular paper. Teleseismic data includes the Hongo record on the Omori seismograph, theworld's first continuous seismograph, from the 1899 Alaskan earthquake. While they are archived as
microfilms by 1990's, the resolutions were poor for some records and users need to go back to the originalrecords. Second one is collection of foreign seismograms. Old seismograms between 1899 and 1917 at
Taiwanese stations can be searched at http://wwweic.eri.u-tokyo.ac.jp/record-W/taiwan_kisyo-e.html.
Microfilms of Canadian Seismograph Network between 1981 and 1989 are archived. For WWSSN stations,
Almost complete microfilm data (~100 stations) from 1963 to 1988 are available. The coverage can be seen
at http://wwweic.eri.u-tokyo.ac.jp/wwssn/filmlist.html (only in Japanese). The last one is tsunami waveform
data http://wwweic.eri.u-tokyo.ac.jp/tsunamidb/index.html (only in Japanese). Tsunami waveforms
recorded on Japanese tide gauges from large earthquakes between 1911 and 1996 are scanned andarchived. Guest uses can see the list (sorted dates, earthquakes or locations) of 3097 records, butregistration is required to download the images.

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*S05-1-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

The current status of archives of the old analog seismograms in Japan, andsome examples of their preliminary contribution to seismology* Ritsuko S. Matsu'ura 1) , Norihito Umino 2) , Yoshiaki Tamura 3) , Yoshihisa Iio 4) , Minoru Kasahara 5)
Association for the Development of Earthquake Prediction, Tokyo, Japan 1) , Tohoku University, Sendai,
Japan 2) , National Astronomical Observatory of Japan, Mizusawa, Japan 3) , Kyoto University, Uji, Japan 4) ,Hokkaido University, Sapporo, Japan 5)
Since 2004, we have been cooperating to make digital image archives of old analog seismograms preservedin the following institutes:
National Astronomical Observatory of Japan, Mizusawa (records of Latitude Observatory), Tohoku
University (records of Mukaiyama Observatory, and Yagiyama Seismological Observatory), and Kyoto
University (Kamigamo Observatory, Abuyama Observatory, and Aso Volcanological Observatory) aremainly for smoked paper-seismograms.
Hokkaido University (Urakawa Seismological Observatory, Sapporo Center, and some temporal stations),and Earthquake Research Institute, the University of Tokyo (Tsukuba Observatory, and Dodaira
Observatory) are mainly for 35mm film-seismograms and ink-recorded seismograms recorded after 1960's.
We also made the digital image archive of world seismograms on 1933 Showa Sanriku Earthquake, whichwere collected by the late Prof. Takeo Matsuzawa soon after the event. Although most archives are still
under construction, here we would like to show our current achievement and some examples of theirprimitive usage.
Although we have the very good earthquake catalogue in Japan for the period from 1885, there still remainsome earthquakes of questionable hypocenters and magnitudes for old events. 1911 off the Kikaijima
Island earthquake of M8.0 is one of these events. It was felt even in Osaka, separated nearly 900 km fromthe epicenter. Gutenberg (1954) assigned 160km depth to this event. However, tsunami damage wasreported in some nearby islands. When we could compare a seismogram recorded in Mizusawa of 1911
event with that of the 1901 shallow event of M7.0, whose epicenter is very close to the 1911's, it is reallyeasy to conclude that the both events are shallow. It was confirmed by some seismograms preserved inabroad, too. We will report some other examples of the power of digital image archives of old analog
records.
We appreciate the late Prof. Motoya, and many persons who have involved in the archiving operations.

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*S05-2-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

Historical seismograms: Preservation efforts for an endangered species* Emile OKAL
Northwestern University, Evanston, IL USA
The long recurrence times characteristic of major earthquakes (typically one
to several centuries) result in severe undersampling of the Earth's seismicity
as documented by digital seismic networks (at most 40 years old), or even
their immediate predecessor, the WWSSN (55 years old). For this reason,
historical seismograms (typically from 1900 to 1962) are
absolutely crucial to the understanding of seismic cycles, notably at major subduction zones.
Yet, these precious datasets are often perceived by administrative stakeholders as
antiquated, obsolete and of little value, and are thus threatened with disposal andirreversible destruction. This situation is aggravated by the aging and eventual
disappearance of the older generations of seismologists who were trained in the techniques allowing
the modern processing of such records.
We present a review of typical analog datasets of historical seismograms
and of the techniques available for their preservation through transfer to digital supports.
We focus on the Northwestern University Seismogram Archive Facility, which presently holds anestimated 5 million seismograms on photographic support, including a rich WWSSN collection,and complete archives of the Pasadena/Southern California network for 1923-1962, as wellas significant holdings of records from the former Soviet Union, Japan, and other criticalstations.

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*S05-2-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

Modern methods applied to historical seismograms: Perspective andexamples* Emile OKAL
Northwestern Univesity, Evanston, IL USA
The long recurrence times characteristic of major earthquakes (typically one
to several centuries) result in severe undersampling of the Earth's seismicity
as documented by digital seismic networks (at most 40 years old), or even
their immediate predecessor, the WWSSN (55 years old).
Yet, crucial information can be extractedusing variations of modern techniques routinely applied to digital data.
We present a review of these algorithms, notably the PDFM moment tensor
inversion and the application of energy- moment discriminants. We will review
several examples, including the resolution of the "twin eights" of 17 August
1906, the quantification of the slowness parameters of the 1932 Manzanillo,
1947 Hikurangi and 1934 Santa Cruz tsunami earthquakes, and focal mechanism solutions fortwo major plate boundary events, on 01 May 1915 in the Kuril Islands and
26 June 1941 in the Andaman Islands, which are both shown to be incompatible
with a shallow-angle thrust geometry. Application to large normal faulting
intraplate earthquakes (e.g., Sanriku, 02 March 1933) is particularly
important given the probably longer recurrence times of such events,
which are thus even more undersampled by modern records.

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*S05-2-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

Instrumental polarities of the most important historical seismographs of theEuro-Mediterranean area
* Graziano Ferrari , Barbara Palombo , Rodolfo Console , Paola Vannoli
Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
One of the many critical issues in the use of historical seismograms is the knowledge of the polarity of theseismographs with mechanical and galvanometric recording system.
This information is not easy to find and rarely appears in the seismological literature or seismic bulletins.
Periodical collection, on a global scale, of this and other information of instrumental parameters is notalways reliable or it do not refer to the same definition of polarity.
The considerable efforts to use scientifically historical instrumental records (i.e. pre-WWSSN), to calculate
for example the focal mechanism are often made vain due to the uncertain reliability of information on thepolarity of the historical instruments.
For the most popular historical instruments that have operated in the Euro-Mediterranean during theperiod 1910 – 1980 we determined the instrumental polarity comparing those expected for a set of 10
earthquakes of known mechanism with those read on over 700 seismograms.

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*S05-2-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

PRESERVING ANALOGUE SEISMOGRAMS OF REGIONAL NETWORKS
AND OTHER DOCUMENTS. EXPERIENCE AT THE INSTITUTCARTOGRAFIC I GEOLOGIC DE CATALUNYA (ICGC)* Josep Batllo 1) , Jose Antonio Jara 1) , Judith Unamuno 2) , Maria Teresa Merino 3)
Institut Cartografic i Geologic de Catalunya, Barcelona, Spain 1) , AdHoc Synectic Systems S.A., Barcelona,
Spain 2) , Observatori Fabra (RACAB), Barcelona, Spain 3)
Catalonia, in the NE of the Iberian Peninsula, has a long tradition on seismic recording. First seismic
station in this regions, EBR, still active, was installed in 1904. The second one, FBR, started in 1906 and it
is also active. Both keep their seismograms and a large amount of complementary information. Since thenseveral initiatives succeeded.
One of them is the Catalan seismic network. Started in 1985, it can be classified as regional network. As it
was quite common at the time, short period vertical sensors were used. Most of the seismograms obtained
up to year 2000 were recorded on thermal paper support. At ICGC we keep at present around 28000
record sheets from the period 1985-2000. Such kind of support is unstable and records become whitened
after few years. Thus, even we are dealing with post WWSSN era records, actions to preserve them areneeded urgently and the posed problems and needs are similar to those of the WWSSN and earlier records.
To save these records for the future, a campaign to scan them as images has been undertaken. These
seismograms show some specific features when compared with WWSSN or older records (ex. The highfrequency content of the signal obliges to use high density scanning -1200 dpi). As this successful
experience can be useful to preserve records of other regional networks, we present here the adopted
strategies for scanning, classification and diffusion and some preliminary results from their analysis.
These projects joint other initiatives developed at ICGC for preserving and diffusion of other materials as
seismic bulletins, macroseismic records, etc. of the older stations EBR and FBR. Some examples will bealso presented.

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*S05-2-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

Observations of large earthquakes in the Mexican subduction zone over 110
years* Vala Hjorleifsdottir 1) , Shri Krishna Singh 1) , Bjorn Lund 2) , Chen Ji 3)
Universidad Nacional Autonoma de Mexico, Mexico City, Mexico 1) , Department of Earth Sciences,
Uppsala University, Sweden 2) , Department of Earth Science, University of California, Santa Barbara, USA
3)

Fault slip during an earthquake is observed to be highly heterogeneous, with areas of large slip
interspersed with areas of smaller or even no slip. The cause of the heterogeneity is debated. One
hypothesis is that the parts of the rupture surface that have large slip during earthquakes are coupled morestrongly, whereas the areas in between creep continuously or episodically, partially releasing strain energy
during the interseismic period. This would lead to subsequent earthquakes having large slip in the sameplace, or persistent asperities. A second hypothesis is that in the absence of creeping sections, theprestress is governed mainly by the accumulative stress change associated with previous earthquakes.
Assuming homogeneous frictional properties on the fault, a larger prestress results in larger slip, i.e. thenext earthquake may have large slip where there was little or no slip in the previous earthquake, whichtranslates to non-persistent asperities.
The study of earthquake cycles are hampered by short time period for which high quality, broadband
seismological records, needed for detailed studies of slip distributions, are available. The earthquake cyclein the Mexican subduction zone is relatively short, with about 30 years between large events in many
places. We are therefore entering a period for which we have good records for two subsequent eventsoccurring in the same segment of the subduction zone.
In this study we compare seismograms recorded either at the Wiechert seismograph or on a modern
broadband seismometer located in Uppsala, Sweden for earthquakes in the Mexican subduction zone
rupturing the same patch. The Wiechert seismograph is unique in the sense that it recorded continuously
for more than 80 years, without changes in the instrument response. In total we have registers from morethan 20, M>6.9 earthquakes in seven along trench segments.
Our observations indicate that some asperities are persistent over time, whereas others are not.

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*S05-2-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

ANALYSIS OF THE ANALOG SEISMOGRAMS RECORDED DURING THE
NOVEMBER 19, 1912 (M~7.0) ACAMBAY, CENTRAL MEXICOEARTHQUAKE: TOWARDS A FINITE SOURCE INVERSION
Raul Daniel Corona , * Miguel Angel Santoyo
Institute of Geophysics. National Autonomous University of Mexico, Morelia, Mexico.
The Acambay earthquake of November 19, 1912, was an M~7.0 shallow intraplate rupture that broke alarge portion of the Acambay-Tixmadeje Fault System in central Mexico. The earthquake produced
extensive damage in several towns close to the fault and was strongly felt in Mexico City. This event
generated a 40.0-km-long surface rupture trace, with a peak observed dislocation of ~0.5m. To date this is
one of the most important continental earthquakes occurred in Mexico. During 1912 six seismographic
stations were operating in Mexico with different Wiechert and Bosch-Omori mechanical seismographs. An
extraordinarily detailed report shows it was recorded by most of horizontal and vertical instruments at thesix stations. Up to 2016, only 11 from the original 22 smoked-paper seismograms, from five of the stations
that recorded the earthquake were found to be recovered.
In this work using standard and ad-hoc methodologies we obtained the digital, evenly-sampled time series
for the ground motion velocities for each of the available seismograms. To do this, we first carried out ahigh resolution scanning of the original traces. Then, due to the condition of the seismograms we manually
digitized them, following the seismic trace in ascending time. Therefore we corrected the distortions ofseismic traces for their pen curvature, uneven paper speed, skews, and non-zero baselines following theGrabrovec and Allegretti (1994) procedure, and additional ad-hoc corrections were made using linear
approximations when abrupt changes in traces occurred. After this, we resampled the unevenly digitized
traces to a constant-time interval to 100 samples per second using a spline interpolation method. Finally
we performed an instrument correction procedure to obtain the actual ground velocities for each
instrument and component. Once corrected, the unclipped portions of seismic data were used to perform alinear finite-source inversion for the slip distribution on the fault surface.

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*S05-P-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

Database of digitized data of analog seismic and tsunami records forhistorical earthquakes in Japan* Satoko Murotani 1) , Kenji Satake 2) , Hiroshi Tsuruoka 2) , Hiroe Miyake 2) , Toshiaki Sato 3) , Tetsuo
Hashimoto 4) , Hiroo Kanamori 5) , Masahiro Osako 1)
National Museum of Nature and Science, Tsukuba, Japan 1) , Earthquake Research Institute, the Universityof Tokyo, Tokyo, Japan 2) , Ohsaki Research Institute, Inc., Tokyo, Japan 3) , Japan Meteorological Agency,
Tokyo, Japan 4) , California Institute of Technology, California, United States 5)
Seismic and tsunami instrumental observations by seismographs and tide gauges in Japan started in 1875,
and a huge number of analog records of earthquakes and tsunamis are stored at various universities andinstitutes in Japan. Re-analysis of historical records based on modern waveform analysis methods, highperformance computers and current knowledge on the velocity structure would produce new results andinterpretations of the mechanisms of earthquakes and tsunamis that can improve hazard mitigation
practice. However, it requires extensive time and skills to digitize the analog waveforms recorded on paper.
We are currently constructing the database of digitized historical records for major earthquakes in Japan,
for example, the 1923 Kanto, 1944 Tonankai, and 1946 Nankai earthquakes, with the cooperation of many
institutes such as universities, government agencies, and companies. In this presentation, we introduce theprototype of the database. The data can be searched by event name, station name, and seismograph name.
Users can obtain the instrumental constants if they are available, in addition to the digital data. We target toopen this database in a few years via National Museum of Nature and Science and Earthquake ResearchInstitute of the University of Tokyo. Contribution of digitized waveforms are welcome from any
seismologists in the world. The database on the museum website will play an important role for outreach ofseismology.

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*S05-P-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

HERP data retrieval system of JMA analog seismograms* Mitsuko Furumura 1) , Koji Iwasa 1) , Yasunori Suzuki 1) , Tomotsugu Demachi 2) , Takeo Ishibe 1) , Ritsuko
S. Matsu'ura 1)
ERC, ADEP, Tokyo, Japan 1) , Graduate School of Science, Tohoku University, Sendai, Japan 2)
Since 2006, we have scanned selected analog seismograms observed at about 150 stations deployed by
Japan Meteorological Agency (JMA), and constructed a database of the scanned digital images.
Digital image of each seismogram is obtained by scanning the entire seismogram at once using a large
flatbed color scanner with a 400 dpi resolution, and saved as a TIFF-format file. Due to the depth of focus,
we can get clear seamless images even for not-flat seismograms. As of January 2017, we obtained morethan 138,000 image files of seismograms recorded at 100 stations, by various types of seismographs, suchas Gray-Milne-Ewing type seismograph (G.M.E), Wiechert Seismograph, and mechanical strong motion
seismographs. In those data, there are many precious records of the destructive earthquakes like the 1891
Nobi earthquake.
The images of seismograms for 91 stations can be now available through the web site:
http://www.susu.adep.or.jp/
The images for the rest stations are under processing to be added to the database.
In the database, the seismograms can be searched by date, station name, and components. The size of one
original TIFF-format image file is around 200 MB, then all images are highly compressed as JPEG2000 files
for easy preview and download.
Constants of static magnification, natural period and other parameters of the used seismographs are alsocollected.
The database has begun to be utilized for research, such as re-investigation of the 1914 earthquake at
Kagoshima (Ogata et al., 2016). We are planning that the web site will become one of the Wiki page, inwhich data of the seismograms digitized by researchers are open after getting their permission.
Acknowledgement
This project has been supported by the Headquarters for Earthquake Research Promotion (HERP) of the
Ministry of Education, Culture, Sports, Science, and Technology in Japan. We thank to Dr. Masayuki
Okuno, Mr. Yukio Hirai, Mr. Atsushi Kamata, and Mrs. Yoshiko Suzuki.

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*S05-P-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

A trial application of analog seismograms of the Kanto-Tokai observation
network for crustal observation to the detection of deep low frequency
tremor* Takanori Matsuzawa , Tetsuya Takeda
National Research Institute for Earth Science and Disaster Resilience
Continuous digital seismic data from dense seismographs network lead to the discovery of deep low
frequency tremor (hereinafter, tremor; Obara, 2002). In this study, we examined whether the analog
recordings are useful to reveal past activities of tremor in the Tokai region, central Japan. National
Research Institute for Earth Science and Disaster Resilience (NIED) operated the Kanto-Tokai observation
network for crustal observation since 1979 (hereinafter, Kanto-Tokai network; Okada et al., 2000). While
this data was mainly used to locate hypocenters of earthquakes around the Kanto and Tokai region in
Japan, continuous seismic data in the vertical component has been stored as analog seismograms onrecording paper. In the early 2000's, the seismographs of the Kanto-Tokai network were taken over to Hinet and fully digitized.
The seismograms of the Kanto-Tokai network were recorded by pen recorders. Two-hours recordings are
divided into four blocks in a sheet. Upper and lower blocks are the odd and even hours, respectively.
Blocks in the left and right columns show seismograms from 0 s to 35 s, and from 30 s to next 5 s (i.e. 65 s)
for each minute, respectively. Each block contains 60 traces. Small and large time ticks are marked every
second and every minute, respectively.
We checked the analog recording around the period in which SSEs are detected by a tiltmeter since 1984
(Kobayashi et al., 2006). Actually, signals dominant in several Hz with the amplitude of several hundreds of
nm/s are found at some stations in the Tokai region. This is characteristic to tremor, while time difference
between recognized tremor and the SSE catalog is sometimes about two days. This may be attributed to thespatial migration speed of tremor and SSE (typically 10-20 km/day), as the tiltmeter station is about 20 km
south from the closest seismograph. In addition, we found possible tremor from Oct. 29 to Nov. 2 in 1980,
before the period analyzed in Kobayashi et al. (2006).

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*S05-P-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

Source parameters of the 1952 Pyeongyang, North Korea, earthquake* Tae-Seob Kang 1) , Myung-Soon Jun 2)
Pukyong National University, Busan, Republic of Korea 1) , Korea Institute of Geoscience and Mineral
Resources, Daejeon, Republic of Korea 2)
There was a rather large felt earthquake on March 19, 1952 from Nampo City, west of Pyeongyang, thecapital of North Korea. The North Korea Seismological Institute estimated the magnitude of the event
around 6.5 (Seismological Institute of North Korea, 1987). They might estimate the magnitude fromtraditional method, i.e. felt area survey since there was no seismic station in the Korean Peninsula at thattime. Furthermore it was during the Korean War. Considering the low to moderate seismicity around the
Korean Peninsula, the 1952 North Korean event is exceptional and may be the largest event since the 20th
century. For this event, we collected eight seismogram copies from Japan, China, and Russia. However
many seismograms show very weak traces. We could digitize rather good quality data only from threestations, Abuyama and Matsushiro in Japan and Sverdlovsk in Russia. To determine the earthquake source
parameters, we applied moment tensor grid searching method and compare the observed and synthetic
seismograms for the above three station data. We found the best fitting with strike 120 degrees, dip 90
degrees, rake 340 degrees, and seismic moment 2.45*10^25 dyne-cm, which is relevant with moment
magnitude (Mw) 6.17.

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*S05-P-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

STUDY OF THE 7TH JULY, 1923, CANAL DE BERDUN EARTHQUAKE, IN
THE PYRENEES FROM CONTEMPORARY SEISMOGRAMS AND
BULLETINS
Rosa Martin 1) , Daniel Stich 1) , * Josep Batllo 2) , Ramon Macia 3) , Jose Morales 1)
Instituto Andaluz de Geofisica, UGR, Campus Universitario de Cartuja s/n, E-18071 Granada, Spain 1) ,Institut Cartografic i Geologic de Catalunya, ICGC, Parc de Montjuic s/n, E-08038 Barcelona, Spain 2) ,Dept. Matematica Aplicada II, UPC, Pla de Palau 18, E-08003 Barcelona, Spain 3)
Seismicity rate in the Pyrenees can be considered moderate. Nevertheless, damaging earthquakes occurs
in this region as it is well known from their historical seismicity records. Among them, the 7th July, 1923,
known as Canal de Berdun earthquake, is probably the largest one, according to the moment magnitude
Mw = 5.4 that we compute in this study. Its size and unique location among the large earthquakes in the
Pyrenees, in the central, south part of the chain, make this event of great interest for a better definition of
the regional seismicity. For this reason we decided to study its source from the analysis of the available
contemporary seismograms and related documents.
After a throughout collection and selection, 20 records for this earthquake have been digitized andprocessed. They were obtained at 9 different European stations. The event has been relocated and its
magnitudes recalculated. We further characterized the earthquake through time domain moment tensor
inversion. We obtain appropriate fits to regional recordings filtered in an intermediate period band (20 s to50 s) for a pure normal faulting source with strike parallel to the Pyrenees (N292E), dip of 66 degreesandrake angle of -88 degress. The best fitting depth is 8 km. While previous normal faulting events in the
Pyrenees occurred close to the axial zone and the highest topographies, suggesting a relation of seismicity
to postcollisional extension, the location of this important normal faulting event at the southern frontal
thrust of the Pyrenees suggests that this interpretation may be too simplistic.

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*S05-P-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S05. Preservation and usage of analog seismogram archives

ROMANIAN NETWORK OF ANALOG SEISMOGRAMS: CONTRIBUTIONTO IMPROVE GLOBAL EARTHQUAKE CATALOGS
Daniel Nistor Paulescu 1) 2) , Eugen Oros 1) , Mircea Radulian 1) 2) 3) , * Elena Manea 1)
National Institute for Earth Physics, Magurele, Romania 1) , University of Bucharest Faculty ofPhysics,Magurele, Romania 2) , Academy of Romanian Scientists, Bucharest, Romania 3)
Romania has a long tradition in recording and investigating seismic events. The first historical instrumental
recordings are available starting with 1902. Since then, the number of analog stations has continuously
increased reaching in 50' a number of 7 observatories equipped with different seismographs withrecordings on black paper, photo paper and ink paper. After the major earthquake of 4 March 1977,
benefiting from UNDP-UNESCO assistance, the national network was improved with a telemetric networkof 15 seismic stations with data recorded on paper.
Over time, Romania analogue network provided and exchanged seismic data (bulletins, seismograms,
reports) with international agencies (International Seismological Summary, International SeismologicalCentre, National Earthquake Information Center, National Earthquake Information Service) andparticipated with a significant number of analog seismograms recorded at strong earthquakes in Europe tothe international projects EUROSEISMOS, SISMOS and NERIES. Recently, in addition to the classicarchive of analogue recordings, a modern digital database has been created in the National Institute for
Earth Physics (http://archive.infp.ro/). Until now, over 200000 seismograms have been scanned. With the
new digitization and vectorization software which is now available, the source parameters can bereconsidered.

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*S06-1-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S06. Advancement in methodologies for CTBT monitoring

Trends in ground-based nuclear explosion monitoring research anddevelopment* Michael Pasyanos 1) , Monica Maceira 2) , Dale Anderson 4) , Stephen Arrowsmith 3) , Michael Begnaud 4) ,Philip Blom 4) , Leslie Casey 5) , Garrett Euler 4) , Sean Ford 1) , Michael Foxe 6) , Jonathan MacCarthy 4)
Lawrence Livermore National Laboratory 1) , Oak Ridge National Laboratory 2) , Sandia National
Laboratories 3) , Los Alamos National Laboratory 4) , National Nuclear Security Adminstration 5) , PacificNorthwest National Laboratory 6)
There have been significant technological and scientific revolutions in the fields of seismology, acoustics,
and radionuclide sciences with regard to the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which
opened for signature in 1996. It is valuable to pause now and observe the arcs of progress evident in the
body of research results reported in the literature related to improving monitoring capabilities. To this end,
authors from several national laboratories have prepared a report entitled “Trends in Ground-Based
Nuclear Explosion Monitoring Research & Development – A Physics Perspective". The document reviews
the accessible literature for four research areas: source physics (understanding signal generation), signal
propagation (accounting for signal changes with distance), sensors (recording the signals), and signal
analysis (processing the signal). It addresses over 40 trends, such as moving from 1D to 3D earth models,from pick-based methods to full waveform methods, and from separate analysis of sensor data to integrated
analysis. Highlighted in the document for each trend are the value and benefit to the monitoring mission,
key papers that advanced the science, and promising research and development for the future.

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*S06-1-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S06. Advancement in methodologies for CTBT monitoring

The ISC datasets for monitoring research* Dmitry Storchak , James Harris , Konstantinos Lentas
International Seismological Centre (ISC), Thatcham, Berkshire, UK
The International Seismological Centre (ISC) is a non-governmental organization based in UK and fundedby 69 research and operational institutions in 45 countries. The main mission is to produce the global
definitive Bulletin of earthquakes and other seismic events based on reports from over 130 seismic
networks worldwide. The ISC Bulletin is the most long-term and comprehensive source covering the period
from 1904 to 2017.
Soon after seismic event occurrence, the ISC collects preliminary bulletin reports from various seismic
networks and agencies around the world. Once integrated together, they form a bulletin of very recent
global seismicity. These preliminary reports are later substituted, one by one, with fully reviewed reports
from the same agencies and form the basis for the comprehensive and reviewed ISC Bulletin. Thus, at any
time with respect to each seismic event occurrence, the ISC Bulletin remains a great reference source of
information for various studies of monitoring product's completeness, quality and calibration.
In addition, the ISC maintains and distributes several derivative datasets that are used in monitoring
research: the ISC-EHB bulletin - a groomed subset of the ISC Bulletin containing well-recorded teleseismic
events; the IASPEI Reference Event List (GT) – a bulletin of events for which the hypocentral information is
known with high confidence (to 10km or better); the ISC Event Bibliography - an interactive facility thatenables searches for references to scientific articles devoted to specific natural and anthropogenic seismic
events that occurred within a region and time period of interest.
Here we describe major advances recently made by the ISC to extend and improve these datasets that are
openly available and widely used in monitoring research. These datasets are also used by the ISC as a basisof its interactive service “The CTBTO Link to the ISC database" used by the personnel of many National
Data Centres.

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*S06-1-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S06. Advancement in methodologies for CTBT monitoring

Synthetic seismograms of explosive sources calculated by the Earth
Simulator* Seiji Tsuboi 1) , Hiroyuki Matsumoto 1) , Mikhail Rozhkov 2) , Josh Stachnik 3)
JAMSTEC, Kanagawa, Japan 1) , CTBTO, Vienna, Austria 2) , ISTI, USA 3)
We calculate broadband synthetic seismograms using the spectral-element method (Komatitsch & Tromp,
2001) for Jan. 6 2016 DPRK event (Mw(USGS) 5.1). We use Earth Simulator system in JAMSTEC tocompute synthetic seismograms using the spectral-element method. The simulations are performed on
8,100 processors, which require 2,025 nodes of the Earth Simulator. We use one chunk with the angulardistance 40 degrees to compute synthetic seismograms. On this number of nodes, a simulation of 10
minutes of wave propagation accurate at periods of 3.0 seconds and longer requires about 2 hours of CPU
time. We use CMT solution of Rozhkov et al (2016) as a source model for this event. This source model has
43% CLVD component, 19% double couple component and 38% isotropic component. The hypocenter
depth of this solution is 1.4 km but we put the hypocenter at the surface for this computation. Comparisonsof the synthetic waveforms with the observation show that the arrival time of Pn and Pg waves matches wellwith the observation The surface waves observed are also modeled well in the synthetics, which shows that
the CMT solution we have used for this computation correctly grasps the source characteristics of thisevent.

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*S06-1-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S06. Advancement in methodologies for CTBT monitoring

Model ensembles for estimation of seismic travel time and event location
uncertainty* Stephen Myers , Nathan Simmons
Lawrence Livermore National Laboratory, Livermore, California, USA
We explore the use of model ensembles to characterize the uncertainty of seismic travel time predictions.
Our emphasis is on 3D earth models and we include a standard, radially symmetric (1D) models forcomparison. Traditional parameterization of travel time prediction uncertainty – as a function of eventstation distance – provides a representative global average, but uncertainty characterization can be
unrepresentative when errors throughout a large geographic region deviate significantly from the average.
Recent efforts to characterize path-specific travel time uncertainty have made great strides, but ad hoc
multiplication factors must be applied to uncertainty estimates for them to be reconciled with observed
error. The mismatch between estimated uncertainty and observed error is likely due to epistemic errors, forwhich model-error covariance is typically unknown. The model ensemble approach leverages the efforts ofmany research groups that have rendered images of earth structure. To the extent that researchers use
differing data sets, model parameterization, methods of travel-time prediction, or imaging, predictions
based on an ensemble of models will improve robustness of travel time uncertainty. In our initial effort, we
use a set of seismic models to compute P-wave travel times for a global set of events with well-characterized
location uncertainty. Agreement and divergence of travel time predictions for each model globally,
regionally, and for each path are examined to study the variability of model predictions. The test events are
relocated and epicenter uncertainties are estimated using each model and using estimates of uncertainty
based on an ensemble calculation. The consistency of location errors and uncertainties are used to assess
the model ensemble approach. This work was performed under the auspices of the U.S. Department ofEnergy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

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*S06-1-05
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S06. Advancement in methodologies for CTBT monitoringOn similarities and differences of signals measured by IMS stations from five
DPRK underground tests
Dmitry Bobrov , Ivan Kitov , Mikhail Rozhkov , * Pierrick Mialle , Peter Nielsen
Comprehensive Nuclear-Test-Ban Treaty Organization, Vienna, Austria
Seismic, hydro-acoustic, and infrasound stations of the International Monitoring System detected
seismoacoustic signals from five declared underground tests conducted by the DPRK. These data allow
thorough quantitative comparison aimed at understanding of the similarities and differences in seismoacoustic wave generation by underground explosions. In routine automatic and interactive processing, theInternational Data Center found all five events, fused seismo-acoustic, estimated absolute locations andmagnitudes together with their uncertainties. The International Seismological Centre makes these results
available for the broader monitoring community. In this study, we extend the estimates of relative
characteristics of detected signals to station level using standard methods adapted at the International Data
Centre (IDC). In addition, we apply several techniques based on waveforms cross correlation (WCC), which
are under development at the IDC. The WCC method allows significant improvement in the accuracy ofrelative location, magnitude, and seismic moment tensor estimation.

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*S06-1-06
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S06. Advancement in methodologies for CTBT monitoring

Source array analysis for accurate relative event location at the North Korea
nuclear test site
Steven Gibbons , * Tormod Kvaerna , Sven Peter Naesholm , Svein Mykkeltveit
NORSAR, Kjeller, Norway
Between October 2006 and September 2016, 5 declared underground nuclear explosions carried out at the
Punggye-ri test-site in North Korea were detected both at regional and teleseismic distances. Doubledifference relative location estimates are quite network-sensitive with inter-event distance estimates fromregional Pn phases consistently longer than estimates from teleseismic P-phases. The seismic wavefieldleaving the test-site is more complicated than predicted by a 1D velocity model. Slowness corrections foreach of the rays leaving the source region can be found which reduce the double-difference time residuals
and provide relative location estimates which are consistent for all seismic measurements. Source-array
analysis provides a different approach to modelling the seismic wavefield leaving the DPRK test-site andsupports the hypothesis that the slownesses for regional Pn waves are frequently underestimated. Given
the number of events now recorded at the test-site, source-array analysis provides an important tool for
analyzing subsequent events which may be problematic for classical double-difference methods. One such
scenario is a low magnitude event recorded only regionally, with limitations in azimuthal coverage. Anotheris a test in a different part of the site for which the waveform similarity is significantly diminished at somestations.

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*S06-P-01
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S06. Advancement in methodologies for CTBT monitoring

Seismic wave analysis of North Korean nuclear tests using seismographic
networks in Japan* Kazunori Yoshizawa 1) 2) , Ryo Narita 2)
Faculty of Science, Hokkaido University, Japan 1) , Graduate School of Science, Hokkaido University, Japan
2)

Seismic waves generated by a series of North Korean nuclear tests in the past decade have been observedin seismic networks deployed throughout the Japanese Islands. Seismic signals corresponding to Pn
arrivals are observed clearly at seismic stations of Hi-net (High Sensitivity Seismograph Network) and F-net(Broadband Seismograph Network) deployed by NIED (National Research Institute for Earth Science andDisaster Resilience).
We analyzed the waveforms of the five nuclear tests recorded at Hi-net and F-net stations. Apparent pathaverage velocities of Pn waves and their maximum amplitudes are estimated from observed seismograms inthe vertical component. We found significant regional variations of apparent path-average velocity andmaximum amplitude along propagation paths, which are likely to reflect the structural variations in thecrust and uppermost mantle beneath the Sea of Japan. For example, fast apparent Pn velocity and larger
amplitude are observed in the paths across the Japan Basin in the northern part of the Sea of Japan, which
is characterized by thinner curst (about 9 km), while slow velocity as well as relatively smaller amplitude
are found in the paths to Kyushu, which traverse the eastern margin of the Korean Peninsula with thicker
crust.
Such regional variability of Pn wave speeds and amplitudes makes it difficult to precisely estimate thesource parameters and yield of explosion, by using only the Japanese seismographic network without any
proper correction for 3-D structure in the curst and uppermost mantle beneath the Sea of Japan. Such Pn
wave anomalies derived from the past explosions observed throughout Japan may be of help in empiricalcorrections for the rapid and precise determination of hypocenter and yield of explosive source.

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*S06-P-02
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S06. Advancement in methodologies for CTBT monitoring

Long-range underwater acoustic propagation from controlled underwater
sources received at IMS hydroacoustic stations* Tomoaki Yamada 1) , Georgios Haralabus 2) , Mario Zampolli 2) , Kevin Heaney 3)
The University of Tokyo, Tokyo, Japan 1) , CTBTO, Vienna, Austria 2) , OASIS Inc., Lexington, USA 3)
Controlled impulsive scientific underwater sound sources in the Northwestern Pacific used for lithospherestudies, and observed at two IMS hydroacoustic stations in the Pacific Ocean were studied. Although theenergy released from these sources is significantly smaller than that of nuclear explosions, the signals wererecorded by ocean bottom seismometers and IMS hydroacoustic stations thousands of kilometers awayfrom the source. These experiments provide calibrated yield, time and locations for long-range acoustic
transmissions, which enable the examination of the physics of long-range acoustic propagation. The IMS
stations employed in this study were HA03 (Juan Fernandez Island) off the coast of Chile in theSoutheastern Pacific, and HA11 (Wake Island, USA) in the western Pacific. Both stations have two tripletsof hydrophones located in the SOFAR channel and monitor the oceans for signs of nuclear explosions.
HA03 detected sources that were located above flat terrain at distances of 15,000 km across the Pacificand above the landward slope off the coast of Japan at distances of 16,000 km across the Pacific. These
records demonstrated that bubble pulse characteristics in the signal could be preserved over the longpropagation distances.

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*S06-P-03
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S06. Advancement in methodologies for CTBT monitoring

The CTBTO Link to the ISC Database* Konstantinos Lentas , Dmitry Storchak , James HarrisInternational Seismological Centre
The "link to the International Seismological Centre (ISC) database" is a database visualisation web
interface, specifically designed and implemented to fulfil the needs of the monitoring community. It
provides both PTS and National Data Centres with dedicated access to seismological datasets maintainedby ISC, notably, the ISC/ISS bulletins of natural seismicity of the Earth, mining induced events as well as
nuclear and chemical explosions; the ISC-EHB bulletin and the IASPEI Reference Event list (GT). Special
access to the datasets is provided by four basic categories: the Area based spatio-temporal search (basedon ISC Bulletin), the REB based spatio-temporal search (based on specific REB events), the GT event based
search and the IMS station based search (historical reporting patterns of stations close to IMS sites). Via
the dedicated searches the user can submit queries to the ISC database, create various maps and plots,
download the data, carry out comparisons of the parametric data, and relocate REB and GT events on the
fly. The ISC is committed to maintain and further develop the link's capabilities as it is extensively used by
the NDCs and PTS and is proved to be a useful tool during both the NDC Preparedness Exercise and the
OSI Integrated Field Exercise.

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*S06-P-04
IASPEI Symposium / IASPEI01. Seismological Observation and Interpretation /S06. Advancement in methodologies for CTBT monitoring

Similarities and differences of a hydrogeological response to undergroundnuclear explosions and earthquakes
Evgeny Vinogradov , Ella Gorbunova , * Alina Besedina
Institute of geospheres dynamics, Moscow, Russia
We analyzed hydrogeodynamic state change due to large-scale underground nuclear explosions that had
took place on the Semipalatinsk testing area (USSR, present Kazakhstan) in 1983-1989. We performed tomark out several key stages of hydrogeodynamic state change:
1. Excess pressure camber forming at the moment of the explosion
2. Drop-like or gradual level decrease to the initial value or even below depending to entire volume ofinduced fracturing and existence of hydraulic link to zones that were weakened by explosion andconnected to explosion epicenter.
3. Establishment of quasi-stationary underground water flow and subsequent level recovery to the initialstatic state.
Marked stages' duration depends on explosion characteristics, geological-structural and hydrogeologicalconditions of testing area. We discovered that both co-seismic and post-seismic hydrogeological effects due
to explosions are often similar to those associated with the passage of the waves of large-scale earthquakes
in the case of solid massif but can differ in the affected zones of faults of different range. We consideredvertical velocity of ground motion as the parameter of comparison.
We found out differences in the nearest zone of explosions and earthquakes in case of peak ground velocity
exceeding 40 cm/s. Maximum water level decrease lasted more than three months after the burst in the
wellbore on the Semipalatinsk testing area whereas post-seismic level changes after earthquakes usually
end in hours or days. Certain exceptions tend to fault zones where water level alterations sometime comeup to tens of meters. Following research will show does this difference relates either to local geologicalstructural peculiarities of different fault zones or inherent physics of impact.
This work was supported by the Russian Science Foundation (Project No. 16-17-00095) and Russian
Academy of Science (Project No 0146-2015-0012).

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*S07-1-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Source parameters, path attenuation, and site effects from strong-motion
recordings of the Wenchuan aftershocks (2008-2013) using nonparametric
generalized inversion technique* Yefei Ren , Ruizhi Wen , Hongwei Wang , Dongwang Tao
Institute of Engineering Mechanics, China Earthquake Administration, Harbin, China
S-wave amplitude spectra from 928 strong-motion recordings, which were obtained at 43 permanent andtemporary strong-motion stations in 132 Ms 3.2-6.5 earthquakes occurred in the vicinity of the fault planeof the 2008 Wenchuan earthquake from May 12, 2008 to December 31, 2013, are collected for determining
the source spectra, path attenuation, and site responses using a nonparametric generalized inversion
technique (GIT). Some source parameters are determined by the grid-searching method. Seismic moment(M0) and corner frequency (fc) vary from 2.0*10^21 to 1.7*10^25 dyne*cm and from 0.1 to 3.1 Hz,
respectively. Stress drop mainly ranges from 0.1 to 1.0 MPa, significantly lower than the globally averaged
level. S-wave energy-to-moment ratio is approximately 1.32*10^-12. The source scaling properties arestudied by analyzing these parameters. It shows that the moment magnitude (Mw) is universally lower than
the surface-wave magnitude (Ms) or local magnitude (ML) measured by China Earthquake Network Center(CENC). M0 is proportional to fc^-3, and stress drop has no significant dependence on the size ofearthquake, which implies self-similarity for earthquakes in this study. It shows that larger stress drop ofaftershocks generates at the areas where smaller slip occurs in the main shock. The inverted pathattenuations show that geometrical spreading in region of the Wenchuan earthquake sequence is weak andsignificantly depends on the frequency. The frequency-dependent S-wave quality factor (Qs) is regressed to
be 143.9f^0.97 at frequencies from 0.5 to 20 Hz. The inverted site responses are compared with thosegiven by the previous study (Ren et al. 2013), showing that both studies provide compatible results for mostof stations. The site responses are obviously different at different stations of a terrain array, higher at thehilltop and lower at the hill foot, which indicates ground motion is significantly affected by the local
topography.

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*S07-1-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Estimation of Source, Path and Site Effects in Hangay region Mongolia usinga dense broadband seismic array* Baigalimaa Ganbat 1) , Yokoi Toshiaki 2) , Hayashida Takumi 2)
Institute of Astronomy and Geophysics of Mongolian Academy Science, Ulaanbaatar, Mongolia 1) , The
Building Research Institute,Tsukuba, Japan 2)
We applied a spectral inversion method to data from a broadband seismic array in Hangay region,
Mongolia to estimate source, local site and propagation path effects. The 72-stations database comprises a
total of 1331 waveforms from 32 earthquakes (3.0 < Ml < 5.6). To secure the accuracy of hypocenter
locations, first we relocated hypocenters using the detected P-wave arrival times. The averaged P and Swave velocities estimated from the relocated hypocenters are 6.1 km/s and 3.5 km/s, which corresponds
well to those of upper crust model (CRUST 2.0). We also obtained seismic moment and focal mechanism ofeach earthquake based on the time-domain moment tensor inversion and P-wave polarities. The results
show that strike-slip faults are dominant in the target region and estimated magnitudes range from Mw 2.9
to Mw 4.5. In the spectral inversion method, we applied two kinds of approaches, which use reference site
and reference events in the inverse problem for computational stability. We found that two different
inversion approaches gave similar results in the frequencies range between 0.5 and 10 Hz. The
predominant frequencies at each site correspond well to those from horizontal-to-vertical (H/V) spectral
ratios of S-wave portion. Finally we estimated seismic moment, corner frequency and static stress drop foreach event using our inversion results. Our results indicate that a large amount of dataset from the dense
seismic network provides fundamental and useful information for seismic hazard assessment in this region.

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*S07-1-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Estimation of site amplification using ground motion records at strong
motion stations in Turkey* Hiroaki YAMANAKA 1) , Ozgur OZMEN 2) , Ulubey CEKEN 2) , Mehmet ALKAN 2)
Tokyo Institute of Technology, Kanagawa, Japan 1) , Prime Ministry Disaster and Emergency Management
Authority, Ankara, Turkey 2)
A strong ground motion network has been operated in whole of Turkey by AFAD (Prime Ministry Disasterand Emergency Management Authority, Turkey). Strong motion records from the observation haveprovided important data in understanding strong motion features and reasons of damage in many pastearthquakes in Turkey. Many studies on local site effects in many areas in the country have been
conducted using strong motion records, such as Avcilar area in the west Of Istanbul (Ozel et al., 2002).
In this study we have estimated site effects at the AFAD stations in whole of Turkey. Strong ground motion
data observed during 754 earthquakes at 465 strong motion stations were used to estimate effects ofsource, propagation path and site amplifications using a spectral separation technique in the frequency
domain at a frequency range of 0.5 to 20Hz. Since we used theoretical amplification of soil layers over thebasement with an S-wave velocity of about 2km/s as similar to Ozmen et al. (2016), the estimatedamplification factors in our analysis can be regarded as effects of all geological layers over the basement.
Q-values are slightly larger than those from previous studies. Most of the source spectra can be explainedwith the omega-square model. The amplifications at most of the sites in the central part of Turkey are small
at all the frequency, while large amplification factors are found at sites in the south-western part of Turkey
and along the east Anatolian fault. In particular the amplification factors are large at high frequency atsome stations around the Marmara sea suggesting effects of shallow soil. We furthermore discuss
relationships of the amplification factors with averaged S-wave velocity values in some depths at some ofthe stations.

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*S07-1-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Preparation of 1D velocity structure using records from moderate sizedearthquakes* Subeg Bijukchhen 1) , Nobuo Takai 1) , Michiko Shigefuji 2) , Masayoshi Ichiyanagi 1) , Tsutomu Sasatani 1)
Hokkaido University 1) , Kyushu University 2)
Kathmandu Valley is a tectonic basin filled with thick (~600 m) fluvio-lacustrine sediments. It carries a
history of many damaging earthquakes occurring in and around Nepal Himalaya; 2015 Gorkha Earthquake
being the latest one. Its thick unconsolidated sediment and location in seismically active region has made alarge population vulnerable to earthquakes. An understanding of underground structure is necessary for
mitigating the earthquake damage. We've used earthquake records from four strong motion seismometers
to estimate the 1D velocity structure of the valley. Moreover, records from six additional temporary seismic
stations are also used for the purpose. This is a step towards preparation of 3D basin structure of the valley.
We considered the records from station KTP, installed over rock site, as input motion and simulated theobserved waveform of sediment sites by Propagator Matrix Method. The initial velocity model for thesimulation was prepared by consultation of available borehole logs, geological map, and geological crosssections of the Kathmandu Valley. We fixed the average velocity and density of the geological layers basedon previous studies. The models were then adjusted to fit the simulated and observed waveform of amoderate earthquake (mb4.9) occurred in 2013 August 30. We then checked the adjusted models with two
Mw5.1 aftershocks of the Gorkha Earthquake with encouraging agreement between observed andsimulated waveform. We also used the Diffused Field Theory Method to cross-check the 1D velocity
models. Since, the temporary sites were installed after the Gorkha Earthquake, we tried adjusting thevelocity models using the DFT method and checking them with Propagator Matrix Method for anothermoderate sized (mb5.5) earthquake resulting in good agreement. The adjusted velocity models show
bedrock depth at 150-480 m indicating an uneven basin topography of the valley.

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*S07-1-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Regional Difference of Ground Motion for Shallow Crustal Earthquake in
Taiwan and California* Shu-Hsien Chao , Chiao-Chu Hsu
National Center for Research on Earthquake Engineering
While performing the probability seismic hazard analysis, one most important question is if the groundmotion model developed for one region can be used directly to another region. In order to answer thisquestion, we should confirm if there is a significant difference of ground motion between two regions at
first stage, identify the origin of the difference in second stage, and quantify the difference for different
ground motion scenario in third stage. Generally, it can be evaluated by different approaches including (1)comparison of available ground motion models; (2) analysis of variance for ground motion database; (3)verification of ground motion model relative to regional data; (4) development of ground motion modelwith basic function form for two regions. In this study we discuss the regional difference of ground motion
for shallow crustal earthquake in Taiwan and California as a case study by developing the ground motion
model with basic function form for two regions. We compare the spectral shape, magnitude scaling, depth
scaling, distance scaling, style of faulting factors, linear and nonlinear site effects for two regions to identify
the origins of the difference. The ground motion difference is quantified by evaluating the ground motion
ratio between two regions for different ground motion scenario. This ground motion ratio can be used toadjust other ground motion model from one region to another region for the probability seismic hazard
analysis.

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*S07-2-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Determination of Design Spectra with considering different siteclassification, in Andisheh suburb of Bandar Abbas, South of Iran* maryam sedghi 1) 3) , ramak heidari 2) , abbas jazayeri 3) , Mohamadreza Gheitanchi 1)
Azad university north Tehran branch, Tehran, Iran 1) , Islamic Azad University, Science and Research
Branch, Tehran, Iran 2) , Natural Disaster Research Institute, UNESCO chair on natural disastermanagement, Tehran, Iran 3)
A design spectrum is based on a statistical analysis of a collection of numerous spectra of different
recorded ground motions in different earthquakes, with possible modifications based on engineeringexperience. By application of design spectra in seismic analyses, determination of design spectra fordifferent site conditions improved the accuracy of seismic analysis results. Since Bandar Abbas is locatedin a high relative hazard zone (0.3 g) and the soil is soft in this region, also the city is in the presence ofwater, probability of liquefaction is high when the earthquake occurs. In this study we used 15
accelerograms with considering four characters such as: magnitude, epicentral distance, focal mechanismand site effect conditions for calculating hazard assessment. Seismosignal, EERA and Seisrisk 3 softwares
were used to process data. Based on boreholes data and seismic profiles, the shear wave velocity model
was obtained. Finally the design spectra parameters and microzonation maps were produced andpresented to structural designers.
Keywords: Bandar Abbas, Design spectra, ground motion, seismic analysis, shear wave velocity,
Microzonation, Hazard assessment

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*S07-2-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Joint project on seismic hazards in the Indo-Gangetic Plain, India: Resultsfrom Ground Motion Sensor network* Rajender Chadha 1) , Kazuki Koketsu 2) , Srinagesh Davuluri 1) , Shri Krishna Singh 3) , Satoko Oki 4) ,Srinivas Dakuri 1)
National Geophysical Research Institute Hyderabad, India 1) , Earthquake Research Institute, University ofTokyo, Tokyo, Japan 2) , Institute of Geophysics, UNAM, Mexico 3) , Keio University, Tokyo, Japan 4)
An Indo-Japanese “SATREPS-DISANET" project was jointly implemented by the Earthquake ResearchInstitute, Tokyo and National Geophysical Research Institute, Hyderabad, India during 2010-15 in which a
network of 26 Strong Motion Velocity meters was established in the Indo-Gangetic plains (IGP) to assess
seismic hazard in the region. The Himalaya represent a continent-continent collision boundary and is the
locale of four M>8.0 earthquakes in the past. The project was taken up to map shallow subsurface structureof the sediment filled fore land basin and to study seismic wave amplification to assess seismic hazard in
the region and to develop ground motion prediction equations.
The network became operational from October 2012 and recorded two significant earthquakes, viz., the2014 Bay of Bengal earthquake (Mw 6.1) and the 2015 Gorkha earthquake (Mw 7.9), as well as the larger
aftershocks. The analyses of the data provide a glimpse of seismic-wave amplification in the IGP on aregional scale. During the 2014 Bay of Bengal earthquake, the PGA and PGV values in the IGP were up to 3
and 4 times the corresponding values on the adjacent hard sites, respectively. The observed SSRs in the
IGP estimated from the data of the relatively deeper 2014 earthquake (depth between 60 and 80 km)
recorded at far distances (975 ≤ Δ ≤ 1650 km) are found to be reasonably similar to those from theshallow Gorkha earthquake at closer distances (350 ≤ Δ ≤ 680 km). Details of sediments thickness
estimation and shear wave velocity in the IGP highlighting the implication of seismic risk in the region arepresented. A passing remark on the outreach activities undertaken under the joint project will be made.

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*S07-2-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Seismic Hazard Assessment of the 1995 Kobe Earthquake: Before and After* Hiroe Miyake
The University of Tokyo, Tokyo, JapanThe 1995 Kobe earthquake was a turning point for the seismic hazard assessment in Japan. Since then, theHeadquarter of Earthquake Research Promotion has been established at the government. Crustal andsubduction earthquake potentials are evaluated, and the national seismic hazard map was released in
2005. The ground motion prediction technique for broadband time histories is validated for recent crustal
earthquakes (e.g., 2000 Tottori and 2005 Fukuoka) and past subduction earthquakes (e.g, 1944 Tonankai,
1946 Nankai, 1968 Hyuga-nada, 1978 Miyagi-oki, and 2003 Tokachi-oki). However, there are no validationof crustal earthquakes before the 1995 Kobe earthquake. From this motivation, we estimate groundmotions for the 1995 Kobe earthquake using the prediction technique and information before and after theearthquake. The first approach is based on the ground motion prediction equation (GMPE). Fukushima andTanaka (1990) is used as the pre-Kobe GMPE with site amplification factors released before 1995. As forthe post-Kobe GMPE, Si and Midorikawa (1999) is used with latest site amplification factors. The
comparison is performed at each mesh following the procedure of Ishikawa et al. (2011). The second
approach is based on the empirical Green's function method with source modeling. We compare ahomogeneous source model that follows the scaling laws of Matsuda (1975) and Takemura (1998) as the
pre-Kobe source model, and a characterized source model from Kamae and Irikura (1998) and the recipeof Irikura and Miyake (2001, 2011) as the post-Kobe source model. In addition to the above fault models,various source models are recently proposed by kinematic, pseudo-dynamic, and dynamic approaches.
Since the comparison technique is valid for these approaches at each period, it is useful to judge groundmotion pulses that enhance response spectra.

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*S07-2-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Recent Seismicity and Potential Earthquake Risk in Major Ethiopian Cities* Atalay Ayele
Addis Ababa University
The East African Rift is one of the most classic examples of active continental rifts that we witness to date.
Active tectonics manifests itself through moderate magnitude seismicity and volcanism in the region. Major
cities and towns in Ethiopia are located either within the active rift floor or the nearby margins where small
farming villages got highly urbanized over the years which is unintended overlap that exacerbatedearthquake risk in the area.
The January 24, 2016 earthquake of magnitude 4.4 Mw occurred nearby the highly populated Awasa town
at 18:34:32 UTC which was widely felt all over the town with minor damage on buildings. The Awasa
University students panicked from high rise student dormitories and minor injuries were reported. Anotherearthquake of magnitude 4.6 Ml occurred on December 4, 2016 at 01:56:15 UTC at the rift margin 40 km
south of Ankober town and about 90 km NNE of Addis Ababa. It was widely felt in Addis Ababa where anumber of residents from different part of the city reported their feeling to the media. On January 27, 2017an earthquake of magnitude 5.3 Mw ruptured at 16:29:23 UTC, 160 km south of Addis Ababa just on theeastern side of Lake Langano. This earthquake was widely felt in most of rift valley towns in Ethiopia as far
as Addis Ababa and it has been a subject of discussion both in the public and mainstream media in the
country.
Addis Ababa being one of the fastest growing cities in sub-Saharan Africa and as the capital of Africa, there
is a threat due to potential earthquake risk which has never got due attention by the concerned. The
Ethiopian Seismic Station Network (ESSN) is beaming real-time data, though limited by frequent power
failure and poor internet connectivity, and monitoring earthquake and volcanic activity in the Horn ofAfrica region. However, awareness in the society and all the concerned is still low which demands acoordinated effort in the years ahead so as to mitigate possible earthquake risk.

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*S07-3-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Reconciliation of Canada's 5th Generation Seismic Hazard Model resultswith those from the OpenQuake-engine* John Adams 1) , Trevor Allen 2) 3) , Stephen Halchuk 1)
Geological Survey of Canada, Ottawa, Canada 1) , Geological Survey of Canada, Sidney, Canada 2) ,Geoscience Australia, Canberra, Australia 3)
The Geological Survey of Canada (GSC) has contributed earthquake hazard information for the National
Building Code of Canada (NBCC) since the 1953 edition. The 2015 national hazard model update included
many important advances on its predecessors, including: probabilistic treatment of the Cascadia
subduction zone; reconfigured seismic source zones and special consideration of rare large easternearthquakes; explicit definition of crustal fault sources in the Yukon Territory and offshore western margin
faults (north of Cascadia) based on GPS observations and paleoseismic slip rates; catalogue magnitudes
expressed consistently in terms of moment magnitude for improved magnitude-frequency statistics; and theuse of a suite of representative backbone ground-motion models. The GSC is now working towards the2020 building code model. A major element will be changing from 1980s-era FRISK88 software to the
OpenQuake-engine for hazard computation. To ensure comparability we have performed comprehensive
tests using our 2015 model implemented in OQ. Without adjustments for how some elements of the model
are treated by the two codes, the engines give results within 2-3% for much of Canada, but up to 15%
different in some places. When adjustments are made for magnitude-recurrence distribution, integration
slice size, cutoff distance, and floating-rupture distribution along fault sources, the differences reduce to<2-3% everywhere.

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*S07-3-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

A Novel Geodetic-based Probabilistic Seismic Hazard Model for Iran
* Alireza Lotfi 1) , Hamid Zafarani 2) , Alireza Khodaverdian 3)
PhD student of International Institute of Earthquake Engineering and Seismology, Tehran, Iran 1) ,Associate Professor of International Institute of Earthquake Engineering and Seismology, Tehran, Iran 2) ,PhD of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran 3)This study develops a preliminary probabilistic seismic hazard (PSHA) model for Iran using seismic
moment rates obtained through combined analysis and modeling of Iranian seismic, geodetic, and geologic
data. PSHA has previously been based on the extrapolation of the large earthquakes frequency from ratesof small ones that recorded instrumentally in 50 – 100 year-long earthquake catalogs. Unfortunately, factors
such as incomplete catalogs, long term return period of large and strong earthquakes and short term
catalog give not reliable results. Therefore the hazard analysis that is based on inputs which leads to lessuncertainty is necessary. For some place in the world such as California, Canada, Japan, New Zealand and
Italy, geodetic and geological data is used in hazard analysis by researchers. The results show that
estimated earthquake rates are larger than those derived from earthquake catalogs. In this regard, usingnovel and alternative approaches in hazard assessment will greatly improve our knowledge and manyquestions about spatial-temporal distribution of earthquakes could be answered. Moreover, the groundmotion parameters uncertainty as hazard analysis output will be reduced. In a recent study (Khodaverdian
et al. 2015) the long-term deformation of the Iranian Plateau is estimated by the Neokinema software using
updated Iranian database including latest fault traces, geologic fault offset rates, GPS velocities, principal
stress directions, and velocity boundary conditions. Accordingly in this study, for the first time an
independent hazard estimate for the Iranian Plateau will be obtained through the seismic moment raterequired to accommodate current rates of deformation from geodetic and geological data. The estimations
could be compared with the results of traditional seismic-based hazard analysis. The final outcomes aretime-dependent and time-independent probabilistic seismic hazard models.

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*S07-3-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

ANALYSIS OF RESPONSE SPECTRA OF CHARACTERISTIC GROUNDMOTIONS RECORDED IN NORTH EAST INDIAN REGION* Babita Sharma 1) 2)
Presently JICA Trainee (Seismology) from October 2016 to September 2017 at IISEE, Tsukuba, Japan 1) ,Parent Organization National Centre for Seismology, Ministry of Earth Sciences, New Delhi, India 2)
The response spectra are influenced by the local site conditions and regional geology. For various
categories of rock sites like hard rocks (Proterozoic period), sedimentary rocks (Tertiary period) andalluvium (Quaternary period) exhibit this effect for North East (NE) Indian region. This has been analyzed
using 195 strong ground motion histories from 45 earthquakes occurred in NE India having the magnitude
range of Mw 3.5 to 6.9 recorded from 2008 to 2014 on strong motion network of India. The ground motion
is amplified at higher frequencies for stations located on hard rock while for stations located on alluvium
sites are amplified comparatively at lower frequencies. Also the sites located on hard rock show lower
spectral acceleration than alluvium sites. The acceleration response spectra in the current Indian code
designed for the entire country is applicable for all rock types for the study area. The effects of important
ground motion parameters like magnitude, distance, local geology and site conditions on acceleration
response spectra are studied. The response analysis constitutes the importance in representing the seismic
hazard assessment of an area especially for NE Indian region as this falls in the zone V on the seismic
zonation map of India. This study is important for the seismic hazard assessment of the NE India which isan active plate boundary having complex seismotectonics.

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*S07-3-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

TIME-DEPENDENT SEISMIC HAZARD DUE TO MINING-INDUCEDEARTHQUAKES IN GAUTENG, SOUTH AFRICA* Brian Zulu 1) 2) , Vunganai Midzi 1) 2) , Brassnavy Manzunzu 1) 2) , Raymond Durrheim 2)
Council for Geoscience, Silverton, Pretoria, South Africa 1) , School of Geosciences, University of
Witwatersrand, Johannesburg, South Africa 2)
A time-dependent probabilistic assessment of the seismic hazard along the densely populated northern rimof the Witwatersrand Basin of the Gauteng Province, South Africa, is described. Seismicity in this region ismainly induced by deep gold mining and the flooding of worked-out mines. Seismic hazard assessment in
the gold mining regions has not been incorporated in global projects such as the GSHAP, although theseismicity related to the gold mining activities accounts for about 90% of the seismicity of South Africa.
Time-dependent seismic hazard estimates are given in terms of peak ground acceleration and 5% damped
response spectra at periods, 0.1 s, 0.5, 1.0 and 2.0 s for 10% probability of exceedance in 50 years (475year return period) for two different periods named Period A (1970 - 2004) and Period B (2005 - 2015).
Seismic hazard estimates are higher in Period A owing to higher activity rates than in Period B. The highest
estimated PGA value was approximately 0.250 g for a return period of 475 years in the western part of theregion in Period A while the corresponding estimated PGA value was 0.206 g for a return period of 475
years in the same region in Period B. The spectral acceleration values also decreased from Period A to
Period B. It was observed that the Far West Rand seismic zone contributes more hazard in the study region,
followed by the West Rand seismic zone and then the East Rand seismic zone. The Central Rand seismiczone is the least active seismic zone and contributes least to the hazard of the study region. The hazard
estimates are higher in the western parts of Johannesburg than in the eastern parts of Johannesburg.

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*S07-4-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Rapid estimation of ground-shaking maps for seismic emergency
management in Turkey
Ulubey Ceken 1) , * Eren Tepeugur 2) , Turgay Kuru 2) , Elcin Gok 3) , Caglar Ozer 3) 4) , Orhan Polat 3) 5)
Head of the Earthquake Department, Disaster and Emergency Management Presidency (AFAD), Prime
Ministry of Turkish Republic, Ankara, Turkey (ulubey.ceken@afad.gov.tr) 1) , National Strong-Motion
Network of the Earthquake Department, Disaster and Management Authority (AFAD), Prime Ministry of
Turkish Republic, Ankara, Turkey (turgay.kuru@afad.gov.tr) 2) , Division of Seismology, Department
Geophysics, Engineering Faculty, Dokuz Eylul University (DEU), Izmir, Turkey (orhan.polat@deu.edu.tr) *Corresponding Author 3) , DEU Graduate School of Natural and Applied Sciences, Department Geophysics,
Izmir 35160 Turkey 4) , Corresponding Author 5)
Strong ground-shaking mapping soon after a moderate-to-large earthquake is crucial to recognize the areasthat have suffered the largest damage and losses. These maps have a fundamental role for emergency
services, loss estimation and planning of emergency actions by the Civil Protection Authorities. This isparticularly important for the Eastern Mediterranean areas with high seismic risk levels, such as theTurkey. Rapid (3-5 minutes) generation of maps of instrumental ground-motion and shaking intensity isaccomplished through advances in real-time accelerometric data acquisition combined with newly
developed relationships between recorded ground-motion parameters and expected shaking intensity
values.
Taking advantage of the National Strong-Motion Network (TR-NSMN) of Turkey which belongs to
Earthquake Department of the Disaster and Emergency Management Authority (AFAD, Ankara) of theTurkish Prime Ministry, we have implemented the algorithm for rapid estimation of ground-shakings soonafter moderate-to-large earthquakes occurred in Turkey.
Estimation of shaking over the Turkey is obtained by the spatial interpolation of the measured groundmotions with geologically based frequency and amplitude-dependent site corrections. Production of themaps is automatic, triggered by an earthquake (M>4.0). Maps are made available within several minutes ofthe earthquake for public and scientific needs. The algorithm produces ground-shaking maps byhighlighting its ability to predict peak ground-motion parameters of large magnitude earthquakes(Corresponding Author, O.Polat)
Acknowledgments
This study was granted by the AFAD National Earthquake Research Programme (nr. UDAP-G-14-15) of theTurkish Prime Ministry. We appreciate C.B. Worden, D.J. Wald, O.Razinkov and all AFAD team for their
ongoing supports.

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*S07-4-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Development of a pilot seismic risk assessment for British Columbia,
Canada, through the application of Global Earthquake Model's OpenQuake* Alison L. Bird 1) , J. Murray Journeay 2) , Trevor I. Allen 3) , John F. Cassidy 1) , Nicky Hastings 2) , Michelle
M. Cote 1)
Geological Survey of Canada, Victoria, Canada 1) , Geological Survey of Canada, Vancouver, Canada 2) ,Australian National University, Canberra, Australia 3)
The Geological Survey of Canada (GSC) has employed Global Earthquake Model's (GEM) OpenQuake as apotential tool for undertaking a national-scale earthquake risk assessment, beginning with a provinciallyfocussed assessment of British Columbia (BC), the most seismically hazardous region of the country. While
the GSC has traditionally focused on probabilistic seismic hazard models, we endeavour to provide theengineering and emergency management communities with a suite of deterministic scenarios, evaluationsof secondary hazards such as tsunami and liquefaction, and impact assessments. There are numerous
feasible scenario earthquakes along British Columbia's tectonically active west coast with the potential tocause extensive damage. A small number of these will be presented, including an M~7.0 event along therecently profiled extension of the Devil's Mountain Fault just off the City of Victoria's waterfront, and a
megathrust earthquake of M~9.0 with tsunami along the Cascadia Subduction Zone, off BC, Washington,
Oregon and northern California. The resulting scenarios provide anticipated ground motions which areapplied to vulnerability data (including site conditions, infrastructure and population exposure) to develop
impact models. These outputs are crucial for effective emergency planning, risk mitigation measures anddisaster management.

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*S07-4-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Ground motion predictions in the backdrop of recent claims for megaearthquake in Bangladesh* Tahmeed Malik Al-Hussaini
Bangladesh University of Engineering & Technology, Dhaka, Bangladesh
The main plate boundaries between north moving Indian plate and the Eurasian plate have been
traditionally depicted in seismo-tectonic maps to the east and north of Bangladesh. However, recent
seismological studies claim the plate boundary to be extended well inside Bangladesh, and that the major
cities of the country may face the risk of a mega earthquake with a magnitude between 8.2 and 9.0. This
claim can drastically redefine the seismic zoning map of Bangladesh with ground motion values way above
present building codes and way beyond our present perception.
This paper attempts to investigate the possibility and implication of a mega earthquake in the backdrop ofsuch claim. Seismic hazard assessment studies incorporating such mega earthquakes have been
conducted, results indicate severely high ground motions for major cities of Bangladesh including thecapital city of Dhaka.
A critical review of literature on historical earthquakes affecting the country is done. A rationale for thelocation and magnitude of the maximum considered earthquake (MCE) is developed through careful
review. Ground motion predictions using such MCE have been conducted using both probabilistic anddeterministic seismic hazard assessment approaches. Finally the author's perception of the possibility ofmega earthquakes and the way forward in seismological research is presented.

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*S07-4-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Automatic detection of earthquakes, quarry blasts, rockfalls and avalanches
on the Swiss permanent broadband network
Conny Hammer , * Donat Faeh
Swiss Seismological Service, ETH Zurich, Switzerland
In common observatory practice, seismic events are detected automatically using a classical STA/LTA
trigger. Then, a trained expert manually assigns a specific seismic signal class such as tectonic event or
quarry blast to verified detections. However, this approach absorbs manpower and happens generally withconsiderable time-delay. To overcome these problems we test an automatic classification approach on the
Swiss permanent broadband network. The approach is based on a probabilistic description of the signals,
called hidden Markov models, that allows the robust identification of corresponding signals and has beensuccessfully applied in various environments. The automatic system is set up at 15 stations of which mostare located in alpine regions. Once a transient is detected by the preceding trigger, the signal is fed into theautomatic system and labeled as one of the following signal types: earthquake, quarry blast, rockfall,avalanche or noise. So far, the procedure is tested on a data period of one year. To evaluate the system
performance automatically and manually assigned labels are compared. Achieved results show large
differences between individual stations. While at some stations classification rates of up to 95 % areachieved, classification rates are much lower at other stations. The overall performance can be further
improved by using the complete network information. For this, the classification results of different stations
needs to be combined. We present various approaches to combine the outcome of the automatic systemdependent on source-receiver distance and confidence of classification result. A majority based voting
system completes the post processing. In the next step, we aim to detect signals directly on the continuous
data stream, in order to avoid missing small local events due to the preceding trigger algorithm. The
performance provides a base for deciding about implementation of an early information system.

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*S07-4-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Evaluation of the P-wave detection method using higher order statistics* Masumi Yamada , Hirofumi Ishida
Kyoto University, Kyoto, Japan
Detecting P-wave onsets in on-line processing is one of the important components for the real-time
seismology. Conventionally, the STA/LTA method (the ratio between short-time average and long-time
average) has been widely used for the P-wave detection (Allen, 1978). Since this method is reasonably
robust and computationally less expensive, it has been used for long years, and the trigger time is used forthe estimation of the location of earthquakes.
The P-wave detection method using higher order statics has been attracted researchers recently. The key ofthe method is to identify the change of distribution of amplitudes. In general, seismic noises tend to follow
the Gaussian distribution. However, when a seismic signal arrives and the amplitude suddenly increases,
the distribution of the amplitude becomes skewed. This change of distribution can be measured by the
kurtosis, which is the forth moment of the data divided by the square of the variance. The kurtosis is zerofor the Gaussian distribution, and it increases as the distribution is away from the Gaussian.
We applied this method to the strong motion dataset after the Tohoku earthquake in March 2011. The
results are compared with the P-wave arrival time estimated by the STA/LTA method, which showed thearrival times estimated by the kurtosis approach was closer to the manually detected P-wave arrival times.

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*S07-5-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Simulation of Strong Ground Motions in and around Iwaki City, Fukushima
Prefecture, using Pseudo Point-source Model* Takumi Hayashida 1) , Toshiaki Yokoi 1) , Hiroto Nakagawa 1) , Toshihide Kashima 1) , Shin Koyama 2)
Building Research Institute, Tsukuba, Ibaraki, Japan 1) , National Institute for Land and InfrastructureManagement, Tsukuba, Ibaraki, Japan 2)
After the 2011 Mw9.0 Tohoku earthquake, a great number of aftershocks occur near the source region off
the Pacific coast of eastern Honshu. We deployed a dense temporary seismic array consisting of 16 stations
in Iwaki city, Fukushima prefecture from November 2014 to September 2015. During the observation
period, at least 100 felt earthquakes (Mw in the range of 3.5-7.9) including 75 intraslab and interplate
earthquakes along the subduction zone were detected. Previously we applied spectral inversion method tothe event data and estimated site amplification factors at each station as well as seismic quality factor(Hayashida et al., 2017). In this study we performed spectral inversion method again by adding event datafrom K-NET (six stations) and KiK-net (three stations) of National Research Institute for Earth Science andDisaster Resilience (NIED) in and around Iwaki city, and strong motion data of Building Research Institute(BRI) recorded at basement floor of Iwaki city hall, during the same observation period. To perform theinversion, several constraints (rock site assumption, proposed site amplification model, proposed
attenuation model or source spectra for selected aftershocks) were employed and we found that theinversion with proposed site amplification model (at K-NET FKS011 station) provides reasonable results.
Next we simulated strong ground motions with the pseudo point-source model (Nozu, 2012) using modeled
source spectra, the estimated quality factor and site amplification factors for the mainshock of the 2011
Tohoku earthquake and the 2016 Fukushima earthquake (November 22, Mw7.0). The seismic source
spectra are modeled using the omega-square model from available source models with phasecharacteristics of the selected subevents (point source) from our dataset. The synthetic waveforms and its
Fourier spectra of S-wave portions show reasonable agreements with observed ones in the frequency range
between 0.2 and 10 Hz.

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*S07-5-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Inversion seismic parameters model for stochastic ground motion simulationin Taiwan* Jyun-Yan Huang 1) , Kuo-Liang Wen 1) 2) , Che-Min Lin 1) , Chiao-Chu Hsu 1)
National Center for Research on Earthquake Engineering, Taiwan 1) , Department of Earth Sciences, NCU,
Taiwan 2)
Stochastic ground motion simulation technique (Boore, 1983; Boore, 2003) is useful tool to get synthetic
ground motions for future possible earthquakes when applying suitable seismic parameters. The parametermodels are varied within different regions due to difference in seismogenic structure. Regional parameters
used in stochastic simulation that need to be checked are including stress drop, Q, geometric spreading,kappa, site transfer function etc. Parameter models for stochastic point source or finite fault simulation inprevious Taiwan researches are usually collected each piece of seismogenic parameters from different
studies and composed them together to deal with prediction problems (Sokolov et al., 2000; Sokolov et al.,
2001; Sokolov et al., 2009; Huang et al., 2017) or inverted parameters together but some of the pathattenuation relation might are far from traditional imagination about wave propagation tectonics in Taiwan(D'Amico et al., 2012).
In this study, seismological records from TSMIP rock sites (Vs30 within 600-900 m/s) will be separated
into shallow crust earthquakes and intraslab earthquakes for parameter inversion for shallow and deep
events. Initial path attenuation models will be fixed first to solve other parts of the parameter setting. The
inverted results could have more confident that all of them are goes together and fix the Brune's spectrum(Brune, 1970) assumed in stochastic simulation technique with physical meanings of each of theparameters but not composed ones. The inverted model could be applied to study regional difference ofdifferent area such as Taiwan against Japan or California region when comparing seismograms in different
regions.
Keywords: seismic parameters, stochastic ground motion simulation, Taiwan

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*S07-5-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Strong ground motion simulations for potential earthquakes around Taiyuan,
China based on dynamic rupture sources* Zhenguo Zhang , Wei Zhang , Xiaofei Chen
Southern University of Science and Technology, Shenzhen, China
Using the curved grid finite-difference method, we develop dynamic spontaneous rupture models ofearthquakes on the Jiaocheng Fault (JF) near Taiyuan, which is the capital and largest city of Shanxi
province in North China, and we then model the wave propagation and strong ground motion generated bythese scenario earthquakes. A map of the seismic hazard distribution for the potential M7.5 earthquake isgiven based on dynamic rupture and true 3D modeling. The tectonic initial stress fields derived from theinversion of focal mechanisms of history earthquakes, a non-planar fault, and a rough surface areconsidered in the dynamic rupture simulation. Base on the geological structure of the Taiyuan basin, thenormal faulting with a dipping angle of 60 degree is implemented for the scenario earthquake simulations.
The largest uncertainty of the potential earthquake in the JF zone is the hypocenter. Four cases are used tonucleate the earthquake at different locations. Using these dynamics rupture sources for JF, we further
simulate and analyze both the seismic wave generated by the scenario earthquake and the strong groundmotion. It is found that the low-velocity media of the Taiyuan basin redistribute the ground motion well.
The effects of the regional stress fields on the dynamic rupture and hazard distribution are investigated anddiscussed further. Moreover, a scenario earthquake, which can cause great damage to Taiyuan City ismodeled and analyzed.

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*S07-5-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

3D numerical modeling of seismic wave propagation and amplification in
Qaidam basin* Yanyang Chen 1) , Takashi Furumura 2) , Yanbin Wang 1)
Department of Geophysics, School of Earth and Space Sciences, Peking University, Beijing, China 1) ,Earthquake Research Institute, The University of Tokyo, Tokyo, Japan 2)
Qaidam basin is the largest basin within Qinghai-Tibetan plateau with area of ~120,000 km2. Maximum
thickness of basin sediments is about 12 km. Seismograms recorded by International Deep Profiling ofTibet and the Himalaya Phase IV (INDEPTH IV) seismic stations during 2008 show clear spatial variations
and seismic ground motion amplification was observed in several events.
In this study, we constructed a three-dimension seismic wave velocity model of Qaidam basin based on
previous studies, including three sedimentary layers from Paleogene to Quaternary and perform 3D
numerical modeling of seismic wave propagation in Qaidam basin with 3D Finite-difference method (FDM).
We employ a high-performance parallel supercomputer to simulate seismic wave propagation in the areaaround the large Qaidam basin. Based on modeling, we will explain the mechanism of the development ofobserved long-period surface wave in the data and dramatic amplification of ground motion in the Qaidam
basin.
Three different models, 1) model only contains crust with flat surface, 2) crust model with topography, 3)model contains sedimentary layers and topography over crust, were simulated to evaluate the effects on
seismograms in basin. Based on simulation, slightly amplification from 0.4 -1.0 Hz caused by topography invertical component of stations installed in mountain area (higher altitude) around basin. Considerably
amplification by sedimentary layer from 0.1 - 0.8 Hz in three components of stations in the middle of basin.
2008 Da-Qaidam Mw6.3 earthquake together with two aftershocks and 2001 Kunlunshan Mw7.8
earthquake around Qaidam basin were simulated to estimate amplification effects of basin on earthquakewith different magnitude and with different azimuth.

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*S07-5-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Strong-Motion Observation Network in the Philippines* Rhommel Grutas , Robert Tiglao , Melchor Lasala , Janila Deocampo , Ishmael Narag , Renato Solidum, Jr.
Philippine Institute of Volcanology and Seismology (PHIVOLCS-DOST), Philippines
Issues raised after the July 16, 1990 M7.8 Luzon Earthquake and public concern over a possible large
earthquake that may occur along the Valley Fault System that transects Metropolitan Manila prompted
Philippines Institute of Volcanology and Seismology (PHIVOLCS) to establish a Strong-Motion (SM)observation network in the Philippines in 1992. The SM network initially consist of only four stations
operating within the metropolis and this has expanded to a network of ten stations by early 2000. Since
then, the network has expanded its coverage and is presently composed of thirty-five and twelve
instruments in cities in Luzon and Davao respectively, with plans to cover other areas of the country. The
establishment of this network aims to truly record earthquake ground motions especially near active faults
and areas with concentration of population and different types of buildings.The Kinemetrics K2 strongmotion accelerograph is the major instrument of the network. The recording sensor is Episensor triaxial
force balance accelerometer mounted orthogonally in one small convenient package within the recordedbox.
Some of the significant earthquake events that have been recorded by different stations of the SM network
include the 1999 M6.8 Hermana Mayor Island Earthquake, the 16 June 2012 M6.0 Zambales Earthquake,the 31 August 2012 M7.6 Offshore Eastern Samar Earthquake and 25 June 2014 M5.8 Occidental Mindoro
Earthquake. Records of these events exemplify varying site responses at different geologic conditions.
Recorded events are initially analyzed and catalogued in a databased of digital strong ground motion
together with station information and important operational dates. The strong-motion database will serve asa centralized resource for accelerograms of relevant Philippine earthquakes to support scientific research,earthquake engineering and the updating of the National Structural Code of the Philippines.

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*S07-6-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

HVSR site classification method for Chinese seismic code based onJapanese strong motion data
* Ruizhi Wen 1) 2) , Yefei Ren 1) 2) , Kun Ji 1) 2) , Haiying Yu 1) 2)
Institute of Engineering Mechanics, China Earthquake Administration,Harbin,China 1) , Key Laboratory of
Earthquake Engineering and Engineering Vibration,Harbin,China 2)
The local site condition is a very important factor for strong motion data. We performed the siteclassification of the strong motion stations for China National Strong Motion Observation Network System(NSMONS), by using an empirical Horizontal-vertical spectral ratio (hereafter, HVSR) method. Due to notenough Chinese strong motion data and borehole, we firstly selected all needed information from Japanese
KiK-net and statistically assigned the mean HVSR curve of the site classification (CL-I, CL-II, or CL-III)
defined in the Chinese seismic code. The mean the HVSR curve for each site class was computed using
Chinese strong motion recordings captured during the period 1996–2012 . For each strong motion
stations, the station HVSR curves were compared with those proposed by Zhao et al. (2006a) for four typesof site classes (SC-I, SC-II, SC-III, and SC-IV) defined in the Japanese seismic code (JRA, 1980). It was
found that an approximate range of the natural period could be identified by the predominant peak of the
HVSR curve for the CL-I and SC-I sites, CL-II and SC-II sites, and CL-III and SC-III + SC-IV sites.
Meanwhile, an empirical method of Chinese site classification was proposed based on comprehensive
consideration of peak period, amplitude, and shape of the HVSR curves. 178 NSMONS stations werecomputed based on recordings from 2007 to 2015 and the sites classified using the proposed method. The
mean HVSR curves were re-calculated for site classes and compared with those from KiK-net data. It was
found that both the peak period and the amplitude were similar for the HVSR curves derived fromNSMONS and KiK-net data, implying the effectiveness of the proposed method in identifying different siteclasses. It is also found that this classification has a good agreement with site classes based on 81 boreholedata in China, which indicates that this site classification results are acceptable.

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*S07-6-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Nonlinear Site Response at KiK-net KMMH16 (Mashiki) and Heavily
Damaged Sites during the 2016 Kumamoto Earthquake, Japan* Hiroyuki Goto 1) , Yoshiya Hata 2) , Masayuki Yoshimi 3) , Nozomu Yoshida 4)
Kyoto University, Kyoto, Japan 1) , Osaka University, Osaka, Japan 2) , National Institute of Advanced
Industrial Science and Technology, Ibaraki, Japan 3) , Tohoku Gakuin University, Miyagi, Japan 4)
Severe ground motion damages occurred in the downtown area of the Mashiki town, Kumamoto Prefecture,
during the 2016 Kumamoto earthquake, Japan, and several heavily damaged zone appeared in the centerof the downtown. Nonlinear site response for the first (14th Apr., 2016) and main shocks (16th Apr., 2016)is important factors to explain the reason why the heavily damaged zone appeared. We analyzed the soil
nonlinearity by using the surface and borehole records at KiK-net KMMH16 (Mashiki) station. Optimal Swave velocity models clearly depended on the amplitude of input ground motions. Strain dependent shear
stiffness and damping ratio were estimated to explain the S-wave velocity dependence on the input motion
amplitudes. We conducted nonlinear analyses at KMMH16 site on the basis of the nonlinear model. The
synthetic surface ground motions agreed well with the observed ones, especially at S-wave amplitude andphase for the first and main shocks. In addition, we also conducted the same analyses at TMP3 site, which
was located in the heavily damaged zones. The synthetic motions well represented the observed ones, anddifference of spectral accelerations was well explained by the analyses. The results indicated that the soil
nonlinearity played a big role to cause the difference of ground motions, and thus the damaged zone
appeared in the downtown of the Mashiki town.

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*S07-6-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and riskLong-period later phases observed in the Echigo Plain, Japan during thedeep earthquake in the west off Ogasawara Islands of May 30, 2015
* Tomiichi Uetake 1) , Kazuhito Hikima 2) , Masatoshi Fujioka 2) , Yoshihiro Sawada 3) , Shutaro Sekine 3)
Tokyo Electric Power Company Holdings, Yokohama, Japan 1) , Tokyo Electric Power Company Holdings,
Tokyo, Japan 2) , Association for the Development of Earthquake Prediction 3)
On May 30, 2015, a deep earthquake of magnitude 8.1 occurred at a depth of 682 km off the west of the
Ogasawara Islands. In case of a deep earthquake, the incident wave to a basin structure can be regarded asa body wave, and therefore the surface wave generated at the basin edge can be evaluated separate fromincident surface waves. In addition, since almost the same incident wave can be expected for inside andoutside of the basin, it is considered to be effective for evaluation of site factor. The Echigo Plain, Japan is
known as an area where the seismic bedrock is deep and long-period ground motion is dominant. To see
the influence of the basin structure, we examined the waveform change along the line from Mt. Yahiko to
the Echigo Mountains across the Echigo Plain. The waveform of S wave part was common to all
observation points. On the other hand, no significant later arrivals were recognized in the waveform of themountain region, whereas there were complicated later arrivals and the duration was long in the waveformof the plain part. Also, it was able to be confirmed that the travel time delay of the S wave by the lowvelocity sedimentary layers and the later phases seemed to propagate from the edge to the center of thebasin from the comparison of wave traces. Numerical simulations were carried out to confirm thegeneration of the later phases by the underground structure. For the numerical calculation, a twodimensional finite difference method was used. The numerical simulation was able to reproduce theamplification of ground motion and the generation of later arrivals in the basin. However, the reproductionof the duration of the ground motion was insufficient.

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*S07-6-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Revision of 3D Model of the Kanto Basin based on Earthquake Records of
MeSO-net* Haruo Yoshida 1) , Yoshiyuki Sato 1) , Kikuji Kobayashi 1) , Naoko Umeda 2) , Shinichi Sakai 3) , Hirata
Naoshi 3)
Research & Development Institute, Takenaka Corporation, Chiba, Japan 1) , Building Design Department,
Tokyo Main Office, Takenaka Corporation, Tokyo, Japan 2) , Earthquake Research Institute, The Universityof Tokyo, Tokyo, Japan 3)
In recent years, numerous simulations using 3D finite-difference method are performed to predict
earthquake ground motions due to large earthquakes. In order to improve the prediction accuracy ofearthquake ground motions, Accuracy of 3D underground structure model is one of the important factors.
To obtain a 3D Kanto Basin model, Yoshida et al. (2007) estimated the underground structure under 120 KNET and KiK-net sites in Kanto Basin by using the method of Kobayashi et al., (2005). In this method thehorizontal-to-vertical (H/V) spectral amplitude ratios and receiver functions of P wave part of seismic
observation records were simultaneously inversed. Then a 3D model of the Kanto Basin was constructed byspatial interpolation using the estimated underground structures and gravity anomaly data. In order toimprove the accuracy of this model, we increased estimation points of underground structure utilizing
about 200 sites of MeSO-net (Sakai and Hirata, 2009) which were located at 296 sites in Kanto region, and
we also used the improved method of Umeda and Kobayashi (2010) which is added H/V spectral
amplitude ratio of coda part of seismic observation records to the method of Kobayashi et al. (2005). Thenthe model was modified by adding the estimated underground structures. Medium earthquakes occurred
below the Kanto Basin were simulated using the revised 3D model to compare the calculated and observed
velocity waves. By comparing the simulation results from the original model, the influence of addition of
estimated underground structures on the improvement of the prediction accuracy was discussed.

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*S07-6-06
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Direct evaluation of site amplification factors based on observed motions ofearthquakes and microtremors* Hiroshi Kawase 1) , Fumiaki Nagashima 1) , Kenichi Nakano 2) , Yuta Mori 3)
DPRI, Kyoto University, Uji, Japan 1) , TRI, HAZAMA ANDO CORPORATION, Tsukuba, Japan 2) , J-Power,
Tokyo, Japan 3)
It has been used for more than three decades to characterize earthquake S-wave site amplifications frommicrotremor Horizontal-to-Vertical ratios (MHVR), although the skepticism has been surfaced throughmany studies on such a direct substitute after the proposal. To solve the controversy based on the conceptof the recently proposed diffuse field assumption, we calculated MHVR as well as those from observed
weak earthquake motions (EHVR) and compared fundamental characteristics of the MHVRs and EHVRs
with those calculated theoretically from 1-D S-wave velocity structures. Either for MHVRs or EHVRs wefound that we can reproduce their fundamental characteristics by the corresponding theories of diffuse
field concept. MHVRs and EHVRs share similarities but have significant differences in their shapes,
especially after the first peak frequency. This is because MHVR mainly consists of surface waves fromsurface sources while EHVR consists of S-waves from the bedrock. We then tried to establish a simple
method to estimate velocity structures using single-station microtremor records. To that end we comparedsystematically EHVRs and MHVRs at 100 K-NET and KiK-net sites in Japan and calculated EHVR-to-MHVR
ratios (EMRs) to get EMRs averaged over five different peak-frequency categories. We converted MHVRs to“pseudo EHVRs" from EMRs and MHVRs, which are found to have higher correlation with EHVRs than
MHVRs. Then we proved that pseudo EHVRs give us similar S-wave velocity profiles than the direct use of
MHVRs as substitute of EHVRs. Finally, we calculate average Vertical-to-Vertical spectral ratios (VVR) fromthe generalized spectral inversion (Nakano et al. 2015) and calculated the average VVRs for the same
category of MHVRs. By multiplying VVRs with pseudo EHVRs we can obtain S-wave amplification ofearthquakes, which can be favorably compared with actual S-wave amplification factors.

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*S07-7-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Shallow shear wave velocity model of Taiwan constructed from Receiver
Function Analysis of strong motion stations* Che-Min Lin 1) , Kuo-Liang Wen 1) 2) , Chun-Hsiang Kuo 1) , Jyun-Yan Huang 1) , Hung-Hao Hsieh 1)
National Center for Research on Earthquake Engineering, Taipei, Taiwan 1) , Department of Earth Sciences,
National Central University, Taoyuan, Taiwan 2)
The high seismicity and major tectonic features of Taiwan are resulted from the active collisions. The young
and fast orogeny in the island also forms a wide range of alluvium plains and basins that are filled withunconsolidated Quaternary sediment covering the bedrock. The obvious seismic site effect amplifies andextends incident seismic waves and can result in earthquake disasters. Therefore, a shallow velocity model,
reflecting the real and complex seismic site effects in these areas, is necessary for ground motion
simulation and prediction in Taiwan.
The advantage of the even strong motion stations and numerous records in Taiwan has been taken to apply
the Receiver Function (RF) technique to high-frequency acceleration seismograms recorded by Taiwan
Strong Motion Instrumentation Program (TSMIP) stations to estimate the shallow shear wave velocity (Vs)structures. In the RF analyses of this study, an average RF of each station was calculated to enhance theconverted phases and reduces the inharmonic arrivals. Based on the geological, geophysical, andEngineering Geology Database for TSMIP (EGDT) drilling data, an initial layer model with variable Vs andthickness was assumed to model RF and estimate Vs profile of a station by Genetic Algorithm (GA) search.
Finally, the one-dimensional shallow Vs profiles of over 700 stations were estimated by RF analysis andforward modeling with GA search. All the results proved that this method is not only effective in teleseismic
but also strong motion records to construct a shallow Vs structure of alluvium plain (or basin) overlaying a
hard bedrock. Based on the Vs structures estimated in this study, a shallow velocity model of Taiwan was
preliminarily constructed for applications of seismology and earthquake engineering. In addition, theresults were also compared with the Vs30 of EGDT to confirm the site conditions of TSMIP stations andprovide important site parameters such as engineering bedrock and Z1.0.

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*S07-7-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Liquefaction Monitoring and Observations of Excess Pore Pressure
Generation During Strong Motion* Jamison Steidl
University of California, Santa Barbara, USA
Unique dense observations of excess pore pressure generation and dissipation during earthquakes arepresented from multiple borehole arrays within ~100 meters of each other in the confined 5-meter thicksilty sand layer at the Wildlife Liquefaction Array (WLA), Imperial Valley, California. In what is the mostdensely instrumented liquefaction array anywhere in the world, continuous recordings of acceleration andpore pressure are providing in situ empirical evidence documenting the range of ground motion anddynamic strain levels at which the onset of excess pore pressure and nonlinear soil behavior begins,
augmenting previous case history data, and cyclic tri-axial and centrifuge laboratory testing. The
observations with depth within the liquefiable layer shows the excess pore pressure develop quickly at the
top of the layer just below the impermeable clay cap, and then migrate towards the bottom of the layer as
the ground motions subside and the pressure dissipates over the course of minutes to hours depending on
the level of ground motion. Confirmation of this behavior is provided by monitoring multiple locations
within ~100 meters of each other, with 8 transducers at one location and 5 transducers at a second location(both operating for more than a decade now), and 5 transducers at a third location (since 2014). The 5
sensors at the third location densely cover the upper two meters of the liquefiable layer, while the sensors
at the other two locations sample the top, middle, and bottom of the layer. A comparison of theserecordings to demonstrate the spatial variability both with depth in the liquefiable layer as well as within
the 100-meter areal distance at the field site with be presented. This spatial variability is analyzed withrespect to both the fine-scale heterogeneous soil properties (percent fines, relative density, saturation) as
well as with respect to installation methods and site improvements to potentially increase liquefaction
resistance.

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*S07-7-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Temporal nonlinear site response during Kumamoto Mw7.0 earthquake
inferred from borehole strong motion data
* Junju Xie
Institute of Geophysics,China Earthquake Administration
The Mw 7.0 Kumamoto earthquake (Japan) occurred on 15 April 2016 – 16:25 UTC. Using both boreholeand surface ground accelerations recorded by Japanese Strong Motion Network KiK-Net, we investigate
temporal changes of nonlinear site response in the shallow crust associated with Kumamoto main shockand the triggered Mj 5.7 event. We compute the spectral ratios of windowed records from a pair of surface
and borehole stations, and then use the sliding-window spectral ratios to track the temporal changes in thesite response of various sites at different levels of peak ground acceleration (PGA). Our preliminary results
show clear drop of resonant frequency of up to 60% during the main shock at 8 sites with PGA from 200 to1000 Gal. We investigate the percentage drop of peak frequency and peak spectral ratio during the main
shock at different PGA levels.

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*S07-7-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

DETERMINATION OF DEEP SUBSURFACE SHAREWAVE VELOCITYSTRUCTURE IN THE CENTRAL PART OF THE KATHMANDU BASIN,
NEPAL USING BROAD BAND SEISMOGRAPH ARRAYS FOR LONGPERIOD MICROTREMOR* Mukunda BHATTARAI 1) , Dinesh NEPALI 1) , Santosh DHAKAL 1) , Suresh SHRESTHA 1) , Toshiaki
YOKOI 2) , Takumi HAYASHIDA 2)
Department of Mines and Geology, Kathmandu, Nepal 1) , International Institute of Seismology and
Earthquake Engineering, Building Research Institute, Tsukuba, Japan 2)
We conduct microtremor array exploration in the central part of the Kathmandu Valley, Nepal assuming thedeepest part of the basin in order to determine the shear wave velocity structure of deep sedimentarylayers for strong ground motion simulation within the frame work of SATREPS (JST - JICA) project for 5
years. The four seismographs used are consist of the broadband seismometer CMG40T (Gularp) and thedigital data logger LS8800 (Hakusan) for exploration as deep as 500 – 600 m using long period
microtremor (ambient noise), the power of which is weak due to a distance as long as 700 Km from thenearest ocean Bay of Bengal. Up to Feb. 18 2017, the following three arrays have been performed. First an
irregular shape array consist of three deployments was performed at and around the strong ground motion
observation site in the office building of Department of Mines and Geology, Lainchaur (DMG). A
seismograph was installed and worked for more than three nights at DMG and other three were set forovernight measurement, at different sites every night, within a distance of approximately 1.2 Km situated at
Narayanhiti Durbar Museum, Durbar Marg and Nepal Police Head quarter, Naxal in the single storey
buildings or on the open ground during December 2016. Second an array consists of two almost equilateraltriangular deployments and an irregular quadrilateral one has been deployed inside Singhadurbar an
administrative center of Nepal government and also the third at and around the gas well point of DMG in
Teku during February 2017. Preliminary analysis showed a clear peak of the power spectra of thehorizontal components at a little longer period than 3 seconds that has not been detected by the
microtremor observation using accelerometer due to the low power of long period microtremor.

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*S07-7-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

The spatial variability of the directionally dependent microtremor horizontalto-vertical spectral ratios at the boundary of the basin edge in Uji, Japan* Shinichi Matsushima 1) , Keita Sato 2) , Yuri Fukuoka 3)
DPRI, Kyoto University, Uji, Japan 1) , Sch. Eng., Kyoto University, Kyoto, Japan 2) , Grad. Sch. Eng., Kyoto
University, Kyoto, Japan 3)
Directionally dependent microtremor horizontal-to-vertical spectral ratios (MHVRs) have been observed in
Uji, Japan, close to the basin edge which is formed as a result of the reverse fault movement of Obaku fault,
in the south-eastern part of Kyoto basin and the directionally dependent MHVRs are assumed to be a resultof the effect of the two dimensional basin structure from on the theoretical MHVR calculated based on the
diffuse field assumption (Matsushima et al., 2014). The study was focused on the MHVRs where thedirectional dependence of the MHVRs were very clear.
In this study, we have conducted microtremor observations in a wider area compared to the previous
studies in order to investigate the spatial variability of the directionally dependent MHVRs in and aroundthe target area. We extended the observation area to sites further away from the basin edge, i.e. closer tothe central part of the basin, and sites up the hills to the hanging wall side of the Obaku fault. The observed
MHVRs showed that if the site is further enough from the basin edge it does not show much directional
dependency, where we can assume that the subsurface structure is flat-layered. On the other hand, if we go
up the hills, the peak diminishes as predicted by numerical calculations by Matsushima et al. (2014). These
information obtained from MHVRs can be used to specify the detailed shape of the basin edge combinedwith numerical calculations of MHVRs assuming the diffuse field.

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*S07-8-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Ground motion pattern generated by the undercrustal seismic source of the
Vrancea region, Romania* Luminita Angela Ardeleanu , Cristian Neagoe , Bogdan Grecu , Bogdan Zaharia , Andreea Craiu
National Institute for Earth Physics, Bucharest, Romania
The seismogenic source of strong earthquakes (Mw > 7) from the bend of the Southeastern Carpathians islocated in the undercrustal lithosphere, in a complex tectonic setting.
A modest number of strong motion records – all analogue – is presently available for Vrancea events with
moment magnitude above 6, due to the low occurrence rate of these seisms, as well as to the poor seismic
instrumentation in the region, before 1980. The strongest digitally recorded intermediate-depth earthquake
is the Mw 6.0 event of October 27, 2004.
Detailed macroseismic maps are available for the strongest Vrancea seisms which occurred at the end of
the XXth century (4 earthquakes with moment magnitude 7.4, 7.1, 6.9, and 6.4, respectively). They all
display a peculiar shape of the isoseismals, with a pronounced asymmetry. The few existing instrumental
records support these features.
During the past decades the Romanian seismic network has continuously been developed and upgraded; atpresent, it covers the entire country, and comprises 118 permanent digital stations equipped with
3-component accelerometers.
Taking advantage of the significant amount of recently collected high-quality data, we examine the space
distributions of the ground motion parameters (PGA, PGV) yielded by several tens of moderate-sizedundercrustal earthquakes, with Mw between 4.0 and 5.6. Their hypocenters cover well the seismogenic
zone. The focal mechanisms indicate – with few exceptions – reverse faulting, nevertheless, the orientationof the nodal planes show a notable diversity.
The individual ground motion distributions display noticeable differences, but also important common
characteristics – largest parameter values in the Extra-Carpathian area, rapid decrease of ground shaking
towards the Intra-Carpathian region. The study evidences that the local and regional geological conditions
control the ground motion pattern to a larger degree than the source parameters (magnitude, mechanism,hypocenter location).

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*S07-8-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Strong ground motions due to the 2016 mid Tottori prefecture earthquake,Japan* Takao Kagawa , Tatsuya Noguchi , Shohei Yoshida , Hiroshi Ueno , Sho Nakai , Kazu Yoshimi , Shoya
Arimura , Shinji Yamamoto
Tottori University, Tottori, JapanAn earthquake with Mj 6.6 hit mid area of Tottori prefecture, Japan on October 21st., 2016. In the area,
earthquake swarms have been activated since mid October in 2015. Large number of seismometers
installed by the prefectural government, JMA(Japan Meteorological Agency), NIED(National Institute for
Earth Science and Disaster Resilience) and Tottori University, observed strong ground motions in the area.
We also conducted aftershock observations just after the main shock at several temporary sites in the areawith housing damages. From prompt analysis of the observed strong motions, it is understood that the
ground motions were affected strongly by local site conditions, especially their predominant period causedby sedimentary response. The observed predominant periods at strong motion sites agree well with thoseestimated by previously conducted microtremor observations by ourselves. We will report characteristics ofthe observed ground motion and structural damages due to the earthquake considering effect of surface
geology in the area.

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*S07-8-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Peculiar strong ground motions from the very deep (h=680 km) Mw 7.9
Ogasawara Islands earthquake of 2015 May 30* Takashi Furumura 1) , Brian LN Kennett 2)
The Earthquake Research Institute, The University of Tokyo, Tokyo, Japan 1) , Research School of Earth
Sciences, The Australian National University, Canberra, Australia 2)
The Mw 7.9 earthquake beneath the Ogasawara Islands on 2015 May 30 at 6780 km depth, produced ananomalously large shock over Japan. This event is about 100 km deeper than other seismicity in thevicinity and produced a distinctive pattern of ground motion.
Usually deep earthquakes in the subducting Pacific slab near Ogasawara develop anomalously large
ground motions along the east coast of Honshu due to an efficient slab waveguide effect for high-frequency(f > 1 Hz) signals. However, the waveforms of regional distances (1000 - 2000 km) for the very deep event
indicate that the large ground acceleration arises from relatively low-frequency (f < 1 Hz) S-wave pulses
and following long-period (f < 0.1 Hz) signals with long tails. The arrival of the slab-guided high-frequency
signal was very late and weak compared with ordinary slab events.
Numerical simulation of seismic wave propagation shows how the deep source outside the main slab
affects the wavefield. S waves from the source travel upwards and impinge on the crust at around 1000 km
epicentral distance with similar slowness to P in the crust and produce strong S-to-P conversions at the freesurface. The converted P waves are trapped in the crust with multiple Moho and surface reflections
interfering to produced a long-period PL wave. The S-PL wave can travel substantial distances in the crust.
Weak slab-guided S waves from the very deep event are also transferred injected into the crust andcontinue as an Lg wave in the crustal waveguide.
The very deep event produces a broader distribution of strong ground motion, but much stronger
concentrated effects with potentially disastrous consequences can arise due to much enhanced slab
waveguide effect when a very large event lies in the core of the slab.

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*S07-8-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Slip Rates Inversion of 3-D Faults around Ordos Constrained by GPS andLeveling Observation* Yilei Huang 1) 1) 1) , Shiyong Zhou 1) 1) 1) , Shimin Wang 2) 2) 2)
Peking University, Beijing, China 1) , University of Chinese Academy of Sciences， Beijing, China 2)
Development of geodetic observation shadows light to inversion of crust motion which is crucial to seismic
hazard potential analyze. Vertical fault models are always used for inversion in traditional researches, but
we find inclined faults will result in different near-field surface velocity.Therefore, we first construct a 3-D
fault model of Ordos by using micro-earthquake relocation data. GPS data and vertical high-resolution
leveling data are implied in this geodetic inversion and they are processed by our designed method called‘Pair Difference'. Leveling data is essential for the fault's dip-slip motion is more sensitive to leveling data
than GPS data. By using data and inversion method, we remove the continuous fault slip rate constraint
which is traditionally used in geodetic inversion and derive an overall and detailed fault slip rate map ofOrdos. Furthermore, we point out the areas with high seismic risk by utilizing the inversion results andhistorical earthquake catalog to calculate seismic deficit.

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*S07-8-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Near-field long-period strong ground motion during the 2016 Mw 7.0
Kumamoto earthquake* Kojiro Irikura , Susumu Kurahashi
Aichi Institute of Technology, Toyota, JapanThe mainshock with Mw 7.0 of the 2016 Kumamoto earthquake occurred at 01:25JST on April 16, 2016
along the Futagawa fault zone and the northern part of the Hinagu fault zone. Surface breaks caused by themainshock were found associated with Futagawa-Hinagu fault system by field surveys (Earthquake
Research Institute, 2016). Near-field strong motions with high accuracy during the earthquake wererecorded by the NIED strong motion network (K-NET and KiK-net) and the JMA and local-government
seismic-intensity network. In particular, there are located two stations, Mashiki town-hall (MTH) about 2 km
and Nishihara village-hall (NVH) about 1 km close to the surface traces along the Futagawa fault zone
(Iwata, 2016). We simulated the ground motions of the 2016 Kumamoto earthquake using a characterized
source model consisting of strong motion generation areas (SMGAs) based on the empirical Green's
function (EGF) method. The locations and areas of the SMGAs were determined inside the seismogenic
zone deeper than 3 km through comparison between the synthetic ground motions and observed motions.
The synthetic ground motions obtained using the EGF method agree well with the observed motions interms of acceleration, velocity, and displacement within the period range of 0.1 to 3 s (Irikura et al., 2017).
However, the long-period motions more than 3 s seen at MTH and NVH are not well simulated against theobservation. We put a long-period motion generation area near Earth surface above the SMGA to produce
long-period ground motions. The ground motions at MTH and NVH show clearly the fling steps as shown innear-field ground motions during the 1992 Landers earthquake (Hisada and Bielak, 2003). We assume along-period (about 3 s) modified-ramp-functions as slip velocity time functions on the LMGA learning fromthe inversion results of Kubo et al. (2016). The synthetic ground motions as a sum of ground motions fromthe SMGA and those from the LMGA agree well with the observed ones.

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*S07-9-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Influence of vertical acceleration in seismic hazard. Observations ofearthquakes in Ecuador* Juan-Carlos Singaucho
Instituto Geofisico - Escuela Politecnica Nacional (IG-EPN), Quito, Ecuador
The effect of vertical component is usually neglected in the design process of new structures. Somebuilding codes, such as the Ecuadorian Standard (NEC-15), suggest a value of 2/3 of the horizontal
component when the structure is located near an active fault; however, the definition of “near" remains
under discussion.
Using the data recorded by the local strong motion network since 2009, a comparison with ground motion
prediction equations (GMPEs) for the vertical component is performed. Data show that low-magnitude
crustal events can generate vertical accelerations comparable to the ones observed on the horizontal
counterparts. In this article, the city of Quito- Ecuador is chosen as a case study to demonstrate the effectof vertical acceleration in existing buildings. For this city, several earthquakes between 4.5 and 5.1
magnitudes, generated by a local fault system, have produced high accelerations. On the other hand,records of subduction earthquakes, including the 2016 megathrust Muisne event, are used to define
appropriate distance metrics.

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*S07-9-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Validating a source model for the 2011 Tohoku Earthquake using a dense
strong-motion array* Atsushi Nozu
Port and Airport Research Institute, Yokosuka, Japan
After the 2011 Tohoku, Japan, Earthquake, the importance of reliable predictions of strong ground motions
for mega-thrust earthquakes has become more widely recognized than ever. For this purpose, it is essential
to validate source models and simulation methods using the strong-motion data of the Tohoku earthquake.
From engineering point of view, one of the most striking features of strong ground motions of the Tohoku
earthquake was the generation of pulses; strong ground motions in the frequency range from 0.2 to 1 Hz
observed at stiff stations along the coast of Miyagi through Ibaraki were characterized by distinctive pulses(Nozu et al., 2012). The importance of the pulses is that they appeared in the frequency range relevant tostructural damage.
A source model called the "SPGA (Strong-motion Pulse Generation Area) model" was developed to explainstrong ground motions from the Tohoku earthquake including the pulse (Nozu et al., 2012). The source
model involved nine subevents with relatively small size (on the order of several kilometers), located off thecoast of Miyagi through Ibaraki. This source model satisfactorily reproduced strong ground motions of theearthquake along the coast of Miyagi through Ibaraki including the pulses. In contrast, source models withlarger subevents (SMGAs) with a size of tens of kilometers failed to reproduce those pulses.
Although the SPGA model was already validated using strong motion records along the coast, it isnecessary to further investigate the reliability of the source model especially by using records from dense
strong-motion arrays such as the Small-Titan (Kamiyama et al., 1999). In this study, the SPGA model will beapplied to simulate strong ground motions at 17 Small-Titan stations and its performance will be discussed.

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*S07-9-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Features of long-period spectrum of SMART-1 array strong motion records* Haiying Yu 1) 2) , Baofeng Zhou 1) 2) , Xuan Xu 1) 2) , Ruizhi Wen 1) 2) , Dongwang Tao 1) 2)
Institute of Engineering Mechanics, China Earthquake Administration, harbin, China 1) , Key Laboratory of
Earthquake Engineering and Engineering Vibration, harbin, China 2)Long period features of strong motion on the same kind of sites are analysed using the records of digital
accelerographs deployed in SMART-1 array of Taiwan. Although the differences of epicentral distances fordifferent stations are small for the same earthquake, the short period spectral components of accelerograms
are different obviously, while the long period spectral components are same mainly. The effects ofmagnitude and epicentral distance on long period spectral components are not so stronger as for shortperiod components. Finally, the average spectrum for SMART-1 array of Taiwan is compared with thedesign spectra of the new seismic design code of buildings. Some useful conclusions are summarized asfollows.
(1)For accelerogram of the same class site at the same epicentral distance of one earthquake, there is somesignificant difference between the acceleration response spectra in the short period parts, but little
difference in long period parts. The effects of exiguous difference of the local site and other random factors
can be neglected in the long period parts.
(2)For accelerogram at the same place from difference earthquakes, there is some significant difference
between the periods at which the peak values the acceleration response spectra, and values of spectra arealso different in long period parts. That is to say, it is maybe not proper that the characteristic period ofdesign spectra is adjusted only according to the site conditions.
(3)From the shape of average spectra for soil sites, it is obviously that the declined speed of long period
parts is slower than that of short period parts. It shows that it is reasonable that the declined segment ofdesign spectra is divided into two parts in the revision of Seismic Design Code of Buildings. and on theother hand, the characteristic period of design spectra should be extended further.

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*S07-9-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Processing Strategy On Strong Motion Records Of Bizarre Waveforms* Baofeng Zhou , Haiying Yu , Ruizhi Wen , Dongwang Tao
Institute of Engineering Mechanics, China Earthquake Administration
Strong motion records are the first-hand data and precious indeed for research on earthquake engineering,which play an important role in improving structural seismic design, rapid earthquake-intensity reportingand earthquake early warning. However, there are some abnormal data in strong motion records, which
reduces the application confidence of the observed data so as to affect the conclusion of scientificresearch. So, a rich set of strong motion records are analyzed in some typical earthquakes domestic andabroad in this paper. Four kinds of abnormal phenomena on the acceleration waveform are revealed, suchas spike, asymmetric waveform, obvious baseline drift and strong motion records packets separation. Thenreasonable recognition and processing approaches are derived from the preliminary analysis of thegeneration mechanism for abnormal phenomena. It is shown that spikes can bring ill effect on the rapid
earthquake-intensity reporting and so on, so it should be identified with ‘jerk' method, ratio method andthe consistency of the three-component PGA time, and then corrected with average value. For asymmetricwaveform, the diversity mechanism is due to instrument pier, instruments and wrong operations. And thearea average method and modified moving average method can be applied to identify acceleration records
with the characteristics of asymmetric waveform. At the same time, the asymmetric waveform correction forstrong motion records from Yibin Gaochang in Wenchuan earthquake is obtained by using the Butterworth
low-pass filtering. In addition, two pieces of strong motion record packets can be connected by searchingcontinuous and repeated data. Finally, the method of cumulative adding are used to find the clear baseline
drift. At the same time, it is found that the abnormal waveform directly affects the characteristics of time
history and frequency spectrum.

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*S07-9-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Site-specific investigations in the ongoing renewal project of the Swissstrong motion network (SSMNet)* Manuel Hobiger 1) , Donat Faeh 1) , Clotaire Michel 1) , Paolo Bergamo 1) , Walter Imperatori 1) , John
Clinton 1) , Carlo Cauzzi 1) , Eric Zimmermann 1) , Franz Weber 1) , Blaise Duvernay 2)
Swiss Seismological Service (SED), ETH Zurich, Zurich, Switzerland 1) , Federal Office for the Environment(FOEN), Bern, Switzerland 2)
In 2009, the Swiss Seismological Service started a project to renew and expand its strong motion network.
A total of 100 new stations are planned to be installed until 2019. The goals of the enlargement of the
network are a better coverage of regions with increased seismic hazard and risk, a better knowledge of thevariability of ground motion and site effects in Switzerland, the study of secondary phenomena such as
landslides and liquefaction and finally the verification and improvement of seismic hazard models.
All new stations are free-field and mainly installed in densely populated areas of high seismic risk, but also
in more rural areas with relevant historical seismicity.
Installing the new stations is a step-wise process. After the identification of suitable target areas, a first ideaof the local site effects is obtained from H/V surveys and geological information. Important infrastructures,such as hospitals, schools or fire departments, where free-field stations could be built, are identified. At
these places, test stations assess the local noise level for several days.
Taking all available information into account, the final station locations are decided. After the station
construction, passive and active seismic measurements are performed to characterize the site response.
Passive seismic array measurements yield Love and Rayleigh wave dispersion curves as well as theRayleigh wave ellipticity. Where it seems necessary, active measurements with MASW and body-wave
refraction are carried out. CPT measurements aim at assessing the potential for nonlinear soil effects andliquefaction.
The inversion of the surface wave properties supplies shear-wave velocity profiles for the soil structure
under the strong-motion station. Based on these, the theoretical amplification can be calculated andcompared to the observed empirical amplification. In this way, site-specific phenomena such as edgegenerated surface waves or resonance can also be identified.

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*S07-3-06
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

SEISMIC RISK FOR CITIES AROUND THE LAKE KIVU BASIN, WESTERNBRANCH OF THE EAST-AFRICAN RIFTS SYSTEM* WAFULA MIFUNDU 1) , KONGBO TAMBALA 2)KINSHASA, D.R. CONGO, THE UNIVERISITY OF KINSHASA, KINSHASA, D.R. CONGO 1) , CRSN/ LWIRO,
D.S. BUKAVU, D.R. CONGO 2)
The tectonic conditions of the dome uplift, faulting, volcanism and shallow seismicity around the Lake Kivu
(the highest 1462 m) are believed to be the indications of actual rifting and may represent a nascent stage
in the development of plate boundary. Since 1997, it was observed in the Lake Kivu Basin the
recrudescence of seismic activity. This seismic activity is mostly concentrated in the South-Western part ofthe Basin where earthquakes are regularly felt. Three large earthquakes associated with foreshocks andlong duration aftershocks mostly confined around the epicenter areas were already recorded in the Basin:
The October 24th event with magnitude mb (6.1), the February event with magnitude mb (6,0) and theAugust 7, 2015 event with magnitude mb (5,8). Three events occurred at shallow depth around 10 km. It
was observed small Tsunamis during these earthquakes reaching 5 m high and landslides on the shorelines
near the epicenters. Many damages are regularly recorded in the villages and towns mostly near the
epicenters area. Most of damages are correlated with the secondary faults which move when large
earthquake occurred. More than 50 persons are already killed since 2002, by the earthquakes. The
maximum intensity observed near the epicenter area is usually more than 8. According to the actual
development of seismic activity, more large event is expected. The occurrence of such large earthquake
may be catastrophe for the dense cities around the Lake Kivu basin in D.R. Congo and Rwanda side. The
situation may be more catastrophe if it occurs inside the lake containing dissolved gas; carbon dioxide(CO2) and methane (CH4) in the deep water, with the possibility of gas explosion. This assertion is
supported by the existence of active faults in this lake.
Keywords: Lake Kivu Basin, seismic, risk, faults, catastrophe.

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*S07-P-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Seismic Microzonation and Site Effect Response of Al Auja District* Hatem Alwahsh
An Najah National University, Nablus, Palestine
The town of Al-Aluja is one of the important Palestinian towns. The spatial distribution of the natural
periods over a map is presented. It shows the important characteristics of soil deposit that will affectsignificantly the mitigation of the seismic risk impacts. The microtremors are very important and usefulmeasurements in site response which could compensate the shortage and deficiency of the seismicallyrecorded data, especially when there are missing seismic stations.
The aim of this study is to prepare a GIS-based microzonation map of Al-Aluja area for the purposes ofurban planning theme. The predominant natural frequency at each site within Al-Aluja area wasdetermined using the Horizontal to Vertical Noise Ratio (HVNR) of the microtremor records. It was applied
to about 80 points which covered the whole studied area. Al-Aluja area was divided into cells by a grid
system of 300 m x 300 m to estimate the effects of site conditions. The impedance contrast of soil depositof sediments shows the distribution of frequencies and by using the outputs of these results, Al Aluja area
is classified into four frequencies zones from 0.8 - 1.4, 1.4 - 2, 2 - 2.5 and 2.5 - 3.8 Hz. The results show thatthe lower bound estimate of amplification factor for a soil site is from 2 up to 18 times using microtremor
peak values. And such of this study will use in seismic risk assessments and urban planning purposes inorder to enhance the seismic design of the structure and implement some of the sound rules in natural
disaster managements scenarios.

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*S07-P-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Source effects of intraslab and interplate earthquakes off Miyagi Prefecturein Northeastern Japan and their relation to source depths* Yasumaro Kakehi
Kobe University, Kobe, Japan
Two different views have been presented as to the source effects (especially, the high-frequency level ofacceleration spectrum) of intraslab and interplate earthquakes: (a) high-frequency level of intraslab
earthquake is higher than that of interplate earthquake, and (b) high-frequency level depends simply on
source depth, independent of tectonic environments, and high-frequency level is higher for deeper source.
Kasatani and Kakehi (2014) (hereafter, KK) made spectral inversion analysis of the intraslab and interplate
earthquakes off Miyagi Prefecture in Northeastern Japan using K-NET strong ground motion data of NIED.
Their result supported (b). In this study, three events are selected from the events KK studied, and theirstrong ground motion data are analyzed. They are composed of two shallow events: S1 (intraslab, Mw 5.5,
35.94 km) and P (interplate, Mw 5.0, 42.86 km), and one deep event: S2 (intraslab, Mw 5.5, 83.10 km). In
the comparison of attenuation relations of acceleration amplitudes, the slope of decay of deep S2 isobviously steeper than those of shallow S1 and P. On the other hand, in the spectral inversion of KK,
common attenuation relation is assumed for all the events, independent of source depths. Actually, theattenuation relations of the acceleration amplitudes with the site effects (obtained in the spectral inversion)
removed shows similar gentle slope of decay for all of the three events. This means that in the spectral
inversion of KK, the strength of attenuation is underestimated for deeper events, and therefore, the highfrequency level of source is also underestimated for deeper events. When the steep decay of for deeper
events are considered, high-frequency levels of deeper events will be higher than those obtained in KK, andthe difference of high-frequency levels between shallow and deep events will become larger and moreclear. This enhances the validity of the conclusion of KK that high-frequency level is higher for deeper
source.

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*S07-P-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Strong Ground Motion Simulation by Combining Stochastic Green's
Function Method with Hybrid Slip Model for February 6, 2016 Meinong,
Taiwan Earthquake* Cheng-Feng Wu , Huey-Chu Huang
National Chung Cheng University, Chiayi, Taiwan
A damage earthquake (Mw 6.53), which has struck the southern Taiwan, occurred in Meinong District ofKaohsiung City on February 6, 2016 (February 5 07:57:26.1 UTC). According to the relevant reports, manybuildings collapsing during the seismic shakings were caused by local site effect in Tainan. To investigate
the effect of shallow velocity structure on seismic ground motion, we calculate the broadband groundmotions between 0.1-10 Hz by using the stochastic Green's function method. In this study, the velocity
structures are established by integrating the crustal velocity structures and the near-surface velocity
structures (0-1500 m) estimated from the microtremor array data. About the source model, we adopt a
hybrid k-squared slip model with an asperity covering 1/4 of the fault area. The shallow velocity structures
can well improve the synthetic results including amplitudes and phases and the directivity pulses are
successfully reproduced at many stations. They indicate that the possible reasons for the earthquake
disasters in Tainan are associated with a combination of forward-directivity and soil amplification effects.
Thus, it is feasible to do the 1-D broadband strong motion simulations at the area using the stochastic
Green's function method with hybrid k-squared slip distribution.

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*S07-P-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Nonlinear Site Response During the 2016 Meinong, Taiwan Earthquake* Kuo-Liang Wen 1) , Chun-Te Chen 2) , Shun-Chiang Chang 1)
Department of Earth Sciences, National Central University, Taoyuan, Taiwan 1) , Institute of Earth Sciences,
Academia Sinica, Taipei, Taiwan 2)
The Meinong earthquake occurred on February 6, 2016, at 03:57 (UTC+8) with ML 6.6. The epicenter was
located in the Meinong district of Kaohsiung City, Taiwan, however, the highest intensity appears in the
Tainan City. The strong ground motion induced soil liquefaction in the Sinshih and Annan districts of
Tainan City. To investigate the nonlinear site response during Meinong mainshock, the degree of nonlinear
site response (DNL) which summation of the horizontal to vertical spectral ratios (HVSR) differences
between weak-motions and Meinong mainshock records from the TSMIP network is calculated. We
compare the DNL values with the ground motion parameters such as PGA, PGV and also the ratio between
PGV and VS30. The DNL show a positive correlation with ground motion intensity, particular with PGV,
and the surface site conditions also leading the DNL strength. The areas that have high DNL values are
consistent with the high potential liquefaction map that published by the Central Geological Survey,
Taiwan.

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*S07-P-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Evaluation of site effect by aftershock observation data due to the 2016 mid
Tottori prefecture earthquake and microtremor observation in the mid areaof Tottori Prefecture, Japan* Tatsuya Noguchi 1) , Takao Kagawa 1) , Shohei Yoshida 1) , Sho Nakai 1) , Hiroshi Ueno 1) , Kazu Yoshimi 1) ,Shoya Arimura 1) , Shinji Yamamoto 1) , Hayato Nishikawa 2)
Tottori University, Tottori, Japan 1) , NIT. Maizuru college, Mizuru, Japan 2)
An earthquake (Mj6.6) occurred in central Tottori Prefecture in Japan on October 21, 2016. We conducted
aftershock (strong motion) observation at several temporary sites in this area with housing damages. Also
densely microtremor observations were carried out to estimate the characteristic of ground vibration in thedamage area. Microtremor H/V spectra and a distribution of the predominant period were obtained fromobservation data. In addition, we checked the relationship between the site amplification effects and theresults of analysis of strong motion and microtremor at the temporary observation sites. We found thecharacteristics of ground vibration form transfer functions of SH-wave by S-wave velocities, H/V ofmicrotremor and receiver function and H/V of strong motion.

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*S07-P-06
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

The Probabilistic Seismic Hazard Assessment of South Africa* Vunganai Midzi 1) 2) , Brassnavy Manzunzu 1) , Thifhelimbilu Mulabisana 1) , Brian Zulu 1) 2) , Tebogo Pule 1), Sinovuyo Myendeki 1) , Ganesh Rathod 1)
Council for Geoscience, Pretoria, South Africa 1) , University of the Witwatersrand, Johannesburg, South
Africa 2)
More than 10 years has passed since previous national seismic hazard maps were prepared for South
Africa. In those maps, zone-less techniques were applied. The availability of more reliable seismicity andgeological data has made it possible to update those maps using probabilistic assessments that take into
consideration all available data. Presented in this report, is a summary of the work conducted to produce
the latest hazard maps for South Africa. This involved the systematic compilation and homogenisation of anearthquake catalogue, which comprised both historical and instrumental events.Work conducted in anotherproject IGCP-601 to prepare a seismotectonic map of Africa, contributed much to the preparation of acorresponding seismotectonic map of southern Africa. The map consisted of major faults including possibly
active faults in the region, focal mechanisms and seismicity. This information was also used in the
preparation of seismic source zones for the hazard assessment. Two GMPEs were identified from available
international models for regions that are tectonically similar to South Africa. These two models were thenimplemented in the hazard calculations, which were done using the OPENQUAKE software. Uncertainties
associated with input parameters in both the seismic source and ground motion models were taken into
account and implemented using the logic tree technique. Maps showing distribution of acceleration at
three periods (PGA, 0.15s and 2.0s) computed for 10% probability of exceedance in 50 years were
produced. The maps showed a strong influence of source zones associated with mining activity on thehazard of the country. The same mining regions were also observed to have the highest hazard. These maps
constitute a valuable product of this study that can be useful in the mitigation of earthquake risks in South
Africa especially considering the growth of its cities and also the location of major cities close to areas ofhigh hazard.

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*S07-P-07
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Generation conditions of long-period ground motions in the Kanto Basin* Yurie Mukai , Takashi Furumura
Earthquake Research Institute, The University of Tokyo, Tokyo, Japan
In the Kanto (Tokyo) Basin in Japan, the long-period ground motion with period between 3 to 10 s arestrongly developed when large (>M7) and shallow earthquakes occur nearby Tokyo. It is reported that thelevel of the long-period ground motion was very large from the earthquakes in Niigata but is several times
weaker from the earthquake of Tohoku. In this study, we examined the cause of larger long-period groundmotion in the Kanto Basin based on numerical simulation of seismic wave propagations. We first examinedthe directional amplification properties of the long-period ground motion in the Kanto Basin using a 3D
heterogeneous sedimentary structure and a source model of the 2004 Niigata Chuetsu (Mw6.8)
Earthquake. It is confirmed that the level of the long-period ground motion in Tokyo is strong when thesource in Niigata, and is weak in Tohoku. However, it is insufficient to explain the large differences in theobservation. Thus, we examined the source radiation effect of this event by modifying the strike of thissource. It is found that the level of the long-period ground motion in central Tokyo is largely fluctuated withchange in the strike of the fault, which had a largest when it corresponds to the case of the Niigata Chuetsu
Earthquake. To examine the contribution of the surface wave propagation from the source to the Kanto
Basin we conducted an another simulation with modified the free surface with a rigid boundary to suppress
the surface wave propagation. As a result, the long-period motion in central Tokyo is dramaticallyweakened to about 1/2, indicating the importance of the surface wave propagation from the outside to thebasin. The above results demonstrated that the strong long-period ground motion developed in the Kanto
Basin during the Niigata Chuetsu earthquake was due to the fact that the surface wave is strongly radiatedfrom the source to the direction to the Kanto Basin and that it can propagate well in the path to the Kanto
Basin.

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*S07-P-08
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Shallow to deep velocity structure modeling of Oita Plain, Japan, using
microtoremor and borehole data
* Masayuki Yoshimi 1) , Takumi Hayashida 2) , Shinichi Matsushima 3) , Hiroshi Kawase 3) , Hiroshi Takenaka, Nobuyuki Yamada 5) , Hiroe Miyake 6) , Takeshi Sugiyama 7) , Tetsuyoshi Tokumaru 7) , Haruhiko Suzuki
8), Atsushi Yatagai 8) , Hisanori Matsuyama 8)
Geological Survey of Japan/AIST, Tsukuba, Japan 1) , IISEE, Building Research Institute, Tsukuba, Japan 2) ,Disaster Prevention Research Institute, Kyoto University, Uji, Japan 3) , Okayama University, Okayama,
Japan 4) , University of Teacher Education Fukuoka, Munakata, Japan 5) , University of Tokyo, Tokyo, Japan
6), Tokumaru PE Office, Bungo-takada, Japan 7) , Oyo Corporation, Tokyo, Japan 8)
4)

Shallow to deep velocity structure around Oita Plain, Kyushu Island, Japan, has been modeled using dataobtained by dense microtremor array survey and boreholes. Large aperture microtremor array surveys of
their radius about 20 to 1000 m were deployed at 12 sites in the Oita Plain using T=10s velocity
seismometers to estimate the phase velocity of the Rayleigh wave to constrain S-wave velocity down to theseismic bedrock. In addition, small aperture array surveys with radius less than 20 m were conducted atabout 100 sites to constrain shallow S-wave velocity structure. About 3,000 borehole data comprised of soil
types and SPT values are carefully interpreted to create 250 m mesh model of a layered soil structure(down to 100 m depth at most) composed of three significant layers. S-wave velocity structure of each meshhas been converted from the layered soil structure using an empirical equation among the N-value, depth,
soil type and S-wave velocity. Synthetic dispersion curve of the phase velocity calculated with the S-wave
velocity model agree well with the observed ones.

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*S07-P-09
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Strong Ground-Motion Simulation of 2016 Meinong Earthquake Using
Empirical Green's Function Method* Ying-Chi Chen , Huey-Chu Huang
National Chung Cheng University, Chiayi, Taiwan
The Meinong Earthquake (ML 6.6) occurring at 03:57 local time (UTC+8) on February 6, 2016 has struck
the southern part of Taiwan. It is very important to understand the characteristics of strong ground motions
for the earthquake. Therefore, we simulate the ground motions of the Meinong mainshock using theempirical Green's function method. We first choose one small event to be the empirical Green's function(EGF) and select some CWBSN (Central Weather Bureau Seismic Network) stations surrounding thesource area. Next, we calculate the averaged spectral ratios of the Meinong mainshock relative to the EGF
records and then get the seismic moment ratio between these two events and their corner frequencies by
the source spectral ratio fitting method. We further estimate two important parameters, the ratios of fault
dimensions (N) and stress drops (C) between the Meinong mainshock and the EGF event, which areneeded for the empirical Green's function method. Finally, we simulate the waveforms of the mainshock at
all stations used and then get the best fit source model by comparing the synthetic waveforms with theobserved data. According to the simulated results, the size of the strong motion generation area is about 55
square kilometers. The rupture started at the right-bottom of the strong motion generation area andextended radially to the left-upper direction.

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*S07-P-10
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Segmentation of slow slip events in south central Alaska possibly controlled
by a subducted oceanic plateau* Haotian Li 1) 2) , Meng Wei 2) , Shiyong Zhou 1) , Duo Li 3) , Yajing Liu 3) , YoungHee Kim 4)
Peking University, Beijing, China 1) , University of Rhode Island, United States 2) , McGill University,
Canada 3) , Seoul National University, South Korea 4)
GPS data in south central Alaska show possible segmentation of slow slip behavior along the subduction
zone. We hypothesize that the subducted Yakutat plateau created such segmentation through modificationof stress or friction property of the fault zone. To test this hypothesis, we simulate the SSEs in theframework of rate and state friction. We use non-planar fault model to incorporate the geometric effect on
SSE behavior. We also systematically explore the parameter space to find the most likely scenario and ruleout some possibilities. The goal is to identify how such segmentation can be related to the subducted
plateau in a physics model. Simulations show different effective normal stress could create suchsegmentation even though other mechanism exists. This is consistent with an idea that subducted plateau
caused elevated effective normal stress in the fault zone, producing larger SSEs above it. The buoyant
plateau provides additional normal stress on the fault interface, which results in larger SSEs in the east
segment. Our results indicate that geological features have a long-lived impact on slip behavior of
subduction faults. We also explored the interactions between the two SSE patches, as shown in the
2008-2013 slip events. Simulations show that the closeness of these two patches creates additional
complexity in the behavior of SSEs.

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*S07-P-11
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Difference in Ground Motion and Seismic Source Characteristics Between
the Surface and Buried Rupture Crustal Earthquake in Japan* Shohei Yoshida , Takao Kagawa , Tatsuya Noguchi
Tottori University, Tottori, Japan
Appearance of surface fault rupture in inland crustal earthquake affects significantly on ground motion
characteristic. Somerville (2003) has indicated that the observed ground motion from buried ruptures arelarger than those from surface rupture earthquakes in the period between range 0.3 and 3 sec. Following
researchers explain the differences by fault rupture processes analysis using kinematic and dynamic source
models of several part earthquakes (e.g. Kagawa et al., 2004). In Japan, inland crustal earthquakes haveoccurred frequently after the 1995 Kobe earthquake, and some of them had surface fault ruptures (e.g.
2016 Kumamoto earthquake). Yoshida et al.(2016) evaluated ground motion characteristics of the inland
crustal earthquakes in Japan using the similar method as Somerville (2003). As a result, ground motions
from buried rupture earthquakes are twice larger than those from surface rupture earthquakes in period
range between 0.1 and 0.4 sec. We will report difference in the seismic source characteristics between thesurface and buried rupture earthquakes using kinematic source models in Japan and discuss the differenceof dominant period range between the result by Somerville (2003) and Yoshida et al.(2016).
Somerville(2003): Physics of the Earth and Planetary Interiors, 137, 201-212.
Kagawa(2004): Earth Planets Space, 56, 3-14.
Yoshida et al.(2016): Japan Geoscience Union Meeting 2016 Abstract, SCG061-P03.(in Japanese withEnglish Abstract)

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*S07-P-12
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Combining deterministic simulation of ground motions and probabilistic
approach: Large scale simulation for heterogeneous source models by FDM
reciprocity method* Anatoly Petukhin 1) , Haruko Sekiguchi 2) , Hiroshi Kawase 2) , Katsuhiro Kamae 3) , Masato Tsurugi 1)
Geo-Research Institute, Japan 1) , Disaster Prevention Research Institute, Kyoto University, Japan 2) ,Research Reactor Institute, Kyoto University, Japan 3)
Due to recent progress in velocity structure modelling, 3-D finite difference simulations have been proved
to be accurate for simulation of long-period response spectra and waveforms. However, large scale
simulations, e.g. for anticipated M9 Nankai Trough earthquake, are time consuming and becometroublesome in case of probabilistic approach, which require simulation for many heterogeneous source
models. Fortunately, for typical case in engineering seismology, namely for only one site that is hostingtarget structure of high importance (e.g. super high-rise building or long span suspension bridge)
reciprocity method is an effective tool.
In this study we demonstrate effectiveness of reciprocity method. For this we use heterogeneous source
modeling procedure of Sekiguchi et al., 2008. Generated ground motions can be studied in probabilistic
way. For example, we can estimate effect of many heterogeneous source models, and find average, averageplus standard deviation, or level of a certain probability of non-exceedance. In order to estimate average wemay need to calculate 10 models, 30 models for average plus standard deviation and 100 models for 5%
level of non-exceedance. We applied above methodology to study long-period ground motions in the Osaka
sedimentary basin, Japan, from a hypothetical M9 earthquake in Nankai Trough. 100 source models having
randomly generated slip, rupture velocity and location of SMGAs are prepared. Moreover, in order toaccount for variations of directivity effect, we generated ground motions for three cases of rupture start: incenter and in west and east sides of model. Results show that in the deepest landward part of Osaka basin(site Konohana) the ground motions for periods 3-20sec are estimated to have peak velocities of
40–80cm/s, prolonged durations exceeding 300s, and long predominant periods of 5–10s; velocity
response spectra for this periods are 190cm/s in average, and 290cm/s for average plus standard
deviation.

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*S07-P-13
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Maps of Volcanic and Seismic Hazards on the Web* Jayvie Nadua , Analyn Aquino , Kervin Macaranas , Enrico Santos , Mabelline Cahulogan , Renato
Solidum, Jr.
Philippine Institute of Volcanology and Seismology
The MV SHOW it Project (Maps of Volcanic and Seismic Hazards On the Web) started in 2014 with the
purpose to: (1) standardize 1:50,000 quadrangle scale hazard maps; and (2) make this information
available online through the PHIVOLCS website. The project connotes a journey towards showing all
available volcano- and earthquake-related hazards information online, servicing all its stakeholders in amore efficient way.
For the last two years, MV SHOW it has spearheaded standardization of hazard maps derived from the
READY Project. It produced more than 800 images of 1:50,000 scale hazard maps.
In order to showcase hazards information on the web, it partnered with NAMRIA's (National Mapping andResource Information Authority) Philippine Geoportal: One Nation One Map Project, and the GeologicalSociety of Japan (GSJ). Partnership with NAMRIA resulted to the PHIVOLCS Geoportal and collaboration
with GSJ made the progress of The PHIVOLCS Faultfinder possible. NAMRIA and GSJ developed theapplications while PHIVOLCS manages, maintains and manipulates hazards information in its own server.
Both applications utilize base maps provided by NAMRIAThe PHIVOLCS Geoportal app displays all available 1:50,000 scale earthquake-related and volcano-related
hazard maps in the Philippines, as well as other geospatial information available in the Institute while the
PHIVOLCS Faultfinder displays the distance of a user's location with respect to nearby active faults. Active
faults shown in the application are results of various active fault mapping projects conducted by
PHIVOLCS or in collaboration with international partners since the 1990s.
The MV SHOW it Project has also already started standardizing hazard maps in other relevant map scales,
and has initiated ways to pro-actively engage its stakeholders through more user-friendly WebGIS andmobile applications.
Keywords: Philippines, earthquake, hazards, PHIVOLCS, webGIS, faultfinder, geoportal, MVSHOWit

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*S07-P-14
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Characteristics of Seismic Response of the Taipei Basin* Kou-Cheng Chen , Jeen-Hwa Wang
Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
The Taipei Metropolitan area is located on a triangular-shaped alluvium basin filled with the Quaternary
unconsolidated sediments overlying the Tertiary basement. The sediments thicken northwestward from athin basin margin in the southeast to about 700 m in the northwest corner of the basin. In order toinvestigate the characteristics of seismic response of the Taipei basin, the 5%-damped response spectral
accelerations with periods, T, of 0.2 and 1 sec are calculated from the accelerograms recorded at thestations on the Taipei basin. The horizontal response spectra are calculated from the geometric mean of thespectral amplitudes of two horizontal components. Obviously, the spectral accelerations are higher in the
Taipei basin than in the surrounding area due to the amplification of waves in the sedimentary basin. For
the three Hualien offshore earthquakes, the maximum horizontal spectral accelerations are distributed near
the eastern edge of the basin at T=0.2 sec and near the eastern and northern edges of the basin at T=1.0
sec. For two earthquakes occurred in central Taiwan, the maximum horizontal spectral accelerations at
T=1.0 sec are distributed mainly near the eastern and western edges of the basin.

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*S07-P-15
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Surface deformations caused by underground nuclear explosions
Ella Gorbunova , Evgeny Vinogradov , * Alina Besedina
Institute of geospheres dynamics RAS
We observed surface deformations at several sites within alluvial plain in the Semipalatinsk testing area.
Field research included geomorphological observations and topogeodesic leveling along profiles with thelength of 1,5-3 km. Technogenic forms of relief include:-intensive ground loosening,-ground swelling of amplitude from 0.5 to 1.0 m, length up to 20 m,-local depression with a radies of 2 to 10 m, 0.5-0.7 m depth and-ground fractures with a length of the first meters to 20 m and opening of 3-4 cm, rarely 10 cm.
We analyzed data that were carried on 20 objects before and after explosion and established that explosion
caused deformation amplitude relates to the vertical peak ground velocity as a power function. Deformation
area has a radius of 0.5 to 1.5 km. It is interesting that point of maximum deformation is displaced from theburst epicenter to the distance of 100-400 m.
The zonality of surface deformation corresponds to anthropogenic massif change due to the experimentand depends on massif lithologic-facial structure and physical-mechanical properties, underground waterlevel, faults existence and paleorelief. In case of sedimentary and clastic rocks deformation area isasymmetric and corresponds to stratum attitude conditions. In tuffs it is usually uniform with the center atburst epicenter. In case of an explosion within shale and aleurolite massifs an elliptic cone is being formed
along rock strike.
Shallow underground waters result increase of explosion impact on surface deformation. Maximum groundelevation without rupturing forms along the slope from terrace to flat due to soil displacement.
Large-scale experiments consequences corresponds to real post-seismic processes that were found out
after earthquakes.
Described results are useful both for forecasting of areas of expected landslip processes and estimation oflocation and magnitude of historical earthquakes.
This work was supported by the Russian Science Foundation (Project No. 16-17-00095)

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*S07-P-16
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Broadband Ground Motion along the Joetsu Shinkansen during the 2004
Chuetsu Earthquake and Aftershock Sequence* Yifei Chen 1) , Hiroe Miyake 2)
GSII, The University of Tokyo, Tokyo, Japan 1) , III, The University of Tokyo, Tokyo, Japan 2)During the 2004 Mw 6.6 Chuetsu earthquake, many aftershocks occurred following the main shock. In themain shock, the seismic intensity meter of Kawaguchi-cho in Niigata prefecture recorded seismic intensity
level 7, and equivalent seismic intensity level 7 was observed at K-NET Ojiya of NIED and Shinkawaguchi
electrical substation of JR East (ARAIC, 2007). Large seismic intensity was observed in the watershed of
the Shinano river where was near the epicenter and has a complex velocity structure with large site
amplification factors. During the 2004 Chuetsu earthquake, the first derailment of Shinkansen underoperation ever occurred in which was slight south of the Nagaoka station of the Joetsu Shinkansen. The
strong motion along the Joetsu Shinkansen has been discussed by Mori and Kazuni (2005), Nakamura(2006), and ARAIC (2007). Mori and Kazuni (2005) pointed out the influence of strong motion whose
period was less than 0.5 second. On the other hand, the predominant period of the observed strong motion
ranged from Ojiya to Nagaoka during the 2004 Chuetsu earthquake was 1 second. The 2004 Chuetsu
earthquake and its aftershocks occurred in conjugated fault plane systems, both the hypocenter andvelocity structures of which were complex. We here focus on the arrival times of P-wave and S-wave for the2004 Chuetsu earthquake and the distribution of strong ground motions. We also discuss the strong motionof the 2004 Chuetsu earthquake along the Joetsu Shinkansen by conducting ground motion simulation ofaftershocks with point-source assumption. We deal with seismic intensity meters such as Niigata
prefecture, JMA, K-NET, and KiK-net, using earthquake source models from F-net and Hikima and Koketsu(2005). We use J-SHIS as the initial velocity structure model. We also conduct broadband ground motion
simulation by using 3-D finite difference method and the stochastic Green's function method. Calculation
results are compared with the ground motion prediction equation.

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*S07-P-17
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Multi-use seismic stations for earthquake early warning
Bruce Townsend , * Stephen Kilty , Geoffrey Bainbridge , David Easton , Tim Parker
Nanometrics Seismic Monitoring Solutions, Ottawa, Canada
Earthquake Early Warning (EEW) network performance improves with the number and density of sensing
stations, quality of the sites and of strong-motion instrumentation, degree of coverage near at-risk
populated areas and potential fault zones, and minimizing latency of signal processing and transmission.
Seismic research tends to emphasize competing requirements: low-noise sites, high-performancebroadband seismic instrumentation, and high-quality signal processing without regard for latency. Recent
advances in instrumentation and processing techniques have made feasible the concept of a multi-use
seismic station in which strong- and weak-motion seismometry are both cost-effectively served withoutcompromising the performance demands of either.
Our concept for a multi-use seismic station meets the needs of both EEW and high-quality seismic research.
One significant enabler is a 6-channel dual-sensor instrument that combines a 120s broadband
seismometer and a class A accelerometer in a single ultra-compact sonde suitable for direct burial.
Combining two sensors effectively adds broadband capability to a station without increasing the already
optimized site footprint, preparation and management costs associated with shallow direct-burial
installations. The combined sensors also simplify and speed up installation (for example, the accelerometer
provides real-time tilt readings useful to leveling the seismometer). Integration simplifies alignment tonorth, as there is only one instrument to orient. A dual-use 6-channel digitizer simultaneously provides two
sets of independently processed streams from both sensors, one set optimized for low-latency earthquake
warning, and the other set for high-quality seismic research purposes.
Such a dual-use seismic station can serve both seismic research and civil warning infrastructure objectives
without adding significantly to the cost of a single-use station, while increasing the utility for all users of thestation's data.

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*S07-P-18
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Studies on Qs of Kyushu district in Japan* Kenichi Nakano , Shigeki Sakai
HAZAMA ANDO CORPORATION, Tsukuba, Japan
We have reported the variability of Qs in southern part of the Kyushu district, in the previous paper. In that
paper, we used seismograms, which are from the M4-5 small-adequate scale earthquakes observed by KNET and KiK-net operated by the National Research Institute for Earth Science and Disaster Resilience, forevaluating the Qs in those areas. As a result, it showed that the average apparent Qs of the line, connecting
the seismic source location to the earthquake catalog of JMA and the observation point, changes
significantly, depending on regions (route combination of propagations).
In this paper, we evaluate the Qs for the northern part of Kyushu, as the damping properties, using thetwofold spectral ratio method and according the condition we assumed in previous papers. First, thenorthern part of the Kyushu district was divided into “Region A" and “Region B". In addition, the area inthe southwestern part of the Kyushu district was indicated as “Region C". The evaluation of Qs was carriedout in an area having a planar spread (Area), and as a propagation route (Line) respectively.
The results show clearly that different Qs are evaluated in Area-case and Line-case at each region, and also,
Qs are very similar in “Region A" and “Region C". On the other hand, the Qs model of “Region B" which
is very different from other regions agrees to the Qs estimated by Izutani (2000). He assumes the
propagation path as just under Mt. Krishima. The Qs in other regions are harmonious with the ones
estimated by Uchiyama and Yamamoto (2016).
Our results include only small number of earthquakes and the area to be analyzed, we have to continue theinvestigation for evaluating attenuation properties to perform the analysis, considering the variability ofearthquakes and propagation path. As our future tasks, we plan to develop a method for evaluating complex
damping structures in order to improve the accuracy of strong ground motion prediction.

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*S07-P-19
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Estimation of Empirical Green's Tensor Spatial Derivative Elements: A
Preliminary Study using Strong Motion Records in Southern Fukui
Prefecture, Japan* Michihiro Ohori
University of Fukui, Fukui, Japan
In this report, I demonstrate the applicability of the EGTD method to simulate near-field strong-motion
records for seven small events (MJ 3.7-4.2) that occurred in the southern part of Fukui Prefecture, Japan.
Fukui Prefecture is an area with relatively low seismicity compared with other parts of Japan and strong
motion data for EGTD estimation is less abundant. I targeted several nearby stations of the K-NET operated
by the National Research Institute for Earth Science and Disaster Prevention (NIED). I performed EGTD
inversion independently for each component for all time-sampling data. Using the estimated EGTD, I
simulated the strong ground motion records for these events. The agreement between the observed andcalculated waveforms for the all events is satisfactory over a long duration and there is a good match for theamplitude. The EGTD estimates in this report should be confirmed when future earthquakes occur aroundthe same source area. This study targeted components lower than the corner frequencies of all events.
Estimation of the broadband EGTD, including frequency ranges higher than corner frequencies, will be
investigated in future work. I hope that this preliminary study in an area of relatively low seismicity is
encouraging for the further investigation of EGTD estimation and evaluation of strong motion predictions
using EGTD.

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*S07-P-20
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

S-wave structure in the Nansei Islands, Japan, inferred from microtremor
array explorations* Nobuyuki Yamada 1) , Hiroshi Takenaka 2) , Masanao Komatsu 2)
University of Teacher Education Fukuoka, Munakata, Japan 1) , Okayama University, Okayama, Japan 2)
The Nansei Islands area of the southwestern part of Japan has often been damaged by large earthquakes
and tsunamis. Strong-motion prediction for this area is so important for the disaster mitigation. The basic
information for strong ground motion estimation is the subsurface velocity structure. Several seismic
explorations have been carried out in the sea area around Nansei Islands to retrieve the P-wave velocity
structure. However, few data of S-wave velocity structure for land part of these islands have been reported
except our studies (e.g. Yamada and Takenaka, 2016). Although the J-SHIS model by NIED gives threedimensional (3D) P- and S-wave velocity structures for the shallow part of the crust in the Nansei Islands aswell as the other area in Japan, they have not been seismologically validated for this area, yet. In this study,
we present the results of the microtremor array explorations at more than 40 sites in the Nansei Islands,
where an S-wave velocity 1D model is given for each site. Based on them we could improve the J-SHIS
model to construct a better 3D seismic velocity model. This velocity model could be used for seismic
motion simulations of some actual earthquakes to check the validation of the model.

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*S07-P-21
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Effect of shallow S-wave velocity structure on ground motion characteristics
at temporary aftershock observation stations of the 2016 Kumamoto
earthquake* Kosuke Chimoto 1) , Hiroaki Yamanaka 1) , Seiji Tsuno 2) , Hiroe Miyake 3) , Nobuyuki Yamada 4)
Tokyo Institute of Technology, Tokyo, Japan 1) , Railway Technical Research Institute, Tokyo, Japan 2) , The
University of Tokyo, Tokyo, Japan 3) , University of Teacher Education Fukuoka 4)
Immediately after the 2016 Kumamoto earthquake, we have performed temporary strong motion
observation for aftershocks of the event. Yamanaka et al. (2016) reported about this temporary observationand showed variety of the ground motions in the damaged areas in Kumamoto prefecture, Japan. It isobserved that the stations where severe damage was observed shows larger ground motions than the lessdamaged areas. To understand the cause of variety in the ground motion characteristics, we haveconducted microtremor array exploration at each temporary strong motion observation stations to reveal
the S-wave velocity structure at near-surface. Chimoto et al. (2016) revealed that the low velocity layer atnear-surface widely distributes in the damaged area from town of Mashiki to village of Minamiaso. This low
velocity layer theoretically contributes to large amplification on ground motions. This study compares theground motions observed due to aftershocks with the site amplification from shallow S-wave velocity
structure. The spectral ratio was computed for site amplification characteristics calculated from the shallow
S-wave velocity structures at each stations to that at the reference station as Yamanaka et al. (2016) did.
Both spectral ratio for the observation and the calculation show peak at the period of about 0.2-0.3 seconds
at most of the sites. However, large spectral ratio at the period around 0.5 sec. in observation was notobserved in calculation especially at the heavy damage sites. This indicates the difference of deep structure
which is not considered in this study. It is also investigated about the relationship between the averagevalue of spectral ratio and AVS30. It is observed good correlation that large spectral ratio at the site withsmall AVS30. However, the value for observation shows larger value than calculation. This also indicatesthe large amplification may have been caused by not only shallow but also deep structure.

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*S07-P-22
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

SATREPS MarDiM Project on Earthquake and Tsunami Disaster Mitigationin the Marmara Region and Disaster Education in Turkey* Seckin Ozgur CITAK 1) , Yoshiyuki KANEDA 2) 3) 4) , Haluk OZENER 5) , Nurcan Meral OZEL 5) 6) , Dogan
KALAFAT 5) , Narumi TAKAHASHI 1) 4) , Takane HORI 1) , Muneo HORI 7) , Mayumi SAKAMOTO 8) , Ali
PINAR 5) , Asim Oguz OZEL 9) , Ahmet Cevdet YALCINER 10) , Gulum TANIRCAN 5) , Ahmet DEMIRTAS 11)
Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Research and Development (R&D)
Center for Earthquake and Tsunami (CEAT), Yokohama, Japan 1) , Kagawa University, Takamatsu, Japan 2) ,Japan Agency for Marine-Earth Science and Technology (JAMSTEC) 3) , National Research Institute for
Earth Science and Disaster Resilience (NIED), Tsukuba, Japan 4) , Bogazici University, Kandilli Observatory
and Earthquake Researches Institute (KOERI), Istanbul, Turkey 5) , International Monitoring System
Division, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), Vienna, Austria 6) , Earthquake
Research Institute, University of Tokyo, Tokyo, Japan 7) , Disaster Mitigation Research Center, Nagoya
University, Nagoya, Japan 8) , Department of Geophysical Engineering, Istanbul University, Istanbul, Turkey
9), Department of Civil Engineering, Ocean Engineering Research Center, Middle East Technical
University, Ankara, Turkey 10) , Disaster and Emergency Training Center (AFADEM), Disaster andEmergency Management Presidency (AFAD), Ankara, Turkey 11)
Since 1939, devastating earthquakes with magnitude greater than seven ruptured North Anatolian Fault(NAF) westward, starting from 1939 Erzincan (Ms=7.9) at the eastern Turkey and including the latest 1999
Izmit-Golcuk (Ms=7.4) and the Duzce (Ms=7.2) earthquakes in the eastern Marmara Region. The only unruptured segments of the NAF in the last century are within the Sea of Marmara, and are identified as a"seismic gap" zone.
Istanbul with high population similar to Tokyo in Japan, is located around the Sea of Marmara where
severe damages expected to be generated as compound damages including Tsunami and liquefaction,
when the next destructive Marmara Earthquake occurs. It was considered that Japanese and Turkish
researchers can share their own experiences during past damaging earthquakes and can prepare for the
future large earthquakes in cooperation with each other. Therefore, in 2013 the two countries, Japan andTurkey made an agreement to start a multidisciplinary research project, MarDiM SATREPS.
The Project is consisting of 4 research groups with the following goals.
1)"Earthquake Source region observational research". OBS, Electromagnetic and Seafloor extensometer
observations has been conducted in order to identify the detailed seismic zone, fault geometry, 3D Velocity
structure and reliable crustal deformation.
2)"Tsunami prediction based on earthquake cycle simulation research" focuses on scenario earthquakes
and tsunamis occurrence along the NAF and precise tsunami simulation.
3)"Seismic characterization and damage prediction research" aims improvements and constructions ofseismic characterizations and damage predictions based on observation researches and precise
simulations.
4)"Disaster education using research result visuals from each research". Seminars with media
representatives and local authorities have been organized in order to have effective dissemination ofdisaster information flow.

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*S07-P-23
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

The ground motion signature of supershear rupture in Burrdge-Andrews andfree-surface-induced mechanisms* Jiankuan Xu , Xiaofei Chen
Southern University of Science and Technology, Shenzhen, China
There are two main mechanisms of supershear transition. One is usually called `the Burridge-Andrews
mechanism' (BAM), on which a daughter crack nucleates ahead of the main crack tip by a high enoughstress combining the peak shear stress moving at the shear wave speed developing ahead of the main cracktip (Andrews, 1976). The other one occurs on the free surface causing by the phase conversion of SV-P at
the free surface (Kaneko and Lapusta, 2010; Xu et al., 2015), which we call `the free-surface-induced
supershear' (FSI). Compared the rupture scenarios in BAM and FSI as shown, an evident different
phenomenon is observed. That is, only one secondary supershear rupture front is nucleated in the in-plane
direction in BAM whereas the secondary supershear rupture front is nucleated at the free surface in FSI.
Besides, if the level of shear stress is high enough, both tow supershear rupture fronts are nucleated. These
differences will finally results varying ground motion characteristics and radiation frequency contents. We
perform systematic studies about this ground motion signatures of tow supershear mechanism. It will offera practical tool to identify the supershear mechanism from the observation conversely and even thetectonic stress state since which cause different supershear mechanisms.

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*S07-P-24
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Observed Near-Fault Ground Motion Characteristics during the 2016
Kumamoto, Japan, Mainshock* Tomotaka Iwata , Kimiyuki Asano
DPRI, Kyoto University
Strong motions of JMA seismic intensity of 7 were observed near the surface rupture at Mashiki town andNishihara village during the 2016 Kumamoto, Japan, mainshock. We carefully integrated the observed
acceleration records to velocities and displacements with correcting the base-line change in acceleration
records, which would be caused by the effect of tilting of the seismometer. The corrected observations
show large permanent displacements, which include near-fault terms. The amounts of permanent
displacements coincide to geodetic observation results. We discuss those ground motion characteristics
and compare those with other near-fault ground motion records.

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*S07-P-25
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Different spectra in the vertical seismic observation array* Osamu Murakami , Yasuhiro Asai , Hiroshi Ishii , Takahiro Kunitomo
Tono Research Institute of Earthquake Science, Mizunami, JapanWe deployed the vertical seismic observation array in the Mizunami Underground Research Laboratory(MIU) constructed by Japan Atomic Energy Agency (JAEA). The vertical array consists of 4 seismic stations
whose depths are 100, 200, 300, 400 meters, respectively. We installed 3 components accelerometer(JEP-6A3-10, Mitutoyo co.) in each station.
Although the seismic activity around MIU in the Tono region, Japan, is not high, some inland earthquakes
occurred around MIU. We observed the seismic waves from these events in our vertical array. For an
example, we observed the seismic waves from the event occurred at 21:10 JST on September 19, 2016. The
JMA magnitude and the depth of this event are 3.0 and 7.3 km, respectively. The hypocentral distance
between this event and MIU is about 30 km. The amplitude of the initial P wave at the shallow station islarger than the one at deeper station. We calculated the Fourier spectra of the direct P and S waves of theseseismic waves. We found that the spectra in the 100-meter depth have more low-frequency (about 3 Hz)
components than the ones in other depth. There is the geological boundary with the Mizunami group andToki granite between 100 and 200-meter depth. We consider that the differences of the spectra in our array
were caused by the geological boundary.
We have a plan of installing another seismic station to the stage 500 m in MIU (The depth of stage 500 m is
500 meters from the surface).

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*S07-P-26
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S07. Strong ground motions and Earthquake hazard and risk

Surface wave propagation and magnitude (Mj) overestimates in westernJapan* Hiroki Kawamoto , Takashi Furumura
Earthquake Research Institute, Division of Disaster Mitigation Science
It is recognized that the Mj of the Japan Meteorological Agency (JMA)'s scale sometimes shows large
discrepancy between Mw. Typical examples were the Western Tottori earthquake in 2000 (Mj=7.3;
Mw=6.7) and the Yamaguchi earthquake in 1997 (Mj=6.6; Mw=5.8), both are shallow, inland earthquakes
in western Japan. Since the estimates of the Mj for shallow (h < 60 km) earthquake use the amplitude of
the ground motion recorded by long-period (T0=5 s) seismometers, the propagation of the long-period
ground motions might be different between northern and western Japan. In this study we examined thecause of such larger Mj by examining the long-period wave propagation from shallow inland earthquakes.
First we conducted regression analysis between Mj(from JMA catalog) and Mw(from GCMT catalog), for 47
inland earthquakes of shallow (h < 40 km) and large (Mj > 5.5) events occurred from Sep. 1994 to Nov.
2016 and obtained an equation of Mj = Mw + 0.16. We then selected the peculiar events which are largely
deviated from the regression line, with larger Mj in Chugoku-Kinki area and a line area from south
Fukushima to south Niigata, and smaller Mj in Tohoku area.
We then examined the strong motion record of the K-NET and KiK-net for the 2000 Western Tottori and the2004 Mid Niigata earthquakes, and find that the attenuation of the long-period (5 s) ground displacementfrom the Mid Niigata earthquake is very strong with propagation in northern Japan, while very weak for theWestern Tottori earthquake. Since the large ground motions appear in tangential motion, the observed
large ground motion in western Japan is expected the fundamental-mode Love waves.
Therefore, the overestimates of the Mj in western Japan might occur due to the efficient development of thelong-period (5 s) Love wave from shallow, strike-slip fault sources which propagates longer distances
without significant attenuation and dispersion, probably due to the peculiarity of the shallow structure inthat area.

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*S08-1-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

Paleoseismological evaluation and surface faults of the 2016 Kumamoto
earthquake along Futagawa fault zone, central Kyushu, Japan* Takashi Azuma
Geological Survay of Japan/AIST
Futagawa fault zone was a main part of the source fault of the 2016 Kumamoto earthquake of Mj 7.3, which
was the first case that a large earthquake accompanied with surface fault occurred on an active fault zone
evaluated by the Earthquake Research Committee of Headquarters of the Earthquake Research Promotions(HERP). Therefore it is good opportunity to compare an evaluation before earthquake with surface faulting
accompanied with the 2016 Kumamoto earthquake.
Futagawa fault zone is located in Kumamoto prefecture in Central Kyushu. HERP published Longterm
evaluation of this fault zone in 2002 and 2013. Paleoseismological surveys were conducted by Kumamoto
prefecture in 1995 and by AIST in 2007 and 2015. Paleoseismological trenching survey at Tanaka site by
Kumamoto prefecture showed that the accumulated offset of sediments including AT volcanic ash (28 ka)
was 5.2 m. They estimated average interval as 0.25 m/ka. And they also interpreted this offset was formedby 2 or 3 faulting events based on the observations of deformation of geological layers on the trench walls.
Maximum surface displacement accompanied with the 2016 earthquake along the Futagawa fault zone wasca. 2 m in the central part of this fault. It is consist with active fault evaluation by HERP. But amount of slip
at Tanaka site caused by the 2016 Kumamoto eartquke was 0.5 m in the right-lateral component. Therefore
amount of slip was over-estimate at this site, whereas recurrence of this fault was underestimated. If 0.5 m
of displacement was recognized as a parameters of the characteristic deformation before occurrence of the2016 Kumamoto earthquake, the recurrence interval would be rather short and probability of occurrence ofearthquake would be rather high.

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*S08-1-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

Paleoseismic history of the Hinagu fault zone, Kumamoto, Japan;
Preliminary results of a trench excavation survey on the Takano-Shirahata
segment* Yoshiki Shirahama 1) , Yukari Miyashita 1) , Takashi Azuma 1) , Tetsuhiro Togo 1) , Masao Kametaka 2) , Yuji
Suzuki 2)
Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology 1) , Dia
Consultants Co. Ltd. 2)
We report preliminary results of the trench excavation survey of the Hinagu fault zone, one of the source
faults of the 2016 Kumamoto Earthquake (Mw 7.0).
The Hinagu fault zone, striking NNE-SSW, is 81-km-long, strike-slip fault with dextral sense of shear
accompanying vertical displacement. The fault zone is composed of three segments, Takano-Shirahata
segment, Hinagu segment, and Yatsushiro Sea segment, from north to south (Headquarters for Earthquake
Research Promotion, 2013). Associated with the 2016 Kumamoto earthquake series, approximately 6-kmlong surface ruptures were produced by dextral strike-slip motion along the northern part of the TakanoShirahata segment (Shirahama et al., 2016). We conducted paleoseismological investigations on the TakanoShirahata segment, in order to estimate the future earthquake potential caused by each segments and theentire of the fault zone.
The Yamaide trench site is located on the middle part of the Takano-Shirahata segment. Soon after the2016 Kumamoto Earthquake, we found slight tilting of the rice field surface and en echelon clacks at thesouthernmost part of the surface rupturing area, and we dug a trench across the ruptures. On the trenchwall, fluvial sediments were observed and several obvious reverse faults cut them. The faults steeply dippedto the east and branched upward.
Based on the detailed observations for crosscutting relation between faults and sediments, we recognized
several surface rupturing event horizons. The accumulative vertical displacements along the faults strongly
support them. The results of radiocarbon dating showed that the three or four surface rupturing events after
15,000 yBP. In this presentation, we will report the seismic history of the Takano-Shirahata segment of the
Hinagu fault zone revealed by the trench excavation survey, and discuss the relationship with paleoseismic
histories of other segments.

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*S08-1-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

Recent indications to improve evaluation of short active faults provided by
the 2016 Kumamoto and Ibarakiken-hokubu, Japan, earthquakes* Shinji Toda 1) , Daisuke Ishimura 2)
Tohoku University, Sendai, Japan 1) , Tokyo Metropolitan University, Tokyo, Japan 2)
Inland large earthquakes occur not only on major active faults but also in areas no active fault and/or
minor short fault mapped. The number of potential destructive earthquakes of M~7 estimated from the
major active faults would be significantly underestimated. It leads a conservative evaluation thatseismogenic fault up to ~20 km is hidden or slightly truncated by the surface, and an M~7 earthquake is
assigned on each short fault. Based on field investigation and InSAR analysis for the 2016 Kumamoto
earthquake, we here counter-argue that some of such minor and low-slip-rate faults might have beendeveloped by insignificant but frequent slips triggered by nearby large earthquakes. Another implication toproperly evaluate such short faults is provided by recent M~6 class earthquakes at Ibaraki-ken-hokubu, innorthern Kanto region, Japan. March 19, 2011 (Mj=6.1) and November 22, 2016 (Mj=6.3) Ibaraki-kenhokubu earthquakes that might have shared a same short fault based on InSAR images and field survey. It
enables us to interpret many short active faults might have been also developed by more frequent slip at
only upper seismogenic layer due to M~6 earthquakes.

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*S08-1-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

Late Quaternary Faulting Along the Different Segments of the Philippine
Fault in Mindanao Island, Philippines* Jeffrey Perez 1) , Hiroyuki Tsutsumi 2)
Philippine Institute of Volcanology and Seismology - Department of Science and Technology (PHIVOLCSDOST), Quezon City, Philippines 1) , Department of Geophysics, Kyoto University, Kyoto, Japan 2)
The Philippine fault is one of the most active tectonic structures in the western Pacific region that has
generated at least 10 surface-rupturing earthquakes in the past 400 years. This sinistral strike-slip fault,
with a length of about 1250 km, traverses the entire Philippine archipelago from northwestern Luzon in thenorth to eastern Mindanao Island in the south. Consisting of several segments, this arc-parallel and NNWtrending fault is related to the oblique subduction of the Philippine Sea plate beneath the archipelago.
In Mindanao Island, the Philippine fault traverses the eastern portion of the island for about 320 km. It ischaracterized by fault parallel ridges, systematic deflection of streams and fluvial terraces, sag ponds andtectonic scarps related to historical surface rupture. Based on tectonic geomorphic mapping using aerial
photos and field surveys, the Philippine fault in Mindanao is divided into at least nine geometric segments
separated by geometric discontinuities like dilatational steps and branching. In terms of its activity, at least
two historical surface-rupturing earthquakes have been documented such as the 1879 M7.4 Surigao
earthquake and the 1893 M7.3 Monkayo earthquake. Paleoseismic investigations conducted along thedifferent segments in Mindanao also revealed multiple faulting events during the late Quaternary.

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*S08-1-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

Paleoseismology of the Himalayan Frontal Zones* Koji Okumura 1) , Javed Malik 2)
Hiroshima University, Higashihiroshima, Japan 1) , Indian Institute of Technology Kanpur, Kanpur, India 2)
The damages of the April 25 2015 Gorkha earthquake aroused much concern about seismic risks along theHimalayan front though the rupture occurred only in a deeper part of the megathrust. 20 years of
paleoseismological research have brought a lot of information on time and space of past earthquakes.
However, we are still far from confidence on our ability to assess sesismic risks owing to the lack of
information on both inter-plate and intra-plate earthquakes. From 2010 to 2014 within a JICA-JST SATREP*
project in India, we have conducted paleoseismological studies on frontal and upper-plate faults at 7 sites.
A few strike-slip faults in the upper plate were newly recognized and one of them, the Kangra Valley fault is
supposed to be the source of the 1905 earthquake instead of the frontal fault. This indicates a possibly near
future frontal earthquake in NW India. The last large event from the central seismic gap is still
controversial, but one big event in 15 century or 1505 is being confirmed in one of our trenches. The next
earthquake in the gap will be the most serious issue for India and Nepal. In order to know more about the
future 1505 type earthquake, we need further studies in Nepal, where there is no consensus on the rupture
sequence in space and time in the last millennium. (*Science and Technology Research Partnership for
Sustainable Development by Japan International Cooperation Agency and Japan Science and Technology
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*S08-2-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

Large earthquakes in historical and pre-historical times in Switzerland: An
overview of earthquake induced effects* Donat Faeh 1) , Gabriela Gassner-Stamm 1) , Michael Strasser 2) , Remo Grolimund 1) , Stephanie Wirth 3) ,Katrina Kremer 1)
Swiss Seismological Service, ETH Zurich 1) , Geological Institute, University of Innsbruck 2) , Centre for
Hydrogeology and Geothermics, University de Neuchatel 3)
During the last years, many studies have investigated pre-historical and historical earthquakes from traces
left in sediments and the environment. The goal of this study is to gather and systematize available data
potentially relevant for understanding seismic activity in Switzerland before the start of reliable historical
records and to analyze it for the first time all together. The Earthquake Catalogue of Switzerland (ECOS-09)
covers the period from 250 to 2009 AD and is only scarcely populated with events before 1100 AD. The
new database extend back 0.5 Ma years, but is more rich in information for the time since 20'000 BP.
Primary data for this new data collection come from recent paleoseismic studies and from studies fromother disciplines (Sedimentology, archaeology, speleology, geomorphology and historical research) that
focused on other goals, but include observations of potential relevance for understanding past strong
ground shaking. Considering the combined data set, we identify 23 periods with an increased number ofpossible earthquake-induced effects. While all these effects could belong to various small earthquakes, or
have a totally different, earthquake-independent origin, one admissible hypothesis we want to follow up in
this study is also, to cluster these effects within time periods of increased number of observations, and toassign them to single earthquakes. For events after 1600 AD, highly reliable historical records are available,
and earthquake induced effects can be assigned to known historical earthquakes. For the older period,
eight events can be identified with paleoseismological evidence distributed over a wider area, possibly
indicating a strong earthquake or a period of overall increased seismicity throughout Switzerland. The mostprominent event occurred in the period 1900-2270 cal years BP. If assumed to be one single earthquake, itwould be the strongest earthquake in the last 5'000 years in Switzerland.

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*S08-2-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

Application of the paleoseismic record of great Cascadia earthquakes for use
in the 2015 and 2020 National Building Code of Canada seismic hazard
maps* John Adams 1) , Stephen Halchuk 1) , Garry Rogers 2) , Trevor Allen 2) 3)
Geological Survey of Canada, Ottawa, Canada 1) , Geological Survey of Canada, Sidney, Canada 2) ,Geoscience Australia, Canberra, Australia 3)
The 2005 National Building Code of Canada (NBCC2005) used a deterministic model to derive the shaking
from great Cascadia subduction interface earthquakes. The resultant values were used for design only ifthey exceeded the hazard values from other sources. NBCC2015 introduced a probabilistic treatment ofCascadia's Juan de Fuca segment. The rate of great earthquakes used the complete-rupture chronology
established from turbidite analysis by Goldfinger et al. (2012 pre-print). Partial, southern ruptures were
neglected as being too distant from Canada. The analysis used 18 turbidites of a 10,097-year record, givinga mean interval of 532 years and a standard deviation of 234 years. The rupture intervals (time since thelast earthquake) were turned into magnitudes using fixed rupture length and width together with choices
for slip rate and crustal rigidity to give central, upper and lower recurrence rates. Magnitudes were in therange 8.55-9.28. Three choices for the down-dip extent of the rupture were used, to capture the uncertainty
in how close the energy release would be to sites on land. The model was combined with other crustal andinslab sources to give probabilistic seismic hazard estimates. The analysis neglected issues of partial
rupturing and event clustering. Shaking from the offshore Cascadia subduction fault dominates 2015
design values in Victoria and Vancouver for periods > 1 s. For the NBCC2020 maps an updated turbidite
history adds 4 events off Washington that decreases the mean interval to 434 years and reduces thestandard deviation to 168 years, making the events appear more regular. The change in rate increases theonshore seismic hazard by about 9%.

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*S08-2-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

The Great 1787 Earthquake (M 8.6) and Tsunami along the Mexican
Subduction Zone – history, geology and tsunami hazard assessment* Maria Teresa Ramirez Herrera 1) , Marcelo Lagos 2) , Avto Goguitchaichvili 3) , Maria Luisa Machain 4) , AnaCarolina Ruiz-Fernandez 4) , Gerardo Suarez 5) , Maria Ortuno 6) , Margarita Caballero 5)
Laboratorio Universitario de Geofisica Ambiental & Instituto de Geografia, Universidad Nacional Autonoma
de Mexico, Mexico City, Mexico 1) , Instituto de Geografia, Laboratorio de Tsunamis, Pontificia Universidad
Catolica de Chile, Santiago, Chile 2) , LIMNA, Instituto de Geofisica, Unidad Michoacan, UNAM, Campus
Morelia, Morelia, Mexico 3) , Instituto de Ciencias del Mar y Limnologia, UNAM, Ciudad Universitaria,
Ciudad de Mexico, Mexico 4) , Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Ciudadde Mexico, Mexico 5) , Ciencias de la Tierra, Universidad de Barcelona, Barcelona, Spain 6)
The 1787 great earthquake (M 8.6) triggered a deadly tsunami that poured over the coast of Oaxaca,
Guerrero, and Chiapas, along more than 500 km of the Mexican Pacific coast and up to 6 km inland. Thistsunami, according with historical documents, destroyed mostly farmlands and livestock, and damaged few
villages since the density of population was sparse at the time.
We report first on geological evidence from the Corralero lagoon and adjacent coastal plain that seem inagreement with historical accounts. The deposit left by the 1787 tsunami can be traced along a transect ofcores and test pits from the coastline and up to 1.6 km inland. The test pits showed an anomalous sandlayer that was deposited in a single event in the swales of a series of beach ridges. The anomalous layer isalmost continuous along the transect, about a 1000 m-long, and is formed of coarse to medium sand, atvariable depths up to 36 to 64 cm, with variable thickness, reaching about 28 cm and pinching up with the
distance from the coastline. We used stratigraphy, grain size, microfossils (foraminifera and diatoms),
magnetic susceptibility and anisotropy of magnetic susceptibility proxies to reveal the nature of thisanomalous sand layer. Stratigraphy, abrupt contacts, and magnetic susceptibility support a sudden andrapid event, consisting of sands transported most probably by an extreme sea-wave far inland. Furthermore,
based on the accounts of the 1787 earthquake (M 8.6) and tsunami, and estimates from Pb210
sedimentation rates, we suggest that this is the tsunami deposit left by the 1787 event. Tsunami modelingwill further enhance the hazard and risk assessment of this area in Mexico.

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*S08-2-04
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

Has the unusual “mega-tsunami" ever occurred along the Nankai Trough?
* Osamu Fujiwara
Geological Survey of Japan, AIST, Tsukuba, Japan
Following the 2011 Tohoku-oki earthquake and tsunami, Japanese government reviewed their policies forearthquake and tsunami disaster management and mitigation measures. This review includes the idea of
defining maximum magnitudes for earthquake and tsunami in the Nankai Trough subduction zone; M9earthquake is supposed as the maximum possible class of earthquake in this area. However, at least in theeastern Nankai Trough region, this supposition does not concern the paleotsunami data such as tsunami
inundation area reconstructed from the tsunami deposits. As a case study, we have researched the tsunami
deposits by the excavation survey and reconstructed the Holocene tsunami inundation history in the
Hamamatsu plain, facing the eastern Nankai Trough. Because of the progradation of the beach system
during the last 7000 years, about 4 km seaward migration of the coastline has occurred in Hamamatsu
plain. We reconstructed the location of the former coastlines based on the beach ridges, and estimatedtheir ages by using the radiocarbon dating of the beach deposits. We found some tsunami sand layersintercalated in the inter beach ridge marsh deposits and determined their ages by radiocarbon dating
method. Taking the location of contemporary coastline into account, we have not recognized the tsunami
deposit suggesting an exceptionally large inundation area in the last 4000 years. It was found from theresult that “mega-tsunamis" with much larger size than historical tsunamis have not occurred in thisregion at least in the last 4000 years.

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*S08-2-05
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

A large slip area of the 2011 Tohoku-oki earthquake has been alreadyruptured by the 1611 Keicho Tsunami earthquake (Mw9.0)* Yuichiro Tanioka , Genta Fukuhara
Hokkaido University, Sapporo, JapanThe 1611 Keicho Tsunami earthquake generated huge tsunamis and caused a disaster along the Pacificcoast of Tohoku area from Fukushima to Miyako. There are several historical documents, but some of themwere controversial. Recently, Ebina and Imai (2012) checked historical documents in detail and made themost reliable data set of the tsunami inundation of the 1611 Keicho Tsunami. We compared the data set
with the tsunami inundation of the 2011 Tohoku tsunami and found that the tsunami from the 1611
tsunami earthquake inundated larger distance than the 2011 Tohoku tsunami at many places.
The numerical tsunami inundation computations were carried out along the Pacific coast of Tohoku wherereliable tsunami evidences of historical documents were available, such as tsunami evidence about 30 mheight at Koyadori in Iwate or tsunami evidence at Suwa in the Sendai plain about 7 km away from thecoast. Result indicates that the tsunami generated from the combination of two rectangular fault models,
north fault with the length of 100 km, the width of 100 km, and the slip amount of 80 m and south fault
with the length of 150km, the width of 100 km, and the slip amount of 40 m, explains all reliable evidencesvery well. The moment magnitude of the 1611 tsunami earthquake is calculated to be 9.0 by assuming thatthe rigidity is 3 x 10**11 N/m**2.
The northern part of the fault is located the north of the large slip area of the 2011 Tohoku-oki earthquake.
The southern part of the fault, where 40 m slip was estimated, is located at the almost same area of thelarge slip area of the 2011 Tohoku-oki earthquake. This suggested that the 2011 Tohoku-oki earthquake reruptured the southern part of fault area ruptured by the 1611 Keicho tsunami earthquake. Because theplate convergence rate of Pacific plate along the Japan Trench is about 9 cm/year. A large slip of about 45
m estimated for the 2011 Tohoku-oki earthquake is similar to 36 m estimated from the convergence rate.

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*S08-P-01
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

Description and interpretation of the surface ruptures in northwest of theouter rim of the Aso caldera triggered by Kumamoto Earthquake* Hiroshi UNE 1) , Takayuki NAKANO 1) , Satoshi FUJIWARA 1) , Tomokazu KOBAYASHI 1) , Yu MORISHITA, Kazumi IWATA 1) , Hiroshi, P. SATO 2) , Hiroshi YAGI 3)
Geospatial Information Authority of Japan, Tsukuba, Japan 1) , Nihon University, Tokyo, Japan 2) , Yamagata
University, Yamagata, Japan 3)
1)

Associated with the 2016 Kumamoto Earthquake, many surface ruptures were emerged in northwest areaof the outer rim of the Aso caldera, which were located apart from the Futagawa and Hinagu Fault System,
considered as the source fault of the earthquake, and rarely accompanied by seismicity. Overall distribution
and deformation patterns of the surface ruptures in this area were shown by satellite radar interferometry
analysis using ALOS-2 data, suggesting half-graben-like normal faulting triggered by north-south tensional
stress field derived secondarily from the stress changes associated with the main source faulting (Fujiwara
et. al. 2016, Morishita et. al. 2016). We carried out field surveys and identified characteristic surface
ruptures at many places. Some of those have characteristics in shape that can be misread as surface
earthquake faults. Recently such passive, or “accompanied" deformation of existing structure triggered by
the change of stress field or seismic motion associated with earthquakes have been often reported since
SAR interferometry has enabled the seamless and detailed understanding of surface deformation. Thesepassive deformation might have occurred not specially for the reported events but universally in nature.
Such passive deformation may be possibly included in the list of past surface earthquake faults and events
recognized by trench surveys. We should start the discussion on the issue of reexamination of identificationof characteristic earthquake events of active faults.

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*S08-P-02
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

Temporal clustering and occurrence probability of large earthquakes on
active faults in Japan* Hisao Kondo 1) 3) , Kazuhiro Iwakiri 2) 3) , Hirota Tani 3) , Kenji Satake 4)
Geological Survey of Japan, AIST, Tsukuba, Japan 1) , Japan Meteorological Agency, Tokyo, Japan 2) ,Earthquake and Disaster-Reduction Division, MEXT, Tokyo, Japan 3) , ERI, The University of Tokyo, Japan 4)
The 2016 Kumamoto earthquake (Mj 7.3) caused devastating damages and more than 180 casualties. It
occurred in an active fault zone and surface ruptures appeared mostly along the previously mapped active
faults (HERP, 2016). Meanwhile, the occurrence of large (greater than Mj 6.8) earthquakes on minor active
faults has been more frequent in recent years. We here re-examined the frequency and probabilities oflarge earthquakes on active faults in the last 125 years, based on the historical catalogue of damaging
earthquakes in Japan and previous reports. In total, 28 large damaging crustal earthquakes occurred in thelast 125 years, and 22 of them (80 %) are related with mapped active faults, and 6 (20 %) are not. The 22
earthquakes in 125 years yield the average recurrence interval of 5.7 years. Using the individual
recurrence intervals, 4.6+/-3.7 years is obtained for all damaging earthquakes and 6.0+/-5.5 years for thoseon active faults. The frequency distribution of recurrence intervals shows a bimodal distribution consistingof two groups. The average recurrence interval in the shorter group is 2.9+/-1.5 years. The longest interval
is 17 years before the 1995 Kobe earthquake. It is thus apparent that the occurrence of the damaging
earthquakes exhibits the temporal clustering and long quiescence periods. The temporal clustering isrelated with the occurrence of mega-thrust earthquakes such as the 2011 Tohoku earthquake, the 1944
Tonankai and 1946 Nankai earthquakes. Under the assumption of Poisson process, we obtained 72%, 92%,
100% probabilities within the next 5, 10 and 30 years for all damaging large earthquakes, and 62%, 86%,
99.7% for active fault earthquakes, respectively. If the present day is within a clustering period, theprobability increases up to 68-97% within the next 5 years. To forecast them more accurately, theearthquake probability based on the BPT model for individual active faults and time-dependent seismic
hazard assessment are necessary.

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*S08-P-03
IASPEI Symposium / IASPEI02. Earthquake Hazard, Risk and Strong Ground M
otion / S08. Paleoseismology and paleotsunami studies: their potential and limitation

REFINEMENT OF PHILIPPINE TSUNAMI HAZARD MAPS: The TsuHaMEI
Project* Analyn D. Aquino , Jayvie H. Nadua , Joan C. Salcedo , Maria Leonila P. Bautista , Ishmael C. Narag ,Bartolome C. Bautista , Renato U. Solidum, Jr.
Philippine Institute of Volcanology and Seismology
The TsuHaMEI (Tsunami Hazard Map Enhancement using Interferometric Synthetic Aperture Radar(IfSAR)) Project of the Philippine Institute of Volcanology and Seismology (PHIVOLCS), initiated in 2016,
aims to refine 1: 50,000 scale Philippine tsunami hazard maps, which were previously generated under the
DOST-GIA Tsunami Project in 2007 and the READY Project from 2007 to 2013.
The TsuHaMEI Project finetunes tsunami inundation extent defined by previous projects by utilizing
topographic contours extracted from 5m x 5m resolution 2013 IfSAR digital terrain model which has
recently been available in the country. Resulting enhanced tsunami maps now indicate one-meter-interval
tsunami wave height gradations, unlike previous maps which only showed generalized inundation areas.
Maximum tsunami inundation distances and wave heights are adopted from previous results that used
empirical and modelling techniques.
For the period 2016-2017, a total of 22 out of 67 tsunami prone provinces would have been completed.
The maps are distributed to respective local government units for their use for local disaster mitigation andpreparedness planning.
Keywords: Philippines, tsunami, TsuHaMEI, IfSAR, PHIVOLCS

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*S09-1-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Round-the-world seismic echo effect in aftershock sequences of strong
earthquakes: a statistical analysis* Alexey Zavyalov 1) , Oleg Zotov 2) , Anatol Guglielmi 1) , Ivan Lavrov 2)
Schmidt Institute of Physics of the Earth RAS 1) , Borok Geophysical Observatory of Schmidt Institute ofPhysics of the Earth RAS 2)
The existence of the effect of the round-the-world seismic echo was shown in the work on a broad evidence
base, including hundreds of the main shocks and thousands of aftershocks. The effect is that the surface
waves excited in the earthquake source by the main shock makes a complete revolution around the Earthand excites strong aftershock in the epicentral area of the main shock. The physical nature of the effect isthat a critical concentration of wave energy in epicenter is created by converging surface waves underachieving of epicentral area. Effect of the first seismic echo is manifested most clearly. Thus, in this reportconfirmed the hypothesis of the authors on the activation of rock failure under the cumulative impact of theround-the-world seismic echo onto the focal area unloading ("cooling off") after the main shock. Spatial
patterns of effect manifestation and independence probability of its occurrence from the magnitude of themain shock were established. Theoretically predicted and experimentally observed phenomenon of theseismic echo can be used to improve the reliability of strong aftershocks forecast in determining the
scenario of seismic process in the epicentral area of occurred a strong earthquake.
This work was supported by the Russian Foundation for Basic Research, the project # 15-05-00491.

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*S09-1-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Synchronization of Stick-Slip Oscillator by Periodic External Forces–Implications for Earthquake Activity Rhythms* Kazuro Hirahara
Kyoto University, Kyoto, Japan
Activities of small and large earthquakes and slow slip events (SSEs) have several rhythms, such as
periodicity and seasonality, and earthquake recurrences on faults. They are caused by external forces suchas tidal forces and interaction between fast or slow slips of earthquakes.
‘Synchronization'is now recognized as a universal concept in nonlinear sciences. In this respect, I
investigate responses of stick-slip oscillator to periodic external forces. In the numerical experiments, I
examine stick-slip motions of a spring-slider pulling with a constant rate, where the friction following thelaboratory-derived rate and state friction law is working on the contact surface between the block and thefloor,
I found m:n synchronization, which is called as Devil's Staircase, when applying periodic external forces
with the amplitudes of 1/10 and 1/100 relative to the stress changes in cycles. Synchronization occurs incases of fe:fc(Tc:Te)=m:n (m and n are coprime integers) where fe(Te) and fc(Tc) are frequencies (periods)of external force and simulated system, respectively. In the non-synchronization cases, there appear somecomplex irregularities in the recurrence intervals with large fluctuations.
Earth and ocean tidal loading has stress with the amplitude of kPa-10kPa, and such loading may cause
synchronization of SSE with small stress changes of several 100 kPa. Numerical experiments show apossible existence of repeating large long-term SSEs causing stress perturbation of MPa in the downdip ofmegathrust zone. My experiments indicate a possible synchronization of the megathrust recurrences. The
recurrence intervals of large and megathrust earthquakes have some complex irregularity. Thesefluctuations may be caused by some complex non-synchronization effects between some adjacent fault
segments.
Finally, we add some discussions on the viscoelastic cases where the elastic spring is replaced by astandard linear viscoelastic element.

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*S09-1-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Synchronization and chaotic behavior of earthquake cycles in a model withinteracting fault patches* Naoyuki Kato
Earthquake Research Institute, University of Tokyo, Tokyo, Japan
Numerical simulations are conducted to investigate the effect of interacting fault patches on complex
earthquake cycles. In the model, circular patches of steady-state velocity-weakening frictional property areembedded on a planar fault in uniform elastic medium, and shear loading with a constant slip rate isapplied to the fault. When a single isolated velocity-weakening patch exists on a fault plane, earthquakes
repeatedly occur in the patch at a constant recurrence interval in usual cases. When two or three patches
exist, earthquakes on the patches are synchronized with each other for cases where natural recurrence
intervals of the patches are almost the same or close to integer multiple, resulting in single- or multiperiodic earthquake occurrence. In other cases, earthquake cycles tend to be chaotic, where the timeintervals between successive earthquakes vary and no periodicity is found. Chaotic behavior of earthquake
cycles is observed also for cases where slip in a velocity-weakening patch changes from seismic toaseismic. In these chaotic earthquake cycles, long-term forecast of earthquakes is impossible in strict sense.
However, statistical property of earthquake recurrence can be used for probabilistic forecasts. An iteration
map of the recurrence intervals of simulated earthquakes in chaotic pattern is expressed by a simple curve,
indicating that the timing of an event is predictable from the previous time interval, and the sequence ofslip events exhibits deterministic chaos.

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*S09-1-04
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Observations and modeling of short-term phenomena in the preparatory
stage of large earthquakes* Kiyoshi Suyehiro 1) 2) , Selwyn Sacks 2) , Paul Rydelek 2) , Deborah Smith 2) , Tetsuo Takanami 2)
JAMSTEC, Kanagawa, Japan 1) , DTM, Carnegie Institution for Science, Washington DC, USA 2)
Past large earthquakes have ample but somewhat inconsistent short-term precursor reports. Utilising theseinformation as prediction before a big event has proved to be formidably difficult. Meanwhile the data
quantity has increased rapidly requiring high performance computers to analyse seismic or geodetic data.
This trend has greatly contributed in understanding the details of how earthquakes rupture, but not verymuch on how they prepare themselves. We now know that slow slips contribute to stress re-distribution tocomplicate the matter.
We refer to a simple cellular automaton model of earthquake adopting Coulomb's failure criterion (Sacks
and Rydelek, 1995) and incorporate the effect of dilatancy hardening. This numerical experiment
reproduces Gutenberg-Richter's law, b-value decrease with tectonic stress increase and cut off of larger
magnitude events after dilatancy hardening sets in. All these are observed in nature.
We speculate based on observations that fluid redistributions become evident when dilatancy breakdown
starts to occur leading to triggering a large earthquake. Currently, this phase of the earthquake preparation
process is not well established by observations, because they tend to appear sparsely and weakly. We
review the Tokai area of the Nankai Trough where an M8 earthquake may be pending considering 1891
Nobi earthquake possibly affecting the sequence of >500 year historical recurrence of M8 events. We notethat magnitude dependent seismic quiescence may be evident above the subjecting plate in Tokay area.
This suggests that the ongoing preparatory stage is advancing involving a volume outside the platesubduction boundary where the eventual M8 may occur. We propose that the detection and understanding
the current phase of preparation need to consider all possible models with physical plausibilities.

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*S09-2-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Remote triggering of earthquakes as a possible stress-meter: the case of the2016 M7.3 Kumamoto (Japan) mainshock* Bogdan Enescu 1) , Kengo Shimojo 2) , Anca Opris 2) , Yuji Yagi 3)
Department of Geophysics, Kyoto University, Japan 1) , Graduate School of Life and Environmental
Sciences, University of Tsukuba, Japan 2) , Faculty of Life and Environmental Sciences, University ofTsukuba, Japan 3)
Activation of seismicity at remote locations due to the passage of seismic waves from large earthquakes iswell-documented. However, distant earthquake triggering is scarce in Japan, with the notable exception of
the remote seismicity activated by the 2011 M9.0 Tohoku-oki earthquake. Here we report on a relatively
widespread remote triggering of small events following the 2016 M7.3 Kumamoto earthquake andhypothesize on its causes.
We have processed waveform data recorded by high-sensitivity Hi-net and broadband F-net stations,operated by NIED, as well as JMA stations.
The activated seismicity correlates well with the passage of surface waves from the Kumamoto earthquake.
The furthest triggered event was observed at Akan volcano (Hokkaido) at ~1630 km epicentral distance.
Triggering has been also observed at other volcanoes in Tohoku, Chubu and around Izu Peninsula. Some
active fault areas like Tottori and Noto Peninsula were also activated. The dynamic stresses at the triggered
locations range from several to tens of kPa. Since most of the remotely triggered earthquakes wereobserved at volcanoes, the excitation of crustal fluids was likely the main triggering mechanism.
We found that the regions activated this time, in particular some volcanic areas in Tohoku, have been also
activated after the 2011 Tohoku-oki earthquake. We hypothesize that mechanical weakening of apressurized crust in these regions due to the 2011 megathrust might be responsible for an increased triggerability. In addition, the activation of some active crustal faults might be related to the levels of tectonic
stress along these fault lines. These observations suggest that remote triggering might be used as a stressmeter at volcanoes and active faults.
Reference paper:
Enescu, B., Shimojo, K., Opris, A., and Y. Yagi, Remote triggering of seismicity at Japanese volcanoes
following the 2016 M7.3 Kumamoto earthquake, Earth, Planets and Space, 68:165,
doi:10.1186/s40623-016-0539-5, 2016.

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*S09-2-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Coulomb Stress Transfer and Accumulation on the Sagaing Fault, Myanmar
over the Past 110 years and Its Implications for Seismic Hazard* Xiong Xiong 1) 2) , Bin Shan 1) , Yuming Zhou 3) , Shengji Wei 4) , Yongdong Li 1) , Rongjiang Wang 5)
China University of Geosciences, Wuhan, China 1) , Institute of Geodesy and Geophysics, Chinese Academyof Sciences, Wuhan, China 2) , Saint Louis University, Saint Louis, USA 3) , Nanyang Technological
University, Singapore, Singapore 4) , GFZGermanResearchCentreforGeosciences, D-14473
Potsdam,Germany 5)
The seismic hazard of Myanmar has attracted little attention from the world in the past. The economy andurban population of Myanmar is presently growing rapidly. In contrast, the buildings in big cities, such as
Mandalay, Nay Pyi Taw and elsewhere, are poorly constructed. Therefore, many more people are now at
risk from the earthquakes than before. So, the seismic hazard of Myanmar is drawing rapidly increasing
attention from the world. The Sagaing Fault (SF), an active right-lateral strike-slip fault passing throughMyanmar, has been being the source of serious seismic damage of the country. Thus, awareness of seismic
hazard assessment of this region is of pivotal significance by taking into account the interaction andmigration of earthquakes with respect to time and space. We investigated a seismic series comprising ten
earthquakes with M>6.5 that occurred along the SF since 1906. The Coulomb failure stress (CFS) modelingexhibits significant interactions among the earthquakes. After the 1906 earthquake, 8 out of 9 earthquakes
occurred in the positively stress-enhanced zone of the preceding earthquakes, verifying that the hypothesisof earthquake triggering is applicable on the SF. Moreover, we identified 3 visible positively stressed
earthquake gaps on the central and southern SF, on which seismic hazard is increased.

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*S09-2-04
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Testing the Coulomb stress triggering hypothesis for three recent megathrustearthquakes* Takeo Ishibe 1) , Yosihiko Ogata 2) 3) , Hiroshi Tsuruoka 2) , Kenji Satake 2)
Association for the Development of Earthquake Prediction, Tokyo, Japan 1) , Earthquake Research Institute,
the University of Tokyo, Tokyo, Japan 2) , The Institute of Statistical Mathematics, Tokyo, Japan 3)
We test the static Coulomb stress triggering hypothesis for three recent megathrust earthquakes (the 2004
Sumatra-Andaman earthquake, the 2010 Maule earthquake, and the 2011 Tohoku-Oki earthquake) using
focal mechanism solutions for actual earthquakes as receiver faults to calculate Coulomb stress changes.
For the 2004 Sumatra-Andaman and 2011 Tohoku-Oki earthquakes, the median values of the Coulomb
stress changes for 100 consecutive earthquakes revealed temporal changes from approximately zero before
the megathrust earthquake to significant positive values following the mainshock, followed by a decay overtime. Furthermore, the ratio of the number of positively to negatively stressed receiver faults increased after
the megathrust. These results support the triggering hypothesis that the static stress changes imparted bymegathrust earthquakes cause seismicity changes. This is in contrast to the results of a previous study thatused optimally orientated receiver faults to calculate Coulomb stress changes, and this difference indicatesthe importance of considering the spatial and temporal heterogeneities of receiver fault distributions. For
the 2010 Maule earthquake, however, the results are strongly dependent on fault-slip models. Since mostreceiver faults are concentrated in the mainshock source region, slip models significantly affect thecomputed Coulomb stress changes and sometimes cause anomalous stress concentrations along the edgeof each sub-fault.

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*S09-2-05
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Fluid injection effects on induced seismic activity in multi-degree-of-freedom
rate-and-state model* Sergey Turuntaev 1) 2) 3) , Vasily Riga 3)
Institute of Geosphere Dynamics, Russian Academy of Sciences, Moscow, Russia 1) , Moscow Institute ofPhysics and Technology, Moscow, Russia 2) , All-Russian Research Institute of Automatics, Moscow, Russia
3)

The fluid injection influence on induced seismic activity was studied by numerical calculations of thepeculiarities of motions of a system of blocks (consisted from up to 25 blocks) elastically connected witheach other and linked by elastic springs to a constant-velocity moving driver (multi-degree-of-freedom
spring-block model). The rate-and-state friction model with two-parametric friction law was adopted fordescription of the friction between the blocks and the substrate. Initially, the block system was in steadysliding state, then its state was disturbed by the fluid injection and corresponding pore pressure increase.
Influences of the model parameters (number of the blocks, the spring stiffness, velocity weakening
parameter) on the process of the induced seismicity variations were considered.
It was shown that the considered spring-block system could exhibit different types of the motion patterns.
The motion could be periodic or chaotic; the magnitude of the seismic events depends on fragmentation of
the fault system (the number of blocks in considered model) and may have different values. The analysis
shows, that the stiffness of link between the blocks affects significantly the behaviour of the model andresulting seismicity, so the main seismic activity could appear directly after the start of the fluid injection orin the post-injection phase. Different manifestations of the injection influence on the seismicity areobserved also in the real cases. However, the parameters in the rate-and-state model are usually taken fromlaboratory experiments, and it is hard to believe that one should use the same values to describe the real
scale phenomena. Yet our study showed, that it is possible to select more suitable parameters that willallow one to match results of calculations and data of real observations. It can be concluded, thatconsidered model has the potential to be used for the estimations of the possible fluid-induced seismicity
activity variations.

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*S09-3-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Seismic valve as a driving mechanism of the 2014 aftershock sequences inWest Bohemia* Tomas Fischer 1) 2) , Ctirad Matyska 3) , Jens Heinicke 4) , Sebastian Hainzl 5)Charles University, Faculty of Science, Prague, Czechia 1) , Institute of Geophysics, Czech Academy of
Science, Prague, Czechia 2) , Charles University, Faculty of Mathmematics and Physics, Prague, Czechia 3) ,TU Bergakademie Freiberg, Institute of Geophysics and Geoinformatics, Germany 4) , Helmholtz Centre
Potsdam, GFZ, Germany 5)
The West Bohemia/Vogtland region is specific for its collocation of earthquake swarm activity anddegassing of CO2 of mantle origin in a relatively small area. We present an analysis of three mainshockaftershock sequences that occurred in May-August 2014 and was associated by fast increase of CO2 flow ina mofette, which reached six-fold of the original level during the subsequent 150 days. The following slow
decay suggests that the seismic activity could have been driven by the fault-valve mechanism.
Our analysis of the spatiotemporal characteristics and focal mechanisms of the aftershock sequencesshows that the three mainshocks occurred with unfavorably oriented mechanism in a step-over region of
the fault plane with increased coulomb stress due to previous activity. The ETAS modeling shows that anadditional aseismic source with an exponentially decaying strength was needed to trigger a large fraction of
the aftershocks. Corresponding pore pressure simulations with an exponentially decreasing flow rate show
a good agreement with the observed spatial migration of the aftershocks. We propose a scenario that themainshock opened fluid pathways into the fault plane participating in the aftershock triggering. The
migrating fluid pulse is then supposed to reach the surface and be observed as a long-term increase of CO2
flow rate in the mofette few days later.
We simulated gas flow in a two dimensional model of Earth crust composed of a sealing layer located in the
hypocentre depth, which is penetrated with earthquake fault and releases fluid flow from a low-permeable
lower crust to vertical high-permeable channel pointing to the surface. We get excellent and robust fit of thesimulated flow to the data using a realistic vertical channel diffusivity showing that even this simple modelis capable of explaining the observations including the short travel time of the flow pulse from 8 km depth
to the surface, the following flow increase and later long-term decrease.

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*S09-3-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

A NEW APPROACH TO FAULT ZONE SEISMIC MONITORING* Svetlana Kishkina , Gevorg Kocharyan , Dmitriy Pavlov
Institute of Geosphere Dynamics, Russian Academy of Science, Moscow
The universal macroscopic parameter controlling the seismic efficiency of a slip on a fault is the shear
stiffness or the rate of decreasing the resistance to shear during relative fault side displacement. An abrupt
decrease of the fault shear stiffness, judging by the results of laboratory experiments, is caused by thepresence of some minerals or watered clays in the fault principal slip zone. The decrease of stiffness insidea rock mass can be registered as an increase of the amplitudes of waves reflected from the fault zone, andthereafter as a decrease of the amplitudes of refracted waves.
Summarizing information about large-scale man-caused and tectonic earthquakes (structure of focal zones,
triggering factors, mechanics of generation of different slip modes in faults, seismic efficiency, etc.) andmethods of fault shear stiffness assessment allowed to elaborate a remote monitoring of potentially
dangerous sections.
In order to test the measuring techniques and the principles of the observation system arrangement,
measurements were set up in the pit of the "Korobkovskoe" deposit of ferruginous quartzites (Kursk Magnet
Anomaly, Russia). Deformation and seismic measurements in the pit were held on two faults of different
scales: the local one (about 50 cm thick) and the regional one (about 100 m thick). Relative displacements,
accelerations and velocities of fault sides under the action of seismic waves produced by explosions in thequarry and in the pit were recorded. Durations of both disturbances were actually the same but thenoticeable difference array reaction was noted on these two types of sources.
The change of waveforms caused by passage through a tectonic discontinuity was registered.
Records of the deformograph showed creep and slow events - abrupt changes of deformation character(failures) during which the deformation rate increases noticeably, but doesn't reach values intrinsic fornormal earthquakes.

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*S09-3-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Seismic sources under tensional regime - TRM and DEM approaches* Wojciech Debski , Piotr Klejment , Alicja Kosmala , Natalia Foltyn
Institute of Geophysics PAS, Warsaw, Poland
Seismic sources are most often modeled as shearing fracture processes (mode II and/or mode III
fracturing) accompanied by complex frictional phenomena. Such approach has a solid support in field
evidence for large natural earthquakes. Thus, the most of afford of describing seismic sources haveconcentrated on shearing-type models. However ,a situation is more complex
in case of anthropogenic siesmicity induced, for example, by mining. A large number of mining induced
seismic events with significant volumetric (isotropic) component in the moment tensor solution have beenreported suggesting that non shearing processes in seismic foci are not negligible. The sharing-likeapproach becomes even more problematic when micro-seismic events accompanying hydro-fracturing areconcerned. In this case a tensional fracturing of reservoir rocks is highly desirable for engineering purposeand hydro-fracturing is design to meet this goal. However, in such a case to describe seismic/acoustic
sources we cannot further on use a formalism developed for shearing-like sources – including tensional
rupture mechanisms (mode I fracturing) is absolutely necessary.
In this presentation we discuss two different approaches to modeling non-shearing seismic/acoustic
sources under tensional regime based on two well developed approaches. The first one, is based on thetime reversal imaging (TRM) of acoustic sources. The second approach relies on a direct ``brute-force''
simulations of material fragmentations based on the discrete element method (DEM).

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*S09-3-04
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Estimating the Locations of Past and Future Large Earthquake Ruptures in
California using Recent M4 and Greater Events* John Ebel
Boston College, Weston, MA, USA
Although most aftershock activity dies away within months or a few years of a mainshock, there is evidence
that aftershocks still occur decades or even centuries after mainshocks, particularly in areas of low
background seismicity such as stable continental regions. There also is evidence of long-lasting aftershock
sequences in California. New work to study the occurrences of recent M4 and greater earthquakes in
California shows that these events occur preferentially at the edges of past major ruptures, with the effectlessening with decreasing magnitude below M4. Prior to several California mainshocks, the M4 and greater
seismicity was uniformly spread along the future fault ruptures without concentrations at the fault ends. On
these faults, the rates of the M4 and greater earthquakes prior to the mainshocks were much greater than
the rates of the recent M4 and greater earthquakes. These results suggest that the spatial patterns and ratesof M4 and greater earthquakes may help identify which faults are most prone to rupturing in the near
future. Using this idea, speculation on which faults in California may be the next ones to experience major
earthquakes is presented. The results of these analyses also indicate that the locations of recent M4 andgreater earthquakes may be useful for determining the spatial extents of historic and paleoseismic
earthquake ruptures.

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*S09-3-05
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

CSEP-Japan earthquake predictability experiment for physics-basedmodeling and testing* Naoshi Hirata 1) , Hiroshi Tsuruoka 1) , Danijel Schorlemmer 1)
The University of Tokyo, Tokyo, Japan 1) , GFZ German Research Center for Geosciences, Potsdam,
Germany 2)
It is 6 years since we have established the Japanese testing center for the Study of Earthquake
Predictability (CSEP) in Earthquake Research Institute, the University of Tokyo. During the period of
testing, in March 2011, Tohoku-oki earthquake with M9.0 occurred. The testing experiment consists of 12
categories, with 4 testing classes with different periods (1 day, 3 months, 1 year and 3 years) and 3 testingregions called “AllJapan," “Mainland," and “Kanto." A total of more than 160 models are currently under
testing in the CSEP Japan official suite. For three-month and one-year testing experiments, more than 30
runs of fully prospective experiments have been completed and evaluated.
After the 2011 Tohoku-oki event, most models show poor N-test performance due to large effects of theevent. We found that the performance is improved if the effects were modeled explicitly by Omori-Utsu
formula. The direct effect of the 2011 event needs to consider a post-seismic slip on the source fault andviscoelastic relaxation of the M9 event in the crust and the mantle.

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*S09-P-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

The relation between the deep lithospheric structure and observed
seismicity in the European Arctic
Galina Antonovskaya 1) , Irina Basakina 1) , Irina Fedorenko 1) , Natalia Kapustian 1) 2) , Evgeniy Rogozhin 2), * Alexey Zavyalov 2)Federal Center for Integrated Arctic Research, Arkhangelsk, Russian Federation 1) , Institute of Physics ofthe Earth of the RAS, Moscow, Russian Federation 2)
Installation of new seismic stations on Franz Josef Land allows us to use also weak earthquakes to refine
the seismicity of the European Arctic (mb 0.9-6.6, representative magnitude 2.9, assumed location
uncertainty 5-10 km). The new data are used as the base for studying the geodynamics of the area i.e., toinvestigate the relation between the lithospheric structure and seismic activity. Profiles of lithosphericstructure were taken from published DSS data. One long north-south profile intersects the Gakkel Ridge,
the Nansen Basin, the Barents shelf, part of the Fennoscandian shield, the White Sea and the continental
uplift of the East European platform. One long west-east profile intersects the Svalbard anticline, the North
Barents Basin, the North Kara Basin and the Taimyr-North-Zemaljskaya fold systems.
The correlation of the earthquake spatial distribution with the lithosphere structure of the European Arctic
region was studied and the agreement of seismicity with different morphological structures was shown. A
new approach was applied to identify zones with different seismicity. It is based on the events grouping on
grounds of similar spectra. For this, spectral-temporal analysis of earthquakes was performed. By thespectra we observed a clear distinction of earthquakes occurring at the junction of continental and oceanic
lithosphere from earthquakes occurring at the Graben Franz-Victoria and falling in the ruptured zone.
There are two groups of events on the Gakkel Ridge, associated, probably, with volcanic and tectonic
processes. Also two groups of events were defined on the shelf, which are representing the different
tectonic structures of the South-Barents depression and Novaya Zemlya Foreland Basin.
Our study allows for the first time to propose a geodynamic zoning of the lithosphere in the European
Arctic. This result is important for seismic hazard studies in the region, in particular in the case of futureindustrial development of the offshore areas.

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*S09-P-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Postseismic Process of Moderate and Large Interplate Earthquakes within
the Source Area of the Megathrust Earthquakes Along the Nankai Trough
Mamoru Hyodo 1) , Ryoichiro Agata 1) , Tsuyoshi Ichimura 2) , * Takane Hori 1)
Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan 1) , Earthquake ResearchInstitute, The University of Tokyo, Tokyo, Japan 2)
Recent two M6~7-class earthquakes occurred within the source area of great interplate earthquakes nearby
the Japanese Islands were followed by contracting consequences: the 2016 Kumano-nada earthquake
above wasn't followed by the great interplate earthquake, while an M7-class interplate earthquake which
occurred at off-Tohoku region in March 9, 2011 was followed by the 2011 Tohoku-oki earthquake, and wasregarded as one of the foreshocks of the off-Tohoku earthquake. Such different consequences are probably
caused by the different preparation level of the great interplate earthquake at the timings of occurrences ofthese M6~7-class earthquakes. When the occurrence of great earthquake is approaching, postseismic slips
after the M6~7-class earthquakes can easily propagate to the surrounding region and can trigger thesubsequent great event. While, if the fault is not urgent to the great event, strong coupling on the fault may
prevent postseismic slip from propagating to the surrounding area. These differences in postseismic slip
patterns strongly affect the corresponding crustal deformation. Hence, from occurrence pattern of thecrustal deformation after the M6-7 earthquake in the target source region, it might be possible to narrow
down the subsequent scenarios that can occur. In this study, we focus on the Nankai Trough region, andfirstly examine the possible propagation pattern of afterslips of the hypothetical occurrence of earthquakes
such as M7-class Hyuga-nanda earthquake or M6-class Off-Kumano earthquake in many Nankai Troughearthquake scenarios deduced from numerical simulations. Then, we classify the expected postseismic
deformation patterns depending on the propagation patterns of particular afterslip. In order to evaluate
realistic crustal deformation, we will evaluate crustal deformation associated afterslips not only in a
homogeneous elastic half-space but also in FE models with heterogeneous crustal structure and theconfiguration of bathymetry.

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*S09-P-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S09. Open session: Earthquake generation process – physics, modeling and monitoring for forecast

Time to instability of the seismic event triggered by SSE* Makiko Ohtani 1) , Nobuki Kame 2) , Masao Nakatani 2)
Geological Survey of Japan, AIST, Tsukuba, Japan 1) , ERI, The University of Tokyo, Tokyo, Japan 2)
At the subduction zone along the Nankai Trough, SW Japan, large earthquakes around M8 had repeatedly
occurred. The existence of short-term large aseismic processes at the deeper extension of the seismogenic
region before the 1944/46 events has been inferred (e.g. Linde and Sacks, 2002).
We showed that such preseismic process could occur in 2D earthquake cycle models controlled by thefriction with intrinsic cut-off time for healing (Ohtani et al., 2016). In the simulated cycles, large slow slip
events (SSEs) occurred at the deeper extension of the seismogenic zone, and sometimes triggered theearthquake. We systematically investigated over a range of model parameters and found that the time
between an earthquake and the most recent SSE, tf, fell into two separate classes; within 38.4 days or over
7.7 years. The former represented SSE-triggered earthquakes, and tf takes a few days on average. Given
that the timing of SSEs is probably not affected by the failure condition of the seismogenic part, theobserved concentration of tf to small values seems to be unexpectedly strong.
In order to understand the result, we here investigate the slip response to the stress perturbation in a 1D
spring-slider model with RSF friction. To model SSE-triggering in the 1D system, we move the load point atthe velocity (1–r)Vpl, and give the step Δu=rVplTr_load every Tr_load=34 years. The slider produces
periodic unstable slip with a recurrence interval of Tr=102 years, that is, an earthquake occurs after third
SSE. Then, we impose the third SSE at a random timing T0 to synthesize the statistics of tf.
For larger SSE, tf concentrates more strongly to smaller values. We calculated the cumulative probability
that earthquake occured by tf. Even in a case of large SSE (r=0.9), 50% of earthquakes required tf>0.36
years. It seems that the strong concentration of tf observed in the 2D model is not simply explained by thedelayed (RSF) failure mechanism represented in 1D model.

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*S10-1-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S10. Develop
ment, testing and application of earthquake forecasting models

Prospective evaluation of the CSEP-Japan earthquake forecasts experiments* Hiroshi Tsuruoka , Naoshi Hirata
The University of Tokyo, Tokyo, Japan
Collaboratory for the Study of Earthquake Predictability (CSEP) is a global project of earthquake
predictability research. The primary purposes of the CSEP is to develop a virtual, distributed laboratory.
The final goal of this project is to investigate the intrinsic predictability of earthquake rupture mechanisms.
A total of 160 models were submitted from all over the world to Japan Testing Center. CSEP-Japan keeps
the prospective experiments from 1 November 2009. The models are currently under test in 12 categories,
with 3 testing regions and 4 testing classes of different time spans (1day, 3 month, 1 year and 3 years). We
evaluate the performance of the models in the official suite of tests defined by the CSEP (L, M, N, S) against
authorized catalogue compiled by Japan Meteorological Agency. In addition, we investigate the model
performance using log likelihood and information gain per event.
CSEP-Japan testing center has conducted over 30 rounds tests for 3-month testing classes including 2011
Tohoku-oki earthquake. We will discuss these results of evaluation test of the prospective experiments, andchecked and compared the performance of the earthquake models.

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*S10-1-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S10. Develop
ment, testing and application of earthquake forecasting models

Using GNSS data to analysis the earthquake potential of Sichuan-Yunnan
region, western China* Fan Wang , Peng Zhang , Zhanyi Sun
National Geomatics Center of China
We used GNSS data to estimate the seismic hazard potential in the Sichuan-Yunnan region, western China
by two approaches.
The first approach, based on the assumption that the earthquake probability is proportional to crustal strain
rate, is to use secular geodetic strain rate deduced from GPS velocity data to constrain the probability
model. Retrospective test of the model with earthquake occurrence of the past 30 years shows that themodel ‘forecasted' poorly. However, the model seems to ‘forecast' spatial intensity of earthquakes for the
past 500 years reasonably well, suggesting that the geodetic strain rate obtained at the decadal scale may
still be a good indicator of long term earthquake activity in the region, but only at a time scale of hundredsof years.
The second approach is to use GPS velocity data to determine the seismic moment accumulation rates on
major faults, and use a historical earthquake catalog to estimate seismic moments released in the past.
Comparison of the two yields estimates of present day seismic moments accumulated on major faults, and a
retrospective test shows some predictive power of the method.
Our result shows that numerous faults in the Sichuan-Yunnan region have accumulated seismic moments
capable of producing M > 7.5 earthquakes, which are the Xiaojiang, Jiali, Northern Nujiang, Nandinghe,
Red River-Puer faults, and the junction fault between the Xianshuihe and Ganzi-Yushu faults.

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*S10-1-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S10. Develop
ment, testing and application of earthquake forecasting models

Seismological and geodetic tools can jointly contribute to the understanding
and prediction of earthquakes
Giuliano F. Panza 1) 2) 3) , Antonella Peresan 4) , Fernando Sanso' 2) 5) , * Mattia Crespi 6) , Augusto Mazzoni 6), Andrea Nascetti 6)
Institute of Geophysics, China Earthquake Administration, Beijing, China 1) , Accademia Nazionale dei
Lincei, Rome, Italy 2) , International Seismic Safety Organization (ISSO) - www.issoquake.org 3) , CRS –Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Trieste, Italy 4) , DICA - Politecnico di Milano,
Milan, Italy 5) , Geodesy and Geomatics Division – DICEA – University of Rome La Sapienza, Rome, Italy 6)
Earthquakes cannot be predicted with precision but, based on seismicity patterns, algorithms exist forintermediate-term middle range prediction of strong main shocks. A first attempt was made in theframework of project SISMA funded by Italian Space Agency to jointly use seismological tools, like CN
algorithm and scenario earthquakes, and geodetic methods and techniques, like GPS and SAR, to constrain
priority areas where to concentrate prevention and seismic risk mitigation.
Here the seismic crisis, started in Central Italy in August 2016 with the Amatrice earthquake is considered
in a retrospective analysis of both SAR and GPS data, including stability tests.
Differently from the common approach, GPS data are not used to estimate the standard 2D velocity andstrain field in the area, but to reconstruct the velocity and strain pattern along transects, properly oriented
according to the known tectonic setting. SAR data related to the Amatrice earthquake coseismic
displacement are used as independent check of the GPS results.
This further development of integration of seismological and geodetic information, clearly shows thecontribution of geodesy to the understanding and prediction of earthquakes. In fact, it turns out possible tohighlight the velocity variation and the related strain accumulation in the area of Amatrice event, within thearea alarmed by CN since November 1st, 2012. Some counter examples, across CN alarmed and notalarmed areas, do not show any spatial acceleration localized trend, comparable to the one well definedalong the Amatrice transect.
The combined analysis of the results of intermediate term middle range earthquake prediction algorithms,
like CN, with those from the processing of adequately dense and permanent GNSS network data, possiblycomplemented by a continuous InSAR tracking, may allow the routine highlight in advance of the strain
accumulation. Thus it is possible to significantly reduce the size of the CN alarmed areas.

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*S10-1-04
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S10. Develop
ment, testing and application of earthquake forecasting models

On what time scales can strain rates contribute to earthquake likelihood
models?
* David Rhoades , Bill Fry , Annemarie Christophersen
GNS Science, Lower Hutt, New Zealand
Recently a multiplicative modelling technique was developed for combining earthquake likelihood models
and gridded covariates into hybrid earthquake likelihood models. Multiplicative hybrids often have larger
information gains than additive hybrids produced from the same inputs. We have applied the technique toevaluate the information gains from incorporating strain rate maps into existing earthquake likelihood
models on two timescales.
In a long timescale study, we use three components of the strain rate in New Zealand estimated over theperiod 1991-2011 – the shear (SSR), rotational (RSR) and dilatational strain rate (DSR). We fit
multiplicative hybrid models using selections of covariates, constructed from earthquake catalogue andfault data as well as the strain rate components, to the period 1987-2006 and test them over the period
2012-2016. The SSR provides the greatest single information gains in forecasting M 5 and greater
earthquakes in the fitting and testing periods. Most models including strain rates are more informative thanthe best models excluding strain rates. A hybrid that combines SSR and DSR with a smoothed seismicity
covariate is the most informative in the fitting period, and a simpler hybrid without DSR is the mostinformative in the testing period.
In a short timescale study, we use daily estimates of strain rate on the shallow Hikurangi subduction
megathrust as a multiplicative covariate. We average daily strain rates over four time windows (1 day, 30days, 100 days, and 460 days) to test the link between duration of strain and triggered earthquakes ofmagnitude 3.5 and greater in subsequent time windows of the same length. We find that the 30-day window
provides the largest information gain, followed by the 460-day window. These results may be related to therapid triggering of earthquakes during slow slip events (SSE). Shallow SSE have typical durations of weeks
and deep SSE have typical durations ranging from months to over a year.

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*S10-1-05
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S10. Develop
ment, testing and application of earthquake forecasting models

Reducing false alarms of annual forecast in the central China north-south
seismic belt by reverse tracing of precursors (RTP)* Zhongliang Wu 1) , Changsheng Jiang 1) , Shengfeng Zhang 1) 2)
Institute of Geophysics, China Earthquake Administration, Beijing, China 1) , Earthquake Administration of
Shandong Province, Jinan, China 2)
The annual consultation on the likelihood of earthquakes in the next year, the ‘Annual Consultation
Meeting', has been one of the most important forward forecast experiments organized by the China
Earthquake Administration (CEA) since the 1970s. In such a consultation meeting, annual alarm regions
are identified by an expert panel considering multi-disciplinary ‘anomalies'. One of the problems in needof further technical solution is its false-alarms. To tackle this problem, the concept of ‘reverse tracing of
precursors (RTP)' proposed by Keilis-Borok is used to the annual consultation. The central China northsouth seismic belt (in connection to the CSEP testing region) is selected as the testing region of such an
approach. Applying the concept of RTP, for an annual alarm region delineated by the Annual Consultation
Meeting, the distribution of ‘hotspots' mapped by the pattern informatics (PI) algorithm, which targets at
the five-year-scale seismic hazard, is considered. The ‘hit', or successful forecast, of the annual seismic
hazard, is shown to be related to sufficient coverage of the ‘hotspots' within the annual alarm region. The
ratio of the areas of the ‘hotspots' over the whole area of the annual alarm region is thus used to identify
the false-alarms which have few ‘hotspots'. The results of the year 2004 to 2012 show that using athreshold 17% can reduce 13 among 38 of the false-alarms without losing the successful hit (being 6 in that
period).

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*S10-1-06
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S10. Develop
ment, testing and application of earthquake forecasting models

Break of slope in earthquake size distribution and aseismic deformation rate
* Peter Shebalin 1) , Inessa Vorovieva 1) , Clement Narteau 2) , Sergey Baranov 3)
Institute of Earthquake Prediction Theory and Mathematical Geophysics, Moscow, Russia 1) , Equipe deDynamique des Fluides Geologiques, Institut de Physique du Globe de Paris, Sorbonne Paris Cite, Paris
Diderot University, Paris, France 2) , Kola Branch of the Geophysical Survey, Russian Academy of Sciences,
Apatity, Russia 3)
Crustal faults accommodate slip either by a succession of earthquakes or continuous slip, and in most
instances, both these seismic and aseismic processes coexist. Recorded seismicity and geodetic
measurements are therefore two complementary data sets that together document ongoing deformation
along active tectonic structures. We show that creep along the San Andreas Fault is responsible for a breakof slope in the earthquake size distribution. This slope increases with an increasing creep rate for larger
magnitude ranges, whereas it shows no systematic dependence on creep rate for smaller magnitude ranges.
This is interpreted as a deficit of large events under conditions of faster creep where seismic ruptures areless likely to propagate. These results suggest that the earthquake size distribution does not only depend on
the level of stress but also on the type of deformation.
Significant part of postseismic deformations is known to be aseismic, and the aftershock process consists ofboth seismic events and aseismic relaxation of stress. Accordingly, we suppose that magnitude-frequency
relation for aftershocks may experience a break of slope. We test this hypothesis on the example of several
aftershock sequences of major earthquakes and show that in most cases a two-slopes model statistically ispreferable. The practical issue is that forecasting models of aftershocks, hypothesizing a single-slope
magnitude distribution of earthquakes, may significantly overstate (or sometimes understate) the expected
rates of large aftershocks. We demonstrate it on examples. The research was partially supported by Russian
Science Foundation (Project N 16-17-00093).

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*S10-P-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S10. Develop
ment, testing and application of earthquake forecasting models

Application of earthquake forecasting models in central New Zealandfollowing the November 2016 Kaikoura earthquake* David Rhoades , Annemarie Christophersen , Matthew Gerstenberger , David Harte
GNS Science, Lower Hutt, New ZealandFollowing the M7.8 Kaikoura earthquake of 14 November 2016, GNS Science, through the GeoNet website,
provided forecasts of future earthquake occurrence, similar to the practice that has evolved during major
earthquake sequences in New Zealand since 2011. The forecasts were expressed in three forms: (1) Tablesof the number of earthquakes expected during future time periods in different magnitude ranges within adefined aftershock region, with associated uncertainties; (2) Maps of the probability of earthquake shaking
exceeding certain Modified Mercalli intensities; and (3) Future earthquake scenarios with associatedprobabilities. Initially the short-term earthquake probabilities (STEP) model was used to estimate theexpected number of earthquakes of magnitude 5.0 and above for time periods of 1, 7 and 30 days. A week
after the mainshock, the 1-day forecasts were discontinued and yearly forecasts were added. After five
weeks, only monthly and yearly forecasts were produced. The latter were based on a hybrid model, withlong-term, medium-term and short-term components derived from well-established models. The long-term
component was provided by a smoothed seismicity model, the medium-term component by two versions of
the Every Earthquake a Precursor According to Scale (EEPAS) model, and the short-term component by
the STEP and Epidemic-Type Aftershock (ETAS) models. The Kaikoura earthquake presented someparticular challenges: (1) Careful communication of changes to the estimated mainshock magnitude, thecontributing models and the method for estimating uncertainties in the expected number of earthquakes (aswitch from the Poisson to the negative binomial distribution); and (2) Amendment of forecasts to allow forincreased slow slip on the North Island subduction interface after the Kaikoura earthquake. In the absenceof any established models to incorporate slow slip into the forecasts, the probability of a triggered major
event was assessed by expert elicitation.

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*S10-P-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S10. Develop
ment, testing and application of earthquake forecasting models

Time-dependent neo-deterministic seismic hazard scenarios for the Italian
territory: recent advances and testing issues
Antonella Peresan 1) 2) , Vladimir Kossobokov 2) 3) , Giuliano F. Panza 2) 4) 5) , * Mattia Crespi 6)
National Institute of Oceanography and Experimental Geophysics, Seismological Research Centre, CRSOGS. Udine. Italy 1) , International Seismic Safety Organisation, ISSO, Arsita, Italy 2) , Institute ofEarthquake Prediction Theory and Mathematical Geophysics. Russian Academy of Sciences, Moscow,
Russia 3) , Institute of Geophysics, China Earthquake Administration, Beijing, People's Republic of China 4) ,Accademia Nazionale dei Lincei, Rome. Italy 5) , Geodesy and Geomatics Division, University "La Sapienza",
Rome, Italy 6)Long-lasting practice and results obtained for the Italian territory in about two decades of rigorous
prospective testing of CN and M8S algorithms, support feasibility of earthquake forecasting based on theanalysis of seismicity patterns at the intermediate-term middle-range scale. The algorithms permit to deal
with multiple sets of seismic transients and allow to identify the region and time interval where a strong
event is likely to occur. Based on routinely updated space-time information provided by CN and M8S
forecasts, an integrated procedure has been developed for the definition of time-dependent seismic hazard
scenarios through realistic modeling of ground motion by the neo-deterministic seismic hazard assessment(NDSHA) approach. This scenario-based methodology permits to construct, both at regional and local scale,actual scenarios of ground motion at the times when a strong event is likely to occur within the alertedareas.
Recent advances and results from real-time testing of the integrated NDSHA scenarios are illustrated, withspecial emphasis on the sequence of destructive earthquakes in Central Italy starting on 24 August 2016.
Some basic operational and testing issues are addressed, ranging from testing homogeneity/reliability of
the input data to the adequate assessment of output information. The results obtained so far support thevalidity of the proposed methodology in anticipating ground shaking from imminent strong earthquakes
and show that the information provided by time-dependent NDSHA can be useful in assigning priorities fortimely and effective mitigation actions.

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*S11-1-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S11. Geo &amp; space technologies to study pre–earthquake processes: Observation, modeling, forecas
ting

TEC anomalies immediately before large earthquakes: Review andperspective* Kosuke Heki 1) , Liming He 1) 2)
Hokkaido Univ, Sapporo, Japan 1) , Northeastern Univ., Shenyang, China 2)
Heki (2011) found ionospheric total electron content (TEC) enhancement starting ~40 min before the 2011
Mw9.0 Tohoku-oki earthquake. Heki & Enomoto (2015) confirmed similar phenomena before all theearthquakes in this century with Mw 8.5 or more. Critical papers claim that (1) the preseismic increase isan artifact popped up by defining the reference curves using the data after earthquakes, and (2) the
anomalies originate from geomagnetic activities rather than earthquakes. In our rebuttals (Heki & Enomoto,2013; 2014; 2015), we demonstrated statistical significance of the preseismic increases of vertical TEC
rates. We also counted the occurrences of similar changes in TEC caused by space weather during times of
no earthquakes and demonstrated it statistically unrealistic to attribute all the preseismic anomalies tospace weather.
Recently, He and Heki (2016) analyzed the spatial distribution of preseismic TEC anomalies of 3 large
earthquakes in Chile, i.e. the 2010 Maule, the 2014 Iquique, and the 2015 Illapel events. There, both
positive and negative anomalies started simultaneously at altitudes of ~200 km and ~400 km, respectively,
with 3-D structure similar to Kuo et al. (2014) predicted as the ionospheric response to positive electriccharges on the ground.
We found three different Mw dependences of the anomalies so far. At first, the amount of the preseismic
TEC rate changes are stronger for larger earthquakes and under higher background TEC. Secondly, larger
earthquakes tend to have longer precursor times. Third, the anomalies of larger earthquakes have larger
spatial dimensions. In the latest work, He and Heki (submitted) studied 32 earthquakes with Mw7.0-8.0 in
this century, and found that 8 earthquakes showed possible preseismic changes starting 20-10 minutes
before earthquakes. We could observe them before Mw7.0-8.0 earthquakes when background VTEC arelarge, say over 50 TECU.

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*S11-1-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S11. Geo &amp; space technologies to study pre–earthquake processes: Observation, modeling, forecas
ting

Modification of ionosphere before March 11 2011 Tohoku earthquake* koichiro Oyama 1) 2) 3) , C.H Chen 1) , L Bankov 4) , M Devi 5) , K Ryu 6) , J.Y Liu 7) , H Liu 2) , T Uozumi 2)
National Cheng Kung University, Tainan, Taiwan 1) , Kyushu University, Fukuoka, Japan 2) , Coltd Asia
Space Enviornment Research Consortium, Sagamihara, Japan 3) , Space Research Institute, Sophia,
Bulgaria 4) , Gauhati University, Assam, India 5) , Korean Advanced Institute of Science and Technology,
Daejeon, Korea 6) , National Central University, Jhong-Li, Taiwan 7)
Ionosphere disturbance which was seen prior to an earthquake which occurred on 11 March2011 off thecoast of Tohoku was studied. Ionosphere data which were used are: O+ density acquired with US satellite
DMSP, and NmF2, and h'F obtained by ionosondes. Global Ionosphere Model (GIM) is used as side
evidence to compliment findings from DMSP data and ground based data..
Although during the earthquake preparation period, magnetic disturbance is strong, global survey ofground based foF2 shows that special disturbance is limited to earthquake area. Satellite data(DMSP andGIM) analysis shows three important findings before the occurrence of the earthquake; (1) Overgeomagnetic equator enhancement of O+ is found, (2) midlatitude trough is formed before the earthquake
and it moves toward lower latitude as EQ day approaches, and (3) no clear difference of O+ behavior
between east and west of the epicenter is identified. Night time NmF2 at high latitude ionosonde stations
such as Khavalovsk, and Beijin shows 2 days oscillation from 5 March and disappears on the 12th March.
As the latitude of the station is lower, 2 days oscillation becomes unclear, and the duration of theappearance is shorter.
In order to explain both ground based and satellite data consistently, one idea of enhanced east/west ward
dynamo electric field during daytime/ nighttime is discussed. We presume gravity wave of very small
amplitude as a source of dynamo E field modification. Internal gravity wave of extremely small amplitudecause d by ground motion interact with planetary scales waves below 10 km , and is amplified. The
amplified IGW propagate to the dynamo region. Several observational facts which are favour to thegeneration of IGW are described. Finally we stress the need of satellite constellation in order to obtain the
global morphology of ionosphere disturbance and to identify the mechanism, which at least provides us thematerial to judge applicability to future earthquake prediction.

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*S11-1-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S11. Geo &amp; space technologies to study pre–earthquake processes: Observation, modeling, forecas
ting

Characteristics of Ionospheric Electron Distribution for large Earthquakes
around Japan* Katsumi Hattori 1) , Mustafa Yagmur 1) , Shinji Hirooka 1) , Jann-Yenq Liu 2)
Chiba University, Japan 1) , National Central University, Taiwan 2)
Pre-seismic electron density anomalies have been widely discussed phenomena in ionospheric studies.
However, it is not well-known what causes these anomalies. The other question is how to distinguishionospheric anomalies from other disturbances such as geomagnetic storms. Therefore, a characterizationand classification of magnetic storm and earthquake signatures is necessary for reliable forecasting. For
this purpose, we investigate the similar and differing effects of magnetic storms and earthquakes on theionospheric structure. In this paper, we mainly focused the time period after magnetic storms and before
earthquakes. We select earthquakes occurred between 1998 and 2013 with M>6 and depth<30 km. We
examined the temporal and spatial distribution of TEC using GIM-TEC data to detect the anomalous
behavior and we found 28 earthquakes had anomalous changes. We further investigate their 3D
distributions for these earthquakes with tomography and found 13 among them show the similar
anomalous structure. Meanwhile, we select magnetic storms between 1998 and 2013 with Dst < -100 nT
and the onset time from 6 am to 6 pm. Then, 42 magnetic storms were extracted. We analyzed arbitrarily 10
different storms and the same analyses were performed. We further employed the ionospheric foEs, NmF2
and hmF2 quantities as complementary data. Then, we prepared time series figures of these parametersand compared their responses against storm and earthquake effects. Results will be shown in thepresentation.

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*S11-2-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S11. Geo &amp; space technologies to study pre–earthquake processes: Observation, modeling, forecas
ting

Estimates of Seismic Danger in Japan by Coherence Properties of GPS
Noise* Alexey Lyubushin
Institute of Physics of the Earth, Moscow, Russia
The dense GPS network at Japan islands (more than 1300 stations) provides the data for detailinvestigation of the Earth surface tremor. We used 3-components GPS data with sampling time step 5
minutes which were downloaded from the site of Nevada Geodetic Laboratory since 2015.03.03 up to thecurrent time. Maps of kernel estimates of probability density functions are presented for nodes of theregular net sized 30x30, which are realized the spatial maximum of the frequency-dependent maximal
values of the multiple spectral function of coherence of GPS time series from the nearest 10 workablestations for all 3 components of GPS time-series within moving time window of the length 5 days. The GPS
station is considered workable in the time window if its registration interval includes the considered time
window and the number of missing values does not exceed a predetermined maximum allowableproportion of the total length equal to 0.1. The missed values are filled using information about records
from neighbor time interval of the same length as the length of gaps. Before calculating the coherencefunction in each window the trend is removed by polynomial of 4th order and 3-sigma winsorizing was
performed. The map of most frequent positions of frequency-dependent maximum of multiple coherence ofGPS noise extracts Nankai Trough with maximum at the vicinity of the point 34N and 138E. This result is
an independent confirmation of the earlier conclusion made by the analysis of seismic noise(http://dx.doi.org/10.4236/ns.2013.58A1001).

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*S11-2-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S11. Geo &amp; space technologies to study pre–earthquake processes: Observation, modeling, forecas
ting

Correlation between earthquake occurrence and the anomalous propagationof VHF radio waves indicated by the gain and the p-value of prediction maps
produced by a simple objective algorithm in the Shimabara area, Kyushu,
Japan* Sho Morita 1) , Masao Nakatani 2) , Toru Mogi 1)
Hokkaido University, Hokkaido, Japan 1) , The University of Tokyo, Tokyo, Japan 2)
Electromagnetic precursors associated with the impending earthquake, such as variations of geoelectric
current, total electron contents in the ionosphere, and anomalous transmission of radio waves in the VLF
or VHF band, have been observed (e.g. Hayakawa, 1996). Recently, some researchers have discussed how
these precursory phenomena relate statistically to the impending earthquake (Le et al., 2010, Orihara et al.,2012, Hattori et al., 2013, Han et al. 2014). Anomalous (i.e., beyond the line of sight) VHF-band radio-wave
propagation is one such claimed short-term precursor; physical preparatory processes of earthquakes may
produce/attract electromagnetic scatterers in the area over the source of the impending earthquake(Kushida and Kushida, 2002, Moriya et al.,2010). Hokkaido University has been monitoring this anomalous
propagation in several regions in Japan. On April 14th 2016, an Mw 6.5 earthquake occurred in
Kumamoto, which was followed by a nearby greater Mw 7.3 event on April 16th. Just before these events,
anomalous propagation of the VHF radio wave from an FM station in Miyazaki was observed at Shimabara
receiving station. Epicenters of these Kumamoto events were between the broadcast and receiving stations.
To evaluate the statistical significance of the tendency that such anomalies precede impending earthquakes
in this region, we made a spatio-temporal map of earthquake alarm (though for only one spatial grid, whichis the region between the Miyazaki broadcast and the Shimabara receiving stations) based on the data for2015 to 2016; after anomaly appears, we turn ON the alarm for a certain period of time L, and thus divide
the whole observation period into “Alarm ON", “Alarm OFF", and “Undecided (due to missing data)"
periods. The alarm map was compared with the occurrence of local earthquakes with M > 4.5 after
declustering. The result, the associated p-value was not low enough to suggest the statistical significance.

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*S11-2-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S11. Geo &amp; space technologies to study pre–earthquake processes: Observation, modeling, forecas
ting

Testing Geospace Technologies for Alerting Large Earthquakes: An
Integrated Approach of Space and Ground Observations* Dimitar Ouzounov 1) 5) , Sergey Puienets 2) , Tiger Liu 3) , Katsumi Hattori 4) , Manuel Hernández-Pajares 5) ,Alberto García-Rigo 5) , Menas Kafatos 1)
Chapman University, Orange, CA, USA 1) , Space Research Institute, RAS, Moscow, Russia 2) , National
Central University, Chung-Li, Taiwan 3) , Chiba University, Chiba, Japan 4) , Technical University of
Catalonia (UPC), Barcelona, Spain 5) , Astrogeo Center, VA, USA 6)
The most recent catastrophic earthquakes (Nepal 2015, Japan 2011, Haiti 2010, China 2009, Pakistan
2007, Sumatra 2004) were providing new information to the science community enabling new ideas in thedevelopment of earthquake hazard mitigation scheme. We are proposing a scheme requiring
interdisciplinary use of latest geospace and remote sensing technology based on multi platform data
observations. This multi sensory approach is analyzing atmospheric and ionospheric signals and searchingfor pre-earthquake signals by using geospace sensing techniques and ground data. The approach is still inan early stage of testing and is based on data fusion of satellite thermal observations (LEO, GEO) in
conjunction with GPS/TEC (GNSS), atmospheric assimilation models and ground multi parameter
continuous measurements. The proposed methodology uses existing satellite sensors and groundobservations in One Web framework to study physical processes described by the Lithosphere-AtmosphereIonosphere Coupling (LAIC) concept. Our initial test results show that simultaneous satellite and groundmeasurements, using as an integrated web, could provide earthquake short-term alert capabilities (severaldays) for major earthquake. The significance of initial results is discussed within the framework of the latest
earthquakes in Nepal and Chile and major activities in 2013-16.

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*S11-P-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S11. Geo &amp; space technologies to study pre–earthquake processes: Observation, modeling, forecas
ting

Quantification of Seismic Hazards with Detrended Fluctuation Analysis ofTime Series: Case Studies of the Japanese Islands and California
Denis Filatov 1) 2) , * Alexey Lyubushin 2)
Sceptica Scientific Ltd, Stockport, United Kingdom 1) , Institute of Physics of the Earth, Russian Academy of
Sciences, Moscow, Russia 2)
We employ the approach of statistical physics to quantify current seismic hazards of two geologically active
regions of the Earth: the Japanese islands and the west coast of the United States. Specifically, we apply atechnique of fractal analysis of time series, a detrended fluctuation analysis (DFA) method [1], to study theevolution of displacements of the land surface and detect those areas of the Earth's crust that are evolving
in a critical mode usually preceding a catastrophe. As the input data, we use freely available time series
from GPS stations densely covering both regions of interest. The high density of the data allows producing
detailed maps of the seismic hazard and highlighting the riskiest areas where disastrous seismic events arelikely to occur in the future [2, 3]. Our findings also demonstrate that vertical and horizontal motions ofblocks of the Earth's crust exhibit qualitatively different mechanisms of transition into critical states, whichindicates the existence of a general nonlinear mechanism of appearance of critical (precatastrophic)
regimes in open stochastic dynamical systems. The results of our analysis were partly confirmed by arecent earthquake struck in Fukushima, Japan, on 21 November 2016.
References[1] D.M. Filatov, A Method for Identification of Critical States of Open Stochastic Dynamical Systems Basedon the Analysis of Acceleration, J. Stat. Phys., 165 (2016) 681-692. DOI: 10.1007/s10955-016-1641-6.
[2] D.M. Filatov and A.A. Lyubushin, Fractal Analysis of GPS Time Series for Early Detection of Disastrous
Seismic Events, Physica A, 469 (2017) 718-730. DOI: 10.1016/j.physa. 2016.11.046.
[3] D.M. Filatov and A.A. Lyubushin, Assessment of Seismic Hazard of the Japanese Islands Based on
Fractal Analysis of GPS Time Series, Izv. Phys. Solid Earth, accepted for publication.

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*S11-P-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S11. Geo &amp; space technologies to study pre–earthquake processes: Observation, modeling, forecasting

Possible conjugated TEC anomalies preceding large earthquakes* Liming He 1) 2) , Kosuke Heki 2)
Northeastern University, Shenyang, China 1) , Hokkaido University, Sapporo, Japan 2)
Ionospheric total electron content (TEC) enhancement instantly before the very large earthquake was firstfound after the 2011 Mw9.0 Tohoku earthquake [Heki, 2011]. Up to now, the similar enhancements wereobserved before eighteen earthquakes with moment magnitude from 7.3 to 9.2 [Heki and Enomoto, 2015;
He and Heki, submitted]. Recently, He and Heki [2016] analyzed the spatial distribution of preseismic
ionospheric anomalies of three large earthquakes in Chile, i.e. the 2010 Maule (Mw8.8), the 2014 Iquique(Mw8.2), and the 2015 Illapel (Mw8.3) earthquakes, and obtained the three-dimensional structures of the
TEC anomalies for the 2015 event based on a projection approach. The observation result showed that theepicenter, the positive and negative anomalies distribute along the field-aligned direction, which resembles
the simulation scenario [Kuo et al., 2014]. Besides this near epicenter phenomenon, another expected
effect is the possible mirror ionospheric TEC anomalies associated with the geomagnetic field, i.e. the TEC
anomalies are probably observed at geomagnetic conjugate points meanwhile. Here, we performed asystematic search for the possible mirror image anomalies that are to emerge at geomagnetic conjugate
points based on GNSS TEC observations.

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*S11-P-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S11. Geo &amp; space technologies to study pre–earthquake processes: Observation, modeling, forecas
ting

Variations of statistical parameters of the background seismic noise before
strong earthquakes in Kamchatka
Victoria Kasimova 1) , * Alexey Lyubushin 2) , Galina Kopylova 1)
1Kamchatka Branch of the Geophysical Service Russian Academy of Sciences 1) , 2Institute of Physics ofthe Earth Russian Academy of Sciences, Moscow, Russia 2)
The network of broadband seismic stations of Geophysical service RAS works on the territory of Kamchatka
peninsula in the Far East of Russia. We used a method for seismic noise analysis which is described in[1-2]. We used continuous records on Z-channels at 21 stations for creation of background seismic noisetime series in 2011-2016 with sampling 1 minute. Average daily parameters of multi-fractal spectra of
singularity have been calculated at each station using 1-minute records. Maps and graphs of their spatial
distribution and temporal changes were constructed at time scales from days to six months. Also, the timeseries of daily median values of the statistical parameters of the noise were calculated on all stations.
Three strong earthquakes with magnitudes M=6.9–8.3 occurred near the Kamchatka peninsula during theobservations. The synchronous variations of the background noise parameters and increase in the coherent
behavior of the median values of statistical parameters was shown before two strong earthquakes 2013
(February 28, MW=6.9; May 24, MW=8.3) within 3–9 months and before the earthquake of January 30,
2016, MW=7.2 within 3–6 months.
Peculiarities in changes of statistical parameters at stages of preparation of strong earthquakes indicate an
attenuation in high-amplitude outliers and the loss of multi-fractality in time series of noise. The changes inthe various statistical parameters before strong earthquakes on Kamchatka corresponds to their behavior
during the preparation of the strongest earthquakes near Japan in 2003, M=8 and in 2011, M=9.
1. Lyubushin, A. Prognostic properties of low-frequency seismic noise. Natural Science, 2012, 4(8A),
659-666. http://dx.doi.org/10.4236/ns.2012.428087
2. Lyubushin, A. A., Dynamic estimate of seismic danger based on multifractal properties of low-frequency
seismic noise. Natural Hazards, 2014, 70 (1), 471-483.
http://dx.doi.org/10.1007/s11069-013-0823-7

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*S11-P-04
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S11. Geo &amp; space technologies to study pre–earthquake processes: Observation, modeling, forecas
ting

Clarification of the mechanism of VLF radiation intensity reduction before
earthquakes observed by DEMETER and WWLLN data
Shoho Togo 1) , Hidetoshi Nitta 1) , Jean-Jacques Berthelier 2) , Tatsuo Onishi 2) , Masashi kamogawa 1) , *Tetsuya Kodama 3) , Toshiyasu Nagao 4)
Tokyo Gakugei University, Tokyo, Japan 1) , LATMOS, Paris, France 2) , JAXA, Tsukuba, Japan 3) , Tokai
University, Shimizu, Japan 4)
Statistical observations by DEMETER have shown that a decrease of the VLF EM wave intensity around 1.7
kHz the cut-off frequency of the Earth's-Ionosphere guide occurs a few hours before an EQ. It is thoughtthat this effect arises from a disturbance in the D-region of the ionosphere.
To further investigate this phenomenon we have analyzed whistler signals observed on DEMETER datausing also lightning data from the WWLLN network. Whistlers that travel through the ionosphere up to thesatellite should indeed be good tracers of possible low altitude ionospheric disturbances that may, inparticular, modify the absorption rate of the propagating EM waves.
Whistler measurements obtained on board DEMETER in March 2010 before the Sumatra EQ have been
compared with similar observations performed before and after the EQ but during seismically quiet
periods. Initial results are consistent with an increase in the whistler wave absorption up to a few dB a few
hours prior to EQ that could result from an enhancement of about 10-15% of the electron density in thelower ionosphere.
In this presentation we report the data processing methodology based on the combined use of in-orbit(DEMETER) and ground-based (WWLLN) measurements and initial quantitative outcomes of the deduced
ionosphere variations. Further studies are required to build the necessary statistical knowledge of thephenomenon and identify the spatial scales of the ionosphere disturbances.

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*S12-1-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Combining probabilistic seismicity models with precursory information:
application to long-delayed aftershocks* Peter Shebalin
Institute of Earthquake Prediction Theory and Mathematical Geophysics
Quantitative assessments of increasing probabilities of earthquakes at a presence of precursors or
precursory patterns still remain a big challenge. A strong and rising interest, however, is manifested lastyears to the methods of combining probabilistic seismicity models with any kind of precursory phenomena.
Shebalin et al. (2014) have proposed a method to combine earthquake forecast rate-based models with any
information that could locally increase the forecasted earthquake rates. The method is based on estimationof differential probability gains calculated in error diagram that evaluates the performance of the input
information with respect to the reference model. The differential probability gain, that depend on ameasurable quantity of the precursory phenomena, is then used at each point in space and time as anamplifying factor of the initial seismicity model. An important advantage of this combining method is its
capacity to produce high expected rates. Recursive application of the method solves also a problem of theinterdependence of the precursory phenomena.
In this talk I present first results on combining simple aftershock rate model with a precursory pattern oflarge aftershocks. The idea came from the premonitory analysis of the early aftershock statistics(forecasting algorithm EAST). In the considered case the EAST method is extended (but actuary drasticallysimplified) to the analysis of seismicity within aftershock sequences, and actually secondary aftershocks
and main shocks, which are themselves aftershocks of the major main shock, are considered. The research
was supported by Russian Science Foundation (Project N 16-17-00093).

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*S12-1-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Nowcasting Global Earthquakes* John Rundle 1) 2)
The University of California 1) , Santa Fe Institute 2)
The term "nowcasting" refers to the estimation of the current uncertain state of a dynamical system,
whereas "forecasting" is a calculation of probabilities of future state(s). Nowcasting is a term that originatedin economics and finance, referring to the process of determining the uncertain state of the economy ormarkets at the current time by indirect means.
We have applied this idea to seismically active regions, where the goal is to determine the current state of asystem of faults, and its current level of progress through the earthquake cycle(http://onlinelibrary.wiley.com/doi/10.1002/2016EA000185/full).
We wish to estimate how far the fault system has progressed through the "cycle" of large recurring
earthquakes. We use the global catalog of earthquakes, using "small" earthquakes to determine the level ofhazard from "large" earthquakes in the region. As an application, we can define a small region around major
global cities, for example a "small" circle of radius 150 km and a depth of 100 km, as well as a "large"
earthquake magnitude, for example M6.0. Also, the region of influence of such earthquakes is roughly 150
km radius x 100 km depth, which is the reason these values were selected.
The statistics are computed from a "large" region surrounding the "small" 150 x 100 km circle. The current
count of earthquakes that is used to compute the nowcast is obtained from small earthquakes in the small
region. The basic assumption is that both the "large" and "small" regions are characterized by the same
Gutenberg-Richter magnitude frequency statistics.
We have used these techniques to compute the relative nowcast rankings of large global cities at risk fordamaging earthquakes. In this talk we discuss these rankings. We also discuss the results of sensitivity
analyses of the rankings to variations in the selected magnitude, small and large regions.

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*S12-1-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

integrated Study and Test for Earthquake Precursors (iSTEP-4)* Jann-Yenq Tiger Liu 1) 2)
Institute of Space Science, National Central University, Taoyuan, Taiwan 1) , Center for Space and Remote
Sensing Research, National Central University, Taoyuan, Taiwan 2)
The iSTEP (integrated Study and Test for Earthquake Precursors) project goal is to study characteristics ofseismo-ionospheric precursors in the total electron content and develop lithosphere-atmosphereionosphere (LAI) coupling models finding possible causal mechanisms for the large earthquake prediction
and forecast of the globe. The project consists of a main project and three sub-projects (Sub-project I:
Seismo-ionospheric/atmospheric precursors, Sub-project II: Seismo-lithospheric precursors, Sub-project
III: Statistics for earthquake hazard). The Main project operates the integrated ground-based seismoelectromagnetic observation system in Taiwan and develop physical models to find possible mechanisms.
The integrated observation system including seven networks of magnetometers, infrasonic wave systems,
atmospheric electric field mills, Doppler sounding systems, ionosondes, GPS receivers, and all sky cameras.
The observation system is used to monitor earthquake precursors in the lithosphere, the atmosphere, andthe ionosphere, and to find the LAI coupling in Taiwan. Currently, it is the most comprehensive groundbased system, which acts a reference for the earthquake precursor studies of the world. Meanwhile, Main
project will utilize existing ionospheric physics models, such as TIEGCM, SAMI3, etc. to reproduce seismoionospheric precursors (SIPs) and seismo-atmospheric precursors (SAPs) observed by Sub-project I andseismo-lithospheric precursors (SLPs) by Sub-project II finding possible causal mechanisms and searching
the LAI link. The observed and simulated precursors in the lithosphere, atmosphere, and ionosphere of acertain event will be further compared with its associated statistical results of Sub-project III to assess thehazard.

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*S12-2-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Coupled interaction of deep Earth gases with quasi-static rupture ofearthquake nuclei; possible source mechanism for seismo-EMs* Yuji Enomoto
Shinshu University , Ueda, Japan
Various types of precursor anomalies preceding earthquakes have been reported in seismic, geodetic,
geochemical and electromagnetic observations. Among them, recent advances in the seismo-EMs;
especially GPS-TEC enhancements associated with strong earthquakes, represent a possible method bywhich to predict an imminent earthquake (Heki, GRL 2011). The underlying causal relationship still remain
equivocal, although various proposals have been discussed on the topics.
In turn release of isotropic C13 and He3 influx from the deep crust reservoirs have been often detected;
e.g. in the 2011 Tohoku-Oki earthquake (Sano et al. Nat. Comm. 2013). This fact suggests that the highlypressurized deep Earth fluids, as well as tectonic stress, play an important role in triggering of quasi-static
rupture of earthquake nuclei. A new source mechanism for the seismo-EMs is needed to elucidate theunderlying causal relationship between the hydro-mechanical and the electromagnetic processes.
Taking into account the coupled interaction of rock ruptures with the gas flowing-in as a working
hypothesis (Enomoto, GJI 2012), we conducted laboratory experiments of uniaxial rock rupture with highpressure CO2 flow, where a flat-ended chisel equipped with a flow-channel was loaded against a rock blockof 15-30 mm thick; quartz diorite and gabbro. The electric currents as high as 0.2-0.7 microampere,depending on the rock thickness, were successfully measured, followed for approximately a few
milliseconds after fully development of the crack. The current flows are transient process, and the following
gases are un-electrified, but they drive the preceding electrified gases; i.e. generation of the pressureimpressed current dipole. The model provides well-reasoned explanation for geomagnetic anomalies as
observed in the 1965-1967 Matsushiro earthquake swarm and in the 2011 Tohoku-Oki earthquake.
The author acknowledges the financial support from Genesis Research Institute, INC.

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*S12-2-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Multi-parameter assessments of pre-earthquake atmospheric signals* Dimitar Ouzouniv 1) , Sergey Pulinets 2) , Tiger Liu 3) , Katsumi Hattori 4) , Peng Han 4) 5)
Chapman University, One, Orange, CA, USA 1) , Space Research Institute, RAS, Moscow, Russia 2) , National
Central University, Chung-Li, Taiwan 3) , Chiba University, Chiba, Japan 4) , ISM Institute of Statistical
Mathematics, Japan 5)
We apply interdisciplinary observations to study earthquake processes, their physics and the phenomenathat precede their energy release. Our approach is based on multi-sensors observations of short-term preearthquake phenomena preceding large earthquakes (M>6). The integrated satellite and terrestrial
framework (ISTF) is our method for validation and is based on sensor web of several physical andenvironmental parameters (Satellite thermal infrared radiation (STIR), electron concentration in theionosphere (GPS/TEC), air temperature/humidity measurements) that were found to be associated withearthquakes. The science rationale for multidisciplinary analysis is based on concept LithosphereAtmosphere-Ionosphere Coupling (LAIC) (Pulinets and Ouzounov, 2011), which explains the synergy ofdifferent physical processes and anomalous variations, usually named short-term pre-earthquake
anomalies. To check the predictive potential of pre-earthquake signals we validate different anomalous
signals in retrospective and prospective modes including M6.0 Napa 2014, M6.0 Taiwan 2016 and M7.0
Kumamoto, Japan 2016. Our findings suggest that pre-earthquake signals (with 1-30 days time-lag) follow ageneral temporal-spatial evolution pattern, which has been seen in other large earthquakes worldwide. This
study was coordinated under the project “Validation of Lithosphere-Atmosphere-IonosphereMagnetosphere Coupling (LAIMC) as a concept for geospheres interaction by utilizing space-borne multiinstrument observations“ supported by International Space Science Institute (Bern and Beijing).

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*S12-2-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Probability tomography and wavelet analysis of self-potential data andpossible application in landslide monitoring* Qinghua Huang 1) , Kaiyan Hu 1) , Katsumi Hattori 2)
Peking University, Beijing, China 1) , Chiba University, Chiba, Japan 2)
Self-potential method is a kind of near-surface geophysical technique, which has been adopted in
exploration of metal ore, monitoring of contaminants and natural hazards. This study focuses on the selfpotential data processing. The source element occurrence probability tomography can give the probabilityof the source location and the charge property. Due to the limited resolution, the probability tomographymethod might yield ambiguous or even misguiding results in case of the multiple sources with a shortdistance. In order to overcome the above disadvantage and enhance the tomography effect, we combine
the charge occurrence probability tomography with the complex wavelet transform method in self-potential
data processing. We adopt the commercial finite element method (FEM) software COMSOL Multiphysics inthe forward modeling. We apply the complex wavelet analysis the synthetic self-potential data obtained
from the forward modeling of some given models. The results show that the complex wavelet analysis not
only can locate the electric sources, but also can identify the electric features (e.g., homogeneity, inclined
angle of dipole or polarized body, etc.). Furthermore, we apply the combined probability tomography andthe continuous complex wavelet analysis to the synthetic self-potential data. The model test shows that the
combined method could reduce the computation of 3D current source probability and enhance the imaging
resolution. We also apply the combined method to the data from sandbox experiments and test the possible
time-lapse tomography. This study may provide an effective approach of monitoring ground water flow, withpotential application in landslide monitoring.

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*S12-P-01
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Characterizing the nature of spatial heterogeneities based on multi-fractal
and seismic b-value analysis of the 2015 Nepal earthquake sequence* Vijay Prasad Dimri , Nampally Subhadra , Simanchal Padhy
CSIR-National Geophysical Research Institute, Hyderabad
The multi-scaling nature of the spatial heterogeneities of the medium in the source region of the 2015
Nepal earthquake is investigated based on the multi-fractal and seismic b-value analyses of the aftershock
sequence of the 2015 earthquake. The aftershock sequence exhibits an apparent multi-fractal structure,
characterized by a spectrum of generalized dimension Dq varying from D2 = 1.61 to D22 = 0.1. We
estimated the bias in Dq that may arise due to finite numbers of data points and limited size of study
volume by comparing the true estimates with those obtained with uniform random distribution of point setsusing the same numbers of events as for the real data. In addition, samples from the real data are randomly
extracted and dimension spectra for these are examined as well. We also discussed the possibility of theapparent multi-fractality that may arise in case of finite data sets. Our results show that the spectrum for theuniform random generation is weakly multi-fractal by comparing the results from real data and simulated
points sets that may help distinguish between true and apparent multifractality,that is expected for a data
set with finite number of samples. Next, temporal correlation between the correlation dimension D2 andenergy released shows a significant drop in D2 before the major events in the sequence, which tries tocome back to the background value. The multi-fractal structure of Dq and their temporal variation suggestthat the spatial distribution of aftershocks is not a random phenomenon, but it self-organizes on a spatiotemporal scale into a critical state, exhibiting a scale-independent structure governed by a power-law
scaling. We also studied the frequency-size distribution of the sequence, characterized by the GutenbergRichter law with an average seismic b-value of 1.11±0.08. Our results are useful for seismic hazard
assessment in the near field due to the subduction zone earthquake in the region.

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*S12-P-02
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Precursory signature of a megathrust earthquake and postseismic effects onregional earthquake induction* Tae-Kyung Hong , Junhyung Lee , Seongjun Park
Yonsei University, Seoul, South Korea
The prediction of great earthquakes has not beensuccessful despite various efforts. Finding a signaturefor impending great earthquakes is crucial for seismic
hazard mitigation. We observed a temporal change of the
Gutenberg-Richter frequency-magnitude relationship (bvalue) before the 2011 Tohoku-Oki megathrust earthquake
for more than 20 years. It is observed that the b values
decrease with time before the events. The change of bvalue of region is proportional to the cumulated stress.
The megathrust earthquake caused large permanent
lithospheric displacements in regional distances. The
seismicity around the Korean Peninsula was increased
significantly after the 2011 M9.0 Tohoku-Oki earthquake,
which is not consistent with the expected
seismic-quiescence. Strong seismic waves cause large
dynamic stress changes, incurring fluid migration andincreasing pore fluid pressure in the media. The
lithospheric displacements directing to the epicenter on
the convergent plate boundary develop transient radial
tension field over the backarc lithospheres. The seismic
velocities in the lithosphere changed abruptly up to 2 %after the megathrust earthquake, which recovered
gradually with time for several years. The ambient stressfield is recovered gradually as the induced stress fielddiminishes with time by tectonic loading. A series ofmoderate-size earthquakes and earthquake swarms occur asa consequence of medium response to the temporal
evolution of stress field. The long-term evolution ofseismicity is expected to continue until the ambient
stress field is fully recovered.

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*S12-P-03
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Resistivity changes during the 2015 seismic swarm detected by real-timemagnetotelluric monitoring system in Taal volcano (Philippines)* Paul Karson Alanis 1) , Paolo Reniva 1) , Juan Cordon 1) , Allan Loza 1) , Lawrence Aaron Banes 1) , Yoichi
Sasai 2) , Akihiro takeuchi 3) , Toshiyasu Nagao 2)
Philippine Institute of Volcanology and Seismology 1) , Institute of Oceanic Research Development, Tokai
University, Japan 2) , Earthquake Research Institute, The University of Tokyo, Japan 3)
Taal volcano is located in the island of Luzon and 60 km south of the capital city of Manila. It is one of themost active volcanoes in the Philippines. The first recorded eruption was in 1573 and since then it has
erupted a total of 33 times, with the last eruption in 1977. These eruptions resulted in thousands ofcasualties and considerable damage to property. In 1995 it was declared one of the “1990s decade
volcano" by IAVCEI. Although the volcano remained fairly quiescent after the 1977 eruption, at the
beginning of the 1990s it began to exhibit several phases of abnormal activities, such as episodes ofseismic swarms, ground deformation and fissuring, and hydrothermal activities, all of which continues tothe present. Past eruptions of Taal Volcano can be divided into 2 distinct cycles, depending on the locationof the eruption: eruptions centered at the Main Crater (1572-1645 and 1749-1911); and eruptions
occurring at the flanks (1707-1731; 1965-1977).
As part of the PHIVOLCS-JICA-SATREPS Project (2010-2014), magnetometers were installed at Taal
volcano. These consist of three (3) Overhauser-type magnetometers (installed at VTBM, VTDK and VTMC)
and one (1) fluxgate-type magnetometer (installed at VTBM). The Project also established (using
magentotelluric method) that a large hydrothermal reservoir is underneath Taal volcano and currently thisis under a state of equilibrium. The state of the hydrothermal reservoir is thus monitored constantly bymagnetometers. In early-2015, remarkable resistivity changes were detected by the flux-gate magnetometer
during an earthquake swarm occurred in Taal volcano. The locations of these earthquakes appears to be in
the approximate location of the hydrothermal reservoir.

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*S12-P-04
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Characteristics of b-value and TEC changes in Space and Time before theLarge Earthquakes in Japan
Takaaki Kobari 1) , Peng Han 1) 2) , * Katsumi Hattori 1)
Chiba University, Japan 1) , Institute of Statistical Mathematics, Japan 2)
In recent years, there are many reports on electromagnetic phenomenon preceding large earthquakes.
Anomaly of the total electron content (TEC) is one of the most promising anomalies for the short-term
earthquake forecast. However, the TEC is disturbed by solar-terrestrial interaction very much. Therefore, it
is difficult to discriminate anomalous changes on earthquakes and solar activities easily at the moment. On
the other hand, it is reported that the b-value around the epicenter region decreases prior to the large
earthquake. In this paper, we investigate the effectiveness of the integrated analyses on the b-value andTEC analysis. We select the 2003, 2008 Tokachi-oki EQs and the 2011 Tohoku-oki EQ at first. As results,
we found the variation of b-value has a tendency to decrease for M7class EQs in the analyzed regions andthe neighbor's area. For the 2003 Tokachi-oki EQ, we found decrease of b-value 16 days and 2-3days
before the main shock. On the other hand, for the TEC anomaly in the Hokkaido region, we foundsignificant increase 2 days before the EQ(M>6.0,D<40 km) using the statistical analysis during 1998-2015.
That is, the positive anomaly is dominant, In the case of the 2003 Tokachi-oki EQ, TEC anomaly occurred 2
days before main shock. These results suggest the effectiveness of the proposed method. We have thesimilar tendency for the 2011Tohoku-oki EQ. Details will be given in the presentation.

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*S12-P-05
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Anomalies of astronomical time-latitude observations before strong
earthquake and discussions on the problems of its application* Bo Wang , Zhiqiang Yin , Lili Tian , Hongqi Wang , Yanben Han
National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China
Strong earthquake may create a large number of casualties and huge property losses. Due to the complexityof crustal structure and movement, the geophysical process during the gestation and occurrence ofearthquake is extremely complex. So it is very difficult to forecast an earthquake in advance. To findeffectual earthquake precursors is one of the key for meliorating earthquake prediction. A phenomenon
that short-term anomalies appeared in residuals of astronomical time and latitude observations before
major earthquakes, which occurred in regions around the astrometric instruments, was discovered by
Chinese astronomers after Tangshan Earthquake in 1976. The phenomenon was called anomalies ofresiduals of astronomical time and latitude observations (ATLR). The major characteristics of thephenomenon have been studied preliminarily. ATLR anomalies may be from the variation of the vertical,
which is the datum line of such astrometric instruments, due to the motion of underground mass.
The possibility that using the observations to provide information for strong earthquakes in advance has
been researched and related tests to provide forecast information have made in China. Present results andtests showed that the phenomenon would possibly become a kind of significant short-term earthquake
precursors. However, observations of one instrument can only reflect the vertical variations within a certain
range around the instrument, so ATLR of one station cannot afford the information of position andmagnitude of an earthquake. To set up an network using seemly astrometric telescopes in seismogenetic
zone will be needful for finding significant forecasting information. The new Digital Zenith Telescope (DZT)
which has characters of high precision, robotization, miniaturization and low cost was made in China
recently years. DZT is propitious to set up such network. The scheme on setting up network is put forward.
The notions and problems related to network are discussed.

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*S12-P-06
IASPEI Symposium / IASPEI03. Earthquake Generation Process / S12. An interdisciplinary approach towards earthquake prediction studies

Abnormal seismicity of slow earthquakes on land prior to 2011 Tohoku
earthquake* Tomoki Tokuda , Hirohiko Shimada
Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
Slow earthquake (EQ) has recently gained much attention as a possible precursor of large earthquake. A
number of studies so far suggest that slow EQ (or slow slip) may serve as an indicator of stressaccumulation/transfer, thus quite useful for predicting a large earthquake. Indeed, it was observed thatslow EQs migrated toward the epicenter of 2011 Tohoku earthquake, which suggests a possible nucleation
process prior to the occurrence of the megathrust earthquake. As regards Tohoku EQ, the current focus ofresearch tends to be on off-shore areas near the epicenter, exploring relationships among slow tremors,slow slip events and the megathrust earthquake. On the other hand, slow EQs that occurred in remoteareas (on land) far from the epicenter receive less attention. Nonetheless, geodetic data suggest that theaccumulation of on-land stress in Tohoku region is associated to that of the off-shore one. So, we cannot
rule out a possibility of abnormal seismicity in on-land slow EQs prior to Tohoku EQ. In this talk, we
discuss such a possibility, examining the relationship between slow EQs in remote areas and Tohoku EQ ina data-driven approach. First, we analyze on-land slow EQ that occurred in northern Japan in the last 20
years (based on the catalogue of Japan Meteorological Agency) by means of cluster analysis. In thisanalysis, three subtypes of slow EQs are identified, which are statistically characterized by short, mid andlong-term intertime between slow EQs. Second, it is found that the short and mid-term slow EQs became
quiescent two months and one month before the Tohoku EQ, respectively. Such a phenomenon is notobserved in generic earthquakes, and would be identified with a unique characteristic of megathrustearthquakes. Finally, we apply OFC (Olami, Feder, Christensen) model to the slow EQ data in question,
giving a theoretical interpretation to the aforementioned phenomenon.

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*S13-1-01
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Challenges in moment tensor resolution: collapses, explosions and shallow
earthquakes* Simone Cesca , Sebastian Heimann
GFZ German Research Centre for Geosciences
Regional moment tensor inversion is extensively used to model the earthquake rupture geometry andestimate earthquake source parameters. Typically, inversion algorithms derive the moment tensor
configuration by fitting low frequency full waveforms or amplitude spectra. Resulting moment tensor
catalogues provide a valuable information on seismic source processes. They can be used forseismotectonic interpretation, to discuss non shear ruptures or as a base to investigate the stressorientation. The resolution of the moment tensor can be reduced by several causes, such as waveform
mismodeling due to a poor knowledge of the crustal structure, low signal-to-noise ration due to seismic
noise and poor azimuthal coverage due to an unfavourable network geometry. Poor conditions may bias
moment tensor solutions, for example introducing non double couple terms. Beside these known problems,
the procedures of moment tensor inversion, decomposition and interpretation are also affected by intrinsic
ambiguities, which can become critical for shallow sources or specific source-network geometries. First,
different uncertainties affect different moment tensor entries, resulting in an uneven resolution of moment
tensor components. In addition, moment tensor components trade-offs affect the uniqueness of thesolution, so that different moment tensor configurations may fit well the data. Finally, the interpretation of
the moment tensor solution may be hindered by the chosen decomposition. We discuss and investigate
some of these often neglected problems and provide example for each of them, combining synthetic tests
with the discussion of significant real data applications. Among the real data cases, the analysis of seismic
signals produced by recent volcanic collapse and shallow underground explosions in North Korea helps toillustrate the problem of moment tensor uncertainties, trade-off and decomposition.

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*S13-1-02
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Uncertainties in moment tensor estimation for induced earthquakes
illustrated at the example of the Groningen gas field, The Netherlands* Daniela Kuehn 1) 2) , Sebastian Heimann 2) , Sven Peter Naesholm 1) , Ben Dando 1) , Hom Nath Gharti 3) ,Elmer Ruigrok 4)
NORSAR, Kjeller, Norway 1) , GFZ German Research Centre for Geosciences, Potsdam, Germany 2) ,Department of Geosciences, Princeton University, Princeton, USA 3) , Royal Netherlands Meteorological
Institute, De Bilt, The Netherlands 4)
The Groningen gas field is one of the largest gas fields in the world, in production since 1963. Since theearly 1990's, induced seismicity started to occur in its vicinity. Approximately 220 earthquakes with M ≥1.5 were registered from 1991 to July 2013 in the vicinity of the Groningen field area. The strongest event
recorded so far (ML = 3.6) occurred on 16th August 2012 near the village of Huizinge, raising huge damage
claims as well as public concerns.
Starting in 1991, a geophone monitoring network operated by KNMI was installed. This network has been
extended several times, providing a detection threshold of M=1.5 since 1995. We will use a newly
developed python-based probabilistic moment tensor inversion tool named“Grond" to re-analyse four
events that occurred from 2006 to 2009, for which focal mechanisms have been computed earlier(Kraaijpoel and Dost, 2012).
Each of the four events has been recorded on up to 6 accelerometers at distances of less than 10 km andon up to 8 shallow borehole strings at distances of 15 to 90 km. Due to the inherent capabilities ofprobabilistic methods, we are able to analyse trade-offs between inversion parameters and to assess
uncertainties. We illustrate the influence of parameters of the forward modelling and the choice of theobjective function on the resulting moment tensor.
“Grond" adapts an optimization scheme using elements of simulated annealing and the bootstrap
technique. Rather than optimizing a single objective function, it tries to find volumes in parameter spacethat satisfy low misfit values over an ensemble of N variations of the objective function. In every
optimization method, there is a trade-off between number of tested models and ability to find the global
minimum without getting trapped in local minima. Usually a compromise is made depending on thecharacteristics of the problem to be solved. In our optimization, however, the degree to which theparameter space is explored can be tuned by the user.

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*S13-1-03
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Moment tensor inversion based on the principal component analysis:
Method and application to the 2014 earthquake sequence in West Bohemia,
Czech Republic* Vaclav Vavrycuk , Petra Adamova , Jana Doubravova , Hana Jakoubkova
Institute of Geophysics, Prague, Czech Republic
We develop and test a new hybrid approach of the amplitude and waveform moment tensor inversions,which utilizes the principal component analysis of seismograms. The proposed inversion is less sensitive tonoise in data being thus more accurate and more robust than the amplitude inversion. It also suppresses
other unmodelled phenomena like a directivity of the source, errors caused by local site effects at
individual stations and by time shifts in arrivals of observed and synthetic signals due to an inaccurate
velocity model. The inversion is simple and computationally less demanding than the full waveform
inversion and thus applicable to large datasets. The approach is numerically tested on synthetic data with avarious level of noise. The applicability of the inversion is demonstrated on inverting more than 800
microearthquakes that occurred during the 2014 activity in West Bohemia, Czech Republic. The analysis
revealed clustering of the moment tensors into several distinct types. Three types of MT are left-lateral
strike slips associated with the most active fault in the focal zone. Another cluster is characterized by theright-lateral strike slips associated with the fault conjugate to the main fault. Finally, we identified a clusterwith pure reverse focal mechanisms which are anomalous and not expected to occur in the region. Thesemechanisms were not detected in the previous seismic activity and they have an unfavourable orientation
with respect to regional tectonic stress. This might indicate a presence of local stress heterogeneities
caused, for example, by an interaction of faults or fault segments in the focal zone.

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*S13-1-04
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Non double couple components of Mw>4.5 events in The Geysers
geothermal field, California revealed by a hierarchical Beyesian inversion* Marija Mustac , Hrvoje Tkalcic
The Australian National University, Canberra, Australia
Earthquakes occurring in geothermal and volcanic environments can have significant non double couple(non-DC) components related to fluid movement. However, significant non-DC components can also
emerge as a consequence of not adequately (or not at all) accounting for the noise in the data in routine
waveform inversions for earthquake source parameters. Here, we apply a hierarchical Bayesian moment
tensor inversion method to a number of earthquakes from The Geysers field in California using data frombroadband stations at regional distances. This probabilistic technique yields parameter uncertainties thatindicate the reliability of the non-DC components. Furthermore, we allow the noise to determine the levelof data fit by treating it as a parameter in the inversion, and account for interdependence of data errors
using an empirically estimated noise covariance matrix.
The structure of The Geysers field involves stacks of permeable and impermeable highly fractured rocks,
probably underlain by a magma body. Seismicity is dominated by microearthquakes, half of which havesignificant non-DC components. We have analysed several Mw>4.5 events using two different assumptions
about the noise (two different noise covariance matrices).
The double couple components of the sources are consistent with strike-slip or normal faults present in thegeothermal field, and the non-DC components show a variety of values. Inversions with the empiricallyestimated cosine covariance matrix result in a slightly lower isotropic component than inversions with apure diagonal covariance matrix. One event is predominantly a double couple, while the others havesignificant non-DC components. They can be explained as a combination of shear faulting and crack
opening, but at least one event requires an additional mechanism that reduces the isotropic component,such as fluid extraction.

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*S13-1-05
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Determination of high precision microseismic source mechanism by
iterative relative moment tensor inversion* Kazutoshi Imanishi , Takahiko Uchide
Geological Survey of Japan, AIST, Tsukuba, Japan
Source mechanism of microearthquakes provides fundamental information about the physical process atthe source, in-situ stress field, etc. However, their reliable estimate is still a difficult task due to our poor
knowledge of the underground structure. Dahm (1996) developed a novel method of source mechanism
determination for earthquake clusters called relative moment tensor inversion (RMTI), in which relative
body-wave amplitudes for two earthquakes recorded at a common station are used to eliminate the effect of
un-modeled propagation paths. If the source mechanism of one of those earthquakes is known a priori, theother source mechanisms can be determined without a computation of Green's function. A difficulty in thismethod is that errors in the mechanism of reference events may lead to biased solutions for other events.
To resolve this problem, we propose a method that iteratively applies the RMTI to source clusters
improving each moment tensor as well as their relative accuracy. The procedure is as follows:(1) Sample co-located multiple earthquakes with focal mechanisms, as initial solutions, determined by an
ordinary method.
(2) Apply the RMTI to estimate the source mechanism of each event relative to those of the other events.
(3) Repeat the step 2 for the modified source mechanisms until the reduction of total residual converges.
Numerical tests showed that the solutions were successively improved by iteration and almost reached the
input mechanisms. Even in the case of poor observation condition, we could obtain reliable estimates by
imposing a DC constraint. Application to natural earthquakes revealed a small-scale heterogeneity which
could not be identified by earthquake locations. The proposed method also has a potential to resolve real
non-DC components, so our next plan is to apply the method to induced microseismic events in oil, gas,
and geothermal fields, in which the relation between fluid injection and non-DC components is an
important issue.

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*S13-1-06
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Microseismic Event Relocation and Focal Mechanism Estimation Based on
PageRank Linkage* Ana C. Aguiar , Stephen C. Myers
Lawrence Livermore National Laboratory, Livermore, California, USA
Microseismicity associated with enhanced geothermal systems (EGS) is key in understanding how
subsurface stimulation can modify stress, fracture rock, and increase permeability. Large numbers of
microseismic events are commonly associated with hydroshearing an EGS, making data mining methods
useful in their analysis. We focus on PageRank, originally developed as Google's search engine, andsubsequently adapted for use in seismology to detect low-frequency earthquakes by linking events directly
and indirectly through cross-correlation (Aguiar and Beroza, 2014). We expand on this application by using
PageRank to define signal-correlation topology for micro-earthquakes from the Newberry Volcano EGS in
Central Oregon, which has been stimulated two times using high-pressure fluid injection. We create
PageRank signal families from both data sets and compare these to the spatial and temporal proximity of
associated earthquakes. PageRank families are relocated using differential travel times measured by
waveform cross-correlation (CC) and the Bayesloc approach (Myers et al., 2007). Prior to relocation eventsare loosely clustered with events at a distance from the cluster. After relocation, event families are found tobe tightly clustered. Indirect linkage of signals using PageRank is a reliable way to increase the number of
events confidently determined to be similar, suggesting an efficient and effective grouping of earthquakes
with similar physical characteristics (ie. location, focal mechanism, stress drop). We further explore thepossibility of using PageRank families to identify events with similar relative phase polarities and estimate
focal mechanisms following Shelly et al. (2016) method, where CC measurements are used to determine
individual polarities within event clusters. Given a positive result, PageRank might be a useful tool in
adaptive approaches to enhance production at well-instrumented geothermal sites. Prepared by LLNL
under Contract DE-AC52-07NA27344.

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*S13-2-01
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Demonstration of improved seismic source inversion method of tele-seismic
body wave* Yuji Yagi , Ryo Okuwaki
University of Tsukuba, Tsukuba, Japan
Seismic rupture inversion of tele-seismic body wave has been widely applied to studies of large
earthquakes. In general, tele-seismic body wave contains information of overall rupture process of large
earthquake, while the tele-seismic body wave is inappropriate for analyzing a detailed rupture process ofM6~7 class earthquake. Recently, the quality and quantity of tele-seismic data and the inversion method
has been greatly improved. Improved data and method enable us to study a detailed rupture process ofM6~7 class earthquake even if we use only tele-seismic body wave. In this study, we demonstrate the abilityof the improved data and method through analyses of the 2016 Rieti, Italy earthquake (Mw 6.2) and the2016 Kumamoto, Japan earthquake (Mw 7.0) that have been well investigated by using the InSAR data set
and the field observations.
We assumed the rupture occurring on a single fault plane model inferred from the moment tensor solutions
and the aftershock distributions. We constructed spatiotemporal discretized slip-rate functions with patchesarranged as closely as possible. We performed inversions using several fault models and found that the
spatiotemporal location of large slip-rate area was stable.
In the 2016 Kumamoto, Japan earthquake, the slip-rate distribution shows that the rupture propagated tosouthwest during the first 5 s. At 5 s after the origin time, the main rupture started to propagate toward
northeast. First episode and second episode correspond to rupture propagation along the Hinagu fault andthe Futagawa fault, respectively. In the 2016 Rieti, Italy earthquake, the slip-rate distribution shows that therupture propagated to up-dip direction during the first 2 s, and then rupture propagated toward northwest.
From both analyses, we propose that the spatiotemporal slip-rate distribution estimated by improved
inversion method of tele-seismic body wave has enough information to study a detailed rupture process ofM6~7 class earthquake.

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*S13-2-02
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

A Bayesian hierarchical model for a seismic source inversion
Amato Kasahara , * Yuji Yagi
University of Tsukuba, Tsukuba, Japan
A source inversion analysis using spatio-temporal displacement field data is able to be formulated as adiscrete linear inverse problem when the Green function and the source fault are known. However, it isdifficult to calculate an accurate Green function. Previous studies approximated the effects of theuncertainty of the Green function by introducing a new correlated or uncorrelated error term, which isadded to data. The approximation fails to capture important characteristics such as peak shift and heavy
tails of the likelihood function under the uncertainty of the Green function.
We propose a hierarchical Bayes model for a multi-data analysis with the multi-time-window finite fault
parameterization. In the model, a Green function is treated as a realization of a random variable G. The
marginalization of the hyperparameters, which control the prior distribution of the model parameters andthe observation errors, is approximated by plugging in of the maximum a posteriori hyperparameters given
G. The marginal likelihood function for G is approximated by the Laplace approximation. The
marginalization of G is approximated by a Monte-Carlo integration method.
We applied the method to synthetic data. We set a 1-D velocity structure at the source region. We drew
thousands of velocity structure samples from the prior distribution of the velocity structure, and thencalculated the corresponding Green functions. For reference, we also conducted a conventional inversion,
which used only a reference velocity structure. We found that the conventional inversion result suffers from
artifacts especially at the later shallow part of the rupture process, while the result with the proposed
method does not suffer from the artifact. Note that the mitigation of the artifact was not possible with thesimple mean-of-the-posterior-mean approach. We also found increase of the variance of the posterior
distribution of the potency due to the marginalization of G.

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*S13-2-03
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Seismicity of the Nordland area, Norway* Jan Michalek , Lars Ottemoeller , Jens Havskov , Marte Louise Stromme , Berit Marie Storheim
University of Bergen, Bergen, Norway
The Nordland area (65-70N; 8-18E) is tectonically active part of Norway. Enhanced seismicity may reflect
on off-shore subsidence combined with the uplift of landmasses usually attributed to glacial isostatic
adjustment (related to Pleistocene unloading). Detailed monitoring of seismic activity in the Nordland area
was done in August 2013 – June 2016 as a part of the NEONOR2 project and information obtained fromanalysis of earthquakes together with geodetic data should be the key inputs for modeling of deformation
and uplift patterns and their mechanisms in the region. A local network of 26 broadband stations was
deployed and together with the permanent NNSN stations in that area, it contained 33+ stations withinspan 350 x 200 km. About 1250 earthquakes of M>0.0 was recorded during the project period and newmap of seismicity of that area was retrieved. The main aim of the project is to reveal the stress field in thatparticular region and therefore the determination of stable focal mechanisms is crucial. Despite the highnumber of stations, enough clear polarity readings (>=6) were obtained for only about 20 strongest events(M<3.2). Hence we developed a methodology using automatic amplitude readings and the standard tools(FOCMEC, HASH) for focal mechanism determination which are implemented in SEISAN. The
methodology is tested using the strongest events and conclusions for further application are suggested.

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*S13-2-04
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

earthquake statistics, spatiotemporal distribution of foci and source
mechanisms as a key to understanding of causes leading to the West
Bohemia/Vogtland earthquake swarms* Josef Horalek , Hana Jakoubkova
Institute of Geophysics of the Czech Academy of Sciences, Prague, Czech Republic
The origin of earthquake swarms is still unclear. West Bohemia-Vogtland represents one of the most active
intraplate earthquake-swarm areas in Europe. There were swarms in 1997, 2000, 2008 and 20011 followedby reactivation in 2013 which forming a focal belt of about 15 x 6 km, focal depths vary from 6 to 15 km.
An exceptional non-swarm activity up to magnitudes ML = 4.5, stroke the region in 2014, the events werealso located in the NK focal belt.
We analysed geometry of the NK focal zone applying the double-difference method to seismicity in the
period 1997 – 2014. The swarms are located close to each other at depths between 6 and 13 km. The mostevents obey the b-value = 1.0 distribution, however, a group of the largest events (~ML > 2.8) departsignificantly from it. Furthermore, we disclose that all the ML > 2.8 swarm events, which occurred in thegiven time span, are located in a few dense clusters. It implies that the most of seismic energy in theindividual swarms has been released in step by step rupturing of one or a few asperities. The mechanism
patters of the individual swarms indicate their complexity. MTs of the most analysed events signify pure
shears except for events the second phase of the 1997 swarm the MTs of which indicate significant amountof non-DC components.
We infer that the individual earthquake swarms in West Bohemia-Vogtland are mixture of the mainshockaftershock sequences which correspond to step by step rupturing of one or a few asperities. The swarms
occur on short fault segments with heterogeneous stress and strength, which may be affected by crustal
fluids. Pressurized fluids may reduce normal component of the tectonic stress and lower friction. Thus,
critically loaded and favourably oriented faults are brought to failure and the swarm activity is driven by thedifferential local stress.

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*S13-2-05
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Induced seismicity of Kuzbass (Russia). Bachatskoe earthquake of 2013,
ML=6.1* Aleksey Emanov 1) 2) , Aleksandr Emanov 1) 3) , Ekaterina Leskova 1) 2) , Aleksandr Fateev 1) 2)
Altai-Sayan Branch of Geophysical Survey of Russian Academy of Sciences, Novosibirsk, RussianFederation 1) , Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian
Academy of Sciences, Novosibirsk, Russian Federation 2) , Novosibirsk State University, Novosibirsk,
Russian Federation 3)
The Kuznetsk coal basin (Kuzbass) is one of the largest coal deposits in the world, located in the South ofWestern Siberia in Russia. The territory of Kuzbass has always proved itself as a district with rare large
earthquakes and a moderate seismicity, much of which is concentrated in mountainous framing of theKuznetsk basin. But a special study of induced seismicity was not carried out until the beginning of the
century because of the sparse network of seismic stations here. Only in recent years in connection with thedevelopment of a network of seismic monitoring stations in the Kuzbass and conducting several
observations using temporary networks of seismic stations has been shown the existence of induced
seismicity. At the moment, the basis of the system of monitoring induced seismicity with 11 additional
stations on the territory of Kuzbass is created. The system works in real time and allows tracking theappearance and the development of dangerous human induced seismic processes formed around minesand quarries. According to registrations of the system shown the induced seismicity in the Kuzbass
significantly dominates over the natural seismicity.
In addition, a strong earthquake with ML=6.1 occurred on the 18th of June, 2013 near one of the largest
open pits of the Kuznetsk basin (Bachatskiy). As a result of studies using temporary seismic stations in theepicentral area of the Bachatskoe earthquake was found that the seismic process area is closely connected
to an open mine workings, and earthquakes are extended in the depth from the cut bed up to 4-5 km.
Seismic regime of induced activation is continuous and not stationary. The orientation of the nodal planesof Bachatskoe earthquake focal mechanism corresponds to the direction of technogenic impact. The
findings suggest that Bachatskoe earthquake and associated activation are induced earthquakes with afairly large energy.

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*S13-2-06
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Crustal stress field in Taiwan inferred from regional-scale damped inversion
of a newly derived homogeneous earthquake focal mechanism dataset* Wen-Tzong Liang 1) , Ping-Han Huang 2) , Yi-Ling Huang 2) , Pei-Ru Jiang 3) , Tai-Lin Tseng 3)
Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan 1) , National Taiwan Ocean University,
Keelung, Taiwan 2) , National Taiwan University, Taipei, Taiwan 3)
A regional seismic stress field of the crust in Taiwan has been obtained by applying the damped stressinversion algorithm to a newly derived focal mechanism dataset. To construct this homogeneous dataset,
which is composed of more than 3000 centroid moment tensor solutions, we have developed a new
multiple solution method to invert the high quality broadband waveforms collected in the past two decades.
Only solutions with high quality and shallower focal depth (<40 km) are selected in the stress inversion. To
test the reliability of the stress field, we implement a series of checkerboard tests with various grid spacing.
Our results show that the maximum principle seismic stress, signma-1, is dominated by the NW-SE collision
direction between the Eurasia plate and the Philippine Sea plat. It presents a fan-shape distribution in thewestern part of Taiwan. A dramatic change of sigma-1 direction at ~24.3N along the eastern coast, which
may mark the transition from collision to subduction in the NE Taiwan area. In addition, we also notice that
there is an S-shape trajectory across the Central Range that is suspected to be associated with spatial
rheology heterogeneity. Normal faultings are mainly observed in the Okinawa Trough, Central Range, andSW offshore Taiwan, which are referred to different tectonic processes in this region. Obvious interface
focal mechanisms in the eastern offshore region are also delineated with their NS striking and shallow
angle thrusting pattern. Our principle seismic stress axes are comparable with the principle strain axes
derived from GPS observation, implying that the crust in Taiwan may deform largely in an elastic manner.
However, remarkable rotational patterns of sigma-1 presented in Ilan and Pingtung area may reflect thecomplicated tectonic forces and geological settings in the Taiwan region.

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*S13-3-01
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Tidal controls on earthquake size-frequency statistics* Satoshi Ide 1) , Suguru Yabe 1) , Yoshiyuki Tanaka 2)
Dept. EPS, The University of Tokyo, Tokyo, Japan 1) , ERI, The University of Tokyo, Tokyo, Japan 2)
The possibility that tidal stresses can trigger earthquakes is a long-standing issue in seismology. Except insome special cases, a causal relationship between seismicity and the phase of tidal stress has been rejectedon the basis of studies using many small events. However, recently discovered deep tectonic tremors arehighly sensitive to tidal stress levels, with the relationship being governed by a nonlinear law according towhich the tremor rate increases exponentially with increasing stress; thus, slow deformation (and theprobability of earthquakes) may be enhanced during periods of large tidal stress. Here, we show theinfluence of tidal stress on seismicity by calculating histories of tidal shear stress during the 2-week period
before earthquakes. Very large earthquakes tend to occur near the time of maximum tidal stress, but thistendency is not obvious for small earthquakes. Rather, we found that tidal stress controls the earthquake
size-frequency statistics; i.e., the fraction of large events increases (i.e. the b-value of the Gutenberg-Richter
relation decreases) as the tidal shear stress increases. This correlation is apparent in data from the global
catalog and in relatively homogeneous regional catalogues of earthquakes in Japan. The relationship is also
reasonable, considering the well-known relationship between stress and the b-value. Our findings indicatethat the probability of a tiny rock failure expanding to a gigantic rupture increases with increasing tidal
stress levels. This finding has clear implications for probabilistic earthquake forecasting.

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*S13-3-02
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

A statistical characterization of earthquake initiation and its implication* Shunta Noda 1) , William Ellsworth 2)
Railway Technical Research Institute, Tokyo, Japan 1) , Stanford University, CA, USA 2)
Rapid magnitude (M) determination is critical for earthquake early warning (EEW). A number of methods
have been proposed to do this. For example, the use of the frequency content of initial P wave (e.g., Allen &Kanamori, 2003), or a combination of displacement amplitude and a ground motion prediction equation(e.g., Odaka et al., 2003) or from the time between the onset of a body wave and the peak amplitude arrivalof that wave (e.g., Noda et al., 2016). It is an essential question for these techniques whether or not the final
M is deterministic at the time of initiation (e.g., Olson & Allen, 2005). To investigate this issue, Noda &Ellsworth (2016, GRL) used Japanese K-NET data from 150 events with 4.5 <= Mw <= 9.0 and hypocentral
distance (R) less than 200 km, and examined the P-wave absolute displacements. They found that the Pwave displacement began in a similar way at the onset and departed from the similarity earlier for smaller
events. In the magnitude range up to Mw 7, the scaling relation between the departure time (Tdp) and thefinal Mw resulted in Mw = 2.29 * logTdp + 5.95 which suggests that Tdp occurs before the completion of
rupture in a statistical sense. Noda & Ellsworth indicated that the scaling relation was consistent with what
Olson & Allen (2005) called the deterministic property of earthquakes in which the P-wave frequency
contents (tau-p) scales with the final M even when the time window is significantly shorter than the typicalsource duration. Here we discuss how such a deterministic property could be explained by the model ofMurphy & Nielsen (2009) where the available elastic energy at the initial rupture patch must exceed acertain threshold in order for the rupture to propagate spontaneously far beyond the initial patch. When theenergy lies below the threshold, the final M is statistically deterministic at the time of initiation. When theenergy exceeds the threshold, final M cannot be reliably determined from initial P wave alone.

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*S13-3-03
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Effective stress drop of earthquake clusters* Tomas Fischer 1) 2) , Sebastian Hainzl 3)Charles University, Faculty of Science, Prague, Czechia 1) , Institute of Geophysics, Czech Academy of
Science, Prague, Czechia 2) , Helmholtz Centre Potsdam, GFZ, Germany 3)
The static stress drop is a standard measure of the average decrease of shear stress on a fault during anearthquake. It has been observed that stress drop does not vary significantly with earthquake magnitude
and may be regarded as an invariant parameter of the rupture process at different scales. While typicalstress drops of earthquakes range between 1 and 10 MPa, much smaller stress drops in fractions of MPa
are reported for slow earthquakes and in some cases also for earthquake swarms. For the latter cases, theeffective stress drop was introduced as an alternative parameter, which makes use of the cumulative
seismic moment and total activated area of the seismic cluster.
We test how the effective stress drop is comparable to the static stress drop of a single earthquake
rupturing the same fault portion. To this purpose, we compare the spatiotemporal evolution of the seismic
moment release and analyze the uncertainties of the resulting stress drop estimates. We show that theeffective stress drop is only comparable to earthquake stress drops in very specific cases. In particular, theeffective stress drop values significantly underestimate the earthquake stress drops in the presence ofaseismic deformation. Furthermore, the values are only scale-independent if pre-stress and post-stressconditions are uniform in space. Our analysis of data from injection-induced seismicity, natural earthquake
swarms and aftershock sequences shows that in most cases the effective stress drop estimate is rather
stable during the cluster evolution. However, slightly increasing estimates for injection-induced seismicity
are indicative for the local forcing of the system, while overall low effective stress drop values hint to theimportant role of aseismic deformations.

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*S13-3-04
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Radiated Energy Enhancement and Rupture Complexity of Large
Subduction-Zone Earthquakes
Lingling Ye 1) , Hiroo Kanamori 1) , * Thorne Lay 2)
California Institute of Technology, CA, US 1) , University of California at Santa Cruz, CA, US 2)
The rupture characteristics of large earthquakes on subduction zone plate boundaries vary substantially.
The asperity model, proposed in the early 1980s, related variations of the largest earthquake size andcomplexity in a region to stress heterogeneity. Repeating earthquakes and geodetic measurements of interseismic strain accumulation support the notion of asperities being surrounded by creeping regions withdifferent frictional properties. The surge of large earthquakes over last decade and the advance inobservations and analysis techniques allow us to evaluate whether asperities differ from region to region.
To quantify variable rupture complexity, we introduce a new energy radiation parameter, the radiatedenergy enhancement factor (REEF): the ratio of directly measured broadband radiated energy to thecalculated minimum radiated energy for an event of equal seismic moment and duration with parabolic
shape moment-rate function). For large earthquakes, REEF is closely related with complexity in theobserved moment-rate function. We find that (1) REEF variation among different subduction zones is
consistent with the level of segmentation proposed in the asperity model; and (2) REEF values are similar
for earthquakes with different magnitudes in each region. Both observations indicate that the regional“asperity" structure observed at scales of tens to hundreds of kilometers is similar to that at smaller scales.
Asperities thus differ from region to region, likely due to variable stress conditions on the plate boundaries.

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*S13-3-05
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Seismic energy release at the seismogenic zone of Guerrero, Mexico.
* Raymundo Plata-Martinez , Xyoli Perez-Campos , Shri Krishna Singh
Institute of Geophysics, UNAM, Mexico.
To study the mechanisms that control seismic energy release along the Guerrero, Mexico, subduction zone,
we estimated radiated seismic energy, stress drop and radiation efficiency of two recent large earthquakes
and their aftershocks. The first earthquake occurred at the border of the states of Guerrero and Oaxaca in
Ometepec on March 2012 (Mw7.5), the second earthquakes occurred 300 km away, in Papanoa on April
2014 (Mw7.2). Estimations of radiated energy scaled with seismic moment (Es/M0), show no evidence ofdependence of radiated seismic energy with distance from the trench, depth, or size of earthquakes.
However, scaled energy distribution behaves in a heterogeneous way parallel to the trench, and it might beinfluenced by lateral heterogeneities along the subduction interface. Stress drop and efficiency also reveals
rough changes parallel to the trench, in a similar way as scaled energy. However, results show that
Ometepec earthquakes had lower stress drops and higher radiation efficiency values compared with
Papanoa sequence.

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*S13-3-06
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Seismic source spectra and the relation between corner frequency andsource properties derived from spontaneous rupture of a circular fault* Jian Wen 1) , Xiaofei Chen 2) , Jianxuan Xu 2)
University of Science and Technology of China, Hefei, China 1) , Southern University of Science andTechnology, Shenzhen, China 2)
Stress drop is an important dynamic source parameter for understanding the physics of source processes.
The estimation of stress drops for moderate and small earthquakes bases on the measurements of cornerfrequency, seismic moment and a specific theoretical model of rupture behavior. As so far, there are several
theoretical rupture models. However, different models will cause big difference for the estimation of stress
drop, even in an idealized scenario of circular earthquake rupture. Moreover, those models are justkinematic models or quasi-dynamic models. Compared to previous models, we use the BIEM to simulatespontaneous dynamic rupture in homogeneous elastic full space and then to investigate the relation of
corner frequency, seismic moment and source dynamic parameters. For unstable rupture, the relation
between corner frequency and dynamic parameters coincides with that in previous models. One asymptoteof the relation between the stress drop and the ratio of seismic moment and rupture radius is close toEshelby's analytical solution for uniform stress drop. For self-arresting rupture, the scaling laws of cornerfrequency, seismic moment and stress drop are contrary to those for unstable rupture. Meanwhile, because
corner frequency and seismic moment are two independent parameters obtained directly from observation,
we check the relation between corner frequency and seismic moment. No matter whether rupture front for
self-arresting rupture arrives at the barrier boundary or not, the relation between corner frequency andseismic moment coincides with the relation obtained from observation in which the corner frequency isinversely proportional to seismic moment. However, for unstable rupture, the relation between cornerfrequency and seismic moment cannot fit the observation.

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*S13-4-01
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Earthquake Source Spectral Studies beyond the Standard Omega-Square
Model* Takahiko Uchide , Kazutoshi Imanishi
Geological Survey of Japan, AIST, Tsukuba, Japan
A scientific methodology is to understand natural phenomena as general properties and variation aroundthem. As for earthquakes, source spectral studies have simplified the information from seismic data andhelped us enhance our knowledge of earthquake rupture process. The standard model in spectral studies isthe omega-square model, where the source spectrum is flat equivalent to the seismic moment at lower
frequencies and inversely proportional to the square of frequency at higher frequencies. The cornerfrequency borders the lower and higher frequencies and is related to the inverse of the source duration,
therefore employed for estimating representative stress drop under an assumption of circular crack model.
The omega-square model and the corner frequency represent the general property and the variation,
respectively.
Recent studies in earthquake source spectra have been examining the validity of the omega-square model
as a general model. Denolle and Shearer (2016) claimed the existence of another corner frequency whichis scaled by Mo^(-1/5), for M > 5.5 earthquakes. However Uchide and Imanishi (2016) claimed that small
earthquakes also have two corner frequencies, whereas some of small earthquakes are fitted well by thesingle-corner-frequency model, as revealed by a spectral ratio analysis using many empirical Green's
function events for each target event.
We show the universality of the double-corner-frequency source spectra by analyzing small inland
earthquakes in Japan by the method of Uchide and Imanishi (2016). In addition, as a byproduct of thestudy, the same analysis indicated the underestimation of the size of microearthquakes by the local
magnitude scale, which significantly affects the b-value estimation.
Then what is the physical meaning of the second (higher) corner frequency? It is still difficult to answer thisquestion, and we need case studies and scaling studies on the second corner frequency.

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*S13-4-02
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Eccentric by-players of the 2011 Mw 9.1 Tohoku earthquake* Ichiro Kawasaki 1) , Hiroshi Ishii 1) , Yasuhiro Asai 1) , Takuya Nishimura 2)
Tono Research Institute of Earthquake Science, Mizunami,Japan 1) , Kyoto University, Kyoto, Japan 2)
We analyzed the low rate GPS displacement records of GEONET and the continuous stress record at TOSof TRIES (about 600 km away in an azimuth of N120W) due to the 2011 Tohoku earthquake. This led us toa recognition of the tree eccentric by-players as below.
(1) Super sub-event of Mw8.4
We perceived a dominant single SH pulse of a width of around 30 s propagating with 3.9 km/s to stationsof epicentric distances of hundreds of kilometers in record sections of a transverse component of therecords. The SH pulse can not be elucidated by subfault/asperity of low angle thrusting along the
subduction interface. Matching synthetic waveforms in a half space to the SH pulse in trial and error
approach, we obtained a extraordinary subfault model in which slip velocity and seismic moment werearound 10 m/s and (4-5)**21 Nm (Mw 8.4), with strike direction N145E, dip angle 85 and slip angle 85,
while a slip and an area of faulting cannot be separately solved because of a trade-off between them.
(2) Hyper-resonanceAt stations in the southern part of the Boso peninsular in azimuths of N145W to N150W, we saw aremarkable resonance of few cycles of SH waves of periods of 15 s to 20 s and amplitude of up to 1 mfollowing the SH pulse, which we call hyper-resonance. It can be attributed to thick tertiary accretional
layer.
(3) Dynamic trigger
Giant near-source seismic waves triggered activity of M6 or larger aftershocks in the source area. Those ofa few hundred kPa triggered aftershock activity at active volcanoes such as Tateyama and Yakedake in the
Hida mountains. These aftershock activity lowered around 50 minutes after the main shock. After one andhalf hours, two and half hours and three hours, the higher mode Rayleigh waves, the fundamental Lovewaves and the Rayleigh waves, respectively, of 200 s to 300 s of a few kPa returned back to JapaneseIslands. They reactivated the aftershock activity.

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*S13-4-03
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Bayesian inference of centroid moment tensors of the April 2016,
Kumamoto (Kyushu, Japan), earthquake sequence* Miroslav Hallo 1) , Kimiyuki Asano 2) , Frantisek Gallovic 1)
Charles University, Prague, Czech Republic 1) , Disaster Prevention Research Institute, Kyoto University,
Uji, Japan 2)
On 2016 April 16, Kumamoto prefecture in Kyushu region, Japan, was devastated by a shallow M7.3
earthquake. The seismic activity in the region started by foreshocks 28 hours before the main shock. The
series of foreshocks have origin in Hinagu fault zone intersecting the main event's Futagawa fault zone
Hence, the tectonic background for this earthquake is rather complex.
We computed centroid moment tensors (CMTs) for 11 events with M between 4.8 and 6.5, using the strong
motion records of K-NET, KiK-net and F-net networks. We used the innovative Bayesian full-waveform
inversion, ISOLA-ObsPy, which takes into account uncertainty of the velocity model structure. Suchapproach allows us to assess uncertainty of the inverted moment tensors.
The moment tensors show significant spatial variations. Dip-slip events are connected to the N-S
extensional tectonic regime and right-lateral strike-slip events are linked to the NE-SW shear zone (Median
Tectonic Line). Strike-slip events located close to the intersection of Hinagu and Futagawa fault zone aredipping slightly to east, while those in the southern area (Hinagu fault zone) are dipping to west. Most of
events contain only minor CLVD component, which is statistically insignificant and can be related to thevelocity model uncertainty. Nevertheless, two of the CMTs involve significantly large CLVD component(~30%), which may reflect complex rupture process. Decomposition of those moment tensors into two pureshear moment tensors is non-unique. Nevertheless, preserving T-axis of the decomposed moment tensors
suggests combined right-lateral strike-slip and dip-slip mechanisms, which are consistent with the tectonic
settings of the intersection of the Hinagu and Futagawa fault zones. Finally, the Bayesian full-waveform
inversion of CMTs of the Kumamoto earthquake sequence demonstrates the abilities of such amethodology, and suggests complex tectonic background for this earthquake sequence.

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*S13-4-04
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Intraplate events off Sumatra – 3-D evolution* Brian Kennett 1) , Alexei Gorbatov 2) , Stewart Fishwick 3)
The Australian National University, Canberra, Australia 1) , Geoscience Australia, Canberra, Australia 2) ,University of Leicester, Leicester, U.K. 3)
The dominantly strike-slip Mw 7.8 event on 2016 March 2 occurred in the northwestern Wharton Basin in
an area with no previously recorded large earthquake. Analysis of the higher-frequency energy radiation (>0.25 Hz) as a function of time using a suite of global stations, with good azimuthal control, indicates that theevent initiated on a nearly east-west fault and then the main energy release was on a conjugate north-south
fault. High frequency radiation is emitted through the full thickness of the lithosphere in the main part ofthe event. Late energy emission comes from depth over a broader area suggesting minor failures at thebase of the lithosphere.
A similar behaviour is seen for the 2000 June 18 much further away from the subduction zone. In eachcase the events occur in a region with slightly lower shear wavespeed than their surroundings, perhaps
indicating weakness in the full lithosphere.

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*S13-4-05
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Rupture evolution during the Mw 8.3 2015 Illapel Chile earthquake inrelation to swarms* Ryo Okuwaki , Yuji Yagi
University of Tsukuba, Tsukuba, Japan
A source model for the Mw 8.3 2015 Illapel Chile earthquake is constructed by using a broad frequency
range of teleseismic P-waveforms recorded at globally distributed stations. A spatiotemporal slip
distribution is obtained with the kinematic waveform inversion method taking into account the uncertainty
of Green's function, and an evolution of high-frequency (HF: 0.3–2.0 Hz) radiation sources is tracked withthe hybrid backprojection method, which resolves locations of the HF sources by stacking cross-correlation
functions of the observed waveforms and theoretically calculated Green's functions.
The source model, in a gross sense, shows apparently slow, unilateral rupture propagation at < 2 km/s
along the strike direction with the maximum slip about 10 m at around 70 km northwest of the epicenter,but in detail, the model involves two independent rupture episodes, both propagating up-dip andnorthward direction at variable rupture velocities (2–3 km/s) along the rupturing paths. The two rupture
episodes are separated by the HF bursts occurred along the deeper (around 35 km depth) parts of the fault,
which possibly triggers and accelerates the secondary rupture episode.
Secondary rupture evolves in a way to avoid the interplate swarms observed in 1997–1998 locating at thenorthern and the northeastern edges of the rupture area, and terminates without the intense HF radiation
around the boundary between the source area and the swarm region. Less excitations of HF waves at
rupture termination suggests the gradual deceleration of rupture, since HF waves are radiated when arupture front abruptly accelerates or decelerates. The HF-deficient rupture termination may correspond to
the frictional property or stress state around the boundary between the source area and the swarm region,
which gradually transitions from the state governing megathrust rupture to that carrying the swarms driven
by the aseismic slip.

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*S13-4-06
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Rupture on the megasplay fault along the Nankai trough during the off-Mie
earthquake (Mw=6.0) on 1 April 2016
* Masaru Nakano 1) , Ayako Nakanishi 1) , Mikiya Yamashita 1) , Takashi Tonegawa 1) , Takane Hori 1) ,Shin'ichiro Kamiya 1) , Kensuke Suzuki 1) , Koichiro Obana 1) , Shuichi Kodaira 1) , Eiichiro Araki 1) , Narumi
Takahashi 2) 1)
JAMSTEC, Yokohama, Japan 1) , NIED, Tsukuba, Japan 2)
On 1 April 2016, a moderate-sized off-Mie earthquake (Mw=6.0) occurred off the Kii Peninsula, southwestof Japan. The epicenter is located updip of hypocenter of the 1944 Tonankai earthquake (Mw=8.2).
Wallace et al. (2016) obtained that this earthquake occurred along the plate boundary of the Nankai trough,but their hypocenter determination was based on a 1D velocity structure. Horizontal heterogeneity along
the dip direction is not negligible in subduction zones.
We determined the hypocenters of the 2016 earthquake by using a 2D velocity structure considering thehorizontal heterogeneity in the study area. We used P-wave arrival time at each DONET station deployed
immediately above the source region (Kaneda et al., 2015; Kawaguchi et al., 2015). The mainshock was
located at 9.7 km depth shallower than 11.4 km of Wallace et al. (2016). By comparing with a reflection
profile obtained from a multichannel seismic survey (MCS), the mainshock is attributed to a slip along themegasplay fault rather than the plate boundary.
In the transition zone of the accretionary wedge between the megasplay fault and the plate boundary is
characterized by a zone of low seismic-wave velocity consisting of fluid-rich sediments, which could notsupport strong shear stress to cause large earthquakes. Accordingly, it is difficult to cause large
earthquakes along the megasplay fault or the plate boundary in the source region of the 2016 earthquake.
Wallace et al. (2016) attributed this earthquake to a slip along an unstable patch in conditionally stablezone of the plate boundary, but its geological meaning has not been clarified yet.
In MCS profiles, we can recognize locally very weak reflections along the megasplay fault or the plateboundary around the mainshock source, which we consider as an unstable patch because of the low
impedance contrast. We hypothesize that fragments of seamounts, of which the main body has been
subducted to deeper part, form the strong patch in the sediments.

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*S13-5-01
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Asperity imaging of the ML6.0 2016 Amatrice, Italy, earthquake fromdynamic rupture simulation* Hideo Aochi 1) 2)
Ecole Normale Superieure, Paris, France 1) , BRGM, Orleans, France 2)
Several damaging earthquakes of magnitude 5.5 – 6.4 have occurred in the Central Italy since August 24th
2016. The earthquakes show normal faulting mechanisms, coherent with the formation of regional
tectonics surrounding the Apennine Mountain. We aim to characterize dynamic source parameters(asperity distribution) from the dynamic rupture and wave propagation simulations, firstly for the ML6.0
August 24th 2016 earthquake. We hypothesis that fault heterogeneity is represented by a combination of
circular patches of asperity and determine their physical parameters. We apply the boundary domain
method combining boundary integral equation and finite difference schemes. The calculation is still too
expensive to run systematic inversion process, but the simulations indicate a better combination of the
dynamic rupture parameters, in terms of patch dimension, location and frictional parameters. Whenfocusing on one of the nearest ground motion record of Amatrice (epicentral distance of about 10 km), asingle patch toward up-dip and strike directions between the hypocenter and this station is suggested. Its
dimension is not larger than a radius of 4 km and static/dynamic stress drops of 4 and 6 MPa or more,
respectively.

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*S13-5-02
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Dynamic Rupture Simulations Constrained by Experimental Data to
Investigate the Fault Behavior of Mega-Thrust Earthquakes* Kenichi Tsuda 1) , Jun'ichi Miyakoshi 1) , Jean-Paul Ampuero 2) , Yoshiyuki Imato 3) , Daisuke Sugiyama 3) ,Seiji Tsuboi 3)
Institute of Technology, Shimizu Corporation, Tokyo, Japan 1) , California Institute of Technology 2) , Japan
Agency for Marine-Earth Science and Technology 3)
The investigation of dynamic rupture propagation is very important to understand the seismic behavior ofmega-thrust earthquakes such as the 2011 Tohoku earthquake. The shallow parts of the fault (near the
trench) hosted large slip and long period seismic wave radiation, whereas the deep parts of the rupture(near the coast) hosted smaller slip and strong radiation of short period seismic waves. Understanding such
depth-dependent feature of the rupture process of the Tohoku earthquake is necessary as it may occur
during future mega-thrust earthquakes in this and other regions. In order to achieve such understanding,dynamic rupture modeling is an important tool (e.g., Galvez et al., 2014). By incorporating the results oflaboratory studies of samples of fault materials collected from plate boundary fault zones, such as the Japan
Trench, dynamic rupture simulations can be made more realistic.
In this study, we developed dynamic rupture models of the Tohoku earthquake based on initial conditions
and fault strength properties constrained by results of experimental studies (Hirono et al., 2016). Our largescale simulation used the 3D spectral element method on unstructured grids (Galvez et al., 2014) withperformance tunning for the Earth Simulator at JAMSTEC.
Our model reproduced the depth-dependency of the rupture process of the Tohoku earthquake. We also
examine the sensitivity of the results to model parameters and assumptions, for instance to the value of theslip weakening distance (Dc). We find that the value of Dc does not affect the final slip distribution, as longas it is small enough to allow the rupture to develop and propagate to the trench. A long Dc (order of 10 m)
is reasonable in terms of fracture energy and promotes the generation of long period seismic waves on theshallow part of the fault.

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*S13-5-03
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Super-shear fault rupture propagation during the 2016 Kumamoto
earthquake (Mw7.1); Possible implication for fault strength* Nelson Pulido
National Research Institute for Earth Science and Disaster Resilience, Tsukuba, Japan
I investigated the fault rupture process of the April 16, 2016 Kumamoto earthquake, using a seismic backprojection methodology (Pulido et al. 2008, Pulido 2016), and a dense array of near-source strong motion
records from the K-NET/KiKnet networks. I selected all the KNET/KiKnet records of the mainshock within
100 km around the Hinet epicenter, and used the fault-parallel component rotated from the horizontal
components. I bandbass filtered the data between 5 to 10 Hz and calculated the envelopes of velocity timeseries. Envelopes were stacked within a horizontal grid mesh covering the regions around the Hinagu andFutagawa fault traces and beyond, to obtain a temporal and spatial image of rupture propagation. My backprojection results show that significant grid energy was released in a region spanning 43km length along
the Hinagu (16km) and Futagawa (27 km) fault zones. Back-projection results show a bilateral fault rupture
propagation along the Hinagu and Futagawa faults, characterized by a slow sub-Rayleigh rupture velocity of
1.4 ~ 1.7 km/s, for the first 5.5 seconds of imaged rupture (4~9.5s from the origin time, OT). The rupture
propagation towards the NE (along the Futagawa fault) experienced a very rapid increase in rupture
velocity by reaching a value ~1.4 times larger than the average S-wave velocity (Vrup= 4.7 km/s) at 9.5s
from OT, and remained super-shear for approximately 4.5 s (9.5 ~14s from OT) until fault rupture arrest. I
also imaged a clear sub-Rayleigh rupture propagation towards the SW along the Hinagu fault zone (Vrup=
3.1 km/s), from 11 to 14 seconds after OT. My results indicate a super-shear transition length L~10 km,
which is approximately 5 times the typical value of the nucleation zone size (Lc) for a Mw7.1 earthquake.
These results may imply a low fault strength value S.

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*S13-5-04
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Why did the moderate size 2010 Yushun, China earthquake (Mw=6.8)
produce supershear rupture?
* Shoubiao Zhu , Jie Yuan
Institute of Crustal Dynamics, China Earthquake Administration
Owing to supershear ruptures, seismic hazards in the 2010 Yushu, China earthquake(Mw=6.8) isparticularly severe. So far, the mechanism remains unclear. To this end, we construct finite element model
based on the actual geometry of the seismogenic fault in the earthquake. In the model, the fault consists of
two segments, and there is an intersection angle of 10º between them, forming fault bent. The simulation
result shows that the main rupture for the Yushu event is composed of two sub-events. Once the rupture
was nucleated at the hypocenter, the rupture first propagated along the first fault segment at speed ofsubshear wave velocity. When the rupture goes over the fault bent, the rupture speed turned into
supershear wave velocity immediately along the second fault segment. Moreover, the calculation results
suggest that dislocations at fault surface, seismic wave speed and strong ground motion acceleration arelargely amplified by supershear ruptures, giving rise to terrible damage. This may be an important reason
why severe seismic damage was caused in the Yushu earthquake. In particular, we can see from numericalexperiment that rupture speed would not change if the strike of the fault in the model does not bend in thecase in which all other model parameters keep unchanged. However, if the intersection angle between theorientation of initial stress and the fault varies, rupture will not necessarily propagate at supershear wave
speed, even if there is a fault turning in the fault system. Only if the relationship between the orientation of
initial stress and the strike of the fault is just perfect, the fault bent possibly promotes supershear ruptures.
Thuse, supershear rupture occurred in the Yushu event may be resulted from optimum state in which
perfect relationship between orientations of initial stress and the strike of seismogenic fault is formed. It is
presumably one of the reasons why natural earthquakes with supershere ruptures are rarely seen.

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*S13-5-05
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Dynamic Source Inversion of Intermediate Depth Earthquakes in Mexico
Aron Yuto Sho Mirwald , * Victor Manuel Cruz Atienza , Shri Krishna Singh SinghNational Autonomous University of Mexico, Mexico City, Mexico
The source mechanisms of earthquakes at intermediate depth (50-300 km) are still under debate. Due tothe high confining pressure at depths below 50 km, rocks ought to deform by ductile flow rather than brittle
failure. Several source mechanisms have been proposed, but for neither of them conclusive evidence has
been found. One viable mechanism is Dehydration Embrittlement, where liberation of water lowers theeffective pressure and enables brittle fracture. Another is Thermal Runaway, a highly localized ductile
deformation. In the Mexican subduction zone, intermediate depth earthquakes represent a real hazard incentral Mexico due to their proximity to highly populated areas and the large ground accelerations.
To improve our understanding of these rupture processes, we use a recently introduced inversion method
to analyze several intermediate depth earthquakes in Mexico. The method inverts strong motion
seismograms to determine the dynamic source parameters based on a genetic algorithm. It has beensuccessfully used for the M6.5 Zumpango earthquake (62 km depth). For this event, high radiated energy,
low radiation efficiency and low rupture velocity were determined. This indicates a highly dissipative
rupture process, suggesting that Thermal Runaway could probably be the dominant source process.
In this work we improved the inversion method by introducing a theoretical consideration for the
nucleation process that minimizes the effects of rupture initiation and guarantees self-sustained rupture
propagation. Preliminary results indicate that intermediate depth earthquakes in central Mexico may varyin their rupture process. For instance, for a M5.9 earthquake at 55 km depth that produced very highaccelerations in Mexico City we found a moderate radiation efficiency and a typical rupture velocity.
Differences and similarities between the earthquakes studied here will help to better elucidate the physicalprocesses originating intermediate depth earthquakes.

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*S13-5-06
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Slip-weakening distance and strength drop inferred from near-fault
deformation during the 2016 M7.8 Kaikoura earthquake* Yoshihiro Kaneko 1) , Eiichi Fukuyama 2) , Ian Hamling 1)
GNS Science, Lower Hutt, New Zealand 1) , NIED, Tsukuba, Ibaraki, Japan 2)
The 2016 M7.8 Kaikoura (New Zealand) earthquake struck the east coast of the northern South Island,
resulting in large surface offsets (>10 m), numerous landslides, extreme surface ground motions (over 1g),
a regional tsunami, and large-scale slow slip events on the Hikurangi subduction interface. Since theearthquake was well recorded by GeoNet strong motion and GPS networks, near-fault ground motion may
provide direct measurements of dynamic parameters associated with the fault-weakening process. Here weestimate a proxy of slip-weakening distance Dc'', defined as double the fault-parallel displacement at thetime of peak ground velocity, from accelerograms recorded at near-fault stations. Three-component grounddisplacements were recovered from the double numerical integration of accelerograms, and thecorresponding static displacements are validated against those derived from InSAR data. We estimate Dc''of about 5 m at KEKS station located at 2.7 km from a segment of the Kekerengu fault where a surface
offset of more than 10 m has been found. The inferred Dc'' is the largest value ever estimated from nearfault strong motion data, yet appears to follow the scaling of Dc'' with final slip reported in previous studies.
The corresponding slip-weakening distance Dc and strength drop on the same fault segment may bevalidated against dynamic rupture simulations.

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*S13-6-01
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Photoelastic Study of Dynamic Stress Transfers in Granular Media* Koji Uenishi 1) , Tsukasa Goji 1) , Wojciech Debski 2)
The University of Tokyo, Tokyo, Japan 1) , Polish Academy of Sciences, Warsaw, Poland 2)
In our earlier study (JpGU Meet. 2008, AGU Fall Meet. 2009), using a high-speed camera, we conducted
fully-controlled laboratory experiments associated with large dynamic deformation of granular materials
that may be observed, e.g. in earthquake faulting and landslides. Especially, as a fundamental investigation,
our attention was paid to transient granular mass flow from a (semi-)cylindrical column consisting of dry
granular materials (glass beads). We traced the particle movement and development of slip lines inside thegranular column that was set on a rigid horizontal plane and collapsing due to the action of gravity, andshowed, for instance, the influence of frictional properties of the horizontal plane and beads on the average
flow velocity and the final shape of the collapsed column. However, the details of stress transfers in
granular media subjected to such dynamic deformation have not been well clarified yet. Therefore, here, asa preliminary observation for deeper understanding of stress transfers and propagation of waves andrupture inside granular media, experimental technique of dynamic photoelasticity is used. Penny-shaped
photoelastic particles (diameter 20 or 40 mm) made of epoxy resin are prepared and placed on a rigid
horizontal plane, and dynamic impact is given to a particle by a gun-launched projectile (impact velocity
50-80 m/s) or by another free-falling photoelastic particle (impact velocity 2-3 m/s). The transient stresstransfers are recorded by a high-speed camera at a frame rate of up to 100,000 fps. In a single particle
system, where only one particle is situated on the plane, dynamic wave propagation is recognized insidethat single particle, but in a layered multi-particle system stress is transferred quasi-statically from a particle
to neighboring ones and wave propagation is not clearly identified. This may suggest preloading (and morestatic contact between each particle) is needed for visualization of waves in the layered system.

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*S13-6-02
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Near-fault Tilt Motion and Conjugate Faulting* Eiichi Fukuyama
National Research Intstitute for Earth Science and Disaster Resilience, Tsukuba, Japan
There have been reports of conjugate faults that have ruptured during earthquakes. However, it is still
unclear whether or not these conjugate faults ruptured coseismically during earthquakes. In this paper, weinvestigated near-fault ground tilt motions observed at the IWTH25 station during the 2008 Iwate-Miyagi
Nairiku earthquake (Mw 6.9). Since near-fault tilt motion is very sensitive to the fault geometry on which
the slip occurs during an earthquake, these data make it possible to distinguish between the main fault
rupture and a rupture on the conjugate fault. We examined several fault models that have already been
proposed and confirmed that only the models with a conjugated fault could explain the tilt data observed at
IWTH25. The results support the existence of simultaneous conjugate faulting during the main rupture.
This will contribute to the understanding of earthquake rupture dynamics because the conjugate rupture
releases the same shear strain as that released on the main fault, and thus it has been considered quitedifficult for both ruptures to accelerate simultaneously.

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*S13-6-03
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Supershear rupture induced by step over geometry and its effect on nearfield ground motion* Feng Hu 1) , Xiaofei Chen 1) 2)
University of Science and Technology of China, China 1) , Southern University of Science and Technology,
China 2)
Based on dynamic rupture simulations on step overs, we show that rupture speeds can jump to supershear
speed on the secondary fault of a step over in a 3D full-space after re-nucleation, whose initial shear stresspreclude such a supershear transition according to the Burridge-Andrews mechanism, and the rupture
speed on the primary fault is sub-Rayleigh. The low normal stress zone and the high shear stress zone
beyond the fault step, which radiate from the end of the primary fault if its rupture arrest is sudden,
determine the supershear rupture occurrence on the secondary fault. However, a low shear stress zone
traveling at the shear wave speed is also radiated, making the rupture speed return to subshear in mostcases. Sustained supershear ruptures on the secondary fault are also possible on compressional step overs
under certain conditions. Self-arresting phenomenon are observed in the overlapped area on the secondary
fault. In a half-space model where supershear rupture is induced by the free surface on the primary fault,
the rupture speed on the secondary fault rapidly transits to subshear near the fault step if its width exceeds
a critical value. We further calculate near-field ground motions of the half-space cases to understand its
high frequency radiation pattern.

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*S13-6-04
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Modeling dynamic earthquake rupture with coseismic off-fault damage* Kurama Okubo 1) 2) , Harsha S. Bhat 2) , Yann Klinger 1) , Esteban Rougier 3)
Institut de Physique du Globe de Paris, Paris, France 1) , Ecole normale superieure, Paris, France 2) , Los
Alamos National Laboratory, New Mexico, United States 3)
Off-fault stress concentration induced by dynamic earthquake ruptures can generate coseismic off-fault
damage, which has an effect on source mechanisms of earthquakes. We need continuum-discontinuum
analysis to understand the process of generating the off-fault damage in a brittle material surrounding faults
and the role of it in the source mechanisms and seismic wave radiation.
In this study, we adopt combined finite-discrete element method (FDEM), which can model real cracks in
off-fault fields generated during the dynamic earthquake ruptures. The advantage of FDEM is that it canhandle a wide range of length scales, from metric to kilometric scale, corresponding to the off-fault damage
and the main fault respectively. Every potential failure plane in the medium follows a cohesive law (intension and in shear). The main fault is assumed to follow a linear slip-weakening friction. Thus we canhave an estimate of fracture energy dissipated on the main fault and the off-fault damage separately. We
used the FDEM-based software tool called HOSSedu (Hybrid Optimization Software Suite - Educational
Version), which was developed by Los Alamos National Laboratory.
We firstly demonstrated the cross-validation of the FDEM tool for modeling earthquake ruptures with otherconventional numerical schemes like spectral element method and boundary integral equation method toevaluate the accuracy with various element sizes and artificial viscous damping factors. We then modeled
earthquake ruptures allowing for the coseismic off-fault damage with appropriate fracture nucleation andgrowth criteria. It shows that high-frequency radiation is enhanced by the dynamically generated off-fault
damage. The orientation of maximum compressive principal stress of the pre-stress field with the main fault
plays a role in generating the off-fault damage such that the dynamic off-fault damage is more likely tooccur on the extensional side of the main fault for high principal stress orientation.

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*S13-6-05
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Investigating the variability of near-source ground motions using pseudodynamic source models at the SCEC Broadband Platform* Seok Goo Song
Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon, Korea
The accurate prediction of ground motion intensity and variability is a critical element in seismic hazard
assessment. Especially it is important to note that the variability of ground motions plays an important rolein probabilistic seismic hazard analysis (PSHA) since the exceedance probability of ground motions istaken into account. Physics-based source and ground motion modeling has become popular, given
advanced earthquake rupture and wave propagation modeling schemes and fast growing computing
capability. There have been intensive community efforts to construct a physics-based broadband groundmotion simulation platform, supported by the Southern California Earthquake Center (SCEC). Using
various pseudo-dynamic source models at the SCEC broadband platform, I investigated the variability ofnear-source ground motions. Preliminary results show that the variability of low frequency ground motions
is relatively compatible with the variability of empirical ground motion prediction equations (GMPEs) whilethe variability of high frequency ground motions is not. We may need to pay more attention to thevariability of ground motions by considering the variability of input models when we construct a physicsbased ground motion simulation platform.

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*S13-6-06
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Variation of Earthquake Source Scenarios along the Nankai Trough for
Hazard and Risk Assessment* Hiroe Miyake 1) , Takashi Furumura 2) , Takuya Nishimura 3) , Kimihiro Mochizuki 2) , Kazushige Obara 2) ,Tomoya Harada 2) , Naoya Sekiya 1)
CIDIR/III, The University of Tokyo, Tokyo, Japan 1) , ERI, The University of Tokyo, Tokyo, Japan 2) , DPRI,
Kyoto University, Kyoto, Japan 3)
Historical Nankai Trough earthquakes show a large variation of source characteristics. Recent new
observations reveal the diversity of earthquake sequence not limited to the coseismic rupture andsegmentation. As a framework of the core-to-core collaborative research program of Earthquake ResearchInstitute, the University of Tokyo and Disaster Prevention Research Institute, Kyoto University, weconstruct earthquake source scenarios along the Nankai Trough. To show the variation of scenario
earthquakes, the logic tree is established based on expert opinions of geodesy, crustal structure from
offshore to onshore regions, seismicity, and history for seismic and tsunami hazard assessment and related
risk. The distributions of slip deficit, seamount, fault branch, slow earthquake, repeating earthquake,seismicity, and historical earthquake and tsunami source information are integrated with a weight ranging
from 0 to 100%. The magnitude potential is controlled by the idea of partially coupled regions (Lovelessand Meade, 2015) as a function of the coupling rate as well as overlaying the expert opinions. We validate
seismic intensity and long-period ground motions for seismic hazard, and tsunami height and inundation
area for tsunami hazard. The seismic and tsunami risk is assessed by population density, social andeconomic impact along the Pacific Ocean belt, and locations of nuclear and thermal power plants from theviewpoint of social science. We investigate the factor analyses to link the above mentioned earthquake
scenarios, hazard, and risk.

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*S13-P-01
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

A web-platform benchmark for moment tensor inversion* Torsten Dahm , Sebastian Heimann , Simone Cesca
GFZ German Research Centre for Geosciences
Moment tensor inversion is a powerful tool for the determination of the earthquake source parameters.
Following extensive developments in the last two decades, global and regional moment tensor services arenowadays becoming a standard and a growing number of different moment tensor catalogs are provided tothe community. In parallel, a wide range of software offering standard moment tensor tools are available toseismologists. However, moment tensor results are highly affected by data pre-processing, data selection
and implemented methodologies. As a result, moment tensor catalogs often show systematic differencesamong source parameters. Thus, despite of the widespread diffusion of data and methods, moment tensor
data mining faces new challenges. In response to these problematic, a IASPEI working group (WG) on
routine moment tensor inversion was started, with the main aim of developing and implementing abenchmark and verification platform for moment tensor inversion procedures, and to provide
recommendations for the scientific community. We present a preliminary web-based platform, where new
moment tensor inversion methods can be tested and young researchers new to the field can find and use
the benchmark to test their own developments over a broad range of applications. The platform provides
access to ground truth events representative of a broad type of seismicity and monitoring conditions,
including synthetic and real datasets.

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*S13-P-02
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Centroid moment tensor solution using 3D heterogeneous anisotropic Earth:application to Papua New Guinea and Solomon Islands* Babak Hejrani 1) , Hrvoje Tkalcic 1) , Andreas Fichtner 2)
The Australian National University, Research School of Earth Sciences, ACT, Australia 1) , ETH Zurich,
Zurich, Switzerland 2)
Moment tensor (MT) representation of the earthquake source is well established and is being routinely
calculated on a global scale by Global-centroid moment tensor project (GCMT). Routine calculation of MT
is usually done using Green's functions calculated from a 1D layered Earth velocity structure. Here, wehave calculated CMTs for 318 events with Mw > 5.0 occurred in Papua New Guinea and Solomon Islands
during 2006 - 2016 using a continental scale 3D heterogeneous upper-mantle velocity structure model,
AMSAN19 (Fichtner et al. 2009). Our solutions show considerable differences in comparison to GCMT.
The most prominent difference is in double-couple (DC) percentage which shows a significant increase. We
also observe differences in strike, dip and rake angles of the DC part of MT, which provides new insight
into the tectonics of the region. The resolution in centroid depth has increased specifically for shallow
events (depth < 25 km) and our new centroids shed light on dipping structures at the New Guinea Trench.
The new CMT solutions obtained using the 3D model are superior to those using the spherically-symmetricmodels of the Earth, which is evident in the data fit increase of about 30%.
We have shown the feasibility of using a 3D velocity model on the continental scale to improve therecovery of depth, location and MT components for shallow events, which opens new avenues to morereliable tectonic interpretations and hazard assessments. Our library of synthetic seismograms will be usedat Geoscience Australia to supplement existing tools for moment tensor inversion.
Reference:
Fichtner, A., Kennett, B.L.N., Igel, H. & Bunge, H.-P., 2009. Full seismic waveform tomography for uppermantle structure in the Australasian region using adjoint methods, Geophys. J. Int., 179, 1703–1725.

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*S13-P-03
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Single Layer Recurrent Neural Network for detection of swarm-likeearthquakes in West Bohemia and South-west Iceland* Jana Doubravova 1) , Jan Wiszniowski 2) , Josef Horalek 1)
Institute of Geophysics of the Czech Academy of Sciences, Prague, Czech Republic 1) , Institute ofGeophysics, Polish Academy of Sciences, Warsaw, Poland 2)
We present a new method of local event detection based on neural networks. The proposed algorithm uses
a unique neural network architecture. It combines features used in other neural network concepts like RealTime Recurrent Network and Nonlinear Autoregressive Neural Network to achieve a good detection
performance. We use the recurrence combined with various delays applied to recurrent inputs to make the
network remember history of many samples - the Single Layer Recurrent Neural Network (SLRNN). The
network was first trained and tested on data from local seismic network in West Bohemia (Webnet). Then
we applied the trained network to different dataset from local seismic network in South-west Iceland(Reykjanet). Both networks monitor earthquake swarm areas, both networks have similar number ofstations used for detection and both cover roughly equal areas. We show that the neural network trained onWebnet data could be used on Reykjanet data with satisfactory results.

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*S13-P-04
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

An evolutive quasi-real-time source inversion based on a linear inverse
formulation
Hugo Sanchez Reyes 1) , * Josue Tago Pacheco 2) , Victor Cruz Atienza 2) , Ludovic Metivier 1) 3) , Marcial
Contreras Zazueta 2) , Jean Virieux 1)
Institut des Sciences de la Terre, Grenoble, France 1) , Universidad Nacional Autonoma de Mexico, CDMX,
Mexico 2) , Laboratoire Jean Kuntzmann, Grenoble, France 3)
Finite source inversion is a steppingstone to unveil earthquake rupture. Significant progress has been
made on approaches regarding earthquake imaging, thanks to new data acquisition and methodologicaladvances. However, most of these techniques are posterior procedures once seismograms are available.
Incorporating source parameters estimation into early warning systems would require to update the source
build-up while recording data.
We developed a kinematic source inversion formulated in the time-domain, for which seismograms arelinearly related to the slip distribution on the fault through convolutions with Green functions previously
estimated and stored. These convolutions are performed in the time-domain as we progressively increase
the time window of records at each station specifically. Selected unknowns are the spatio-temporal slip-rate
distribution to keep the linearity of the forward problem with respect to unknowns. Through the spatial
extension of the expected rupture zone, we progressively build-up the slip-rate when adding new data by
assuming rupture causality.
This formulation is based on the adjoint-state method for efficiency. The inverse problem is non-uniqueand, in most cases, underdetermined. While standard regularization terms are used for stabilizing theinversion, we avoid strategies based on parameter reduction leading to an unwanted non-linear
relationship between parameters and seismograms for our progressive build-up. Rise time, rupture velocity
and other quantities can be extracted later on as attributes from the slip-rate inversion we perform.
Satisfactory results are obtained on a synthetic example proposed by the Source Inversion Validation
project (Mai et al. 2011). The application of this method to the Kumamoto 2016 earthquake is currently
being explored. Our specific formulation combined with simple prior information, as well as numericalresults obtained so far, yields interesting perspectives for a quasi-real-time implementation.

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*S13-P-05
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Source properties of large earthquakes in subduction zones using 3D
heterogeneous Earth: application to the Australasian region* Babak Hejrani , Hrvoje Tkalcic
The Australian National University, Research School of Earth Sciences, ACT, Australia
Revealing earthquake source complexity, rupture process and the source time function of large
earthquakes is an important aspect of earthquake seismology. A significant number of researchers haveinvestigated these properties using 1D (spherically symmetric) Earth models. Using a similar approach, we
first investigated 10 selected large earthquakes with moment magnitudes exceeding 7.8 in the Australasia
region, occurred in Papua New Guinea, Solomon Islands, Tonga-Fiji and New Zealand. Acknowledging thatseismic records contain the complexities from both source and Earth structure, we explore a hypothesisthat a simple, spherically symmetric Earth structure introduces spurious effects into the source parameters.
We use 3D heterogeneous upper-mantle velocity structure and create synthetic data for scenarios thatencompass complex ruptures and source time functions (at periods 40 – 200s). We then invert for thesource parameters such as moment tensor, source time function and location using these synthetic data inboth 1D and 3D Earth. We confirm that the source complexity can act as a compensation for theincomplete knowledge of Earth structure. Consequently, we calculate the source time function of theselected large earthquakes from the Australasian region in 3D Earth and discuss our findings. We also
consider the source directivity for large earthquakes as one of the target parameters.

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*S13-P-06
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Complete synthetic seismograms based on a spherical self-gravitating Earthmodel with an atmosphere-ocean-mantle-core structure
Rongjiang Wang 1) , Sebastian Heimann 1) , Yong Zhang 2) , Hansheng Wang 3) , * Torsten Dahm 1)
German Research Centre for Geosciences, 14473 Potsdam, Germany 1) , School of Earth and Space
Sciences, Peking University, Beijing 100871, China 2) , State Key Laboratory of Geodesy and Earth's
Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China 3)
A hybrid method is proposed to calculate complete synthetic seismograms based on a sphericallysymmetric and self-gravitating Earth with a multi-layered structure of atmosphere, ocean, mantle, liquidcore and solid core. For large wavelengths, a numerical scheme is used to solve the geodynamic boundaryvalue problem without any approximation on the deformation and gravity coupling. With the decreasing
wavelength, the gravity effect on the deformation becomes negligible and the analytical propagator scheme
can be used. Many useful approaches are used to overcome the numerical problems that may arise in bothanalytical and numerical schemes. Some of these approaches have been established in the seismologicalcommunity and the others are developed for the first time. Based on the stable and efficient hybridalgorithm, an all-in-one code QSSP is implemented to cover the complete spectrum of seismologicalinterests. The performance of the code is demonstrated by various tests including the curvature effect onteleseismic body and surface waves, the appearance of multiple reflected, teleseismic core phases, thegravity effect on long period surface waves and free oscillations, the simulation of near-field displacement
seismograms with the static offset, the coupling of tsunami and infrasound waves, and free oscillations of
the solid Earth, the atmosphere and the ocean. QSSP is open source software that can be used as a standalone FORTRAN code or may be applied in combination with a Python toolbox to calculate and handle
Green's function databases for efficient coding of source inversion problems.

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*S13-P-07
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Detecting the Temporal Variation in Seismic Velocity Accompanied by 2011
Tohoku-Oki Earthquake and the Slow Slip Event, Using SeismicInterferometry of Ambient Noise* Miyuu UEMURA 1) , Yoshihiro ITO 1) , Kazuaki OHTA 1) , Ryota HINO 2) , Masanao SHINOHARA 3)
The University of Kyoto, Kyoto, Japan 1) , The University of Tohoku, Miyagi, Japan 2) , The University ofTokyo, Tokyo, Japan 3)
Between the end of January and the occurrence of the largest foreshock on March 9 that preceded the2011 Tohoku-Oki earthquake, slow slip events and low-frequency tremors were detected off Miyagi (Ito etal., 2013, 2015; Katakami et al., 2016). We apply seismic interferometry using ambient noise to data from17 OBSs that were installed above the focal region before the earthquake. All OBSs with three components
are short-period seismometers with an eigenfrequency of 4.5 Hz that were deployed between November
2010 and April 2011.
The method is as follows. First, we applied a band-pass filter of 0.25-2.0Hz and a one-bit technique. Second,
we calculated Auto-Correlation Coefficients using a 5-s time window with lag time from -30 s to 30 s atintervals of 0.1 s, using seven continuous days of waveforms to make a daily ACF. Third, we stacked up all
daily ACFs for the entire time period, to make a reference ACF. Finally, we calculated the Correlation
Coefficients between the one-day ACF or the 16-day ACF and the reference ACF.
The primary results are follows. At all OBSs, the 16 days' CC declined after the SSE initiated and then it
recovered in the latter half of the SSE duration. In the region of SSE occurrence, the difference between theabsolute and incremental reduction in the 16 days' CC is small. However, in the area of the largest
foreshock, the difference is significant. The former 16 days' CC values are suddenly decreasing before theSSE, and the latter 16 days' CC values are gradually decreasing starting around November, or around fourmonths before the largest foreshock. The small difference could be related to the occurrence of SSE, while
the large difference could be related to critical conditions preceding the largest foreshock.

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*S13-P-08
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Rupture process of the Ms 7.4 November 15, 2004 Colombia earthquake* Sandra Patricia Molina Garcia , Luis Quintatar
Universidad Nacional Autonoma de Mexico
The subduction zone in the northwestern part of the South American plate presents a complex tectonic
process due to the interaction between the Nazca, Cocos and Caribbean plates. Analyzing the rupture
process in this region is of great importance to understand the occurrence of seismic events in Colombia.
We have determined the space-time distribution of the slip on the fault plane for the November 15th, 2004
earthquake, located in the Colombian-Ecuadorian trench in the Colombian Pacific subduction zone. This
event is one of the most shallow and significant in recent years because it occurred in the region where thelargest earthquakes have been reported such as the 1906 (Mw=8.8), 1942 (7.9), 1958 (Mw=7.8) and the1979 (Mw=8.2). We applied the inversion method developed by Yagi et al. (2003) using the P waveformmodeling at teleseismic distances, which is a numerical method that calculates the slip distribution on thefault plane assuming a seismic source as a sequence of point sources. The slip distribution obtained is theone that best retrieves the observed records in several teleseismic stations. The parameters that best fit todescribe the process of rupture of this event were: strike= 177, dip= 79, slip= 85, depth h = 15 km. The
rupture process obtained indicates that the rupture propagates towards the surface with a maximum slip of
3.7 m at depth of 15 km. The temporal function for this event shows a complex rupture with two peaks anda total duration of 15 seconds.

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*S13-P-09
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Source inversion and stochastic ground motion modelling of the August Mw
6.8 Myanmar earthquake* Hasbi Ash Shiddiqi 1) , Pa Pa Tun 2) , Tun Lin Kyaw 2) , Lars Ottemoller 1)
Department of Earth Science, University of Bergen, Bergen, Norway 1) , Department of Meteorology andHydrology, Ministry of Transport and Communications, Nay Pyi Taw, Myanmar 2)
An intermediate-depth Mw 6.8 earthquake struck Myanmar on 24 August 2016. This earthquake was felt
throughout the country and caused some damage in the Chauk and Bagan areas. USGS reported theearthquake mechanism as a reverse fault (Strike1: 166, Dip1: 83, Rake1: 89 and Strike2: 356, Dip2: 7,
Rake2: 100), which would be cutting the subducting slab near vertically or near horizontally. There has
been no previous intermediate depth earthquake with a similar mechanism in the Myanmar region fromavailable moment tensor catalogs. We study the earthquake source mechanism and slip distribution using
teleseismic body-wave inversion implemented in the Kikuchi-Kanamori code. We used 33 P- and 34 SHwaves data from stations at teleseismic distances (30º to 90 º). Testing different earthquake depths during
the inversion, we found the lowest variance at 85 km depth. We set the fault plane size to 35 x 35 km2 anddivided into a 5 km grid. We obtained a similar earthquake mechanism to the USGS result, i.e. reverse
faulting event (Strike1: 165, dip1: 82, rake1: 97 and Strike2: 303, Dip2: 11, Rake2: 49). Regarding the slip
distribution, we note that the maximum slip is 0.9 m and is located at the down-dip edge of the fault plane.
This earthquake occurred within the subducting Indian-plate indicating slab parallel tension. We appliedstochastic finite-fault ground-motion simulation based on a dynamic corner frequency to simulate theground motion for this event. The results were compared to seven strong motion stations in the Myanmar
region to validate our simulated values. The closest recording was made ~50 km from the epicenter. The
damage reported by the Department of Meteorology and Hydrology of Myanmar is consistent with therelatively high ground motion.

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*S13-P-10
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Early rupture process of the 2016 Kumamoto earthquake inferred fromsource imaging* Takamasa Usami , Masanao Komatsu , Hiroshi Takenaka
Graduate School of Natural Science and Technology, Okayama University, Okayama, JapanThe 2016 Kumamoto earthquake (Mj 7.3) occurred in Kumamoto prefecture, Japan, on 16 April 2016
(JST). The source region includes the Futagawa fault and northern part of the Hinagu fault. In this study, weinvestigate the early rupture process during 2.5 seconds after the origin time by source imaging technique(Takenaka et al., 2009, EPS). We use P-wave portion on vertical components of waveform records at 40
seismic stations from the seismic networks of JMA, NIED and Kyushu University. We assume three fault
segments: first one (segment 0) is the plane of strike N100E and dip 71 degrees passing the hypocenter by
JMA focal mechanism; second one (segment 1) is the plane of strike N205E and dip 72 degrees fornorthern part of the Hinagu fault estimated by GSI; third one (segment 2) is the plane of strike N235E anddip 60 degrees for the Futagawa fault inferred by GSI. In the result of source imaging on these segments,
we found several characteristic slip region. On segment 0, the rupture initiated and propagated. Then, atafter 0.5 seconds from the origin time, relatively larger slip appeared on the intersection line with segment
1, and the rupture transferred to segment 1. On segment 1, we found two strong slip regions: at southwestside of the segment after 2.0 seconds from the initial break; at near the shallower part of the intersection
line with segment 2 after 2.3 seconds from the origin time. The latter slip shows that the rupture did notovercome the intersection line with segment 2. This feature suggests that the shallower part of the junction
with segment 2 worked as a barrier at the stage of initial rupture and the rupture might have transfer tosegment 2 from deeper part of the junction at the later stage.

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*S13-P-11
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Source imaging of the 2016 Kumamoto earthquake by back-projection ofnear-filed P wave records.
* Mitsutaka Oshima
Shimizu corporation, Tokyo, JapanThe direction and the speed at which fault rupture proceeds, as is well known, controls major feature ofground motion around the causal faults. However, heterogeneous rupture process has been only partiallytaken into account in the current framework of strong ground motion prediction.
For more realistic and precise strong ground motion calculation, slip velocity function and rupture velocity
variable on fault planes are expected to be take into consideration in the future. Actually, some attempts toincorporate such heterogeneity for ground motion prediction are under way in the world. In pursuing thegoal, accumulation of information on fault rupturing process is essential to constitute a heterogeneous
source model.
In this study, I applied back-projection technique to reveal the time history of seismic wave emission
during the Kumamoto earthquake. Strong motion records recorded at 27 KiK-net and K-NET stations within
100km hyopocentral distance were used. Traveltime data were processed in the similar way as Takenaka
and Yamamoto(2004) to obtain seismic emission image with more precision in relative location. The backprojection technique used in this study is similar to that by Kao and Shan(2004), and Ishii et al.(2005).
As a result, clear image of rupture propagation from Takano-Shirahata segment of the Hinagu fault zone to
Futagawa segment of the Futagawa fault zone was obtained, where the strike and the dip of those two fault
planes are different. The rupture rapidly increased its seismic wave emission while it's moving toward
northeast.
However, both the accuracy and resolution of the present results still leave plenty of scope for
improvement. In the future study, I am planning to scrutinize data and data processing techniques, such as
traveltime data and waveform stacking methods, to get more exact and high-resolution image of the source
process.
Acknowledgement: I would like to express my gratitude to NIED for providing me with KiK-net and K-NET
data.

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*S13-P-12
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

The intraplate Maranhao earthquake of 2017 Jan 03, northern Brazil:
evidence of uniform regional stresses along the Brazilian equatorial margin.
Fabio Dias 1) , * Marcelo Assumpcao 2) , Marcelo Bianchi 2) , Lucas Barros 3) , Juraci Carvalho 3)
National Observatory, Brazil 1) , Sao Paulo University, Brazil 2) , Brasilia University, Brazil 3)
Lithospheric stresses in intraplate regions can be characterized by many different wavelengths. In someareas stresses vary over short distances of less than ~100 km, but in other regions uniform stresses canrecognized for more than ~1000 km or so. However, not all intraplate regions are well sampled with stressmeasurements to allow a good characterization of the lithospheric stresses. On January 3, 2017, amagnitude 4 mb earthquake occurred near the equatorial coast of the Maranhao State, an aseismic area ofnorthern Brazil. Despite the few permanent stations in northern Brazil, a well-constrained strike-slip
mechanism was obtained from regional moment-tensor inversion. A detailed analysis of the back-azimuthsof tens of aftershocks recorded by the closest station (40 km away) allowed the identification of the fault
plane to be the NNW-SSE trending nodal plane. An estimate of the rupture length, about 1 to 2 km, wasalso possible. The strike-slip mechanism has coast-parallel P axis and coast-perpendicular T axis, inagreement with most of the focal mechanisms found further to the East. The coast parallel P axis is alsosimilar to the SHmax measurements from breakouts further along the coast. The Maranhao earthquake fills
an important gap of stress indicators in northern Brazil and suggests that the intraplate stress field isuniform along the 2000 km long northern coast. In addition, this event can be used as a test for
detectability of the global IMS system, as it was not reported in the NEIC-USGS catalogue.

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*S13-P-13
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Radiation Efficiency of Intraslab Earthquakes beneath Kyushu* Yumenari Adachi 1) , Junichi Nakajima 1) , Toru Matsuzawa 2)
Tokyo Institute of Technology, Tokyo, Japan 1) , Tohoku University, Miyagi, Japan 2)
Although earthquakes in some subduction zones occur down to a depth of ~690 km, earthquakes in Kyushu
are limited to a depth of ~200 km. As the Philippine Sea (PHS) slab is aseismically subducting to a depth of>400 km (Huang et al. 2013), physical properties in the PHS slab that control the genesis of intraslab
earthquakes may change around a depth of ~200 km. This study estimates radiated energy and radiation
efficiency for earthquakes that occurred at depths of 60-200 km beneath Kyushu, and discusses the depth
variation in radiation efficiency.
To obtain reliable stress drop and radiated energy, we need to precisely estimate corner frequency ofearthquakes from amplitude spectra. However, there is a strong trade-off between the corner frequency andquality factor, and so it is difficult to determine the two parameters accurately. Therefore, the cornerfrequency is first estimated by the coda wave spectral ratio method, and then the static stress drop and thequality factor are obtained from the shape of amplitude spectra for S waves using the pre-estimated cornerfrequency.
The obtained results show that the radiation efficiency does not show a depth dependency and the averagevalue of the radiation efficiency is ~0.1, which is relatively small compared to those observed in the Pacificslab beneath Tohoku and Hokkaido. We infer that the small value of the radiation efficiency is due to highslab temperature in Kyushu.

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*S13-P-14
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Source time function archive of deep earthquake: re-examination ofhierarchy source model* Yasushi Ishihara
JAMSTEC, Yokohama, Japan
Rupture evolution process to large earthquake from its initiation is still hot topics in seismology. Many
analysis and seismograms of major earthquakes show complexity of source process resulting fromheterogeneous slip distribution on source fault and its time history. Smaller earthquake generally shows
apparent simple rupture process. As one model to explain source evolution and size relation for smaller
and large earthquake, hierarchy model was proposed (e.g. Fukao and Furumoto, 1985). In this study, we
review last 20 years broadband seismograms excited by world-wide deep earthquakes and re-evaluate
evolution model of rupture process.
Moment rate function of large size earthquake generally shows complexity of rupture process. As forshallow earthquake, body wave inversion are required including realistic earth's shallow structure model toget source time function. Meanwhile moment rate function of deep earthquake is obtained relative easily
and stably using P-wave form. By global seismic network, world-wide deep earthquakes are recorded inhomogenous sensitivity and station coverage.
From earthquake catalogue, recent 20 years deep seismic events are searched and applied grouping in
hypocenters' area. From our broadband seismogram data base, we archived P wave waveforms that theirmagnitude is greater than 4.5. According to attenuation of seismic wave, source duration time of less than
2sec is undetectable. Source time functions of magnitude 5 class events are simple pulse functions. Aroundmagnitude 6 to 6.5 events show also pulse shape function with significant width. Larger quakes thanmagnitude 6.6 have multiple functions in general and sometimes preceding to initial rupture process.
Based on hierarchy model, it seems that an earthquake size locates on step between two hierarchy levels.
Swarm-like deep earthquake sources also could be discussed about smaller scale heterogenous occuurece
field in this presentation.

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*S13-P-15
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

A model of dynamic earthquake triggering based on rate- and statedependent friction law* Shingo Yoshida
Earthquake Research Institute, University of Tokyo, Tokyo, Japan
Dieterich (1994) represented time to instability as a function of slip velocity assuming single spring-block
system based on rate- and state-dependent friction law (RSF), and denoted that increase of the slip velocity
due to static stress change triggers earthquakes. We extend this model to the case of dynamic stresschange, noting that increment of logarithm of slip velocity is proportional to difference between static
stress change and state variable (frictional strength) change. When fault strength is decreased by dynamic
stress change due to seismic waves, earthquake occurrence could be advanced, resulting in delayed
dynamic triggering even if no static stress change occurs.
We conducted numerical simulations of earthquake triggering assuming a circular asperity obeying RSF
law revised by Nagata et al. (2012). In a situation where earthquakes repeatedly occur, we apply dynamic
stress disturbance of sinusoidal variation at a certain time. The dynamic stress change causes increase ofslip velocity following the RSF law, and resultant slip weakens the frictional strength. This leads to dynamic
earthquake triggering depending on the amplitude of the disturbance. When the stress disturbance issufficiently large, earthquake occurs during the period of stress oscillating. This might correspond to
dynamic triggered earthquakes during passage of seismic waves. When static stress is also increased,
smaller dynamic disturbance can trigger earthquakes with a shorter delay. Even if static stress change isnegative, a certain amplitude of dynamic stress change can trigger earthquakes.

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*S13-P-16
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Estimation of the dynamic rupture parameters for the 2016 Tottorikenchubu earthquake* Keisuke Sato 1) , Shoichi Yoshioka 2) , Hideo Aochi 3) 4)
Graduate School of Science, Kobe University, Kobe, Japan 1) , Research Center for Urban Safety andSecurity/Graduate School of Science, Kobe University, Kobe, Japan 2) , Ecole Normale Superieure Paris,
Geological Laboratory, Paris, France 3) , Bureau de Recherches Geologiques et Minieres, Orleans, France 4)
We performed dynamic rupture simulations for the 2016 Tottoriken-chubu earthquake (M6.6). We used aboundary integral equation method, and supposed slip-weakening law as a frictional constitutive law. We
assumed a vertical rectangular fault plane whose depth of the upper edge is 0.5 km, and the fault size is
19.5 km (strike) and 18 km (dip). We attempted to obtain spatial distributions of initial stress and criticalslip weakening distance (hereafter referred to as Dc), which can fit better the slip distribution obtained
from an inversion analysis performed by Kobayashi et al. (2016). The inverted final slip distribution has anarea whose slip amount is large just above the hypocenter, reaching 1.3 m. We divided the fault plane into
two areas; one is the area with a large slip amount (hereafter referred to as asperity), and the other is thesurrounding one with a small slip amount. We fixed values of residual stress, peak stress, and Dc in bothareas. We attempted to obtain initial stress values so as to minimize the residual between the simulated andinverted final slip distributions by a try-and-error method. As a result, we obtained 10 MPa as the optimalvalue of initial stress at the asperity. Next, we attempted to estimate spatial distribution of Dc values. For
this purpose, we assumed the value to be 0.25 m in the surrounding area, and divided the asperity into fourareas in the depth direction (the deepest one included the rupture initiation point (hypocenter)). We
estimated Dc values, by using the same method to estimate initial stress values. As a result, we found thatthe Dc values became larger toward the direction of the ground surface. Comparing the inverted slip
distribution with obtained heterogeneous distributions of initial stress and Dc, we found that initial stressvalues at the asperity were larger than those of the surrounding area, and Dc value was the smallest in thearea including the rupture initiation point than the other upper three areas.

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*S13-P-17
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

Dynamic rupture model of the 2014 northern Nagano, central Japan,
earthquake* Yuko Kase
Geological Survey of Japan, Tsukuba, JapanThe 2014 northern Nagano, central Japan, earthquake occurred on the northern part of the Kamishiro fault(KF) and the northern extension of KF. The hypocenter is located at the northern end of the KF, and therupture propagated bilaterally. Surface ruptures intermittently observed along the northern part of KF in
the south of the hypocenter (Katsube et al., 2016). Waveform inversion, on the other hand, revealed thatlarge slip mainly distributed in the north of the hypocenter (e.g. Asano et al., 2015). On the northern part of
the KF, two M5-class earthquakes recently occurred, thus the slip of the 2014 northern Nagano earthquake
could be suppressed. In this study, we construct a dynamic rupture model of the earthquake to understanda mechanism of the earthquake and the present stress condition on the fault.
Our fault model contains two parallel dipping segments and a vertical segment between the two segments,
based on the aftershock locations (Imanishi and Uchide, 2015), the analysis of the InSAR data (Yarai,2015), and the difference between the focal mechanism and the CMT solution. The tectonic stressproportional to depth is modeled, considering the stress inversion result (MEXT et al., 2004). We calculate
dynamic rupture processes, assuming a slip-weakening friction law.
When the two dipping segments are under the same stress condition, a rupture initiating on the verticalsegment propagates on the two segments simultaneously, and surface slip along the southern segment islarger than the observed one. When the stress drop on the southern segment is less than that on thenorthern segment, on the other hand, the maximum surface slip along the southern segment is consistent
with the observation. The rupture propagates to the southern segment several seconds late, which agrees
with the results of waveform inversion. Our simulation results imply that the stress accumulation on thesouthern segment can be insufficient to rupture because of the past earthquake.

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*S13-P-18
IASPEI Symposium / IASPEI04. Earthquake Source Mechanics / S13. Earthquake source mechanics

A Possible Dynamic Rupture Scenario of the Nankai-trough Earthquakes,
southwest Japan* Yumi Urata 1) , Eiichi Fukuyama 1) , Chihiro Hashimoto 2)
National Research Institute for Earth Science and Disaster Resilience (NIED), Tsukuba, Japan 1) , Graduate
School of Environmental Studies, Nagoya University, Nagoya, Japan 2)
We investigated possible dynamic rupture scenarios of anticipated megathrust earthquakes along the
Nankai-trough, southwest Japan, taking into account the stress accumulation due to tectonic loading driven
by relative plate motion. For the plate interface geometry, we used a realistic 3D non-planar plate interface
geometry in and around Japan constructed by Hashimoto et al. (2004, Pageoph). The quasi-static stressaccumulation was simulated according to Hashimoto et al. (2014, Pageoph), assuming an elastic surface
layer overlying Maxwell-type viscoelastic half-space. We used the slip- and time-dependent constitutive law(Aochi & Matsu'ura, 2002, Pageoph) for the plate interface frictional property. Using the shear stress
distribution for 150 years after the Nankai-Tonankai-like earthquake (Hashimoto et al., 2017, JpGU-AGU
Joint Meeting 2017), we computed the dynamic rupture propagation by the boundary integral equation
method with triangular elements (Hok & Fukuyama, 2011, GJI). A hypocenter location is one of the mostuncertain parameters in the simulation. Therefore we examined various hypocenter locations andnucleation sizes to test whether or not a rupture can propagate. Under a given distribution of slip deficit
and constitutive parameters, the rupture was not initiated in the Tonankai area, in the eastern Nankai area,
nor in the western Nankai area at depth. In contrast, the rupture was initiated in the shallow part of thewestern Nankai area and propagated toward the deep portion of the western Nankai area and toward theeastern Nankai area along the edge of the asperity. The rupture then broke the Tonankai asperity and theslip evolved in the shallow portions of the eastern Nankai area. Such possible dynamic rupture scenario
could not be achieved by traditional experience-based kinematic modeling approaches; thus the procedureshown in this study is quite important to constructing a physics-based earthquake generation model.

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*S14-1-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Observations of Upper Mantle Discontinuity Structure* Nicholas Schmerr
University of Maryland, College Park, USA
There exist a number of seismic discontinuities throughout Earth's mantle that arise from a wide variety ofmechanisms ranging from changes in mineral structure, anisotropy, the introduction of new mineralphases, the presence or production of melts, to more subtle changes in mantle composition. Of the uppermantle boundaries, the 410 km (410) and 660 km (660) discontinuities resulting from phase changes in
the mineral olivine are the most prominent, and globally define the upper mantle transition zone. The
topography, sharpness, and impedance contrasts present 410 and 660 are of great value owing to theirpotential for revealing lateral variations in mantle temperature and composition as well as mantle
dynamics. Imaging of body waves scattered from the boundaries are providing new insights on theheterogeneity present on the 410 and 660 throughout the mantle.
In addition to the 410 and 660, the ever-increasing number of seismic stations deployed around the globe
is enabling study of the geographical characteristics of weaker, regional seismic discontinuities. These
weaker and regionalized discontinuities are proposed to arise from a variety of mechanisms, ranging fromstalled or trapped melt in the upper mantle, either at the base of the lithosphere, or above the 410 km
discontinuity, transitions in the anisotropy of the olivine phase, the presence of phase changes in thepyroxene and garnet of the mantle, to the formation of seismic discontinuities from the presence of thecoesite to stishovite phase transition in the vicinity of subducted and/or plume entrained eclogitic
materials. These new results are adding to the diversity of seismic discontinuities found in the upper
mantle and significantly improving our understanding of mantle chemical and thermal heterogeneity.

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*S14-1-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Cold, hot mantle transition zone beneath Hawaii mapped from teleseismic
Ps receiver functions* Matthew Agius 1) , Catherine Rychert 1) , Nicholas Harmon 1) , Gabi Laske 2)
Ocean and Earth Science, University of Southampton, United Kingdom 1) , University of California San
Diego 2)
Hawaii's remote geographic setting located far away from tectonic boundaries makes it an archetypal
example of hotspot volcanism. Establishing whether this hotspot represents the classic plume theory of avertical plume ascent from the core-mantle boundary to the surface, or perhaps of a plume that may have amore complex path, has proven challenging. In order to determine the exact trajectory of the Hawaiian
plume seismic anomaly in the mantle we determine P-to-S (Ps) receiver functions to illuminate the 410and 660-km depth mantle discontinuities beneath the Hawaiian Islands. The dataset is from waveforms
recorded on land and ocean-bottom seismometers, with the latter having corrections for tilt andcompliance noise. Our 3-D depth-migrated maps provide improved lateral resolution of the mantle
transition zone (TZ) discontinuities. The 410 discontinuity is characterised by a deepened area beneathcentral Hawaii surrounded by an elevated shoulder. At the 660 discontinuity, a shallow topography islocated to the north and far south of the islands, and a deep topographic anomaly is located far west andeast. The TZ thickness varies laterally by +/-13 km depth: thin beneath north-central Hawaii and thickfarther away in a horseshoe-like feature. We test for robust, large-scale characteristics of the TZ thickness,test the effect of a plume in the background velocity model, compare the topographic maps with seismic
velocities, and compare temperature anomalies with those from geodynamic numerical models. We inferthat at 660-km depth a broad or possibly a double region of upwelling converges into a single plumebeneath central Hawaii at 410-km depth. As the plume rises farther, uppermost mantle melting and flow
results in the downwelling of cold material, down to at least 410 km surrounding the plume stem. This
result in the context of others supports complex plume dynamics including a possible non-vertical plume
path and adjacent cold mantle downwellings.

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*S14-1-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Slow velocities and thin transition zone indicate upwelling lower mantle
beneath eastern Eurasia* Christine Houser 1) , Alex Webb 2)
Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan 1) , Department of Earth Sciences,
Hong Kong University, Hong Kong, China 2)
When comparing shear velocity and transition zone thickness, eastern Eurasia and the central Pacific standout with distinctive and robust signals of slow velocities and a thin transition zone. The central Pacific lies
on top of a column of slow material rising off of the Pacific large low shear velocity province. Thus, it seems
the region experiences upward return flow from the lower mantle. The combination of slow velocities and athin transition zone indicate the area is warm or dry or both. However, eastern Eurasia is a convergencezone with a long history of subducting oceanic slabs. In addition, independent compressional velocity
models find the same low velocity structure within the transition zone on top of faster velocities below inthe lower mantle. The tectonic history of the region indicates that the Pacific slab has been rolling to theeast since the beginning of Cenozoic. We suggest that the seismic signals in the transition zone are due to
upwelling lower mantle material caused by the Pacific slab sweeping across the transition zone as it falls
into the lower mantle.

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*S14-1-04
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

A three-dimensional electrical conductivity image of the mantle plume of theSociety hotspot in French Polynesia* Noriko Tada 1) 3) , Pascal Tarits 2) , Kiyoshi Baba 3) , Hisashi Utada 3) , Takafumi Kasaya 1) , Daisuke
Suetsugu 1)
JAMSTEC, Yokosuka, Japan 1) , IUEM, Plouzane, France 2) , The University of Tokyo, Tokyo, Japan 3)
Electrical conductivity is a physical property, which is independent from seismic velocity, and is sensitive
to temperature, melt fraction, and volatiles (hydrogen and carbon). By combining electrical conductivity
and seismic velocity, we could constrain the physical properties of the upper mantle. The previous seismic
studies found a low-velocity anomaly possible corresponding to the mantle plume beneath the Society
hotspot (Suetsugu et al., 2009; Isse et al., 2006). However, because of the sparse observation array, theresolution of these images is insufficient to discuss the thermal and chemical properties of the plume.
Besides, a previous marine magnetotelluric (MT) data (Nolasco et al., 1998) was obtained from too narrow
region in the vicinity of the Society Islands to get a three-dimensional (3-D) image of the plume. Therefore,
we conducted Tomographic Investigation by seafloor ARray Experiment for the Society hotspot Project(TIARES project) to image the possible plume with reasonable resolution using both MT and seismologicalobservations (Suetsugu et al., 2012). In this presentation, we will focus on the results from MT data, bothobtained by the previous study and the TIARES project.
We recently obtained a 3-D electrical conductivity image of the upper mantle beneath the Society hotspot(Tada et al., 2016). One of the most remarkable features is the presence of a distinct high-conductivity
anomaly that extends from the mantle transition zone to a depth of approximately 50 km below the sea
level. The amplitude of electrical conductivity of the anomaly is one to two orders of magnitude higher than
the surrounding mantle. Assuming that the bulk mantle can be represented by a mixture of olivine andmelt, the anomaly is explained by the existence of melt fraction up to 2.2 vol.% regardless of assumption oftemperature. Furthermore, the existence of carbonated silicate melt is confirmed because of CO2 in themelt is well constrained to be at least 8 wt.%.

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*S14-1-05
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Seismic evidence for broad attenuation anomalies in the asthenospherebeneath the Pacific ocean
Alice Adenis , * Eric Debayle , Yanick Ricard
Laboratoire de Geologie de Lyon: Terre, Planetes et Environnement, CNRS, University Lyon 1, Ecole
Normale Superieure de Lyon, France
We present QsADR17, a global model of upper mantle shear wave attenuation based on a massive Rayleighwave dataset (372,629 fundamental and higher-mode attenuation curves measured in the period range
50–260 s). We first correct our dataset for focusing-defocusing effects and geometrical spreading, andperform a stringent selection to only keep robust observations. Then, data with close epicenters recorded at
the same station are clustered, as they sample the same Earth's structure. After this pre-selection, ourdataset consists in a set of about 35,000 fundamental and higher-mode attenuation curves that constrain
the Rayleigh wave intrinsic attenuation in the upper mantle. The logarithms of the attenuation along theindividual rays are then inverted to obtain global maps of the logarithm of the Rayleigh-wave attenuationfor each mode and each period. The set of attenuation maps is finally inverted at depth to obtain a depthdependent model of attenuation QsADR17.
QsADR17 presents strong agreement with surface tectonics in the uppermost 200 km of the mantle, withlow attenuation under continents and high attenuation under oceans. Beneath oceans, the highest
attenuations are found beneath the mid-oceanic ridges at 50 and 100 km depths, but also in old oceanic
basins generally in the vicinity of hotspots. Although attenuation decreases with increasing crustal ages, thepresence of strong attenuating anomalies in the vicinity of hotspots produces departure from a simple halfpace cooling model. In the Pacific ocean, we observe a strong attenuating anomaly in the long wavelengthcomponent of our signal in the depth range 50-150 km. We suggest that this anomaly results from thehorizontal spreading of several thermal plumes within the asthenosphere. Strong velocity reductions
associated with high attenuation anomalies of moderate amplitudes beneath the East Pacific Rise, the Red
Sea and the eastern art of Asia may require additional mechanisms, such as partial melting.

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*S14-2-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Mantle transition zone, stagnant slab and intraplate volcanism in Northeast
Asia* Dapeng Zhao 1) , Chuanxu Chen 2) , You Tian 3) , Shiguo Wu 2) , Akira Hasegawa 1) , Jianshe Lei 4) , Jung-Ho
Park 5) , Ik-Bum Kang 5)
Tohoku University, Sendai, Japan 1) , Chinese Academy of Sciences, Sanya, China 2) , Jilin University,
Changchun, China 3) , China Earthquake Administration, Beijing, China 4) , KIGAM, Daejeon, South Korea 5)
Three-dimensional P and S wave velocity structures of the mantle down to a depth of 800 km beneath NE
Asia are investigated using a large number of high-quality arrival-time data of local earthquakes andteleseismic events recorded at 2388 stations of permanent and portable seismic networks deployed in NE
China, Japan and South Korea. Our results do not support the existence of a gap (or a hole) in the stagnant
slab under the Changbai volcano, which was proposed by a previous study of teleseismic tomography. In
this work we conducted joint inversions of both local-earthquake arrival times and teleseismic relative
travel-time residuals, leading to a robust tomography of the upper mantle and the mantle transition zone
(MTZ) beneath NE Asia. Our joint inversion results reveal clearly the subducting Pacific slab beneath theJapan Islands and the Japan Sea, as well as the stagnant slab in the MTZ beneath the Korean Peninsula
and NE China. A big mantle wedge (BMW) has formed in the upper mantle and the upper part of the MTZ
above the stagnant slab. Localized low-velocity anomalies are revealed clearly in the crust and the BMW
directly beneath the active Changbai and Ulleung volcanoes, indicating that the intraplate volcanism iscaused by hot and wet upwelling in the BMW associated with corner flows in the BMW and deep slab
dehydration as well.

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*S14-2-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Transition-zone imaging below Japan with ScS reverberations* Elmer Ruigrok 1) 2) , Kiwamu Nishida 3) , Katsuhiko Shiomi 4)
Royal Netherlands Meteorological Institute, De Bilt, Netherlands 1) , Utrecht University, Utrecht,
Netherlands 2) , Earthquake Research Institute at the University of Tokyo, Tokyo, Japan 3) , National
Research Institute for Earth Science and Disaster Resilience, Tsukuba-City, Japan 4)
The first-order structure of the mantle transition zone (MTZ) is well known below Japan. The 410 and 660
discontinuities are clearly seen on receiver functions. The 660 shows a marked depression where thePacific Slab is thought to interact with this boundary. The more precise shape of the MTZ, however, is
unknown. Possible smaller discontinuities like the 520, are hard to interpret with clarity. Moreover,receiver functions show clear interfaces below some parts of Japan, but are hard to interpret at other parts,
possibly due to multiples from the slab. To obtain a consistent image below the entire Island arc we apply
seismic interferometry together with reflection imaging. Large magnitude earthquakes nearby Japangenerate a clear ScS phase that is observed over the complete Hi-net array, operated by the NIED. Also,
ScS reverberations of the MTZ can directly be identified on the high-sensitivity accelerometers (tiltmeters).
We apply seismic interferometry to a multitude of these ScS arrivals and reverberations. Doing so, theresponses are retrieved as if there were shear-wave sources at all Hi-net tiltmeter stations and zero-offset(co-located source and receiver) reflection responses were measured. We further migrate the reflection
responses to a reflectivity image. This results in a pseudo-3D image of the MTZ below Japan. The mainfeatures are the topography of the 410 and 660 discontinuities, but also more subtle impedance contrasts
can be followed. We discuss how our image was obtained and show an interpretation of the thus-far
identified structures.

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*S14-2-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Mantle transition zone beneath a normal seafloor in the northwestern
Pacific: Electrical conductivity, seismic thickness, and water content* Tetsuo Matsuno 1) 2) , Daisuke Suetsugu 3) , Kiyoshi Baba 2) , Noriko Tada 3) 2) , Hisayoshi Shimizu 2) ,Hajime Shiobara 2) , Takehi Isse 2) , Hiroko Sugioka 4) , Aki Ito 3) , Masayuki Obayashi 3) , Hisashi Utada 2)
Kobe Ocean Bottom Exploration Center, Kobe University, Kobe, Japan 1) , Earthquake Research Institute,
The University of Tokyo, Tokyo, Japan 2) , Department of Deep Earth Structure and Dynamics Research,
Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan 3) , Department of Planetology,
Kobe University, Kobe, Japan 4)
We conducted a joint electromagnetic (EM) and seismic experiment to reveal the mantle structure beneatha normal seafloor at 130-145 Ma in the northwestern Pacific, where the seafloor is relatively flat and theunderlying mantle is expected to be normal (free from tectonic perturbations). In the experiment, we
deployed state-of-the-art instruments in two arrays from 2010-2015. Here, we report the result of analysesof the EM and seismic data for investigating the mantle transition zone (MTZ) structure. The EM data
analysis revealed that an electrical conductivity structure below both arrays was approximated by anaverage 1-D model of the north Pacific, and showed a possible downward increase in conductivity at the
top of the MTZ. From the P-wave receiver function analysis, perturbations in the MTZ thickness from a
global average were estimated to be +20 km and +2 km below the northern and southern arrays,
respectively, from which temperature profiles in the MTZ below these two arrays were then estimated. We
jointly interpreted the profiles of electrical conductivity and thus estimated temperature, with reference tothe experimental values of the effects of water on the electrical conductivities of MTZ minerals (wadsleyite
and ringwoodite) from mineral physics. The upper bound of the water content below the northern array
was determined to be 0.4 wt.% or 0.04 wt.%, depending on different results of mineral physics, and that
below the southern array was determined to be slightly smaller. The lower bound of the water content was
not constrained by our data. Our results indicate that the MTZ beneath the normal seafloor in thenorthwestern Pacific is drier than subduction zones, and may be a water-poor region in a plum-pudding
mantle model.

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*S14-2-04
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Upper-Mantle Discontinuities Across Stable South American Continent
Marcelo Bianchi 1) , * Marcelo Assumpcao 1) , Jordi Julia 2)
USP - University of Sao Paulo, Sao Paulo, Brazil 1) , UFRN- Federal Univ. Rio Grande do Norte, Natal, Brazil
2)

We stacked receiver function traces from all permanent stations of the Brazilian Seismographic Network(RSBR), as well as stations from a temporary experiment (3-Basins Project) along the SW Brazilian border,
to obtain cross-section images of the major upper-mantle discontinuities in the stable South American
continent.
We selected events with magnitudes > M5 in the distance range 30 to 95 degrees, visually inspected all
traces, confirmed the incoming P-wave azimuth, rotated into the LQT system (using the estimated azimuth
and theoretical incidence angle), deconvolved to obtain the Q-component receiver functions, and stacked
along profiles. Deconvolution used a high-pass filter at 0.02Hz. Before stacking, all traces were move-out
corrected to a ray-parameter of 6.4 s/deg allowing for stacking traces from different events in different
stations with the same piercing-point. Stacking was done by considering piercing point locations at a depthof 520 km. Interpretation and results will be presented along sections constructed to image the major
tectonic provinces in South America.
Most of the study region showed both 410- and 660-km discontinuities at the expected depths. Variations
observed are mostly related to the craton high-speed roots that shift up time images of the discontinuities
beneath cratonic areas. This effect can be seen beneath the San Francisco craton and the Amazon craton.
A newly observed feature is the influence of the cold Nazca Slab in lowering the 660-km discontinuity
under the Pantanal/Chaco basin. The flat geometry of the Nazca slab beneath the Pantanal Basin makes it
closer to the 660-km discontinuity, which could potentially help to interpret the formation and evolution of
the Pantanal Quaternary Basin.

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*S14-2-05
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Towards 3D Kirchhoff Migration of Receiver Functions at Continental Scale* Florian Millet 1) 2) , Thomas Bodin 1) , Stephane Rondenay 2)
Universite Claude Bernard Lyon 1, Lyon, France 1) , Universitetet i Bergen, Bergen, Norway 2)
The coda of seismic body waves contains a wealth of information about heterogeneities and discontinuities
inside the Earth. By using fast Receiver Function migration techniques such as classic Common
Conversion point (CCP) stacking, one can easily interpret structural features down to a few hundred
kilometers in the mantle. However, strong 1D assumptions limit the scope of these methods to stableregions such as cratons and stable basins. Other more accurate 2D and 2.5D methods are based on fewer
assumptions, but rely on dense arrays of stations, and are computationally expensive. Following the ideas
of Cheng et al. (2016), we have implemented a fully 3D prestack Kirchhof Receiver Function migration
scheme where travel times are quickly computed with the use of a fast Eikonal solver. The method is tested
using both 2.5D synthetics generated with a ray theory scheme (Raysum) and 3D synthetics using aspectral element method (specfem3D). Results show that dip angles and depths can be well recovered.
Application of this method to field data should prove interesting, for example, in complex subduction zones
that exhibit strong heterogeneities or multiple slabs.

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*S14-2-06
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Phase speed measurements of multi-mode surface waves using a broad-bandarray: Application to USArray* Hitoshi Matsuzawa 1) , Kazunori Yoshizawa 2)
Graduate School of Science, Hokkaido University, Hokkaido, Japan 1) , Faculty of Science, Hokkaido
University, Hokkaido, Japan 2)
Recent deployment of dense broadband seismic networks enables us to delineate high-resolution regional
3-D upper mantle images using surface waves, although many of surface-wave dispersion analysis withseismic arrays have primarily employed the fundamental mode only. To enhance the vertical resolution of
3-D S-wave models, higher-mode information can be of great help. However, their phase speed analysis is
intrinsically difficult, since the wave trains of several modes are generally overlapped each other in an
observed seismogram. Modal separation is not a straightforward issue because several higher-modes sharesimilar group speeds, but it can be possible by utilizing multi-mode surface waves propagating across adense linear seismic array aligned along the great-circle path. In this study, we develop an efficient method
for measuring the phase speeds of the fundamental- and higher-mode surface waves based on an arraybased analysis in the frequency-wavenumber domain with varying group-speed time window. The method
is then applied to USArray, to map the phase speed distributions of each mode and frequency.
Extensive synthetic experiments suggest that the measured phase speeds using a linear array well
represent the average structural features around the centroid of stations in the linear array. Thus, themeasured multi-mode phase speeds are used as a representation of the average phase speeds around thecentroid location of each station group. In this way, the phase speed distributions in North America aremapped using the measured phase speeds. Preliminary phase speed maps well reflect the major structuralfeatures of the upper mantle beneath the United States, regardless a relatively small number of employedseismic events. This method of multi-mode phase speed measurements can be of use to construct regional
3-D upper mantle models with enhanced vertical resolution.

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*S14-P-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Unusually deep Bonin earthquake of 30 May 2015: A precursory signal toslab penetration* Masayuki Obayashi , Yoshio Fukao , Junko Yoshimitsu
Japan Agency for Marine-Earth Science and Technology, Knagawa, JapanAn M7.9 earthquake occurred on 30 May 2015 at an unusual depth of 680 km downward and away fromthe well-defined Wadati–Benioff (WB) zone of the southern Bonin arc. To the north (northern Bonin), thesubducted slab is stagnant above the upper–lower mantle boundary at 660-km depth, where the WB zone
bends forward to sub-horizontal. To the south (northern Mariana), it penetrates the boundary, where the
WB zone extends near-vertically down to the boundary. Thus, the southern Bonin slab can be regarded as
being in a transitional state from slab stagnation to penetration. The transition is shown to happen rapidly
within the northern half of the southern Bonin slab where the heel part of the shoelace configured stagnant
slab hits the significantly depressed 660-km discontinuity. The mainshock and aftershocks took place inthis heel part where they are sub-vertically aligned in approximate parallel to their maximum
compressional axes. Here, the dips of the compressional axes of WB zone earthquakes change rapidly
across the thickness of the slab from the eastern to western side and along the strike of the slab from thenorthern to southern side, suggesting rapid switching of the down dip compression axis in the shoe-shapedslab. Elastic deformation associated with the WB zone seismicity is calculated by viewing it as an integral
part of the slab deformation process. With this deformation, the heel part is deepened relative to the arch
part and is compressed sub-vertically and stretched sub-horizontally, a tendency consistent with the idea ofprogressive decent of the heel part in which near-vertical compressional stress is progressively
accumulated to generate isolated shocks like the 2015 event and eventually to initiate slab penetration.
The horizontal part of the stagnant slab is mechanically decoupled from the near-vertically downgoing partand is left over the 660-km discontinuity.

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*S14-P-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Structure of Crust and Upper Mantle beneath South China Sea revealed by
Surface Wave Tomography
Thi Giang Ha 1) , Tien Hung Nguyen 1) , Satoru Tanaka 2) , * Le Minh Nguyen 1) , Yasushi Ishihara 2) , Vinh
Long Ha 1) , Quang Khoi Le 1)
Institute of Geophysics, Vietnam Academy of Science and Technology 1) , JAMSTEC 2)
The South China Sea (SCS), the largest marginal sea of West Pacific Ocean, is located in the area of plate
triple-junction that connect the Pacific, Eurasian, and Indo-Australian plates. Knowledge of the 3D crustand upper mantle structure is essential to improve our understandings of the geodynamical regimes andtectonic evolutions in this region. Based on the updated seismic recordings recorded by broadband
stations from cooperation between Institute of Geophysics, Vietnam Academy of Science and Technology(IGP-VAST) and Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and some others
stations from IGP-VAST's seismic network and international networks, we calculated more accurate groupvelocity dispersion curves of fundamental mode Rayleigh wave with periods from 10 s to 200 s by applying
the multiple filter technique for earthquakes occurred around the SCS from 2000 to 2016. We performed
the tomographic maps with the lateral resolution of 5x5 degree over the study region. Our tomographic
results for Rayleigh wave at periods of 15s, 20s, 30s, and 50s showed that the group velocities in the deepseas are greater than in the shallower seas and lands, it implies that the thicknesses of crust in the deepseas are relatively shallow. However, at the periods of 80s and 120s, the low velocities are present in thePhilippine and Java Trench where a lot of active volcanic eruptions exist. The 3D shear wave velocity
results revealed that the crustal thickness is ranging from 10 km to 25 km. The lithospheric thickness
beneath SCS is about 65-80km, it is relatively shallower than surrounding areas. The prominent low
velocity zones (LVZ) exist at the depths of 70km - 200km beneath the active volcanic regions, such as
Hainan island, Hon tro vocano (East Vietnam Sea), Andaman sea, Sunda shelf, southern Indochina,
Sulawesi, Celebes. The LVZs provide greater thermal support suggesting that these anomalies are thesources of the volcanic rocks in this study area.

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*S14-P-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Differences in the lithosphere seismic structure along the Brazilian
continental margin in the South Atlantic from travel time seismic
tomography
Marcelo Rocha 1) , Paulo Azevedo 1) , * Marcelo Assumpcao 2) , George Franca 1) , Giuliano Marotta 1)
Seismological Observatory - University of Brasilia, Brazil 1) , University of Sao Paulo 2)
Results of the P-wave travel-time seismic tomography method allowed observing differences in the seismic
behavior of the lithosphere along the Brazilian continental margin in the South Atlantic. High velocity
anomalies have predominance in the northern portion, which extends from the Rio de Janeiro to Alagoas
States (between latitudes -22.5 and -8.5), and low velocity anomalies in the southern portion, which extends
from Rio de Janeiro to Rio Grande do Sul States (between latitudes -30 and -22.5). Low velocities coincide
spatially with high seismicity areas, as indicated by Assumpcao (1998) and at the high velocities with low
seismicity regions. The high velocity anomalies at northern portion are related to the cratonic and lowstretched lithosphere of San Francisco paleocontinent that was connected to the Congo block before theopening of the Atlantic Ocean. Low velocities can be assigned to more weakened lithosphere, where it
started the South Atlantic Ocean opening process. The oldest lithosphere in the South Atlantic, indicatedby the magnetic anomalies of the oceanic floor, is higher in the southern part than in the northern part,suggesting that the continents in this region were separating, while the northern region was still connected
to Africa, which could explain the lithospheric stretching process.

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*S14-P-04
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Slow recycling of cold slab remnants in vigorous mantle convection* Gary Jarvis
York University, Toronto, Canada
Two dimensional numerical models of mantle convection in a cylindrical shell are employed to investigate
the impact of very high viscosities in mid-mantle and lower-mantle depths as proposed by Mitrovica andForte (2004) and Steinberger and Calderwood (2006). Models are considered with and without mineralphase transitions. Our viscosity profiles are depth dependent with deep mantle viscosities increasing tovalues of 300 times the viscosity of the upper mantle, and then decreasing dramatically on approaching thecore-mantle boundary. The decrease of viscosity near the CMB mobilizes the overall flow despite very highmid-mantle viscosities. However, cold detached slabs sinking below continental collisions become capturedby the high viscosity interior and circulate for times exceeding 200 Myr. This may account for the cold
patches detected by seismic tomography below India and Mongolia.

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*S14-P-05
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Detecting Seismic Anisotropy in the Mantle Transition Zone with SS
Precursors* Quancheng Huang 1) , Nicholas Schmerr 1) , Lauren Waszek 2) , Caroline Beghein 3) , Erik Weidner 3)
University of Maryland, College Park, USA 1) , New Mexico State University, Las Cruces, USA 2) , Universityof California, Los Angeles, USA 3)
Mineral physics experiments predict that the minerals in the transition zone (wadsleyite and ringwoodite)can have up to 8–13 % anisotropy. Seismic anisotropy is produced when anisotropic minerals are aligned
by mantle flow; e.g., upwelling plume or subducting slab. However, the observation of seismic anisotropy inthe mantle transition zone (MTZ) is a challenging measurement due to the limited resolution of current
methods. We use a body wave approach, the SS precursors, to study the anisotropy of MTZ and associatedmantle dynamics. Here, we use a broadband SS data set of 45,624 records to detect azimuthal anisotropy
present near the 410 and 660 km discontinuities. Due to the low amplitude of SS precursors, we employ aslowness stacking method to improve the signal to noise ratio. We partition our data into geographic bins of
SS precursor bounce points that sample with enough azimuthal coverage to be further broken down into
azimuthal bins. Our goal is the detection of travel time and amplitude variance of SS precursors withazimuth. We generate synthetic seismograms by perturbing PREM model in the transition zone to predict
travel time and amplitude change of SS precursors with different strength of anisotropy. We identify bin
locations of South America and South Pacific Ocean that have sufficient azimuthal coverage to produce
stable stacks. These bins have travel time and amplitude variations of the SS precursors that show little tono dependence on azimuth. We combine all the bins above subduction zones to detect azimuthal
anisotropy caused by subduction flows. The subduction zone bins have significant travel time andamplitude variations with azimuth but their uncertainties are relatively large. The azimuthal anisotropy isquantified by fitting modeling curves to data variations, which indicates that the MTZ beneath subduction
zones can have 1- 4% anisotropy. We will do further correction for the topography of MTZ to reduce theuncertainty.

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*S14-P-06
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Seismic attenuation of multiple ScS phases beneath South China Sea* Le Minh Nguyen 1) , Satoru Tanaka 2) , Yashushi Ishihara 2) , Tien Hung Nguyen 1) , Vinh Long Ha 1) , Thi
Giang Ha 1) , Daisuke Suetsugu 1)
Institute of Geophysics, Vietnam Academy of Science and Technology 1) , JAMSTEC 2)
The South China Sea (East Vietnam Sea) is surrounded by the Indochina peninsula, Sumatra and Borneo
islands which form the Sunda block (Sunda micro-plate) and Philippine Sea plate. It plays an important rolein tectonic regimes of the southeastern Asia. In order to acquire more information for understanding thetectonics in the southeastern Asia, we conduct a seismic study that investigates the seismic attenuation
structure by using multiple ScS phases (ScSn) beneath South China Sea (SCS) which recorded by thebroadband stations from the seismic network of Institute of Geophysics, Vietnam Academy of Science andTechnology (IGP-VAST), that by the cooperation between IGP-VAST and Japan Agency for Marine-Earth
Science and Technology (JAMSTEC) and some other international stations.
From approximately 100 earthquakes (Mw > 5.5, the region: 85 – 140 E and 15 – 40 N and the period:
2000–2009), we selected and used 90 seismograms with good quality of ScSn phases obtained from 15
earthquakes and 38 stations. To avoid the effect of shallow structure, selected seismograms were filtered in
bandpass of 0.01 – 0.03 Hz. These 90 event-station pairs can be classified into two directions, northwest –southeast (NW-SE) and northeast – northwest (NE-SW). Therefore, by using a spectral ratio method, we
derived the averaged Q values for NW–SE, NE–SW directions and averaged of these two directions, which
are Q_NW-SE = 133, Q_NE-SW = 455 and Q_Aver = 191, respectively.
The estimated value Q_Aver beneath SCS in this study is consistent with previous results and similar withsome other back arc regions such as Japan Sea and Southwest Pacific. However, the significant higher
Q_NE-SW implies low temperature and confirms the finish of spreading process beneath central of SCS. On
the other hand, the low Q_NW-SE might be affected by active subduction Celebes Sea and it implies thelow Q of upper mantle part beneath this region.

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*S14-P-07
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Lithospheric Shear-wave Structure beneath North America* Risheng Chu 1) , Justin Ko 2) , Shengji Wei 3) , Zhongwen Zhan 2) , Don Helmberger 2)
Institute of Geodesy and Geophysics, Wuhan, China 1) , California Institute of Technology, Pasadena, USA 2), Nanyang Technology University, Singapore 3)
The Lithosphere Asthenosphere Boundary (LAB), where a layer of low viscosity asthenosphere decouples
with the upper plate motion, plays an essential role in plate tectonics. Most dynamic modeling assumes thatthe shear velocity can be used as a surrogate for viscosity which provides key information about mantle
flow. Here, we derive a shear velocity model for the LAB structure beneath the Gulf of Mexico allowing adetailed comparison with that beneath the Pacific (PAC) and Atlantic (ATL). Our study takes advantage of
the USArray data from the March 25th, 2013 Guatemala earthquake at a depth of 200 km. Such data is
unique in that we can observe a direct upward traveling lid arrival which remains the first arrival ahead of
the triplications beyond 18 degree. This extra feature in conjunction with upper-mantle triplication
sampling allows good depth control of the LAB and a new upper-mantle seismic model ATM, a modificationof ATL, to be developed. ATM has a prominent low velocity zone similar to the structure beneath thewestern Atlantic. The model contains strong radial anisotropy in the lid where VSH is about 6% faster than
VSV. This anisotropic feature ends at the bottom of the lithosphere at about the depth of 175 km in contrast
to the Pacific where it extends to over 300 km. Another important feature of ATM is the weaker velocity
gradient from the depth of 175 to 350 km compared to Pacific models, which may be related to differences
in mantle flow.

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*S14-P-08
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Shear-wave velocity model of Palawan, Philippines from receiver function
analysis* Arianne Gail Rivera 1) , Takuo Shibutani 2)
Philippine Institute of Volcanology and Seismology 1) , Disaster Prevention Research Institute, Kyoto
University 2)
Palawan Island is located southwest of the Philippine archipelago. Northern Palawan is part of the rifted
continental margin of Eurasian plate while southern Palawan comprised the Palawan Ophiolite Complex.
The crustal thickness and the regional velocity model beneath the two broadband seismic stations of thePhilippine Seismic Network (PSN) in Palawan have been estimated using receiver function analysis.
Teleseismic waveforms data (30 degrees < x < 85 degrees) with magnitude 6.0 and above recorded by the
PSN from January 2012 to September 2015 were used in the computation. Using the extended-time
multitaper technique, the receiver functions (RFs) were calculated. Consequently, the transverse
components of the stacked RFs from all available back-azimuths were inverted using genetic algorithms tocheck for the presence of any dipping interfaces. This was followed by the inversion of the radial
components to have a more defined velocity model for certain back-azimuths.
Results showed that northern Palawan has thinner crust compared to southern Palawan. This can probably
be attributed to the differences in their geology. There is also an observed velocity jump observed on both
stations that could be the seismic basement.

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*S14-P-09
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S14. Upper
mantle and transition zone dynamics and structure

Seismic discontinuities in the upper mantle around Vietnam inferred fromreceiver functions* Takashi Tonegawa 1) , Minh Nguyen 2) , Satoru Tanaka 1) , Yasushi Ishihara 1) , Giang Ha 2) , Ryuta Arai 1) ,Hung Nguyen 2) , Bor-Shouh Huang 3) , Win-Gee Huang 3)
Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan 1) , Vietnam Academy of
Science and Technology, Hanoi, Vietnam 2) , Academia Sinica, Taipei, Taiwan 3)
Vietnam is tectonically located on Indochina and South China blocks that are separated by right-lateral Red
River fault. Tapponnier et al. (1982) suggested that Indochina block was extruded southeastward by
northward push of India to Asia. To investigate the structure of such blocks and its surroundings in theupper mantle, various seismological studies including tomography and splitting analysis have been
performed around Indochina Peninsula. However, it seems that surveys on the seismic discontinuities in
the upper mantle are insufficient in terms of their detection and determination of their undulation. In thisstudy, we try to image seismic discontinuities in the upper mantle beneath Vietnam by using receiver
functions.
We collected teleseismic P waveforms excited from earthquakes with magnitudes greater than 5.5 that
occurred during March 2008 and Dec. 2015. The number of the used broadband stations deployed in
Vietnam is 11. RFs are calculated through a spectral division of radial component over vertical component
with a Gaussian low-pass filter of 0.16 Hz. The total number of the gathered RFs is 1,884 for all stations.
The depth conversion of the time-domain RF is performed with IASP91 velocity model (Kennett andEngdahl, 1991). RF images are created by common conversion point (CCP) stacking technique.
Beneath Vietnam, the obtained RF images shows the 410 and 660 km discontinuities in the upper mantle(the 410 and 660). In a RF transect for northwest-southeast direction, we could image a depression of the660 by 30 km in the northern part in Vietnam, compared with the depths in the southern part. Because thedepth of the 410 is not changed, it seems that this represents a thickened mantle transition zone. Based ona study of global P-wave tomography, the Indian Plate subducts eastward and lies on the 660 under thenorthern Vietnam. Therefore, the depression of the 660 is presumably caused by cold material of the
subducted slab.

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*S15-1-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S15. Mid-m
antle structureFirst principles investigation of the high-pressure behavior of the FeOOHAlOOH-phase H (MgSiO4H2) system.
* Jun Tsuchiya 1) 4) , Elizabeth C. Thompson 2) , Taku Tsuchiya 1) 4) , Masayuki Nishi 1) 4) , Yasuhiro
Kuwayama 3)
Ehime University, Matsuyama, Ehime, Japan 1) , University of Chicago, Chicago, IL, United States 2) , The
University of Tokyo, Tokyo, Japan 3) , Earth-Life Science Institute-Ehime Satellite (ELSI-ES), Matsuyama,
Ehime, Japan 4)
It is believed that water is carried into the Earth's deep interior by hydrous minerals such as dense hydrous
magnesium silicates (DHMSs) in the descending cold plate. A number of studies have been conducted todetermine the high-pressure behaviors of DHMSs. In recent years, we discovered a new DHMS, phase H,
stable at lower mantle pressure condition; and the solid solution formed by phase H and delta-AlOOH has
been proposed as the most important carrier of water to the deepest part of Earth's mantle (Tsuchiya 2013,
Nishi et al. 2014, Ohira et al. 2014). However, those hydrous phases are not denser than surrounding (dry)mantle minerals (Tsuchiya and Mookherjee 2015) and their gravitational stability in deeper part of the
Earth is questionable. Therefore, the effect of denser elements such as Fe on the stability of DHMS is
intrinsically connected to the ability of these phases to transport water into Earth's deep interior. In order
to assess the effect of Fe on the phase relation of phase H and delta-AlOOH, we determined the highpressure behavior of the end-member composition of this system, epsilon-FeOOH. We have discovered a
new high-pressure phase transition in FeOOH at lower mantle conditions using both theoretical andexperimental methods. Here we show the high-pressure structures and physical properties of the FeOOHAlOOH-phase H system using first principles calculation and discuss possible geophysical implications.

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*S15-1-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S15. Mid-m
antle structure

Large-scale compositional heterogeneity in the Earth's mantle* Maxim Ballmer
ETH Zurich, Zurich, Switzerland
Seismic imaging of subducted Farallon and Tethys lithosphere in the lower mantle has been taken as
evidence for whole-mantle convection, and efficient mantle mixing. However, cosmochemical constraints
point to a lower-mantle composition that has a lower Mg/Si compared to upper-mantle pyrolite. Moreover,geochemical signatures of magmatic rocks indicate the long-term persistence of primordial reservoirs
somewhere in the mantle. In this presentation, I use numerical models to establish geodynamic
mechanisms for sustaining large-scale heterogeneity in the Earth's mantle. Mantle flow is controlled byrock density and viscosity. Variations in intrinsic rock density, such as due to variations in basalt or ironcontent, can induce layering or partial layering in the mantle. Layering can be sustained in the presence of
persistent whole mantle convection due to active “unmixing" of heterogeneity in low-viscosity domains,e.g. in the transition zone or near the core-mantle boundary [1]. On the other hand, lateral variations in
intrinsic rock viscosity, such as due to variations in Mg/Si, can strongly affect the mixing timescales of the
mantle. In the extreme case, intrinsically strong lateral heterogeneity may remain unmixed through the ageof the Earth, and persist as large-scale domains in the mid-mantle due to focusing of deformation along
weak conveyor belts [2]. That large-scale lateral heterogeneity and/or layering can persist in the presenceof whole-mantle convection can explain the stagnation of some slabs, as well as the deflection of someplumes, in the mid-mantle [1,2]. These findings indeed motivate new seismic studies for rigorous testing ofmodel predictions.

[1] Ballmer, M. D., N. C. Schmerr, T. Nakagawa, and J. Ritsema (2015), Science Advances,doi:10.1126/sciadv.1500815.
[2] Ballmer, M. D., C. Houser, J. W. Hernlund, R. Wentzcovitch, and K. Hirose (2017), Nature Geoscience, inpress.

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*S15-1-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S15. Mid-m
antle structure

Mineralogical model of the lower mantle inferred from high-pressure soundvelocity data
* Izumi Mashino 1) , Motohiko Murakami 1) , Nobuyoshi Miyajima 2) , Sylvain Petitgirard 2) , Daniel Frost 2)
Tohoku University, Miyagi, Japan 1) , University of Bayreuth, Bayreuth, Germany 2)
Understanding of the mineralogical composition of the lower mantle provides important information on theevolution of the Earth. The mineralogical model of the lower mantle can be estimated by comparing theseismic velocities of the minerals under lower-mantle conditions with seismic observations. It is widely
thought that spin transitions of iron in the mantle minerals may directly influence the seismic velocity
structure of the lower mantle, and also suggested that the spin transition in Fe-bearing MgSiO3 bridgmanite(Fe-Brd), the major component of the lower mantle, could occur. However, the presence and its effect of
the spin transition in Fe-Brd have been complex to characterize in previous studies. Especially, the effect of
the spin transition on the elastic wave velocities has not been elucidated yet.
Here we present the results of acoustic wave velocity measurements on Fe-Brd by Brillouin spectroscopy ina diamond anvil cell for a pressure range of whole lower mantle in order to clarity the presence and its
effect of the spin transition in Brd and constrain a more realistic model of the lower mantle. Then, we
discuss the mantle convection model of the present Earth and the building materials of the Earth.

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*S16-1-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S16. Large
low shear velocity provinces and deep mantle structure

Shear Wave Velocity Structure and Anisotropy atop the Core Mantle
Boundary Beneath the Indian Ocean Geoid Low* Padma Rao Bommoju 1) , Ravi Kumar Mangalampally 2) 3)
ESSO-National Centre for Earth Science Studies, Thiruvananthapuram, India. 1) , CSIR-National
Geophysical Research Institute, Hyderabad, India. 2) , Institute of Seismological Research, Gandhinagar,
India. 3)
The Indian Ocean Geoid Low (IOGL) that spans a vast areal extent south of the Indian subcontinent is aspectacular feature on the Earth, whose origin is still debated. In this study, we investigate the shear
velocity structure and anisotropy of the lower mantle beneath this geoid low and the adjoining geoid highregion utilizing the differential travel times, amplitude residuals and shear wave splitting of high-quality S
and ScS phases. Results reveal large variations in ScS travel time residuals indicating that the lowermost
mantle beneath the IOGL is heterogeneous. The ScS-S differential travel times are ~3s slower than thosepredicted by IASP91 model, primarily due to velocity increase in lowermost mantle beneath the IOGL and~2s higher than IASP91 beneath the geoid high region, due to velocity decrease in lowermost mantle. The
largest negative residuals (~7.7s) are concentrated below the IOGL. Modeling of differential travel time
residuals reveal that the maximum positive and negative residuals can be explained in terms of a reduction
in shear velocity of 0.9% and an increase of 1.6% respectively in a 1000km thick layer above the Core
Mantle Boundary (CMB). Also, the ScS/S amplitude residuals beneath the IOGL are positive, implying highimpedance contrast at the CMB, owing to the presence of high velocity material. The observed highvelocities are attributed to the presence of dehydrated high density slab graveyards atop the CMB beneaththe Indian Ocean. Further, we investigate the lowermost mantle anisotropy by analyzing high-quality ScS
phases corrected for source and receiver side upper mantle anisotropy. The splitting results reveal
significant anisotropy (~1.01%) in D'' layer. The observed fast axis polarization azimuths in ray-coordinate
system indicate a TTI style of anisotropy. Lattice Preferred Orientation deformation of palaeo-subductedslabs experiencing high shear strain is a plausible explanation for observed D'' layer anisotropy beneath the
IOGL.

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*S16-1-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S16. Large
low shear velocity provinces and deep mantle structure

ON THE NATURE OF LARGE ULTRA-LOW VELOCITY ZONES AT THE
ROOT OF MAJOR HOTSPOT PLUMES* Barbara Romanowicz 1) 2) , Kaiqing Yuan 1)
U.C. Berkeley 1) , College de France, Paris 2)
Ultra-low-velocity-zones (ULVZs) are localized regions of extreme properties detected seismologically at thebase of Earth's mantle, and have been found preferentially within or on the border of large low shear
velocity provinces (LLSVPs). They may come in different shapes and forms. The nature and role of ULVZs
in lower mantle dynamics is still poorly understood, in particular whether they are due to partial melting or
the presence of solid state iron. Depending on assumptions made in geodynamic simulations, they may
occur preferentially at the edges or in the middle of the LLSVPs.
We here discuss a particular class of very large ULVZ's (>800 km in lateral extent) that have been detected
at the roots of broad plumes imaged in the lower mantle by seismic tomography, specifically Samoa(Thorne et al., 2013), Hawaii (Cottaar and Romanowicz, 2012) and most recently Iceland (Yuan andRomanowicz, 2017). In the case of Hawaii, a simple cylindrical ULVZ shape matched the observed shear
diffracted (Sdiff) waveforms, but couldn't be uniquely constrained because of the limited illumination
afforded by available data. The Iceland geometry is favorable for analyzing the effects of the ULVZ on Sdiff
on paths that illuminate the root of the plume from different directions. Waveform modeling of data from 8
different earthquakes observed at arrays in north America and in China shows the presence of a large
ULVZ, which, to a very good first approximation, has a regular, circular-shaped base. This shape suggeststhat this ULVZ is closely related to the dynamic upwelling at the base of the Iceland plume, and is therefore
most likely due to partial melting of a denser and hotter than average core of the plume root, rather than toa solid state process. We also show that such structures are few and far apart, and may be characteristic ofthe dynamics of flow at the roots of the twenty-or-so broad mantle plumes imaged in the lower mantle.

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*S16-1-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S16. Large
low shear velocity provinces and deep mantle structure

Waveform inversion for localized three-dimensional shear wave velocity
structure within the lowermost mantle* Kenji Kawai 1) , Anselme Borgeaud 1) , Yuki Suzuki 1) , Kensuke Konishi 2) , Robert Geller 1)
The University of Tokyo, Tokyo, Japan 1) , Institute of Earth Sciences, Academia Sinica, Taiwan 2)
We formulate the inverse problem of waveform inversion for localized 3-D seismic structure, computing
partial derivatives of waveforms with respect to the elastic moduli at arbitrary points in space foranisotropic and anelastic media. In this study we minimize computational requirements by using the Born
approximation with respect to a laterally homogeneous model, but this is not an inherent limitation of ourapproach. We solve the inverse problem using the conjugate gradient (CG) method, using Akaike's
Information Criterion (AIC) to truncate the CG expansion. We apply our method to invert for 3-D shear
wave structure in the lowermost mantle beneath Central America, the western and northern Pacific using
waveforms at periods from 12.5 to 200 s recorded at stations of USArray and F-net for deep andintermediate-depth events. Various tests show that our model is robust.

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*S16-1-04
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S16. Large
low shear velocity provinces and deep mantle structure

Deep mantle heterogeneity and its relationship with deep mantle heat flow
inferred from 3D spherical mantle convection with plate reconstruction
system in 200 Myrs
* Takashi Nakagawa
MAT, JAMSTEC
In recent progress on geodynamics modeling, a coupled plate-mantle-core system can be addressed fromgeodynamo model incorporating the heat flow across the core-mantle boundary (CMB) computed fromnumerical mantle convection simulations with plate reconstruction in 200 Myrs [Olson et al., 2013].
However, computing the heat flow across the CMB, it is strongly dependent on material properties oflowermost mantle minerals such as post-perovskite phase as well as thermo-chemical piles [Nakagawa andTackley, 2008; Dekura et al., 2013; Ammann et al., 2014]. In previous study [Nakagawa and Tackley, 2008],
simple tests on a relationship between deep mantle heat flow and thermo-chemical heterogeneity havebeen pointed out that such a relationship is not very simple as a heterogeneous boundary condition
incorporating with geodynamo simulations, which is a linear treatment [e.g. Olson et al., 2013]. Here new
scaling relationship between deep mantle heat flow and thermo-chemical heterogeneity derived fromnumerical mantle convection simulations with plate reconstruction data. On the thermo-chemical
heterogeneity, it forms by the segregation of oceanic crust in the deep mantle plus the post-perovskite
phase transition. Preliminary result suggests that no simple scaling relationship can be found between deep
mantle heat flow and thermo-chemical heterogeneity, which is consistent with simple tests [Nakagawa andTackley, 2008]. This also suggests that a linear scaling relationship between heat flow and seismic
anomalies seems to be an over-simplified heterogeneous boundary condition for geodynamo modeling.
This can also imply for a formation mechanism on Large-Low-Shear-Velocity-Provinces (LLSVPs), which
could be either thermal plus post-perovskite phase or thermo-chemical piles plus post-perovskite phase.

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*S16-1-06
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S16. Large
low shear velocity provinces and deep mantle structure

Effect of cation substitution on bridgmanite elasticity
Hiroshi Fukui 1) 2) , Akira Yoneda 3) , Akihiko Nakatsuka 4) , * Seiji Kamada 5) , Takashi Yoshino 3) , Alfred
Baron 2)
Graduate School of Material Science, University of Hyogo 1) , Materials Dynamics Laboratory, RIKEN
SPring-8 Center 2) , Institute for Planetary Materials, Okayama University 3) , Graduate School of Sciences
and Technology for Innovation, Yamaguchi University 4) , Frontier Research Institute for Interdisciplinary
Sciences, Tohoku University 5)
Single crystal elasticity of MgSiO3 bridgmanite and cation-substituted ones has been investigated using
inelastic x-ray scattering technique. The present results demonstrated that iron substitution in bridgmanite
makes bulk modulus of bridgmanite larger and shear modulus smaller at the ambient conditions. This
corresponds to anti-correlated behavior: bulk sound velocity increases while shear wave velocity decreases.
Cation substitution may explain the anti-correlated seismic velocity anomaly observed in the LLSPVs.

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*S17-1-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S17. Outercore structure and dynamics

Seismic structure of the Earth's outermost core
* Satoshi Kaneshima
Kyushu University
In this talk we review seismological studies that investigate the Vp structure of the Earth's outermost core.
The models obtained so far are reviewed. The types of data that can be used are presented. It is shown thatdifferential travel times of SmKS waves are the most powerful data for this purpose. High-quality SmKS
differential times are well fit by a Vp model of the Earth's outermost core, KHOMC (Kaneshima andHelffrich, 2013). The observations obtained so far provide the evidence for the presence at the top of theouter core of a layer that has a distinctively steeper Vp gradient than the bulk of the outer core. The mostrecent estimate of the layer thickness is nearly 400 km. The Vp anomalies relative to PREM for the depths
400 to 800 km below the CMB appear to be insignificant. The Vp structure of the deeper outer core is also
discussed. Finally we compare the seismological models with geomagnetic models and mineral physics
studies.

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*S17-1-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S17. Outercore structure and dynamics

Erosion of a thermally induced stably stratified layer by compositional
convection in the Earth's outer core
* Shi-ichi Takehiro , Youhei Sasaki
Kyoto Univerisity, Kyoto, Japan
We propose to use radial distribution of power induced by thermal and compositional buoyancy (rate of
kinetic energy production) as measure of occurrence of thermal and compositional convection.The power
consists of the terms proportional to heat flux and compositional flux. The region with positive power isconsidered that convection is active there because kinetic energy can be produced by buoyancy force. On
the other hand, in the region with negative power convection is suppressed and stably stratified layer may
be produced.
We constructed a 1-dimensional thermal and compositional balance model of the Earth's core with theupdated values of thermal conductivity under conditions of planetary cores derived by recent high-pressure
experiments and first principle calculations, and obtained radial distributions of power for various values of
the core-mantle boundary (CMB) heat flux Q. When Q > 9.3 TW, it is suggested that convection occurs in
the whole outer core, however, a stable layer with O(100km) thickness could be produced below CMB
when Q < 4.8 TW. Our result is in contrast with the previous studies on the assumption that the region withnegative heat flux is stably stratified, where a stable layer whose thickness of O(1000km) could be
produced when the heat flux across CMB is small.

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*S17-1-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S17. Outercore structure and dynamics

Neutrino oscillations and electron density distribution of the Earth's core
* Akimichi Taketa 1) , Carsten Rott 2)
Earthquake Research Institute, University of Tokyo, Tokyo, Japan 1) , SungKungKwan University, Suwon,
Korea 2)
Neutrinos, a kind of elementary particle, and consist of three species, electron neutrino, muon neutrino,
and tau neutrino. They have unique property. A neutrino can change its specie to another kind of species
as it pass thorough space. This phenomena called as neutrino oscillation. The probability of oscillation
depends on the electron density of the media which is passed through neutrinos, so neutrino oscillation
can be used as a probe to measure the electron density of the media.
Neutrinos are naturally produced in the atmosphere (atmospheric neutrino), the Sun (solar neutrino), andso on. The arrival direction distribution of the atmospheric neutrino is isotropic, so 1D electron density
distribution can be measured by a single detector. The arrival direction distribution of the solar neutrino ispoint source, but we know the relative geometry of the Sun, the Earth, and the detector. And the Earth isrotating and revolving, so we can also measure 1D electron density distribution along solar trajectory, like
CT scan. If we have several neutrino detectors which have enough sensitivity, 3D electron density
distribution of the Earth also can be measured.
The matter density distribution of the Earth is already measured by using seismic data. The ratio of thematter density to the electron density is equal to the ratio of atomic weight to atomic number, i.e. theaverage chemical composition. By combining the matter density distribution and the electron density
distribution, we can measure the average chemical composition distribution of the Earth.
We demonstrate the capability to apply the neutrino oscillation to geo-physics.

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*S17-P-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S17. Outercore structure and dynamics

Seismological evidence for heterogeneous lowermost outer core (F-layer) of
the Earth* Toshiki Ohtaki 1) , Satoshi Kaneshima 2) , Hiroki Ichikawa 3) , Taku Tsuchiya 3)
Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST),
Tsukuba, Japan 1) , Department of Earth and Planetary Sciences, Kyushu University, Fukuoka, Japan 2) ,Geodynamics Research Center, Ehime University, Matsuyama, Japan 3)
The asymmetric release of light-elements at the inner core boundary (ICB) may cause a regional variationof chemical components in the outer core, especially in the layer directly above the inner core (F-layer). To
verify the variation, it is necessary to analyze detailed seismic structure in the layer of two or more laterally
distinct regions. However, conventional observations are insufficient to resolve the detailed F-layer
structure. We developed a new method to analyze dispersion in PKPbc and PKiKP-PKPbc travel times (dT),and investigated the velocity profile beneath the northeast Pacific (Ohtaki & Kaneshima, 2015). These two
observations are particularly sensitive to F-layer and relatively insensitive to the mantle and inner core.
In this study, we analyze seismograms of South Sandwich events observed in Japan using the same
method. The rays turn beneath Australia. The dispersion is sensitive to the velocity gradient just above the
ICB but insensitive to velocity values in the F-layer. The dispersion observations require nearly constantvelocity above the ICB, which is relatively close to AK135. The dT is sensitive to the velocity values
between the PKPbc turning depth and the ICB but insensitive to the velocity gradient. The dT observations
are close to those predicted by PREM. The velocity model that satisfies both the observations has nearly
constant and smaller velocities than PREM on the ICB, and faster ones above.
Both the observations require disparate F-layer structures in between these two regions. Velocity in theliquid core has a little dependence on temperature (Ichikawa+, 2014). Thus the difference in velocities
between the two regions is ascribed to the relative abundance of light elements. The reduced velocity
gradient on the ICB beneath Australia signifies chemically unmixed materials there. The higher velocities
than PREM and our NE Pacific model (FVW) indicate a localized higher abundance of light elements in theF-layer.

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*S17-P-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S17. Outercore structure and dynamics

Outer core stratification by crystallization of SiO2
* George Helffrich 1) , Kei Hirose 1) , Guillaume Morard 2) , Ryosuke Sinmyo 1)
Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan 1) , IMPMC, UPMC, Paris, France
2)

Wavespeeds lower than PREM's near-uniform self-compression profile in the outermost outer core
constitute evidence for a radial compositional gradient there, and possibly for stable stratification. Melting
experiments in the Fe-Si-O system in the diamond anvil cell at outer core pressures and temperatures show
crystallization of SiO2 from a variety of starting compositions. We developed a thermodynamic model of
SiO2 saturation in liquid Fe at high pressure and temperature conditions suitable for modelling magma
ocean and outer core processes. Significant incorporation of Si+O in the metal occurs in magma ocean
conditions, 30-50 GPa, which, after the core evolves to its present temperature (3500-4500 K at the CMB),
leads to exsolution of SiO2. Driving a dynamo by crystallization is quite efficient and allows one of today's
strength to be powered throughout Earth history. We show that the continuous crystallization of SiO2 at the
top of the core produces denser, iron-enriched liquid that mixes downward into the core. This leads toreduced wavespeeds in the top of the outer core from the net effects of the density and mean atomic weightchange. Only a small change in concentration of the SiO2 component in the bulk liquid is required about
0.15 wt%.

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*S18-1-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S18. Innercore structure

Geodynamical modeling and seismic observations: a step towards mapping
regional structures of Earth's inner core
* Lauren Waszek
New Mexico State University
The inner core displays a hemispherical difference in seismic velocity, attenuation, and anisotropy, which
is well-established from seismic studies. Recent observations reveal increasingly complex and regionalfeatures. However, geodynamical models generally only attempt to explain the basic east-west asymmetry.
Regional seismic features, such as depth-dependence anisotropy or variation in hemisphere boundaries,
are difficult to reproduce and relatively poorly constrained by seismic data.
There are two major theories to explain the inner core hemispheres. The first invokes lateral translation of
the inner core to generate a hemispherical difference in age of inner core material. The second requires aasymmetry between the hemispheres in growth rate of the inner core boundary, whereby the east
hemisphere grows faster. Processes to generate the more complicated structures, such as anisotropy, sharphemisphere boundaries, and regional features, are debated.
Seismic data sampling of the inner core is especially limited in some regions, leading to difficultyinterpreting the small-scale features. Here, we present a new trans dimensional tomographic inversion for
inner core seismic velocity, that accounts for the influence of uneven data coverage. The model provides
improved constraints on regional-scale structure within the hemispheres, as well as lateral variation of thehemisphere boundaries, and estimates of the uncertainty in isotropic and anisotropic velocity. We compare
these observations to results from our new, open-source Python code “GrowYourIC". The code simulates
growth, translation, and super-rotation of the inner core, with a goal of reproducing the inner core seismic
properties, as well as revealing the limitations of inhomogeneous sampling in real datasets.

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*S18-1-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S18. Innercore structure

Complex inner core of the Earth constrained by differential travel times anddifferential ray parameters* Tae-Gyu Yee 1) , Junkee Rhee 1) , Hrvoje Tkalcic 2)
Seoul National University 1) , The Australian National University 2)
Various studies over the last decades have revealed complex velocity structures of the Earth's inner core.,
Recently, using high-quality PKPbc-PKPdf differential travel times recorded by the dense Hi-net array, we
reported that compressional velocity field (Vp) in the uppermost inner core (top 350 km of the inner core)is regionally perturbed by about 1% within each quasi-hemisphere. Although we showed the existence ofheterogeneity on regional scale, the precise location and size of heterogeneities could not be constrainedusing exclusively the perturbed differential travel times. To overcome this limitation, here we utilize the
PKPbc-PKPdf differential ray parameters in addition to the corresponding differential travel times to study
the Vp structure of the uppermost inner core. We find that the differential ray parameters measured byphase-weighted stacking of waveforms recorded by the Hi-net array also display regional variations in bothquasi-hemispheres. This observation supports previous results and provides additional constraint oncomplex Vp structure. We examine a number of 2-D models with different nature of heterogeneities
including the inner core boundary topography and a mushy zone to predict the observed regional variationof the differential travel times and differential ray parameters. Our estimates of the heterogeneity spectrum
represent invaluable new constraints on inner core structure.

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*S18-1-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S18. Innercore structure

Temporal change of seismic data associated with the Earth's inner core:
inner core super-rotation or temporal change of inner core surface?
* Lianxing Wen 1) 2) , Jiaoyuan Yao 2)
Stony Brook University 1) , University of Science and Technology of China 2)
Seismic evidence has shown that seismic compressional waves that are refracted (PKIKP) and reflected(PKiKP) off the inner core exhibit temporal changes. Two explanations have been put forward to accountfor the observed temporal change of the seismic data: inner core super-rotation and temporal change of
inner core surface. In this presentation, we present observations of temporal change of seismic data basedon global earthquake doublets found in the last 20 years and discuss the plausibility of their interpretationsin the context of inner core super-rotation and temporal change of inner core surface. We show that innercore super-rotation is not required by the seismic data, cannot consistently explain the seismic data
sampling different regions of the inner core and fail to track the presumed seismic scatterers appeared
between some time intervals of the doublets, while temporal change of inner core surface can explain all
the seismic data without requirement of inner core differential rotation. Accordingly, we present a global
map of temporal change of inner core surface in the last 20 years, and discuss its implications tothermocompositional conditions near the inner core surface and driven forces of geodynamo.

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*S18-1-04
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S18. Innercore structure

Comparison of frequency dependent reflection coefficients at the inner coreboundary beneath the central America and western Pacific* Satoru Tanaka 1) , Hrvoje Tkalcic 2)
JAMSTEC, Yokosuka, Japan 1) , ANU, Canberra, Australia 2)
Reflection coefficients (RC) at the inner core boundary (ICB) inferred from PKiKP/PcP amplitude ratios
have been used for the inferrence of the status at the inner core surface. Recently, Tanaka and Tkalcic(2015) examined the RC's freqeuncy variations and suggested a topographic variation at the ICB beneathwestern Pacific. It was suggested that the frequency characteristics of the RC at the ICB can be qualitatively
explained by the ICB topography with height and wavelength of about 1 km. Here we additionally examine
the RCs at the ICB benath the central America observed by USArray, a dense seismic network in the USA.
Although the frequency characteristics of the RCs at the ICB beneath the western Pacific is complex, theRCs tend to be large at frequencies larger than 2 Hz and small at frequencues less than 2 Hz. To thecontrary, some of the RCs beneath the central America are large at frequencies less than 2 Hz and small at
frequencies greater than 2 Hz.
This difference suggests the existence of a large-scale regional variation at the inner core surface
conditions. This variation is more significant than what we anticipated based only on the results focusing
on the region beneath the western Pacific.

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*S18-1-05
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S18. Innercore structure

Complex Iron Lattice Preferred Orientation Pattern at the Earth's Inner* Maurizio Mattesini 1) 2) , Anatoly Belonoshko 3) , Hrvoje Tkalcic 4)
Departamento de Fisica de la Tierra, Astronomia y Astrofisica I, Universidad Complutense de Madrid,
Madrid, Spain 1) , Instituto de Geociencias (CSIC-UCM), Facultad de CC. Fisicas, Madrid, Spain 2) ,Condensed Matter Theory, Department of Theoretical Physics, AlbaNova University Center, KTH RoyalInstitute of Technology, Stockholm, Sweden 3) , Research School of Earth Sciences, The Australian National
University, Canberra, Australia. 4)
An entangled Lattice Preferred Orientation (LPO) pattern has been found at the Earth's inner core fordifferent types of iron polymorphs. The amount of crystal alienation and its particular spatial distribution at
ICB was achieved by merging the information from high-quality inner core probing seismic data [PKP(bcdf)] together with state-of-the-art ab initio calculations. Results are showing that the obtained LPO
arrangement at ICB can be used as a key boundary condition for novel dynamo simulations, providing afurther way to distinguish in between different geodynamical scenarios.

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*S18-1-06
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S18. Innercore structure

Studies of inner core anisotropy from noise interferometry* Xiaodong Song 1) , Tao Wang 2) , Han Xia 1) 2)
University of Illinois, Champaign, USA 1) , Nanjing University, Nanjing, China 2)
Studies of the inner core have relied on body waves (mainly PKP) and core-sensitive normal modes
generated by strong earthquakes. Despite the complex pattern of the inner core anisotropy, it's shown to be
predominantly cylindrically symmetric with the symmetry (fast) axis parallel to the Earth's spin axis fromearthquake data. However, we recently found that the fast axis in the inner part of the inner core (IIC) isclose to the equator from inner-core waves (PKIKP2 and PKIIKP2 phases) extracted from autocorrelationsof earthquake coda (Wang et al., 2015). To confirm the equatorial IIC anisotropy, we examined stations at
low latitudes (within ±35º), which reduces the influence of the polar anisotropy and possible contaminationfrom the large Fresnel zones. Using a number of improved procedures of both autocorrelation and crosscorrelation, we extracted high-quality empirical Green's functions at 52 globally distributed arrays. We
observed large variations (up to nearly 11 s) between the PKIKP2 and PKIIKP2 phases and the patternmatches very well previous IIC model, providing further support for the equatorial anisotropy model of the
IIC. Separately, earthquake-generated PKP differential travel times have been instrumental in mapping theinner core anisotropy. We found that triplicated PKP phases can be extracted from the stacks ofstation–station correlations (Xia et al., 2016). Both ambient noise and earthquake coda contribute to the
PKP phases. However, the contributions vary with frequency and with body-wave phases. At shorter
periods (5–20 s), three branches of PKP (df, bc and ab) can be extracted from ambient noise and the abphase from earthquake coda. At longer periods (15–50 s), earthquake coda are effective in generating thedf branch, but not the ab branch. The usefullness of the new type of data remains to be explored, but it's
likely to complement the limited distribution of earthquake data with certain critical samplings.

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*S18-P-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S18. Innercore structure

GrowYourIC: a step towards reconciling geodynamical models to seismic
observations of the inner core
* Marine Lasbleis 1) , Lauren Waszek 2) , Elizabeth Day 3)
ELSI, Tokyo Institute of Technology, Tokyo, Japan 1) , Department of Physics, New Mexico State University,
NM, USA 2) , Department of Earth Science and Engineering, Imperial College London, UK 3)
The inner core structure has been well-established from seismic studies, showing heterogeneities at various
scales, both radially or laterally. Yet, no geodynamical model has been successful at explaining all thefeatures observed. One of the main limit for that is the lack of tools to compare successfully seismic
observations and numerical models.
Here, we present a new Python code to compare models of the inner core structure. The code calculates
properties of geodynamical models of the inner core along inner core ray paths, for random or userspecified datasets. It allows easy comparisons between geodynamical models and seismic observation, andprovides various representations of models and datasets. As proof of concept, we test models which
simulate fast lateral translation, and differential growth, and compare to an example inner core dataset
provided with the code that samples the outermost part of the outer core, up to 107km depth. We show thata random dataset with perfect coverage produces the same average results as a real inner core dataset.
However, we also find that neither simplistic geodynamical model is able to recreate the inner core seismic
observations.
We discuss here the possible applications of this code for various geodynamical models. Comparing the
geodynamical models and seismic observations is difficult due to the lack of seismic properties of material
in the models. We will discuss how orientations of crystals can be added in this code, to compute as wellanisotropy in the inner core models.

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*S18-P-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S18. Innercore structure

Full parameter space search for a layered, anisotropic inner core using the
Neighbourhood Algorithm.
* Joanne Stephenson , Hrvoje Tkalcic
Australian National University, Canberra, Australia
The inner core of the Earth has long been modelled seismically by simple cylindrical anisotropy with thefast axis parallel to the Earth's rotation axis. This has been quantified with the use of the inner core phase
PKIKP, utilising both differential and absolute travel times. This simplistic model is popular as, to someextent, it can explain both PKIKP travel time data and anomalous splitting of normal modes. However,recently it has become apparent that such a simple model fails to fit all observed travel time data. Travel
time residuals from PKPbc-PKIKP differential times, plotted against the angle with the Earth's rotation axis,
form a distinctive “L" shape where polar paths, typically from the South Sandwich Islands, have a residual
range of ~0-5 seconds. A simple model of cylindrical anisotropy fails to fit such extreme range of values.
Whilst many models with increasing inner core complexity (e.g. the inner most inner core) have beencreated on an ad hoc or systematic basis, a full parameter space search has not been comprehensively
carried out for travel time data. We employ the derivative free search algorithm, the Neighbourhood
Algorithm, to explore multidimensional parameter space for the case of an anisotropic, layered inner core.
Using a combination of absolute PKIKP travel time data from the ISC catalogue, global high-quality PKPbcPKIKP differential travel time data hand-picked by cross-correlation, and a high volume of high-quality
hand-picked differential travel time data from the South Sandwich Islands earthquakes, we search for the
optimal number of layers within the inner core and the associated parameters of the cylindrical anisotropy
equation. Results from this process are presented, the outcomes of which have implications for geodynamic
and mineral physics interpretations.

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*S18-P-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S18. Innercore structure

Toward probing the deep Earth's interior using spiral-arm arrays andprinciples of seismic interferometry* Thanh-Son Pham , Hrvoje Tkalcic , Malcolm Sambridge
The Australian National University, Canberra, Australia
The observations of different PKP branches on single seismograms have so far provided the primarydataset for studies of the Earth's deep interior. This dataset sheds light on many aspects of the structuresand dynamics of the lowermost mantle and the inner core, such as topography of the core boundaries, or
anisotropy of the inner core. Yet, the spatial coverage of these deep parts of the Earth is still far fromperfect. For example, the sampling of the inner core by ray paths nearly parallel to the Earth's rotation axis
(polar paths) is inherently limited due to the predominant concentration of major earthquakes at tectonic
margins.
Here we focus on exploring the use of core-sensitive phases that are not widely detectable due to highnoise level. Our initial approach is to utilize the array datasets collected across Australia, including threerecently deployed spiral-arm seismic arrays: SQspa (in Southern Queensland), WAspa (in Western
Australia), and PSAR (in Pilbara Craton, Western Australia) and the L-shape Warramunga Array (in Central
Australia). The arrays are at the epicentral distance range of approx. 20-50 degrees to the majority ofsignificant earthquakes from Southern Pacific subduction zones. We target the compressional waves that
get reflected or refracted from the Earth's internal boundaries. We deploy numerical modeling with spectral
element methods and array methods to verify the observations. We also test the feasibility of the seismic
interferometry principles on the array data by generating virtual ray paths probing the inner core indifferent directions.

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*S19-1-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

A Window into Giant Planet Structure using Saturn's Natural Seismograph* Christopher Mankovich 1) , Mark Marley 2) , Jonathan Fortney 1) , Neil Murphy 3)
University of California Santa Cruz, Santa Cruz, United States 1) , NASA Ames Research Center, Moffett
Field, United States 2) , NASA Jet Propulsion Laboratory, Pasadena, United States 3)
Saturn's nonradial oscillations perturb the orbits of ring particles. Saturn's C ring is fortuitous in that it
spans several resonances with Saturn's fundamental acoustic modes, and its moderate optical depth allows
the characterization of wave features using stellar occultations. The growing set of C-ring waves withpattern frequencies and azimuthal order m measured by Cassini provide significant constraints on Saturn'sinternal structure, with the potential to resolve long-standing questions about the planet's distribution ofhelium and heavier elements, its means of internal energy transport, and its rotation state.
We construct Saturn evolutionary models and calculate their mode eigenfrequencies at the solar age,mapping the planet mode frequencies to resonant locations in the rings to compare with observed densityand bending waves. A new feature of the models is the immiscibility of neutral helium in the liquid metallic
hydrogen mantle, which leads to helium rain and the establishment of a deep stabilizing composition
gradient. Similar to the model of Fuller (2014), this stratified region provides a deep cavity wherein modes
close to Saturn's fundamental frequency can propagate as internal gravity waves, yielding modes that havean overall mixed character, as seen in pulsating red giant stars. The result is a more densely packed
spectrum of modes that can excite resonances in the C ring, helping to explain several of the observed
waves that a conventional homogeneous Saturn model--supporting only acoustic modes--cannot.
I'll assess the hypothesis that helium rain is the origin of Saturn's deep stable stratification, as well as therole of the possibly eroded core-mantle boundary. I'll touch on the related question of convective versus
double-diffusive heat transport through the stably stratified region. Finally, I'll give an update on an ongoing
campaign using Doppler imaging to search for Jovian oscillations from the 3m Shane telescope at Lick
Observatory.

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*S19-1-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Probing the interior of Jupiter toward unveiling its formation: A new attemptwith Jovian seismology* Masahiro Ikoma 1) , Bun'ei Sato 2) , Takashi Sekii 3) , Hidekazu Hanayama 4) , Shigeru Ida 2)
The University of Tokyo, Tokyo, Japan 1) , Tokyo Institute of Technology, Tokyo, Japan 2) , National
Astronomical Observatory of Japan, Tokyo, Japan 3) , Ishigakijima Astronomical Observatory, Okinawa,
Japan 4)
The formation of Jupiter remains less well understood. Planet formation theories suggest that heavy
element distribution in the Jupiter's deep interior, in particular, the size of the dense core, provides animportant clue to understanding. The conventional method based on the measured gravitational moments,
however, allows us to probe only shallow regions in the planetary interior. Also, the estimated core size issensitive to high-pressure equation of state of hydrogen and helium, which is still highly uncertain.
Obviously we need more direct constraints to the core size. As well known in the Earth science, the methodthat uses seismic waves is a powerful exploration method for planetary deep interior. Recently, we havelaunched a new project of network observation for detecting the free oscillation of Jupiter's surface, using
Doppler spectro-imagers installed in the 1-2m class telescopes in Okayama Observatory and Ishigaki
Observatory in Japan, Observatoire de Calren in France, and Apache Point Observatory in USA. In thispresentation we first summarize the unresolved issues regarding the interior and origin of Jupiter and, then,introduce the newly launched project for probing the deep interior of Jupiter, which is called JOVIAL.

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*S19-1-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Study of the Seismic Response of Dayside Non-LTE CO2 Emissions ofPlanets* Raphael F. Garcia 1) , Miguel Angel Lopez Valverde 7) , Sébastien Lebonnois 3) , Quentin Brissaud 1) , Attila
Komjathy 4) , James Cutts 4) , Philippe Lognonné 5) , Sébastien Lebonnois 8) , Quentin Brissaud 1) , Attila
Komjathy 9) , James Cutts 9) , Philippe Lognonné 10)
ISAE-SUPAERO, Toulouse, France 1) , Instituto de Astrofisica de Andalucia, Granada, Spain 2) , LMD, Paris,
France 3) , JPL, Pasadena, USA 4) , IPGP, University Denis Diderot, Paris, France 5) , Instituto de Astrofisica
de Andalucia, Granada, Spain 7) , LMD, Paris, France 8) , JPL, Pasadena, USA 9) , IPGP, University Denis
Diderot, Paris, France 10)
The dayside non-LTE emissions of CO2 molecules, at 4.3 micrometers wavelength, have been clearly
imaged by the VIRTIS instrument on board Venus Express (Peralta et al., 2016). The emissions present asmoothly varying pattern as a function of solar zenith and a peak of emission power in the 125-140 km
altitude depending on wavelength.
Previous observations also demonstrated sensitivity to perturbations induced by atmospheric gravity waves(Garcia et al., 2009). Due to the exponential amplification of low-frequency infrasonic waves, CO2 non-LTE
emissions in the upper atmosphere are expected to vary during the pass of infrasounds excited by seismic
surface waves. In this study, we present modeling results as a response of the emissions to groundvibrations-created seismic surface waves.
Modeling work is performed in two steps. First, the infrasonic waves generated by a seismic surface wave
train are propagated in the Venus atmosphere using realistic conditions including wind, attenuation, andsound velocity profiles, using outputs from a state-of-the-art Venus General Circulation Model (Gilli et al,2017). Subsequently, density, temperature and pressure perturbations are used as input to the CO2 nonLTE emission modeling software. The variations of the emissions are predicted for various observationgeometries and quake parameters. Detection limit is analyzed as a function of quake magnitude andepicentral distance to the source.
The modeling results obtained by this study directly apply to the VAMOS mission concept study currently
considering the sounding of Venus internal structure by imaging seismic/infrasonic waves throughvariations of airglow emissions. Applications to other terrestrial planets will also be discussed. Similarsystematic nadir observations on Mars may be possible soon with ACS/Exomars (Korablev et al, 2016).

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*S19-1-04
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Planetary Seismology Using Infrasound and Airglow Signatures on Venus* Attila Komjathy 1) , James Cutts 1) , Michael Pauken 1) , Sharon Kedar 1) , Suzanne Smrekar 1) , Jeff Hall 1) ,Alan Didion 1) , Balthasar Kenda 1) , Jennifer Jackson 2) , David Mimoun 3) , Raphael Garcia 3) , Philippe
Lognonne 4)
NASA Jet Propulsion Laboratory, Pasadena, CA, USA 1) , California Institute of Technology, Pasadena, CA,
USA 2) , ISAE, Toulouse, France 3) , IPGP, France 4)
The planetary evolution and structure of Venus remain uncertain more than half a century after the first
visit by a robotic spacecraft. To understand how Venus evolved it is necessary to detect the signs of seismic
activity. Due to the adverse surface conditions on Venus, with extremely high temperature and pressure, it
is infeasible to place seismometers on the surface for an extended period of time. Due to dynamic coupling
between the solid planet and the atmosphere, the waves generated by quakes propagate and can bedetected in the atmosphere itself.
JPL in collaboration with ISAE and Caltech Campus is in a process of developing an instrument to measureseismic activity on Venus by in-situ measurements of infrasonic waves in the atmosphere. The overall
objective of this research is to demonstrate the feasibility of sensitive barometers to detect infrasonicsignals from seismic and explosive activity on Venus from a balloon platform. The seismic signals are
known to couple about 60 times more efficiently into the atmosphere on Venus than on Earth, which mightallow the detection of small regional quakes (magnitude ~3). We will report results on the first flight
experiment that will focus on using the barometer instruments on a tethered helium-filled balloon. The
results of the experiments are intended to validate the two-barometer signal processing approach using awell-characterized point signal source.
In addition, we will present another mission concept VAMOS (Venus Airglow Measurement and Orbiter for
Seismicity) measuring atmospheric perturbations from an orbiting platform that could provide abreakthrough in detecting seismicity on Venus and in monitoring of seismic surface wave propagation. In
contrary to the in-situ balloon strategy, VAMOS will be based on remote airglow monitoring from orbit andmight allow to track the propagation of the surface waves and to determine group velocities providing key
constrains on crustal and upper mantle structures.

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*S19-1-05
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Seismic Exploration of Europa and Other Ocean Worlds* Steven Vance 1) , Sharon Kedar 1) , Sridhar Anandakrishnan 2) , Bruce Banderdt 1) , Bruce Bills 1) , Fabio
Cammarano 3) , Julie Castillo 1) , Hsin-Hua Huang 4) 5) , Jennifer Jackson 4) , Philippe Lognonne 6) , Ralph
Lorenz 7) , Mark Panning 8) , William Pike 9) , Simon Staehler 10) , Victor Tsai 4)
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, United States 1) ,Pennsylvania State University Main Campus, University Park, PA, United States 2) , U. Roma Tre, Rome,
Italy 3) , California Institute of Technology, Pasadena, CA, United States 4) , Institute of Earth Sciences,
Academia Sinica, Taipei, Taiwan 5) , Institut de Physique du Globe de Paris, Paris, France 6) , Johns Hopkins
University Applied Physics Laboratory, Laurel, MD, United States 7) , Univ of FL-Geological Sciences,Gainesville, FL, United States 8) , Imperial College London, London, SW7, United Kingdom 9) , Ludwig
Maximilians University of Munich, Germany 10)
Seismic investigations offer a view into the deep interiors of planetary bodies and thus into the processes
governing their habitability. The InSight mission and concepts for a Europa Lander and a Lunar
Geophysical Network present unique opportunities for seismology to play a critical role in constraining
interior structure and thermal state. In oceanic icy worlds, measuring the radial depths of compositional
interfaces using seismology in a broad frequency range can sharpen inferences of interior structures
deduced from gravity and magnetometry studies, such as those planned for NASA's proposed Europa
Mission and ESA's JUICE mission. Seismology may also provide information about fluid motions within or
beneath ice, which complements magnetic studies; and can record the dynamics of ice layers, which would
reveal mechanisms and spatiotemporal occurrence of crack formation and propagation. Investigating thesestructures and processes in the future calls for detailed modeling of seismic sources and signatures, inorder to develop the most suitable instrumentation.
We will present results of simulations of plausible seismic sources and wave-field propagation in Europa,
with extension to other oceanic icy worlds, building on prior studies. We will also consider additionalsources: gravitationally forced librations, which create volume-filling turbulent flow, a possible seismic
source similar to that seen from turbulent flow in terrestrial rivers; downflow of dense brines from chaosregions on Europa into its underlying ocean, which possibly resemble riverine flows and flows throughglacial channels and ocean acoustic signals that couple with the overlying ice to produce seismic waves, by
analogy with Earth's ocean-generated seismic hum.

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*S19-1-06
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Investigating the Interior of Icy Worlds with Short Aperture Seismic Arrays* Nicholas Schmerr
University of Maryland, College Park, USA
The interiors of the icy outer satellites are currently of great interest as they may support the largest volumeof habitable space within the Solar System. A key parameter of this habitability is the presence of liquidwater oceans or seas beneath the frozen surface, thus geophysical investigations of the interior are crucial
for understanding the structure, dynamics, and evolution of these liquid water reservoirs. Seismology willbe the preeminent tool for determining the thickness of ice shells, the depth of oceans, underlying silicate
bodies, and assessing Icy Worlds for habitability. Our present understanding of the seismic signals
produced by Icy Worlds is limited, with the level of seismic activity at the surfaces (and interiors) likely
driven by tidal processes. The harsh operating environments will limit mission observation times, making it
is essential that the seismic information returned from a surface mission be of high fidelity in resolving key
questions about the internal environment of an Icy World.
Such measurements can be provided by a short aperture seismic array. We define a short aperture array as
a deployment of multiple 3-component seismometers, with a separation between instruments of 1-10
meters. The instruments in the array must have a sampling rate and frequency range sensitivity capable ofdistinguishing between waves arriving at each station. We will present 3-D synthetic modeling and analog
field results that demonstrate sensing requirements and the primary advantages of such a seismic arrayover a single station, including the improved ability to resolve the location of the source through detectionof backazimuth and differential timing between stations, ambient noise techniques, as well as the ability to
improve the signal to noise ratio by additive methods such as stacking and velocity-slowness analysis. Our
results inform future missions to the surfaces of Europa, Enceladus, Titan, and other objects in the outer
Solar System.

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*S19-2-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Seismic velocity and crustal thickness inversions: Moon and Mars
* Melanie Drilleau 1) , Jean-Francois Blanchette-Guertin 1) , Taichi Kawamura 2) , Philippe Lognonne 1) ,Mark Wieczorek 1) 3)
Institut de Physique du Globe de Paris, Paris, France 1) , National Astronomical Observatory of Japan,
Iwate, Japan 2) , Laboratoire Lagrange, Observatoire de la Cote d'Azur, Nice, France 3)
We present results from new inversions of seismic data arrival times acquired by the Apollo active andpassive experiments. McMC inversions are used to constrain (i) 1-D lunar crustal and upper mantle
velocity models and (ii) 3-D lateral crustal thickness models under the Apollo stations and the impact sites.
A full 3-D model of the lunar crustal thickness is then obtained using the GRAIL gravimetric data. To avoid
the use of any seismic reference model, a Bayesian inversion technique is implemented. We obtain robust
probability density functions of interior structure parameters governed by uncertainties on the seismic data
arrival times. The parameters of the inversion include the seismic velocities of P and S waves as a functionof depth, the crustal thickness under each Apollo station and impact epicentre. The forward problem
consists in a ray tracing method enabling both the relocation of the natural impact epicenters, and thecomputation of time corrections associated to the surface topography and the crustal thickness variations
under the stations and impact sites. The results show geology-related differences between the different
sites, which are due to contrasts in megaregolith thickness and to shallow subsurface composition andstructure. However, we use the more precise LROC-located epicentral locations for the lunar modules andSaturn-IV upper stage artificial impacts, reducing some of the uncertainties observed in past studies. In theframework of the NASA InSight/SEIS mission to Mars, the method developed in this study will be used toconstrain the Martian crustal thickness as soon as the first data will be available. For Insight, impacts will
be located by MRO data differential analysis, which provide a known location enabling the direct inversionof all differential travel times with respect to P arrival time. Due to the high flexibility of the algorithm, theinterior model will be refined each time a new event will be detected.

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*S19-2-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Effects of lateral variations of Moon crustal thickness on lunar seismic wave
propagation: numerical study and comparing with the Apollo seismic data
* Yanbin Wang 1) , Fei Chen 1) , Xianghua Jiang 2)
Department of Geophysics, Peking University, Beijing, China 1) , China Earthquake Networks Center,
Beijing, China 2)
Most recent results derived from an analysis of lunar gravity data reveal drastic lateral variations of crustal
thickness around craters on the Moon. Compared with the crustal thickness of the earth, the lunar crustal
thickness has strong lateral variations, which can vary from as thin as almost zero kilometer to as thick as
more than 60 kilometers. However, effects of drastic variations of crustal thickness on lunar seismic wave
propagation are still not well understood.
In this study we investigate how the lateral variations of crustal thickness affect the propagation of lunar
seismic waves by numerical simulations and comparing with the Apollo seismic data. We apply a 2-D
staggered grid pseudospectral and finite difference hybrid method to perform numerical simulations oflunar seismic wave propagation in a laterally heterogeneous crustal Moon model. The relief of lunar crustand mantle interface is defined with different height, width and position. The effects of these factors on
lunar records are discussed and revealed, respectively. We then apply our method to several 2D crustal
profiles derived from the most recently published global lunar crustal model to model lunar seismic wave
propagation generated from both shallow and deep moonquakes, respective. Comparing between thesynthetic seismograms with the Apollo observations suggests the significant effects of drastic lateral crustal
thickness variation on lunar seismic wave propagation.

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*S19-2-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Scattering attenuation profile of the Moon : implications for shallow
moonquakes and the structure of the megaregolith* Kevin Gillet , Ludovic Margerin , Marie Calvet , Marc Monnereau
IRAP - University of Toulouse, Toulouse, France
We report measurements of the attenuation of short period seismic waves in the Moon based on thequantitative analysis of envelope records of lunar quakes. Our dataset consists of waveforms corresponding
to 62 events, including artificial and natural impacts, shallow and deep moonquakes, recorded by Apollo
missions 12 to 16. To quantify attenuation and distinguish between elastic and inelastic mechanisms, wemeasure the time of arrival of the maximum of energy tmax and the coda quality factor Qc. We employ
diffusion theory in spherical geometry to model the propagation of seismic energy in depth-dependent
scattering and absorbing media. To minimize the misfit between predicted and observed tmax for deep
moonquakes and impacts, we employ a genetic algorithm and explore a large number of attenuation
profiles quantified by the scattering quality factor Qsc or equivalently the wave diffusivity D, and theabsorption quality factor Qi. The profiles that best fit the data display very strong scattering attenuation(Qsc ≤ 10 ) or equivalently very low wave diffusivity (D ≈ 2 km2/s) in the first 10 km of the Moon. These
values correspond to the most heterogeneous regions on Earth, namely volcanic areas. Below this surficial
layer, the diffusivity rises very slowly up to a depth of approximately 80 km where Qsc and D exhibit an
abrupt increase of about one order of magnitude. Below 100 km depth, Qsc increases rapidly up to
approximately 2000 at a depth of about 150 km, similar to Earth's mantle values. By contrast, Qi ≈ 2400 on
the Moon, which is about one order of magnitude larger than on Earth. Our results suggest the existence ofan approximately 100-km thick megaregolith, much larger than what was previously thought. Using ourbest attenuation model, we invert for the depth of shallow moonquakes based on the observed variation oftmax with epicentral distance. On average, they are found to originate from a depth of about 50 ± 20 km.

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*S19-2-04
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Source Time Function and Source Parameters of Lunar Quakes and Impacts.
* Taichi Kawamura 1) , Philippe Lognonne 2)
National Astronomical Observatory of Japan, Iwate, Japan 1) , Institut de Physique du Globe de Paris, Paris,
France 2)
In this study, we present our result from the spectral analysis and source parameters of lunar quakes andimpacts. To improve the spectral analysis, we used both the Apollo long and short seismic data of Apollo.
We numericaly combined the two data stream to have a continuous spectrum that covers the both
frequency bands. This will enable us to have a broader frequency band than single long or short period
seismometer data. We take advantage of the broader frequency band to improve the estimation of spectralfeatures and corresponding source parameters. Here we focused on corner frequencies and DC values ofthe spectra, which are closely related to stress drops and seismic moments. We first discuss the differencein source time function of quakes and impacts where the former is expressed with a heaviside function andthe latter is expressed with a delta prime function. We will discuss how the difference is observed in theactual Apollo seismic data and compare the difference in the seismic signal. Then we will discuss thedifference in the scaling law between the corner frequencies and the DC values of spectra. We studied thedifference in the scaling low between 3 types of lunar seismic events, which are deep moonquake, shallow
moonquake and meteorite impact. We found that not only the scaling law for quakes and impacts differ butthat of shallow and deep moonquakes also differ. We conclude with the implication of the different scaling
law in comparison with terrestrial examples.

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*S19-2-05
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Updated travel time analysis of Apollo artificial impacts' seismic data withthe precise source locations identified by LRO* Keisuke Onodera 1) 2) , Satoshi Tanaka 2) , Taichi Kawamura 3) , Yoshiaki Ishihara 2)
SOKENDAI (The Graduate University for Advanced Studies) 1) , JAXA/ISAS(Japan Aerospace Exploration
Agency/Institute of Space and Astronautical Science) 2) , NAOJ(National Astronomical Observatory ofJapan) 3)
In the previous lunar seismic analyses, the artificial impacts were often used to constrain the lunar crustal
thickness. The S-IVB rocket stages were deliberately impacted on the lunar surface for seismic
investigation and the impact sites were obtained from radio contacts with the booster. Recently, the precise
source locations of the five S-IVB impacts were updated with Lunar Reconnaissance Orbiter(LRO) image
data. The updated locations resulted in change in the reference source locations for the travel time analysis
with these artificial impacts. The most significant change was in Apollo 16 S-IVB. Loss of radio contact
between the booster rocket stage left large uncertainties on the location of the impact. We found that
Apollo16 S-IVB impact site estimated in Apollo era was different from the precise one by about 30 km. In
this study, we re-analyzed artificial impacts' seismic data using the precise source locations to determine
more accurately the crustal thickness of the Moon. We will present the crustal thickness around the Apollo
landing site and discuss the effect of local structure that might affect the travel time analyses. We will also
discuss implications for future lunar seismic exploration for better understandings of lunar crustal
structure.

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*S19-2-06
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Technical Readiness of Japanese lunar penetrator and its application tosmall-class space program: APPROACH* Hiroaki Shiraishi 1) , Satoshi Tanaka 1) , Masahiko Hayakawa 1) , Masanobu Ozaki 1) , Takahide Mizuno 1) ,Ken Goto 1) , Kosei Ishimura 1) , Ryuhei Yamada 2) , Taichi Kawamura 3) , Yoshiaki Ishihara 1) , Kei Shirai 1) ,Hideki Murakami 4)
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency 1) , University of Aizu 2) ,National Astronomical Observatory of Japan 3) , Kochi University 4)
A hard landing probe “penetrator" has been thought to be a very useful tool for constitution of network
stations on the planetary surfaces and subsurface, because it provides light-weight and cost-effective
capabilities of deploying scientific instruments.
The Japanese LUNAR-A penetrator project was started in 1993 and we had been continuing thedevelopment of penetrator system and the related subsystem such as a de-orbit motor, attitude control unit
and tele-communication system for remote operation. Although the LUNAR-A project was officiallycancelled in 2007, we had made a completion of development in penetrator probe in 2010, with a great
deal of difficulties.
In these years, the follow-on mission to utilize the penetrator technology has been considered for theJapanese space program and/or within the framework of international collaborations. As the first attempt,
we propose a new mission named as APPROACH (Advanced Penetrator PRObe Applied for a Challenge of
Hard-landing) using a Japanese small launcher “Epsilon rocket". The APPROACH spacecraft will consistsof a spin-stabilized orbiter and the LUNAR-A like single probe or two miniaturized probes with a de-orbit
motor/attitude control system, and its total weight is assumed to be less than 300 kg excluding fuel, due tothe limited capability of the Epsilon rocket.
After insertion of lunar orbit, one or two penetrator modules will be separated from the spacecraft anddeployed on the lunar surface with an impact velocity of 300 m/sec or less. The probe(s) will penetrate into
the lunar regolith up to 2 or 3 meters, and collect seismic events and heat-flow data during one-year
operation at the maximum.
In this paper, we report the technical readiness of lunar penetrator and design details of APPROACH
spacecraft, and then, we describe the international collaboration on this mission (simultaneous monitoringof impact flashes by ground-based and/or space telescopes).

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*S19-3-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

The Seismic Exploration of Mars by the InSight Mission* W. Bruce Banerdt 1) , Philippe Lognonne 2) , Domenico Giardini 3) , W. Tom Pike 4) , SEIS Team 5)
JPL/Caltch, Pasadena, CA, USA 1) , IPGP, Paris, France 2) , ETH, Zurich, Switzerland 3) , Imperial College,
London, UK 4) , Various, Cities, International 5)
The InSight mission is planned for launch in May 2018 and landing on Mars about 6 months later. The
payload comprises a geophysical observatory, with a seismometer (SEIS), a heat flow experiment, ageodesy experiment, and a suite of environmental sensors measuring the magnetic field and atmospherictemperature, pressure and wind. SEIS is the primary instrument of the mission and consists of a 3-axis VeryBroad-Band (VBB) instrument and a 3-axis Short Period (SP) instrument mounted on a leveling system,
protected by a wind/thermal shield, and connected to the instrument electronics by a tether. The VBBs are
enclosed in an Evacuated Container (EC). A leak detected in the EC late in 2015 forced postponement of
the launch from 2016 to 2018, and the EC has been redesigned to prevent a recurrence.
Despite efforts with the Viking seismometers in 1976, SEIS is expected to provide the very first seismic
records of Mars. Thus achieving our science goals is very challenging due to the almost complete lack of
information on the seismic structure of Mars, as well as the levels of seismic activity and noise. In parallelto the instrument development by the SEIS technical team, SEIS science team efforts have concentrated on
three challenges: single-station seismic analysis methodology; pre-launch estimation of the seismic andstation-generated noise; and amplitude of seismic and gravity signals generated by both quakes and nonseismic sources (e.g., meteorite impacts, atmosphere, Phobos tide).
We present the status of the SEIS experiment as well as the expected performance of the seismic payload
following its characterization during the 2016-17 Flight Model delivery campaign. We then summarize andreview the most recent analyses predicting the seismic performance of the SEIS experiment in the Martianenvironment, and update estimates of seismic signals, noise ( including environmental decorrelation) andplanetary structure inversion perspectives.

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*S19-3-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

The InSight VBB seismometer: status and perspective for future missions* Tanguy Nebut 1) 2) 3) , Sebastien DeRaucourt 1) 3) , Philippe Lognonne 1) 3) , William Banerdt 4) , Glenn
Aveni 1) , Rob Calvet 4) , Pierre-Alain Dandonneau 1) 2) , Melanie Drilleau 1) 2) 3) , Taoufik Gabsi 1) 2) 3) ,Kenneth Hurst 4) , Benoit Lecomte 2) , Michel Parise 1) 2) 3) , Olivier Robert 1) 2) 3) , Sylvain Tillier 1) 2) 3) ,Gabriel Pont 5) , Nicolas Verdier 5) , Philippe Laudet 5) , Lucile Fayon 1) 6) , Hubert Halloin 6) , SEIS/VBB
Team 7)
Institut de Physique du Globe-Sorbonne Paris Cite, FRANCE 1) , Centre National de Recherche Scientifique,
FRANCE 2) , Universite Paris Diderot, Paris, FRANCE 3) , Jet Propulsion Laboratory, USA 4) , Centre
National d'Etudes Spatiales, FRANCE 5) , Astro Particule et Cosmologie, Paris, FRANCE 6) , http://seisinsight.eu 7)
SEIS is the primary payload of the NASA InSight mission due for launch on 5/2018. The instrument
includes notably a Very Broad Band (VBB) 3 axis seismometer developed by the IPGP under CNES funding
and subcontracted to EADS-SODERN for fabrication of the Flight Units.
Oblique VBB axis are inverted pendulum, with a 190 g mobile mass and natural frequency in the range of
0.4-0.5 Hz. A Displacement Capacitive Sensor detect the mobile mass movement with a resolution better
than 5 pm/Hz^(1/2) at 1 Hz and drives the Feedback electronics. A ‘Balance Mechanism' allows adjusting
very precisely pendulum balance position and correct leveling errors, gravity value uncertainty andinstrument ageing. A ‘Thermal Compensation Mechanism' allows minimizing VBB thermal sensitivity
passively with less than 10-5 m/s^2/K. Each axis power is smaller than 60mW and the performances
requirement is 10^(-9) m/s^2/Hz^(1/2) between 0.01Hz and 1 Hz. Space qualification benefited fromexpertise from several CNES, JPL and SODERN experts.
By mid-February 2017, six VBBs had successfully completed their ProtoFlight Test program and one
additional will be delivered before the end of the first 2017 trimester. These sensors will be integrated
either in the FM Sphere (SEIS-SPH) or in its spare.
Performances in accordance with noise models have been demonstrated with previous prototypes andadditional tests in 2017 will be made in BFO seismic observatory. The SEIS experiment will therefore
provide high-quality seismic signal acquisition and associated seismic information during one Martian year,
i.e. the nominal mission duration.
Future VBBs will be candidate for seismic missions requesting low noise sensors, such as those planed to
the Moon in the 2020-2030 decade. Expected performances for a Moon VBBs will be at least one order ofmagnitude better than Apollo, and even larger improvement can be envisaged with an optical version,presently in development through IPGP-APC partnershipPowered by TCPDF (www.tcpdf.org)

*S19-3-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

The SP Microseismometer for the InSight Mission to Mars
* W. T. Pike 1) , I.M. Standley 2) , S. B. Calcutt 3)
Electrical and Electronic Engineering, Imperial College London, London, UK 1) , Kinemetrics, Inc.
Pasadena, CA, USA 2) , Atmospheric, Oceanic & Planetary Physics, University of Oxford, Oxford, UK 3)
The InSight Mars 2018 mission is carrying a 0.3 ng/rtHz sensitivity silicon microseismometer. This
microseismometer provides a sensitivity and dynamic range comparable to significantly more massive
broadband terrestrial instruments in a robust, compact package.
The sensor is micromachined from single-crystal silicon by through-wafer deep reactive-ion etching to
produce a non-magnetic suspension and proof mass. It is robust to high shock (> 1000 g) and vibration (>30 grms). For qualification SP units have undergone the full thermal cycles of the InSight mission and has
been noise tested down to 208K and up to 330K, with no degradation in the performance in both cases.
The total mass for the three-axis SP delivery is 635 g while the power requirement is less than 400 mW.
The microseismometer has particular advantages for future planetary deployment. All three axes deliver full
performance over a tilt range of up to 1 m/s2 which allows for operation without levelling. With nomagnetic sensitivity and a temperature sensitivity below 2E-5 m/s2, there is no need for magnetic field
monitoring and the additional resources for thermal isolation are also much reduced.In terms of
performance the SP has fast initialisation, reaching a noise floor below 1 ng/ Hz in less than a minute froman untilted configuration. The noise floor is 0.3 ng/rtHz from 10 s to 10 Hz, with a long period noise below
10 ng/rtHz at 1000s. This allows tidal measurements as well as seismic monitoring for a number of
proposed planetary missions.

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*S19-3-04
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Conceptual Study of Small Active Seismic Exploration Package on Moonsand Small Bodies
Kazunori Ogawa 3) , * Taichi Kawamura 1) , Yoshiaki Ishihara 2) , Takeshi Tsuji 4) , Taizo Kobayashi 5) , Ryuhei
Yamada 6) , Akito Araya 7) , Satoshi Tanaka 2) , Nozomu Takeuchi 7)
National Astronomical Observatory of Japan, Iwate, Japan 1) , Institute of Space and Astronautical
Science/Japan Aerospace Exploration Agency, Kanagawa, Japan 2) , Kobe University, Hyogo, Japan 3) ,Kyushu University, Fukuoka, Japan 4) , University of Fukui, Fukui, Japan 5) , University of Aizu, Fukushima,
Japan 6) , Earthquake Research Institute, Tokyo, Japan 7)
Seismic exploration is a powerful tool to probe inner structure of planetary bodies. Developing a seismic
observation package that is compatible with small to middle size spacecraft will open a new window toinvestigate deep interior of planetary bodies including asteroids and small satellites such as Phobos. We
have been designing and developing a seismic observation package with 3 axes seismometers, active
seismic source and anchoring system. This was originally designed for Japanese Martian Moons
eXploration (MMX) Mission. We were not selected for the nominal payload but the selection process of
optional instruments is still ongoing. Here we will present the basic concept of our seismic observation
package and describe each subsystem. The seismic observation package consists of 3 components, aseismometer, an active seismic source, and an anchoring mechanism. The seismometer is based on a shortperiod sensor that was designed for Japanese Lunar A mission. In addition to the previous design, we aredeveloping a new feedback for higher sensitivity at lower frequencies. Current sensitivity of the SP
seismometer decrease below 1 Hz but with new feedback, the sensitivity stays high down to 0.1 Hz. The
active seismic source is designed so that we can control the generated waveform. This is a well-developed
method in terrestrial seismology known as ACROSS (Accurately Controlled Routinely Operated Signal
System). By controlling the waveform of the seismic source we can search for the reflected signal throughcross correlation method. The anchoring mechanism will be necessary especially on low gravity condition.
One of the major problems in planetary seismic observation is the coupling between the instruments andthe ground. This will be an important issue especially for active seismic source. We will describe results ofour conceptual study of the seismic observation package and discuss the possibilities of future space
missions.

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*S19-4-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

SEIS/INSIGHT: One year prior the Seismic Discovery of Mars.
* Philippe LOGNONNE 1) 2) , William. B. Banerdt 3) , Domenico Giardini 4) , William Tom Pike 5) , Sebastiende Raucourt 1) 2) , Jeff Umland 3) , Ken Hurst 3) , Peter Zweifel 4) , Simon Calcut 6) , Marco Bierwirth 7) , David
Mimoun 8) , Gabriel Pont 9) , Nicolas Verdier 9) , Tom Hofmann 3) , Don Banfield 10) , John Clinton 4) ,Veronique Dehant 11) , Matt Golombek 3) , Raphael Garcia 8) , Catherine Johnson 12) , SEIS Team 13)
Institut de Physique du Globe de Paris-Sorbonne Paris Cite, Paris, France 1) , Universite Paris Diderot,
Paris, France 2) , Jet Propulsion Laboratory, Pasadena, USA 3) , ETHZ, Zurich, Switzerland 4) , Imperial
College, London, United Kingdom 5) , Oxford University, Oxford, United Kingdom 6) , MPS, Gottingen,Germany 7) , ISAE, Toulouse, France 8) , CNES, Toulouse, France 9) , Cornell University, Ithaca, USA 10) ,ROB, Bruxelle, Belgium 11) , UBC, Vancouver, Canada 12) , ( http://www.seis-insight.eu) 13)
InSight is the next NASA Discovery mission planned for launch in 5/2018 for landing end of 11/2018. The
payload is a complete geophysical observatory, with a seismometer (SEIS), heat flux (HP3) and geodesy(RISE) experiments, a magnetometer (US) and the APSS suite of atmospheric sensors measuring wind
(TWINS, Spain), atmospheric temperature and pressure (US). SEIS is the primary instrument of the mission
with a 3-axis very-broad-band (VBB, F) and a 3-axis short period (SP, UK) instruments mounted on a
Leveling system (LVL, D) protected by a Wind and Thermal Shield (WTS, US) and connected by a Tether(US). The 3 axis VBBs are enclosed in a vacuum thermal enclosure (EC). A leak detected in the EC during
the final integration forced postponement of the launch from 2016 to 2018 and redesign of a new EC by
JPL.
SEIS will provide the very first seismic records of Mars. Science goals implementation is very challenging
due to the complete lack of information on the deep seismic interior structure of Mars, as well as seismic
activity and surface seismic noise. In parallel to the hardware technical developments made by the
hardware team, efforts of the SEIS science team were concentrated in three areas, associated with singlestation seismic analysis methodology, pre-launch estimation of the seismic and station-generated noise andamplitude of seismic and gravity signals generated not only by quakes but also by other non-seismic
sources (e.g. impacts, seismic waves generated by the atmosphere, or the Phobos tide).
We present the status of SEIS as well as the performances of the seismic payload, following its
characterization in the 2017 Flight Model delivery activities. We summarize and review the most recent
analysis made by the SEIS team predicting the seismic performances of the SEIS experiment in the Martianenvironment, including decorrelations performed by the APSS sensors, as well as estimates of seismic
signals, decorrelated noise and structure inversion.

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*S19-4-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Mars' core and what its seismological structure could reveal about theplanet's evolution* George Helffrich
Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
If the meteorite-based inferences of Mars' core composition are correct, it could show peculiar structuralfeatures compared to Earth's core. The liquidus diagram of iron at moderate pressures when enriched insulfur is unusual for a core sulfur content of 11-17 wt%. From a fairly detailed liquidus diagram constructedfrom experimental studies, I identify a set of processes that could act within Mars' core: an iron "snow" fromthe core-mantle boundary's surface and a Fe(3-x)S(2) "ground fog" forming at the base of the core.
Depending on temperature and bulk sulfur composition, these could form an inner core or could stratify
the outer core by enriching it in sulfur, or both. Core stratification could be one explanation for theextinction of Mars' magnetic field early in the planet's history; its feasibility will be discussed. The
crystallization processes in the core could be observable in the seismic data that the future Mars
geophysical mission, InSight, is planned to provide. The core size, the presence of an inner core, and thewavespeed profile of the outer core, whose radial derivative provides a proxy for changes in composition,
are key observables to seek.

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*S19-4-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Preparing for InSight: a Blind Test for Detection and Location of Martian
Seismicity* Domenico Giardini 1) , John Clinton 2) , Philippe Lognonne 3) , Bruce Banerdt 4) , Savas Ceylan 1) , Martin
van Driel 1) , Amir Khan 1) , Mark Panning 5) , Maren Boese 1) 2) , Raphael Garcia 6) , Melanie Drilleau 3) ,Davide Mimoun 6) , Naomi Mudoch 6) , B Kenda 3) , A Spiga 7) , Antoine Mocquet 8) , A Rivoldini 9) , O
Verhoeven 8) , the SEIS Team 10)
SEG, ETHZ, Switzerland 1) , SED, ETHZ, Switzerland 2) , IPGP, France 3) , JPL, USA 4) , U. Florida, USA 5) ,ISAE, France 6) , LMD, France 7) , U. Nantes, France 8) , ROB, Belgium 9) , http://seis-insight.eu 10)
The NASA mission InSight will deploy a lander equipped with geophysical and meteorological sensors on
the Martian surface at Elysium Planitia, including two 3-component ultra-sensitive seismometers, a verybroadband sensor and a short period sensor. InSight mission goals include (1) providing one-dimensionalmodels of Mars' mantle and core to within ±5% uncertainty, as well as three-dimensional velocity models of
the crust; and (2) measuring the activity and distribution of seismic events on Mars, including both quakes
and impacts. The InSight launch is targeted for May 2018, landing in November 2018, with nominal
deployment for 1 Martian year. InSight will return continuous data at 2 sps with the option of retrieving
specific data extracts at 20 sps.
In an effort to seek methodological advances and test current single-station location approaches, and also
to raise awareness and level of preparation within the scientific community for the data that will arrive from
Mars, the InSight team have designed a blind test where we provide a 12 month period of continuous
waveform data that simulates, to the best of our knowledge, data that we can expect to retrieve fromInSight. Synthetic seismograms from tectonic and impact events are combined with expected seismic
noise. We broadly invite all interested scientists to participate by analysing these Martian seismograms andproviding a Martian seismicity catalogue. The test is planned to begin on 1 June 2017, with the release of
the test dataset and all supplementary material, and will close 6 months later on 1 December 2017. This
presentation will summarise the scope of the blind test - including how we set up the synthetic dataset; how
the InSight teams will scan the data and identify and characterize seismicity; how we will evaluate different
catalogues; and of course we explain how scientists can contribute to the test.

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*S19-4-04
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Modeling the seismic signals generated by dust devils on Mars
* Balthasar Kenda 1) 2) , Philippe Lognonne 1) , Aymeric Spiga 3) , Taichi Kawamura 4) , Sharon Kedar 2) ,Bruce Banerdt 2) , Ralph Lorenz 5) , Don Banfield 6) , Matt Golombek 2)
Institut de Physique du Globe de Paris, Paris, France 1) , Jet Propulsion Laboratory, California Institute ofTechnology, Pasadena, USA 2) , Universite Pierre et Marie Curie, Paris, France 3) , National Astronomical
Observatory of Japan, Japan 4) , Johns Hopkins University Applied Physics Laboratory, Laurel, USA 5) ,Cornell University, Ithaca, USA 6)
The 2018 InSight mission to Mars will deploy the Seismic Experiment for Interior Structure (SEIS) at thesurface of the red planet. In addition to the signals generated by quakes and meteor impacts, the SEIS
seismometers will continuously measure the excitation produced by the atmosphere. Among the signals of
meteorological origin, dust devils and convective vortices are of special interest since they are localized,
frequent and ubiquitous on Mars and they have a characteristic seismic signature.
We modeled the long-period (T > 10 s) signals of dust devils based on Large-Eddy Simulations of the
daytime atmospheric dynamics at the InSight landing site and on the quasi-static response of the ground topressure loading. Results show that vortices with typical pressure drops of 1-3 Pa can generate tilt effects of
5-20 nm/s^2 over the weak regolith. These are well above the detection threshold, and the influence area
extends to a few hundreds of meters away from the vortex core. The catalog of episodes in the simulation isused to estimate the detection rate at a single station, which is expected to be as high as one episode per
Martian day. Different subsurface models were considered and the possibility of using pressure andseismic data to determine the compliance of the Martian regolith is discussed. In an analog terrestrial fieldstudy, dust devils also produced infrasounds and higher-frequency seismic waves interpreted as shallow
surface waves propagating in the subsurface. These additional signals contribute to better locate the vortex
and to estimate the seismic velocities of the Martian subsurface down to a few tens of meter depth.

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*S19-4-05
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Planned Products of the Mars Structure Service for the InSight Mission to
MarsMark P. Panning 1) , * Melanie Drilleau 2) , Philippe Lognonne 1) , W. Bruce Banerdt 3) , Raphael Garcia 4) ,Matthew Golombek 3) , Sharon Kedar 3) , Brigitte Knapmeyer-Endrun 5) , Antoine Mocquet 6) , Nick A.
Teanby 7) , Jeroen Tromp 8) , Renee Weber 9) , Eric Beucler 6) , Jean-Francois Blanchette-Guertin 1) , Ebru
Bozdag 10) , Tamara Gudkova 11) 12) , Stefanie Hempel 4) , Amir Khan 13) , Vedran Lekic 14) , Naomi Murdoch
4), and the Mars Structure Service team 15)
University of Florida, Gainesville, US 1) , Institut de Physique du Globe de Paris, Paris, France 2) , Jet
Propulsion Laboratory, Pasadena, US 3) , Institut Superieur de l'Aeronautique et de l'Espace, Toulouse,
France 4) , Max Planck Institute for Solar System Research, Gottingen, Germany 5) , Laboratoire dePlanetologie et de Geodynamique de Nantes, Nantes, France 6) , School of Earth Sciences, Bristol, UK 7) ,Princeton University, Princeton, US 8) , NASA Marshall Space Flight Center, Huntsville, US 9) , Geoazur,
Nice, France 10) , Schmidt Institute of Physics of the Earth, Moscow, Russia 11) , Moscow Institute of Physics
and Technology 12) , ETH Zurich, Zurich, Switzerland 13) , University of Maryland, College Park, US 14) , seisinsight.eu 15)
The InSight lander will deliver geophysical instruments to Mars in 2018, including collocated short-period
and very broad-band seismometers installed directly on the surface (Seismic Experiment for Interior
Structure, SEIS). Here we present the output and inversion results we expect from this mission. Routine
operations will be split into two services, the Mars Structure Service (MSS) and Marsquake Service (MQS),
which will be responsible, respectively, for defining the structure models and seismicity catalogs from themission. The MSS will deliver a series of products before the landing, during the operations, and finally to
the Planetary Data System (PDS) archive. Prior to the mission, we assembled a suite of a priori models ofMars, based on estimates of bulk composition and thermal profiles. Initial models during the mission will
rely on modeling surface waves and impact-generated body waves independent of prior knowledge ofstructure. Later modeling will include simultaneous inversion of seismic observations for source andstructural parameters. We use Bayesian inversion techniques to obtain robust probability distributionfunctions of interior structure parameters. Shallow structure will be characterized using the hammering of
the heat flow probe mole, as well as measurements of surface wave ellipticity. Crustal scale structure will be
constrained by measurements of receiver function and broadband Rayleigh wave ellipticity measurements.
Core interacting body wave phases should be observable above modeled martian noise levels, allowing us
to constrain deep structure. Normal modes of Mars should also be observable and can be used to estimate
the globally averaged 1D structure, while combination with results from the InSight radio science mission
and orbital observations will allow for constraint of deeper structure.

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*S19-4-06
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

The Marsquake Service: generating a seismicity catalogue for Mars
* John Clinton 1) , Savas Ceylan 2) , Maren Boese 2) 1) , Fabian Euchner 2) , Domenico Giardini 2) , Amir Khan
, Martin van Driel 2) , Raphael Garcia 3) , Philippe Lognonne 4) , Melanie Drilleau 4) , Mark Panning 5) ,Bruce Banerdt 6) , Eric Beucler 7) , Antoine Mocquet 7) , Taichi Kawamura 4) , J-F Blanchette-Guertin 4) , theSEIS Team 8)
Swiss Seismological Service, ETH Zurich, Switzerland 1) , SEG, ETH Zurich, Switzerland 2) , ISAE, Toulouse,
France 3) , IPGP, Paris, France 4) , U. Florida, USA 5) , JPL, USA 6) , U. Nantes, France 7) , http://seisinsight.eu 8)2)

The Marsquake Service (MQS) will be one of the ground segment services within the InSight mission toMars, which will deploy a single seismic station on Elysium Planitia in November 2018. The main tasks of
the MQS are identification and characterisation of seismicity, and managing the Martian seismic event
catalogue. In advance of the mission, the InSight team have developed a series of single-station event
location methods using i) multi-orbit surface waves, and ii) differential body and surface wave arrival times
relying on (initially a priori) 1D and 3D structural models (Panning et al., 2015; Bozdag et al, 2016, Boeseet al., 2017). These methods have been included in the operational MQS software framework. In
coordination with the Mars Structural Service (Panning et al, 2016) who will provide the Martian Structure
models catalogue, we expect to use iterative inversion techniques to revise these structural models andevent locations (Khan et al., 2016; Panning et al., 2016). In this presentation, we introduce the methods
and procedures that are being developed by the MQS in order to provide a seismicity catalogue using only
the single seismic station on Mars.

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*S19-P-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Seismic Wave Simulations on Mars : Comparisons between 1D interior
models and effect of 3D structures* Ebru Bozdag 1) 2) , Melanie Drilleau 3) , Philippe Lognonne 3) , Domenico Giardini 4) , Mark Panning 5) ,John Clinton 4) , Antoine Mocquet 6) , Raphael Garcia 7) , Rene Weber 8) , Jeroen Tromp 9) , Mark Wieczorek
10), Bruce Banerdt 11) , Youyi Ruan 9) , Nathan Metthez 4) , Amir Khan 4) , Kuangdai Leng 12) , Martin vanDriel 4) , Carene Larmat 13) , Savas Caylan 4) , Eric Beucler 6) , SEIS Science Team 14)
University of Nice Sophia Antipolis, Valbonne, France 1) , Colorado School of Mines, Golden, CO, USA 2) ,IPGP, Paris, France 3) , ETHZ, Zurich, Switzerland 4) , University of Florida, Florida, FL, USA 5) , Unversity of
Nantes, Nantes, France 6) , ISAE-Supaero, Toulouse, France 7) , NASA-MSFC, USA 8) , Princeton University,
Princeton, NJ, USA 9) , Observatoire de la Cote d'Azur, Nice, France 10) , JPL-Caltech, USA 11) , Oxford
University, Oxford, UK 12) , Los Alamos National Lab., NM, USA 13) , http://seis-insight.eu/ 14)
As part of the Mars InSight mission, we explore the effects of 1D & 3D structural variations on seismic
waveforms using various seismic wave propagation codes. Our motivation is to characterize seismic signals
which we expect to receive from a single broad-band instrument onboard InSight.
Waveform modelling has been done by the team using different modelling techniques: modes summation,
direct solution, AxiSEM, SPECFEM3D_GLOBE & SES3D. Modes, direct solution and AxiSEM seismograms
have been benchmarked down to 2 s for spherically symmetric models whereas SPECFEM3D_GLOBE with
AxiSEM down to 10 s. In all experiments numerical differences are much smaller than the lowest seismic
noise expected for the mission. Similar benchmarks were also performed for travel times, group-velocity
dispersion and body-wave amplitude estimations.
We also performed 3D global and regional simulations with SPECFEM3D GLOBE and SES3D. For 3D
global simulations we superimposed 3D crustal thickness variations on top of 1D model of Sohl & Spohn(1997) capturing the distinct crustal dichotomy between Mars' northern and southern hemispheres, as wellas topography, ellipticity, gravity, and rotation. The global simulations indicate clear enhancement inseismic wave amplitudes travelling through the region of Tharsis Montes where the thickest crust is
located. 3D regional simulations based on 3D crustal models derived from surface composition, address theeffects of various distinct crustal features down to 2 s confirming the strong effects of crustal variations on
waveforms.
In order to compare the effect of the 1D structure on synthetics, we also compare teleseismic waveforms
computed for 14 different 1D models down to 5 s using normal modes summation which enable us tocompare and discuss the effects on waveforms of different crustal & mantle structure, and mantle
attenuation. Similar comparisons are then made on the travel time & group velocities and body waves
amplitudes.

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*S19-P-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S19. Plane
tary seismology

Estimation and detection of Mars' background free oscillations for InSIGHT
mission.
* Yasuhiro NISHIAKWA 1) 4) , Philippe Lognonne 1) , Taichi KAWAMURA 2) , Aymeric SPIGA 3) , Tanguy
BERTRAND 3) , Kei KURITA 4)
Institut de physique du globe de Paris. 1) , National Astronomical Observatory of Japan 2) , Laboratoire deMeterologie Dynamique (UPMC/CNRS) 3) , Earthquake Research Institute, The University of Tokyo 4)
Seismic observation is a powerful tool to investigate its internal structure. The excitations of the seismic
activities have been described and developed in many papers. One of the excitations is martian
atmosphere. The martian atmosphere varies day by day and time by time. The pressure perturbations andwind can be seismic excitations like on Earth. The continuous excitations be enables to excite Mars'
background free oscillations (MBFs). The MBFs have specific frequencies which are function of seismic
properties of internal structure of Mars. The MBFs observation enables us to estimate 1D internal structureof Mars. The excitations are distributed everywhere in the martian atmosphere. It is difficult to observe
whole martian climate. To solve the difficulty, we use General Circular Model (GCM). GCM can predict andreproduct long period global martian climate. The concept of the paper is to calculate MBFs using by
GCMs and describe possibility of the martian hum detection. By the calculations we got minimum
estimation of MBF amplitude. The amplitude is about nano gals and the martian hum can be observed by
SEIS seismometer.

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*S20-1-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S20. Earthand planetary space and remote sensing seismology; i.e., seismology without seismometersSurface waves magnitude estimation from ionospheric signature of Rayleighwaves measured by Doppler sounder and OTH radar* Giovanni Occhipinti 1) , Florent Aden-Antoniow 1) , Virgile Rakoto 1) , Aurelien Bablet 1) , Jean-Philippe
Molinie 2) , Thomas Farges 3) , Philippe Lognonné 1)
Institut de Physique du Globe de Paris, Paris, France 1) , Office National d'Etudes et Recherches
Aerospatiales, Palaiseau, France 2) , Commissariat Energie Atomique, Arpajon, France 3)
Surface waves emitted after large earthquakes are known to induce atmospheric infrasonic waves
detectable at ionospheric heights using a variety of techniques, such as HF Doppler, GPS, and recently overthe-horizon (OTH) radar. The HF Doppler and OTH radar are particularly sensitive to the ionosphericsignature of Rayleigh waves and are used here to show ionospheric perturbations consistent with the
propagation of Rayleigh waves related to 28 and 10 events, with a magnitude larger than 6.2, detected by
HF Doppler and OTH radar respectively. A transfert function is introduced to convert the ionosphericmeasurement into the correspondent ground displacement in order to compare it with classic
seismometers. The ground vertical displacement, measured at the ground by seismometers, and measured
at the ionospheric altitude by HF Doppler and OTH radar, is used here to compute surface wave
magnitude. The presented results are under review for publication and are joined with some preliminary
results of modeling of the Rayleigh wave signature in the ionosphere with the purpose of a full centroid
moment tensor (CMT) estimation. The new magnitude and CMT estimation proves that ionosphericobservations are useful seismological data to better cover the Earth and explore the seismology of otherplanets.

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*S20-1-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S20. Earthand planetary space and remote sensing seismology; i.e., seismology without seismometers

Ionospheric volcanology: GNSS-TEC observation & modeling of the 2015
Kuchinoerabujima eruption* Yuki Nakashima 1) , Kiwamu Nishida 2) , Yosuke Aoki 2) , Giovanni Occhipinti 3) , Kosuke Heki 1)
Hokkaido University, Sapporo, Japan 1) , The University of Tokyo, Tokyo, Japan 2) , Paris Diderot University,
Paris, France 3)
Efforts in last decade prove that ionosphere, mainly observed by GNSS measuring the total electron
content (TEC), is sensitive to geophysical phenomena as earthquakes, tsunamis, and, more recently,
volcanic explosions.
Kuchinoerabujima is a volcanic island located in ~200 km southwest of Kyushu, Japan. The volcano
erupted at 0:59 UT May 2015 (VEI 3).
We found a concentric acoustic wave following the eruption in GNSS-TEC time series. We used 1 Hz
GEONET (GSI) data for this analysis. The observed wave seems include high frequency (5–10 mHz) pulse
disappearing in the first ~300 km around the volcano and a monochromatic wave (~5 mHz) observable formore than ~20 min and reaching the distance of ~400 km. The traveltime indicates the wavefront is almost
spherical. We interpreted those signals as a combination of, first, the direct shock wave propagating within
the atmosphere/ionosphere and, second, the acoustic wave trapped in the lower atmosphere/ionosphereby the effect of the cut-off frequency change with the altitude.
Our observation are also supported by various ground observations: barometers (NIED; AIST),
microphones (NIED; JMA) and broadband seismometer (NIED). We detected ~1 hPa wide frequency range(2–70 mHz) air wave in near-field and ~15 mHz perturbation reflecting or refracting once or twice at ~100km from the volcano. The difference of frequency components derives from the instruments noise level ordispersion of the wave.
In order to validate our hypothesis we support and discuss our observations with the light of the modelingwith the main goal of constrain some physical parameters of interest in volcanology.
Acknowledgement: We thank AIST for barometric records by the integrated groundwater observation well
network for earthquake prediction of the Tonankai/Nankai earthquake. We also thanks IPGP, ERI and
Hokkaido Univ. exchange programs to make our collaboration possible.

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*S20-1-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S20. Earthand planetary space and remote sensing seismology; i.e., seismology without seismometers

Traveling Ionospheric Disturbance Triggered by Tsunami Observed by GPS
and Geostationary Satellites of BeiDou* Jann-Yenq, Tiger Liu 1) , Pei-Hsuan Lin 1) , Tso-Ren Wu 2) , Yu-Lin Tsai 2) , Ho-Fang Tsai 3) , Chien-Hung Lin
3), Chia-Hung Chen 3)
Institute of Space Science, National Central University, Taoyuan, Taiwan 1) , Graduate Institute ofHydrological and Oceanic Sciences, National Central University, Taoyuan, Taiwan 2) , Department of Earth
Science, National Cheng Kung University, Tainan, Taiwan 3)
An earthquake of magnitude 9.0 occurred near the east coast of Honshu (Tohoku area) generates a servetsunami and disturbed the total electron content (TEC) within the ionosphere, which is called the tsunamitraveling ionospheric disturbances (TTIDs). Measurements of ground-based GPS receivers in Japan and
Hawaii are employed to study TTIDs in the Pacific Ocean area. It is found that the TTID periods are ofabout 10-20 minutes. In the Japan region, the TTIDs initially lags tsunami wave by about 9.6 minutes,
which is comparable to the estimated upward propagating time of acoustic gravity waves in theatmosphere, while in the Hawaii region, the TTID leads the underneath tsunami waves by about 1 hour,which might result from the oblique propagation of traveling atmospheric disturbances induced by tsunami
waves. Finally, an observation network of ground-based receivers receiving signals from geostationary
satellites of the BeiDou system is proposed to monitor TTIDs in the Asian area.

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*S20-1-04
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S20. Earthand planetary space and remote sensing seismology; i.e., seismology without seismometers

Inversion of the GPS -TEC induced by tsunami in order to estimate the sea
level anomaly using a the normal mode modeling.
* Virgile Rakoto 1) , Philippe Lognonne 1) , Lucie Rolland 2)
Institut de physique du globe de Paris, Paris, France 1) , Universite Cote d Azur, OCA, CNRS, IRD, Geoazur,
Valbonne, France 2)
Large underwater earthquakes (Mw > 7) can transmit part of their energy to the surrounding ocean throughlarge sea-floor motions, generating tsunamis that propagate over long distances. The forcing effect oftsunami waves on the atmosphere generate internal gravity waves. When they reach the upper atmosphere
THIS produce ionospheric perturbations . Theses perturbations are frequently observed in the total
electron content (TEC) measured by the multi-frequency Global navigation Satellite systems (GNSS) data
(e.g., GPS,GLONASS and the future GALILEO. In this paper, we performed for the first time an inversion of
the sea level variation using the GPS TEC data using a least square inversion (LSQ) through a normal
modes summation modeling technique. Using the tsunami of the 2012 Haida Gwaii in far field as a test
case, we showed that the amplitude peak to peak of the sea level variation inverted using this method canbe compared with less than 10 % error to the one measured by a dart buoy. Nevertheless, we cannot yet at
this time invert the second wave arriving 20 minutes later. This second wave is indeed generaly explain by
the coastal reflection which SPHERICAL normal modeling does not take into account. Our technique isthen applied to two other tsunamis : the 2006 Kuril Islands tsunami in far field, and the 2011 Tohoku
tsunami in closer field. This demonstrates that the inversion using a normal mode approach is able toestimate fairly well the amplitude and waveform first arrivals of the tsunami waveform.

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*S20-1-05
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S20. Earthand planetary space and remote sensing seismology; i.e., seismology without seismometersModeling Earthquake-Induced Travelling Ionospheric Disturbances* Xing Meng , Attila Komjathy , Olga Verkhoglyadova , Anthony Mannucci
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
In this research, we apply the three-dimensional, time-dependent, and physics-based model WP-GITM(Wave Perturbation – Global Ionosphere-Thermosphere Model) to simulate earthquake-ionosphere
coupling via acoustic-gravity waves (AGWs). WP-GITM consists of an analytical model that solves for theneutral atmospheric perturbation at 100 km altitude due to AGWs generated from a ground source, as well
as a fully physics-based model that provides corresponding ionospheric and thermospheric perturbations.
We utilize available seismometer data and explore AGW source representations for two major earthquakes.
Our simulated ionospheric total electron content (TEC) disturbances are validated against Global
Positioning System ionospheric observations. It is expected that we gain more insights into the earthquakeionosphere coupling process using our advanced modeling capabilities and observational data.

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*S20-1-06
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S20. Earthand planetary space and remote sensing seismology; i.e., seismology without seismometers

Exploring the Use of Airglow Measurements for Detecting Seismicity on
Venus* Balthasar Kenda 1) 2) , Philippe Lognonne 1) , Attila Komjathy 2) , Bruce Banerdt 2) , Jim Cutts 2) , Lauriane
Soret 3) , Jennifer Jackson 4)
Institut de Physique du Globe de Paris, Paris, France 1) , Jet Propulsion Laboratory, California Institute ofTechnology, Pasadena, USA 2) , Universite de Liege, Liege, Belgium 3) , California Institute of Technology,
Pasadena, USA 4)
Investigating seismology on Venus is expected to greatly improve our knowledge of the internal structure
and present-day activity of the planet: these are indeed poorly constrained by observations. However,classical seismology is currently unattainable due the extreme surface temperatures and high atmosphericpressure. Nonetheless, the thick and dense atmosphere is strongly coupled to the ground and therefore
Venus is an excellent candidate for atmospheric remote-sensing seismology.
The nightside of Venus is characterized by a bright airglow layer of atomic oxygen at 90-120 km altitude
and we explore the possibility of detecting fluctuations in the airglow intensity induced by quakes. On
Earth, airglow response to tsunamis has been measured both with ground-based (Makela et al., 2011) andsatellite (Yang et al., 2017) techniques. Here, we computed seismograms inside the airglow layer using
normal-mode summation for a fully coupled atmosphere-solid planet system (Lognonne et al., 2016). The
corresponding variations in the volumetric emission rate are calculated for a realistic background model(Soret et al., 2012) and vertically integrated to reproduce the signals that would be seen from orbit. The
noise level of existing airglow cameras suggests that the fluctuations coupled to Rayleigh waves generated
by quakes of magnitude 5 and above occurring on the nightside of the planet may be detectable up to
about 60 degrees in epicentral distance. A major advantage of this technique is that a single orbiting
camera may be sufficient to serve the role of a seismic network. Identification and tracking of the waves
will indeed lead to source localization, magnitude estimation and measurement of Rayleigh-wave velocity.
In particular, it is expected that this would significantly constrain seismicity on Venus and, throughRayleigh-wave dispersion, the structure of the crust and upper mantle.

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*S20-P-01
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S20. Earthand planetary space and remote sensing seismology; i.e., seismology without seismometers

Atmospheric interior resonances : theory and observation on Earth andcomparative analysis for terrestrial planets with atmosphere* Philippe Lognonne 1) 2) , Virgile Rakoto 1) 2) , Foivos Karakostas 1) 2) , Lucile Rolland 3) , Elvira Astafyeva 1) ,Balthasar Kenda 1) 2) 3) , Yasuhiro Nishikawa 1) 2)
Institut de Physique du Globe de Paris-Sorbonne Paris Cite, Paris, France 1) , Universite Paris Diderot,
Paris, France 2) , GeoAzur, Observatoire de la Cote d'Azur, Valbonne, France 3) , Jet Propulsion Laboratory,
Pasadena, USA 4)
Resonance effects occur with the atmosphere when the dispersion curves of the Earth interior normal
modes cross or are close from atmospheric dispersion curves. On Earth, this occurs for example between
the Rayleigh surface waves branch and the acoustic branches and between the tsunami branch and theatmospheric gravity branches.
These resonances are not always retrieved in the atmospheric signals, as the later depend not only on the
coupling with the atmosphere as a whole, but also on the location of the sensor (for in situ observation) orof the sounding zone (for remote sensing observation). We illustrate this altitude effects with boththeoretical examples and observations, noting that ionospheric observation, because of their altitude, aremostly sensitive to the resonances associated no non atmospheric trapped resonances. Observations
shown are either related to Rayleigh waves (with Doppler and GPS sounders) or to tsunamis (mostly with
GPS-TEC). We also discuss how the strength of these resonances changes with Local Time, as well as withother changes in the atmospheric structure.
We then conclude by a comparative analysis of the resonances effects on other terrestrial planets, focusing
on Venus, Mars and Titan, and discuss the expected impacts of these resonances for future atmosphericionospheric seismic observation on these bodies. We especially discuss the impact of the coupling on
Venus, which is strong enough to modify significantly the attenuation factors and group velocity of Rayleighwaves in contrary to the Earth case, where such perturbations remain small for both Rayleigh andTsunamis.

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*S20-P-02
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S20. Earthand planetary space and remote sensing seismology; i.e., seismology without seismometers

Recording TEC profiles from aircrafts for tsunami early warning* Melanie Drilleau 1) , Pierdavide Coisson 1) , Lucie Rolland 2) , Philippe Lognonne 1) , Halflidi Jonsson 3) ,Virgile Rakoto 1) , Khaled Khelfi 1) , Giovanni Occhipinti 1)
Institut de Physique du Globe de Paris, Paris, France 1) , Geoazur, Nice, France 2) , Graduate School ofEngineering and Applied Sciences & Center for Interdisciplinary Remotely Piloted Aircraft Studies,
Monterey, CA, USA. 3)
Up to now, the best system to detect a tsunami in open ocean is the DART network of ocean-bottompressure sensors. While the DART system has contributed significantly to tsunami early-warnings during
recent events, the network suffers from an inadequate distribution of sensors and from serious
maintenance problems. To increase the efficiency of the warning system, we developed a software toestimate the flight route of aircrafts for an optimized data acquisition of the Total Electron Content (TEC)
using their onboard GPS receiver. The fundamental goal is to then invert these data to estimate theminimum tsunami height. This software has been developed in the framework of the TWIST project(Tsunami Warning and Ionosphere Seismic Tomography), funded by the Office of Naval Research of the US
Navy. It estimates the most suitable take-off time(s) for the aircraft to record TEC data. After the calculationof the tsunami travel times, a flight route is estimated for a given take-off time. Knowing the location of thesatellites, the locations of the Ionospheric Pierce Points are determined. Then, the simulated TEC values
are assigned to these locations, using a modified version of the NeQuick electron density model (Nava etal., 2008). Finally, the quality of the data recorded during the flight route is assessed. The criterion isdefined in order to favor (1) the flight routes with a maximum number of satellites in visibility by theaircraft and (2) the flight routes with a maximum of complete data during the recording time for a given
satellite. This processing is made for different take-off times to choose which time interval is the mostappropriate for the recording of TEC data. We are working with the CIRPAS (Center for Interdisciplinary
Remotly-Piloted Aircraft Studies) in Monterey, California, to realize TEC measurements using Twin Otter
aircrafts. We hope that our collaboration will make possible a first flight in the following month.

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*S20-P-03
IASPEI Symposium / IASPEI05. Earth Structure and Geodynamics / S20. Earthand planetary space and remote sensing seismology; i.e., seismology without seismometers

Signals in the ionosphere generated by tsunami earthquakes: observations
and modeling support* Lucie Rolland 1) , Carene Larmat 1) , Anthony Sladen 1) , Marcel Rémillieux 2) , Khaled Khelfi 3) , Elvira
Astafyeva 3) , Lognonné Philippe 3)
Observatoire de la Cote d'Azur, Geoazur 1) , Los Alamos National Laboratory 2) , Institut de Physique duGlobe de Paris 3)
Forecasting systems failed to predict the magnitude of the 2011 great tsunami in Japan due to the difficulty
and cost of instrumenting the ocean with high-quality and dense networks. Melgar et al. (2013) show thatusing all of the conventional data (inland seismic, geodetic, and tsunami gauges) with the best inversion
method still fails to predict the correct height of the tsunami before it breaks onto a coast near the
epicenter (< 500 km). On the other hand, in the last decade, scientists have gathered convincing evidenceof transient signals in the ionosphere Total Electron Content (TEC) observations that are associated toopen ocean tsunami waves. Even though typical tsunami waves are only a few centimeters high, they are
powerful enough to create atmospheric vibrations extending all the way to the ionosphere, 300 kilometers
up in the atmosphere. Therefore, we are proposing to incorporate the ionospheric signals into tsunami
early-warning systems.
We anticipate that the method could be decisive for mitigating “tsunami earthquakes" which trigger
tsunamis larger than expected from their short-period magnitude. These events are challenging tocharacterize as they rupture the near-trench subduction interface, in a distant region less constrained byonshore data. As a couple of devastating tsunami earthquakes happens per decade, they represent a real
threat for onshore populations and a challenge for tsunami early-warning systems. We will present the TEC
observations of the recent Java 2006 and Mentawai 2010 tsunami earthquakes and base our analysis on
the simulation code SPECFEM3D (Komatitsch & Vilotte, 1996), which solves the wave equation in coupledacoustic (ocean, atmosphere) and elastic (solid earth) domains. Rupture histories are entered as finite
source models, which will allow us to evaluate the effect of a relatively slow rupture on the surrounding
ocean and atmosphere.

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*S21-1-01
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Imaging lithospheric seismic discontinuities beneath Cascadia using S-to-P
receiver functions* Catherine Rychert , Nicholas Harmon , Saikiran Tharimena , Saikiran Tharimena
National Oceanography Centre, University of Southampton, Southampton, United Kingdom
Strong, sharp seismic discontinuities in the 60 – 110 km depth range are now frequently imaged andsometimes related to the lithosphere-asthenosphere boundary. However, determining the exact relationshiphas proven challenging, and interpretations diverge particularly between the continents and the oceans.
Here we use S-to- P receiver functions recorded by the Cascadia Ocean Bottom Array and the western mostTransportable Array to image crust and upper mantle discontinuity structure beneath the Juan de Fuca andGorda Oceanic Plates and western North America. We handpick events from epicentral distances 55 – 80
degrees away, choosing 5021 waveforms of which 343 are from ocean bottom seismometers. We use an
extended time multi-taper technique to deconvolve the waveforms and migrate to depth in 3-D. We image apositive phase, or velocity increase with depth, that corresponds to an oceanic Moho at 6 – 7 km depth anda continental Moho at 33 – 37 km depth. We also image a negative discontinuity beneath the ocean platethat thickens with age from 25 – 45 km depth beneath the oceans in general agreement with expectations
from half-space cooling. Waveform and geodynamic modelling indicate that these are defined by melt. Thissuggests that melt exists at the base of the plate, defining it, and that melt is likely transported along thebase of the plate towards the mid-ocean ridge. In addition, we image a deeper discontinuity at 55 – 75 km
beneath the continental lithosphere also likely related to the lithosphere-asthenosphere boundary.

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*S21-1-02
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

The depth of the LAB across Cenozoic Europe from seismological studies* Ulrich Achauer , Michel Granet
IPGS-EOST, university of Strasbourg, Strasbourg, France
In this contribution we shall review the seismological experiments carried out over the last 3 decades
across the Cenozoic regions of Central and Western Europe. In particular we will focus on the studies
dedicated to ECRIS and the Variscan orogeny, the two most important tectonic features across these active
domains.
In order to be able to draw some conclusions on the geodynamic behaviour the complementary methods ofseismic tomography, receiver function and SKS-studies are used.
Since more than three decades, detailed seismic studies have been carried out across the Hercynian
massives (i.e. the Armorican Massif, the Massif Central, the Vosges-Black Forest mountains, the Eifel region
and the Bohemian Massif) and the adjacent graben systems of Cenozoic ages (Limagne graben, the Rhine
graben and the Eger graben). These studies suggest that while the depth of the Moho and crustal structures
across the grabens are only slightly thinner than the general crustal structure across central Europe, do theUpper mantle structures differ quite strongly. While the Massif Central and the Eifel region are underlain
by so-called “Baby plumes", shows the Bohemian Massif a rather broad uplift of the asthenosphere andthe southern Rhine graben – once thought as a “classical plume" – a rather negligible “plume" influence.
The lithosphere-asthenosphere boundary seems to be rather flat at around 100km depths with a narrow but
marked upwarping in some of the regions affected by tertiary volcanism, namely the Massif Central and the
Eifel area, where the heat influx and the regional stress pattern seem to be the crucial element.
We shall compare the different regions in the light of the different studies and their geodynamic context.

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*S21-1-03
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Imaging the lithosphere - top to bottom - of the Hikurangi plateau as it
subducts beneath North Island, New Zealand* Tim Stern 1) , Stuart Henrys 2) , Simon Lamb 1) , David Okaya 3) , Brook Tozer 4)
Victoria University of Wellington, Wellington, New Zealand 1) , GNS Science, Lower Hutt, New Zealand 2) ,University of Southern California, Los Angeles, USA 3) , University of Oxford, Oxford, UK 4)
We present the first images, from active seismic source profiling, for both top and bottom of an oceanic
plateau as it undergoes subduction. Active continental margins provide a useful platform from which to
conduct seismic experiments to image subducting oceanic lithosphere. This is especially so if the
subduction is at a low angle (5-20 degrees), as it is beneath North Island, New Zealand. Here we reportresults of the SAHKE experiment that was designed to image the locked section of the Hikurangi
subduction zone , just north of Wellington city. The on-land section of the SAHKE profile was ~ 90 km long,
along which 900 seismographs were distributed. 12 x 500 kg explosive charges were detonated in 50m
deep bore holes. Structure for the top of the plate, at a depth of 15-30 km beneath the land surface was well
imaged and features a suite of strong reflections that are interpreted to represent a ~ 5 km-thick sequenceof low–wave speed sediments/and or serpentinites. We also recorded the Moho reflection from thesubducted plate. The thickness of the oceanic crust is calculated to be 10.5 ± 1.5 km, which is about 50%
greater than regular oceanic crust. This is significantly less than the ~ 35 km thickness of oceanic crust
associated with the Ontong Java plateau, which the Hikurangi Plateau was once thought to be connectedto.
Coherent reflections within the 8-20 Hz band were recorded at 27-32 s two-way travel time, which turn out
to be from a double band of reflectors at depth of ~ 100 km that dip ~ 12 -15 degrees to the NW, parallel tothe top of the plate. We interpret these reflections as marking a ~ 10-km-thick channel of ponded melt thatdefines the base of the mechanical boundary layer for the ~ 74 km thick plate. This is consistent with the
LAB of a thin oceanic plateau, but a mid–lithospheric discontinuity from a thick, old, oceanic plate cannot
be ruled out.

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*S21-1-04
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Imaging the Pacific lithosphere discontinuities near 60 km depth using SS
precursors and constraints on defining mechanism* Nicholas Harmon , Catherine Rychert , Saikiran Tharimena
National Oceanography Centre, University of Southampton, Southampton, United Kingdom
Oceanic lithosphere provides an ideal location to decipher the nature of the lithosphere – asthenospheresystem which is vital to our understanding of plate tectonics. Although a thermally defined plate explains
many first order observations such as bathymetry and heat flow. Observations of sharp mantle
discontinuities are not well-understood. Here we use SS precursors to image the discontinuity structure
across the Pacific Ocean using 24 years of teleseismic data. We image a sharp velocity discontinuity (3 –15% drop over < 21 km) at 30 – 59 km that increases in depth with age from the ridge to at least 36 My
according to conductive cooling along the 1100 degree C isotherm. The discontinuity is imaged at a depthof 35 – 80 km for seafloor > 36 My. The shallow discontinuity at about 60 km is laterally continuous acrossmost of the Pacific. It has recently been suggested that discontinuities in this depth range may be explainedby an increase in radial anisotropy with depth. We evaluate the potential for an anisotropic variation to
explain the discontinuities. We test surface wave depth resolution of radial anisotropy and estimate theapparent isotropic seismic discontinuities that could be caused by a change in radial anisotropy scatteredwave imaging using synthetic seismograms. We find strong surface wave azimuthal anisotropy at 0 – 50 km
depth at an example case near the East Pacific Rise (EPR) implies a strong shallow radial anisotropy ifcaused by aligned olivine. An additional strong increase in anisotropic strength with depth from 50 – 100
km is not supported. We find that neither an increase in radial anisotropy with depth caused by aligned
olivine or frozen-in compositional layering can easily explain the observations from scattered waves.
Another mechanism such as melt or composition may be required. The strength and pervasiveness of theboundary suggests that it is likely related to the lithosphere – asthenosphere boundary.

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*S21-1-05
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Lithospheric heat production: calculating mantle heat flow from
asthenospheric shear velocity variations* Scott Wipperfurth 1) , Vedran Lekic 1) , William McDonough 1) 2)
University of Maryland, College Park, USA 1) , Tohoku University, Sendai, Japan 2)
Estimates of heat production in the continental crust are derived from a combination of petrological,
geochemical, and geophysical constraints, with some models predicting variability in the abundance anddistribution of the heat-producing elements (HPE: U, Th, K) in the lower and middle layers (fromcorrelation of SiO2 and VP), and constant HPE concentrations in the upper crustal layer. Geophysicalmodels (e.g., CRUST 1.0) define layer density, thickness, and VP variation on a 1x1 degree grid.
Geochemical and geophysical models are used to calculate the surface heat flow, assuming a Moho heat
flux, with up to 100% difference between observed and predicted surface heat flows. Inversion of crustal
heat production from surface heat flow gives non-unique solutions due to a poorly constrained Moho heat
flux. We explore how mantle heat flux variations calculated from seismic constraints affect the agreement
between observed surface heat flux and that predicted by models of continental crust.
Asthenosphere temperatures are derived from dVs/dT relationships, global Vs tomographic models, LAB
depth models, mantle potential temperature and adiabat. LAB temperature is given as the intersection of
the mantle adiabat with the LAB. Using this LAB temperature, mantle adiabat, and estimates of mantle
thermal conductivity, we calculate the LAB heat flux on a 1x1 degree grid. Subtracting the predicted subLAB heat flux from the observed surface heat flow for Archean and Proterozoic crust gives a heatproduction in each lithospheric column. We then calculate the heat production in the continental crust foreach column by removing heat production in the lithospheric mantle, as determined from a xenolithderived geotherm. We evaluate the implications for crustal heat production due to various model
parameters, including biases in the seismic LAB determinations, use of different tomographic models, andassumptions about mantle potential temperature and dVs/dT relationships.

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*S21-2-01
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structureContinental growth in eastern Australia: Insights from the mantle
lithosphere* Nicholas Rawlinson
University of Cambridge, Cambridge, UK
The Tasmanides of eastern Australia is a complex series of Palaeozoic to early Mesozoic orogens which isjuxtaposed against the eastern margin of the Precambrian shield region of central and western Australia.
The subduction-accretion process was accommodated by retreat of the proto-Pacific plate along the eastern
margin of Gondwana, which incorporated both Australia and Antarctica. A large region of the Tasmanides
and its transition to Precambrian terrane in the west has been gradually covered by a transportable seismicarray called WOMBAT, which has been in operation for the last two decades and has involved thedeployment of over 750 stations.
Here, the latest body wave tomography results for the upper mantle will be presented, which reveal anumber of distinctive features underlying the Palaeozoic terrane. The dominant long-wavelength signature
is a gradual decrease in (P-wave) velocity from near the Proterozoic-Palaeozoic transition zone to thecontinental margins in the south and east. However, a pronounced N-S oriented “fragment" of highvelocity mantle material, not present in lower resolution regional and global tomography models, is locatedsome 200-300 km inboard of the east coast, which acts to form a low velocity embayment beneath theLachlan Orogen, the southernmost fold belt of eastern mainland Australia. By using seismic wavespeed
variations to infer changes in lithospheric thickness, we find that the Lachlan Orogen is likely underlain bythin lithosphere, with the high velocity “fragment" to the east forming a salient of thick lithosphere that
attaches to the cratonic interior of Australia to the north. These results support the idea that the core of theLachlan Orogen is a large orocline that formed due to differential roll-back of the proto-Pacific margin ofeast Gondwana, which had the effect of introducing, via continental transform faulting, older and thicker
lithosphere from the north into a region dominated by accreted oceanic lithosphere.

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*S21-2-02
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Tearing of Indian mantle lithosphere from high-resolution seismic images:
Implications for lithosphere deformation coupling in southern Tibet
Jiangtao Li 1) , * Xiaodong Song 1) 2)
University of Illinois at Urbana-Champaign, Champaign, U.S.A 1) , Wuhan University, Wuhan, China 2)
What happens to the Indian mantle lithosphere (IML) during the Indian-Eurasian collision and what role it
has played on the plateau growth are fundamental questions that remain unanswered. Here, we show clear
images of the IML from high-resolution P and S tomography, which suggest that the subducted IML is torn
into at least 4 pieces with different angles and northern limits, shallower and further in the west and eastsides while steeper in the middle. Deep earthquakes in the lower crust and mantle are located almost
exclusively in the high-velocity (and presumably strong) part of the Indian lithosphere. The tearing of the
IML provides a unified mechanism for late Miocene and Quaternary rifting, current crustal deformation,and deep earthquakes in southern and central Tibetan Plateau and suggests that the deformation of thecrust and the mantle lithosphere is strongly coupled.

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*S21-2-03
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Mantle lithosphere edges of Baltic Shield and East European Craton
retrieved by seismic anisotropy* Jaroslava Plomerova , Helena Munzarova , Vladislav Babuska , Ludek Vecsey
Institute of Geophysics, Czech Academy of Sciences, Prague, Czech Republic
Several passive seismic experiments provided data for detailed studies of upper mantle anisotropy, namely
fabrics of the mantle lithosphere. Lateral variations of body-wave anisotropic parameters, retrieved fromteleseismic P-sphere patterns, shear-wave splitting and teleseismic tomography, detected domains ofmantle lithosphere with differently oriented fossil fabrics (Babuska and Plomerova, PEPI 2006) anddelimited their extent in the upper mantle. The south-western edge of the Baltic Shield, adjacent to theSorgenfrei—Tornquist Zone that separates the Precambrian and Phanerozoic parts of Europe, ischaracterised by a sharp change of both the lithosphere thickness and fabrics (Plomerova et al.,
Tectonophysics 2001). On the contrary, in the central part of the Trans-European Suture Zone, a broadtransition between the East European Craton and Phanerozoic Europe, no significant change in the mantle
lithosphere fabric has been detected across the Tornquist–Teisseyre Zone (Vecsey et al., SE 2014), butwestward lithosphere thinning. Results of body-wave tomography (Chyba et al., PEPI 2017) suggest
thrusting the Phanerozoic European lithosphere over the East European craton. Change of the lithosphere
thickness around the contact of the Proterozoic and Archean parts within the Baltic Shield is insignificant(Plomerova and Babuska, Lithos 2010) and the contact appears as a broad transition in the south-central
Fennoscandia, which can be modelled as an Archean wedge penetrating into the Proterozoic mantle(Vecsey et al., Tectonophysics 2007). This model is supported by xenolith ages (Peltonen and Brugmann,
Lithos 2006). Further to the north, the Archean-Proterozoic boundary follows the surface trace of the BalticBothnia Megashear Zone (Plomerova et al., SE 2011). Anisotropic tomography (Munzarova et al., underprep.) indicates a westward continuation of the cratonic lithosphere that retains its own fossil fabric.

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*S21-2-04
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Shear Wave Splitting and Upper Mantle Flow in Mexico* Raul W. Valenzuela 1) 2) 3) , Gerardo Leon Soto 4) 5) 6)
Instituto de Geofisica. Universidad Nacional Autonoma de Mexico 1) , Mexico City, Mexico 2) ,raul@geofisica.unam.mx 3) , Instituto de Investigaciones en Ciencias de la Tierra 4) , Universidad
Michoacana de San Nicolas de Hidalgo 5) , Morelia, Michoacan, Mexico 6)
The results of shear wave splitting studies of the upper mantle in Mexico are presented. Upon entering ananisotropic medium a shear wave becomes split, meaning that a fast and a slow wave are produced. Twoparameters are used to quantify anisotropy. These are the fast polarization direction and the delay time
between the fast and the slow wave. The covariance method of Silver and Chan [1991] was used. Data fromboth permanent and temporary networks were used. Measurements were made mostly from coretransmitted phases such as SKS, but also S waves from local intraslab events were used. A motivation forstudying seismic anisotropy is to determine the nature of upper mantle flow and its relationship to tectonic
processes. Mexico has many diverse tectonic environments, some of which are currently active, or wereformerly active, and have left their imprint on seismic anisotropy. This has resulted in a wide variety ofmechanisms for driving mantle flow. The following regions have been studied: the Middle America Trench,
the Baja California peninsula, the Western Mexican Basin and Range, northern and northeastern Mexico,and the Yucatan peninsula. Depending on the unique characteristics encountered within each region, someof the various explanations proposed for the anisotropy are (1) entrained subslab mantle flow, (2) corner
flow in the mantle wedge, (3) slab rollback, (4) mantle flow driven by the extinct Farallon slab, (5) vertical
upwelling at a former ridge, (6) early episodes of extension, (7) mantle flow around the edge of the North
American craton, and (8) absolute motion of the North American plate.

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*S21-2-05
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Numerical simulation of 3D mantle flow in the Aegean (Hellenic) and
Cyprus subduction systems linking to seismic anisotropy beneath theeastern Mediterranean and Anatolia* Judith Confal 1) , Manuele Faccenda 2) , Tuna Eken 1) , Tuncay Taymaz 1)
Istanbul Technical University, Istanbul, Turkey 1) , University of Padua, Italy 2)
Seismic anisotropy is a key parameter in understanding plate movements in relation to past/present
deformation styles, and is usually controlled by the mantle flow patterns as a consequence of dynamic
interactions between a relatively buoyant and dense subducting oceanic plate and the surrounding mantle.
This study examines the evolution of splitting parameters as one of the most well established measure ofseismic anisotropy and their source for the last 30Ma based on a 3D dynamic modeling performed for theeastern Mediterranean. Our model setting is chosen to be as similar to reality as possible as it consists ofan active and fast moving Anatolian micro-plate, slow moving African and Arabian plates and an oceanic
plate in between. The retreat of the slab in the Aegean, the alleged tear in the subducting slab close to the
Cyprian trench and the break off in the slab in Eastern Anatolia are considered in our modeling study inorder to see their influence on mantle flow and the splitting parameters. The synthetically calculated fastpolarization directions (FPDs) mostly showed a decent matching with those inferred from previous
seismological observations (SKS splitting measurements). Regions of similarities between FPDs measured
from synthetic and observed shear waves mostly indicate N-S to NE-SW orientations of fast shear waves,which are parallel to the extension and in general perpendicular to the trench. Pattern of FPDs seems to be
more complex near the trench. Our modeling results suggest that the development of tear in the Africanslab and the detachment of the Arabian plate appear to have a significant influence on the FPDs. The
mantle flow through the tear close to Cyprus and the break off in the east can be identified clearly, despite
their recent appearances. A circular pattern around the edges of the slab can be observed as well as
disruptions of the overall general fast polarization direction due to the flow through the tear in the slab.

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*S21-3-01
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Seismic anisotropy tomography of the Western Pacific subduction zones* Dapeng Zhao , Xin Liu , Wei Wei
Tohoku University, Sendai, Japan
We present 3-D images of azimuthal anisotropy tomography of the crust and upper mantle of the western
Pacific subduction zones, which are determined using a large number of high-quality P and S wave arrivaltime data of local earthquakes and teleseismic events recorded by the dense seismic networks in andaround the Japan Islands. A tomographic method for P-wave velocity azimuthal anisotropy is modified andextended to invert S-wave travel times for 3-D S-wave velocity azimuthal anisotropy. A joint inversion of the
P and S wave data is conducted to constrain the 3-D azimuthal anisotropy of the Japan subduction zone.
Main findings of this work are summarized as follows. (1) The high-velocity subducting Pacific andPhilippine Sea (PHS) slabs exhibit trench-parallel fast-velocity directions (FVDs), which may reflect frozenin lattice-preferred orientation of aligned anisotropic minerals formed at the mid-ocean ridge as well as
shape-preferred orientation such as normal faults produced at the outer-rise area near the trench axis. (2)Significant trench-normal FVDs are revealed in the mantle wedge, which reflects corner flow in the mantle
wedge due to the active subduction and dehydration of the oceanic plates. (3) Obvious toroidal FVDs andlow-velocity anomalies exist in and around a window (hole) in the aseismic PHS slab beneath Southwest
Japan, which may reflect a toroidal mantle flow pattern resulting from hot and wet mantle upwelling causedby the joint effects of deep dehydration of the Pacific slab and the convective circulation process in the
mantle wedge above the Pacific slab. (4) Significant low-velocity anomalies with trench-normal FVDs exist
in the mantle below the Pacific slab beneath Northeast Japan, which may reflect a subducting oceanic
asthenosphere affected by hot mantle upwelling from the deeper mantle.

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*S21-3-02
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Constraints on Anisotropic Velocity Structure of the Lithosphereasthenosphere System in the Central Pacific from the NoMelt OBS Array* Pei-Ying Lin 1) , James Gaherty 2) , Joshua Russell 2) , Ge Jin 2) , Shu-Huei Hung 3) , John Collins 4) , Daniel
Lizarralde 4) , Rob. Evans 4) , Greg Hirth 5)
Taiwan Ocean Research Institute, National Applied Research Laboratories, Kaohsiung, Taiwan 1) , LamontDoherty Earth Observatory of Columbia University, Palisades, New York, USA 2) , Department ofGeoscience, National Taiwan University, Taipei, Taiwan 3) , Department of Geology and Geophysics, Woods
Hole Oceanographic Institution, Woods Hole, Massachusetts, USA 4) , Geological Sciences Department,
Brown University, Providence, Rhode Island, USA 5)
Seismic anisotropy represents one of the primary mechanisms for probing deformation and melting
processes in the earth. Seismic models of oceanic upper mantle are conflicting regarding the relative
importance of these deformation processes: seafloor-spreading fabric is very strong just beneath the crustmantle boundary at relatively local scales, but at global and/or ocean-basin scales, oceanic lithosphere isfound to be weakly anisotropic when compared to the asthenosphere. There is little consensus on which ofthese factors are dominant, in part because observations of detailed lithosphere structure are limited. To
address this discrepancy, we conducted the NoMelt experiment on ~70 Ma Pacific lithosphere with the aimof constraining upper-mantle circulation and the evolution of the lithosphere-asthenosphere system. The
Rayleigh waves display strongest azimuthal anisotropy with within the high-velocity seismic lid, with fast
direction coincident with seafloor spreading. A minimum in the magnitude of azimuthal anisotropy occurs
within the middle of the seismic low-velocity zone. In no depth range does the fast direction correlate withthe apparent plate motion. High-frequency Love waves suggest positive radial anisotropy (Vsh > Vsv) andazimuthal anisotropy with a strong 4-theta azimuthal signal in the upper 50 km of the mantle. To further
evaluate the processes producing asthenospheric fabric, we measure teleseismic P- and S-wave multichannel delay times to constrain lateral velocity variations beneath the array.

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*S21-3-03
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Upper mantle structure beneath the Pacific Ocean revealed by land andseafloor broadband observations* Takehi Isse 1) , Hajime Shiobara 1) , Kazunori Yoshizawa 2) , Hitoshi Kawakatsu 1) , Hiroko Sugioka 3) , Aki
Ito 4) , Daisuke Suetsugu 4) , Hisashi Utada 1)
The University of Tokyo, Tokyo, Japan 1) , Hokkaido University, Sapporo, Japan 2) , Kobe University, Kobe,
Japan 3) , Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan 4)
Seismic tomography studies have revealed the structures and dynamics of the Earth's interior. However,spatial resolution of the oceanic region is worse compared to the continental region caused by sparse
distribution of the land seismic stations.
In last 20 years, our Japanese seafloor broadband observation groups have conducted several temporary
seafloor seismic array observations using broadband ocean-bottom seismographs (BBOBSs) in the Pacific
Ocean. Total number of BBOBSs we used is more than 100. U.S. groups have also conducted the seafloor
seismic array observations in the Pacific Ocean, and seismograms recorded by their BBOBSs are available
from IRIS data center.
These BBOBS data enable us to improve the spatial resolution of the Pacific region.
We analyze three-dimensional shear wave velocity structure in the upper mantle beneath the Pacific region
using land and seafloor seismic data by surface wave tomography method.
We have used a surface wave tomography technique in which multimode phase velocities of the surface
wave are measured and inverted for a 3-D shear wave velocity structure by incorporating the effects offinite frequency effect and ray bending.
Checkerboard resolution tests suggests that spatial resolution is about 1000 km in the eastern Pacific
Ocean but is about 600 km in the western Pacific Ocean.
Large scale heterogeneity of the upper mantle in our obtained model is consistent with previous
tomography models. Strong radial anisotropy can be seen in the central Pacific at depths of 100 - 200 km
and weak anisotropy can be seen around the subducting slab area.
In the western Pacific Ocean, fastest anomalies are not beneath the oldest seafloor region but beneathsoutheastward of the Shatsky rise.
Depths of negative peak of velocity gradient, which may be used as a proxy to the depth of lithosphereasthenosphere boundary, have an age-dependence in young seafloor but is about 80 km in old seafloor(older than 100Ma).

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*S21-3-04
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Shear-wave Splitting in the Crust and its Tectonic Implications* Yuan Gao , Yutao Shi , Qiong Wang
Institute of Earthquake Science, China Earthquake Administration
Shear-wave will split into two independent components with almost orthogonal polarizations, when it
propagates through anisotropic media. The polarization of fast shear wave (PFS) is parallel to the strike ofthe cracks, as well as the direction of maximum horizontal compressive stress. Therefore the polarization of
fast shear wave can be adopted to study stress in the crust. Stress can influence crack density and aspectratio of cracks in the crust. The time-delay of slow shear-wave suggests the anisotropic degree and stressstatus. However in many typical tectonic zones, the crustal anisotropy, especially the PFS, is strongly
changed by local tectonics, such as faults.
In North China zone, seismic anisotropy from shear-wave splitting in the crust show strong relationship tofaults. PFS on the fault is always parallel to the strike-slip faults. However in the zone away from faults, PFS
turns to parallel to direction of maximum horizontal compressive stress.
In northeastern margin zone of Tibetan Plateau, PFS suggests the influence both from stress field and fromstrike of tectonics/faults. However, in southeastern margin zone of Tibetan Plateau, PFS clearly indicatesconsistent to crustal deformation, as well as corresponding to GPS data. In both zones, seismic anisotropies
in the crust are quite different with those in the upper mantle.
In zone of typical thrust fault, Longmenshan faults, where Wenchuan 8.0 magnitude earthquake occurred in
2008, we found the crustal anisotropy almost is not changed by the thrust faults. PFS is only parallel todirection of maximum horizontal compressive stress. But it shows the influence from faults in the zone
away from pure thrust fault. The anisotropic pattern in the crust is different in the upper mantle.
In this study, we discuss shear-wave splitting of local seismic wave and analyze seismic anisotropy in thecrust and its tectonic implications. Furthermore we compare seismic anisotropy in the crust and in the
mantle.

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*S21-4-01
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Multi-scale Structure and Lithospheric Discontinuities* Brian Kennett
The Australian National University, Canberra, Australia
The continental lithosphere is heterogeneous on a wide variety of scales and apparent seismic
discontinuities arise from the interaction of the seismic wavefield with multiple-scale features. In
consequence the character of such discontinuities is frequency-dependent, and interpretation in terms of
simple structures can be misleading. Nevertheless it is possible to track discontinuities within thelithosphere across closely spaced stations exploiting P-wave reflectivity extracted from stacked
autocorrelograms at each receiver.
Although most inference of finer-scale structure is indirect, corroborative evidence comes from thegeochemistry of xenoliths across southeastern Australia. There is a close correspondence between changes
in chemistry and P-wave reflectivity in the neighbourhood of the xenoliths.

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*S21-4-02
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

On the feasibility and use of teleseismic P-wave coda autocorrelation formapping shallow seismic discontinuities* Thanh-Son Pham , Hrvoje Tkalcic
The Australian National University, Canberra, Australia
Seismic body waves from distant earthquakes which propagate near-vertically beneath recording stations,provide tools for imaging shallow Earth structures with high vertical resolution. The most commonly usedtechniques such as P- and S-wave receiver functions utilize conversion mode from P- to S-waves or viceversa to retrieve information on the gradients of elastic properties in the crust and upper mantle. Here wedemonstrate the feasibility and advantage of utilizing reflection signals through an improved method ofteleseismic P-wave coda autocorrelation. We recover clear reflections independently on vertical and radial
components, which provides complementary constraints on the subsurface structures. Field data fromdifferent geological settings: from ice-covered stations in Antarctica to bedrock stations on the Kaapvaal
craton in South Africa were analyzed. The results from analyses show the feasibility of the method to unveil
P- and S-wave reflection signals from shallow interfaces and the Moho discontinuity. The method holds thepotential to be applied globally to enhance crustal structure in various geological settings.

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*S21-4-03
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Estimating geophysical model uncertainties in testing procedures versus
geodetic data
* Riccardo Barzaghi 1) , Anna Maria Marotta 2)
DICA, Politecnico di Milano, Milano, Italy 1) , Dep. of Earth Sciences A. Desio, Universita' degli Studi diMilano, Milano, Italy 2)
Estimating geophysical model uncertainties is crucial in order to properly compare models prediction withgeodetic data. Usually, model uncertainties are disregarded and this leads to biased results. In this work, amethod for defining the uncertainty of a geophysical model is presented. The empirical covariances of themodel-derived quantities are estimated via a numerical procedure and fitted with proper covariancefunctions that are then used to compute the covariance matrix associated with the model predictions.
The proposed method has been tested in the Mediterranean area. The model's estimated tectonic strain
pattern due to the Africa-Eurasia convergence in the area that extends from the Calabrian Arc to the Alpine
domain is compared with that estimated from GPS velocities while taking into account both the model
uncertainty and the covariance of the GPS estimates.
By considering the estimated model covariance in the χ2 testing procedure lower test values closer tostatistical significance were obtained. Also, through these values a sharper identification of the best-fitting
geophysical models was made possible.

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*S21-4-04
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

The Mid-lithosphere discontinuity beneath North China Craton* Weijia Sun 1) , B. L. N. Kennett 2)
Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of
Sciences, Beijing 100029, China. 1) , Research School of Earth Sciences, Australian National University,
Canberra, ACT 2601, Australia. 2)
We image the mid-lithosphere discontinuity (MLD) beneath North China Craton (NCC) by a novel
approach — seismic daylight imaging (SDI), which analyzes P reflectivity extracted from stacked
autocorrelograms for teleseismic events recorded by several dense arrays. These linear arrays across NCC
have average station interval of about 10-15 km, and was deployed by Institute of Geology and Geophysics,
Chinese Academy of Sciences under North China Interior Structure Project (NCISP). With higher andbroader frequency band (0.5-4Hz) than used with receiver functions, the SDI approach reveals finer scale
components of multi-scale lithospheric heterogeneity beneath NCC, which underwent lithosphericdestruction in the eastern NCC and seemed to be stable in the western NCC, but with locally lithosphericmodification.

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*S21-4-05
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Integrating seismological and satellite gravity data for consistent 3D Earthmodels* Jorg Ebbing
Kiel University, Kiel, Germany
Satellite data are an ideal tool for global modelling due to their spatial and temporal resolution. For
example, the characteristics of satellite gravity gradients allow in combination with seismological models to
study the lithosphere in a consistent manner with great detail, which is one of the aims of the ESA STSE
“3D Earth".
In the integration of seismological models and satellite observation towards a consistent image of the crustand upper mantle in 3D certain challenges arise. For example, the consistency in resolution and accuracyof seismological and density models is often not provided. The spectral content of the models does notnecessarily agree and there is a need for establishing common frames for joint analysis.
We discuss the limitations and sensitivities of different geophysical methods in the context of their imaging
capability and in combination for forward and inverse modelling of the Earth's internal structure. Suchanalysis is the first step to assess the role and feedback of isostatic (lithospheric) and dynamic (deep Earth)effects in shaping the surface of the Earth.

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*S21-5-01
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Tectonic Implications of Lithospheric Attenuation Models* Michael Pasyanos , Rengin Gok , William Walter
Lawrence Livermore National Laboratory
The majority of studies of the earth's lithosphere have focused on travel times and velocity structure. Less
common, but perhaps more insightful, are analyses that center on its attenuation structure. For several
years, we have been developing attenuation models of the lithosphere in different parts of the world(Pasyanos et al. 2009ab; Pasyanos, 2013). We employ a multi-phase attenuation where the amplitudes ofregional phases Pn, Pg, Sn, and Lg are simultaneously inverted for Qp and Qs of the crust and upper
mantle. While this technique has been applied globally, we will mainly focus on the high-resolution models
in Eurasia and North America. The resulting models are sensitive to temperature variations and heat flowwhich is readily seen across the Trans-European Suture Zone and between regions east and west of the
Rocky Mountains in North America. Particularly interesting are areas where we see contrasts between Q in
the crust and upper mantle, like the Arabian Shield where we see a high Q cratonic crust overlying low Q
upper mantle from the Red Sea Rift. Besides tectonic interpretations, attenuation models are used in avariety of applications including accurate magnitude estimation, explosion monitoring (discrimination andyield), and for strong ground motion and seismic hazard.

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*S21-5-02
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Lithospheric structure beneath Thailand as revealed by seismologicalapproach and its future study with Thai Seismic ARray (TSAR)* Sutthipong Noisagool 1) 3) , Kiwamu Nishida 1) , Hitoshi Kawakatsu 1) , Songkhun Boonchaisuk 2) ,Weerachai Siripunvaraporn 3)
Earthquake Research Institute, The University of Tokyo, Japan 1) , Geoscience Program, Mahidol University,
Kanchanaburi Campus, Thailandd 2) , Department of Physics, Faculty of Science, Mahidol University,
Thailand 3)
Seismological methods have been applied to regional seismic data to study the crust and upper mantle
structure beneath Thailand. Receiver function and ambient noise tomography reveal the physicalcharacteristic of crust in each terrane. Crustal thickness beneath Thailand increase from west to east withthe average crustal thickness of 30.8 km for Sibumasu terrane (SBT), 33.1 km for Sukhothai Arc (SA), 36.2
km for Loei-Phetchabun Fold Belt (LPF) and 38.2 km for Indochina Terrane (IT). All terranes in Thailand
have Poisson's ratio (0.24-0.25) lower than the global average (0.27). This suggests that Thailand mightunderlie by relatively high-grade metamorphic rock and/or abundant in a felsic composition. Surface waves
group velocity tomography from ambient noise period 6-20 seconds show low velocities anomalies in IT
and SA. In opposite, ST and LPF have a high- group velocity. The similarity of SA and IT support thegeological hypothesis that SA was rift apart from IT during the subduction process, thus they have a similarcrustal characteristic. From teleseismic travel time anomalies, upper mantle velocity beneath Thailand canbe estimated to increase from west to east. The time-to-depth migration of receiver function data shows nosignificant variation in the mantle transition zone (MTZ) topography and thickness across Thailand. The
MTZ thickness is close to global average with values of 245-250 km. The variation of the mantle beneath
Thailand is then likely to be confined in only lithosphere but not an asthenosphere. However, it is difficult
to examine whether this feature is control by recent activity such India-Eurasia subduction slab or it iscontrolled by their own lithospheric origin. From the end of February 2017, forty broadband seismometersof Thai Seismic Array (TSAR) will be installed cover area of Thailand. The resolution analysis of surface
wave tomography and body wave tomography from this new array will be present.

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*S21-5-03
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Crustal anisotropy in different tectonic regimes inferred from the stacking ofradial and transverse receiver functions* Frederik Link , Georg Ruempker , Ayoub Kaviani
Goethe University Frankfurt, Frankfurt am Main, Germany
The H-κ-stacking algorithm of Zhu and Kanamori (2000) is a standard tool to infer the thickness of thecrust, H, and the average P to S-wave velocity ratio, κ. We extend their method to include anisotropic
properties of the crust such as the fast-axis orientation, φ, and the percentage of anisotropy, a (Kaviani &Ruempker, 2015). The inversion involves the computation of theoretical arrival times and amplitudes for up
to 20 converted phases instead of up to 5 phases in the isotropic case. These calculations are based on
solving the eigenvalue problem of the anisotropic system matrix defined by Woodhouse (1974).
In the stacking algorithm we sum the amplitudes of radial and transverse receiver functions, for all eventsat the computed anisotropic arrival times. The stacking is performed for simple crustal models and bysystematically varying the crustal parameters. The maximum of the stacking function is obtained for themodel that is characterized by the parameters (H,κ,φ,a) that best explain the observed receiver functions.
Application of the method to complex data sets requires additional steps to stabilize the inversion process.
For example, the uncertainty of the results is estimated statistically using a selective bootstrapping analysis
which only considers solutions that allow to minimize the energy on the transverse receiver-function
component when applying an inverse operator to remove the effect of the shear-wave splitting.
We apply the method to recently collected data from permanent seismic networks: (1) strong anisotropy inthe crust has been reported previously for seismic stations in Israel (Ruempker et al. 2003); (2) data fromthe permanent Swiss network will be analyzed as part of the ongoing AlpArray project; (3) anautomatization of this method for its application to large data sets is currently being addressed.
We discuss our results regarding the influence of different tectonic processes on the anisotropic properties
within the earth's crust.

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*S21-5-04
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Active magmatic underplating in an intraplate setting: combined seismic,
seismological, and isotope study in the western Eger Rift, Central Europe* Pavla Hrubcova 1) , Wolfram Geissler 2) , Karin Brauer 3) , Horst Kampf 4) , Vaclav Vavrycuk 1) , Cestmir
Tomek 5)
Institute of Geophysics, Academy of Sciences, Prague, Czech Republic 1) , Alfred Wegener Institute,
Helmholtz-Centre, Bremerhaven, Germany 2) , Helmholtz-Centre for Environmental Research, Halle,
Germany 3) , Helmholtz Centre Potsdam GFZ, Potsdam, Germany 4) , Earth Science Institute, Slovak
Academy of Sciences, Bratislava, Slovak Republic 5)
The Eger Rift is an active element of the European Cenozoic Rift System. It is associated with the intense
Cenozoic intraplate alkaline volcanism and system of sedimentary basins. The intracontinental Cheb Basinat its western part displays concurrent geodynamic activity with fluid emanations, persistent seismicity,
Cenozoic volcanism, and neotectonic crustal movements at the intersections of major intraplate faults. The
CO2-rich gases have increased helium isotope ratios evidencing their lithospheric mantle origin. Active andpassive seismic data show increased lower-crustal velocities, which points to the magmatic addition at thebase of the crust and to a concept of magmatic underplating. However, character of the seismic image
differs laterally, which enables to differentiate two types of the magmatic underplating related to its
different timing and tectonic setting. High-velocity lower crust with increase seismic reflectivity evidences
the first type of magmatic underplating related to Variscan or pre-Variscan age westward of the Eger Rift.
High-velocity reflection-free lower crust together with a strong reflector at its top at depths ~28-30 km forms
a lower-crustal magma body. Lateral extent of this body correlates with the distribution of mantle-derived
fluid emanations at the surface. Thus, seismic and seismological evidence of the crust/mantle Mohotransition supplemented by gas-geochemical investigation and xenolith studies from corresponding depths
indicate the second type of magmatic underplating of the Late Cenozoic to recent. Finally, different
behavior of fluids in the Cheb Basin with the highest isotope mantle fractions together with Quaternary
volcanism points to the ongoing magmatic activity within the broader Late Cenozoic magmatic body and its
reactivation in the last 0.3 Ma during Mid Pleistocene to Holocene.

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*S21-P-01
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Formation of the Earth's lithosphere - asthenosphere surface initialheterogeneities.
* Yurii Khachai 1) 1) 1) , Vsevolod Anfilogov 2) 2) 2) , Alexandr Antipin 3) 3) 3)
Institute of Geophysics UB RAS,Ekaterinburg,Russian Federation 1) , Institute of mineralogy UB
RAS,Miass,Russian Federation 2) , Institute of Geophysics UB RAS,Ekaterinburg,Russian Federation 3)
The present interface between lithosphere and asthenosphere has a relief surface, as it is indicated byseismic and electromagnetic survey. This relief was formed over a long geological history of the planet. To
understand the evolution of these structures it is needed the information about the initial state of thesystem, i.e., the state at the final stage of the Earth's formation. Here are presented the results of numericalmodeling of non-uniform temperature distribution inside the three-dimensional model of the growing Earthat its final stage of dynamical formation. Namely those are heat and matter heterogeneities as objects thatare recorded by the results of modern geophysical and geochemical studies. The simulation takes into
account the random distribution of the falling bodies and particles, which are falling from theprotoplanetary cloud. They are forming the initial distribution of temperature and composition
heterogeneities. The evolution of heterogeneities during time is traced by using the numerical solution ofboundary problem for a system of differential equations describing the change in mass of the growing
planet using Safronov equation, matter flow using Navier-Stokes equations, movement of phase boundaries
with use of Stefan problem. As it can be seen from the numerical results of the system solution, to the endof the planetary accumulation it is formed a relatively non-uniform thin crust and inside the upper mantlethe asthenosphere layer. In the mantle it is able to trace heterogeneous inclusions with sizes from the firstto a few hundred kilometers with a complex interface. The upper boundary of the crust has also acomplicated relief. The formed non-uniform thermal inclusions contribute to the formation of early bottom
and upper mantle plumes. The dynamics of these plumes provide special metallogeny of cratons, which is
no longer repeated in the geological history of the planet.
Those results are supported by the grant RFBR № 16-05-00540

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*S21-P-02
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Oceanic Lithosphere-Asthenosphere Boundary Estimated from Stress
Dependent Deformation after the 2012 Indian Ocean Earthquake* Cecep Pratama 1) , Takeo Ito 1) , Takao Tabei 2) , Ryohei Sasajima 1) , Putra Maulida 3) , Irwan Meilano 3) ,Joni Efendi 4)
Nagoya University, Nagoya, Japan 1) , Kochi University, Kochi, Japan 2) , Bandung Institute of Technology,
Bandung, Indonesia 3) , Geospatial Information Agency, Cibinong, Indonesia 4)
Plate tectonic constitutes of a strong lithosphere overlying weaker asthenosphere. Therefore, the structureof lithosphere-asthenosphere system is essential key element to understand evolution of the earth.
However, the boundary between oceanic lithosphere and asthenosphere under ocean are remaining poorly
understood. On April 2012, an exceptionally large earthquake release high stress beneath Indian Ocean (>17 MPa in average) during Mw8.6 mainshock and Mw8.2 largest aftershock. This high stress released inwider area of oceanic plate and reached more than 1 MPa in several hundreds depth km of mantle. The
2012 Indian Ocean earthquake, which occurred in the oceanic plate, provide strong constraint of oceanic
lithosphere-asthenosphere rheological structure beneath ocean. Here, we try to reveal rheological structure
including water content of hot asthenosphere and thickness of cold lithosphere. The boundary between
lithosphere and asthenosphere is assumed to be dry olivine in the lithosphere and wet olivine in theasthenosphere as suggested by Karato (2012). Therefore, we develop heterogeneous three-dimensional
spherical earth finite element models. The models produce spatial-temporal evolution of stress dependent
deformation after the 2012 Indian Ocean earthquake using power-law rheology based on a thermally
activated flow law obtained by rock experiments. We propose a systematic grid search to obtain trade off
between water content and thickness parameter by using Global Navigation Satellite System (GNSS) data
mainly in Sumatra and surrounding Indian Ocean region. In addition, we also investigate a possible stressdependent postseismic deformation mechanism due to the 2012 Indian Ocean earthquake between
viscoelastic relaxation, afterslip or multiple mechanisms.

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*S21-P-03
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Seismic constraints on thinning of continental lithosphere beneath the
Korean Peninsula: A possible link to oceanic slab subductions and mantle
transition zone heterogeneities* Seongryong Kim 1) , Benoit Tauzin 2) , Hrvoje Tkalcic 3) , Junkee Rhie 1)
Seoul National University, Seoul, Republic of Korea 1) , Universite de Lyon, Universite Lyon 1 and Ecole
Normale Superieure de Lyon, Villeur 2) , The Australian National University, Canberra, Australia 3)
High-resolution structures of the entire lithosphere and the upper part of asthenosphere are investigatedbeneath northeast Asia using independent seismic data and methods. First, three-dimensional shear-wave
velocity structures are estimated from transdimensional Bayesian inversions using ambient noise data.
Second, a stacking analysis of multi-mode receiver function waveforms are performed to detect spatial
variations of seismic interfaces, including Moho and lithosphere-asthenosphere boundary (LAB). The
imaged structures from two analyses are compared to confirm highly reliable features. We observe a
dipping trend of the LAB to the center of the southern Korean Peninsula (KP) from the continental margin.
In addition, more heterogeneous undulation of the lithosphere thickness is shown beneath the northern KP
and northeastern China, where rifted basins and intraplate volcanoes are located. We interpret theobservations as a thinning of the lithosphere by interactions with extended sub-lithospheric low velocity
structures from back-arc regions of Pacific and Philippine-Sea plate subductions (Kim et al., 2016). We
further explore a possible relationship of the lithospheric structure to newly observed heterogeneous
structures in the upper mantle transition zone (Tauzin et al., unpublished manuscript).

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*S21-P-04
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Lithospheric Density Structure of Northwest India* Niraj Kumar , Anand Prakash Singh , Virendra Mani Tiwari
National Geophysical Research Institute, Hyderabad, India
Northwest India is an amalgamation of diverse geological terranes, evolved during past geological periods.
In order to comprehend plausible geodynamic models, which can explain continental evolution in thenorthwest India deep lithosphere density structure of an area encompassing 200 to 300N latitude and 680
to 780E longitude is derived from the integrated modelling of gravity and geoid anomalies and topography
and heat flow data. The derived model is well constrained by available seismic Moho depth. Model showsthat the Moho depth varies from 34 to 38 km in Saurashtra and Kachchh region, which increases gradually
to about 42 km beneath the Jaisalmer region. The deepest Moho at about 50-53 km is found under the IndoGangatic plain. A uniform crustal thickness of 40-43 km is observed beneath the Bundelkhand craton. The
depth of lithosphere-asthenosphere boundary (LAB) is 110-125 km under Saurashtra and Kachchh regions
which remains same under Barmer basin. A moderate LAB under the Aravalli-Delhi fold belt is observed at
a depth of 120-140 km. The LAB depth increases up to 195 km below the Indo-Gangatic plain whereas in
Bundelkhand craton the LAB depth ranges from 130 to 155 km.

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*S21-P-05
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Azimuthal anisotropy in the Northwest Pacific oceanic lithosphere inferredfrom Po/So waves* Azusa Shito 1) , Daisuke Suetsugu 2) , Takashi Furumura 3)
Kyushu University, Fukuoka, Japan 1) , Japan Agency for Marine-Earth Science and Technology, Yokosuka,
Japan 2) , The University of Tokyo, Tokyo, Japan 3)
Po/So waves, which have a high frequency, large amplitude, and long duration, propagate for large
distances across oceanic lithosphere. These waves are generated by multiple forward scattering of P- and Swaves due to small-scale heterogeneities in oceanic lithosphere and P-waves trapped in seawater. To study
the origin of such small-scale heterogeneities, we analyzed the azimuthal anisotropy of Po/So waves
propagating.
Shito [2016, JPGU Abstract] examined the azimuthal anisotropy of Po/So wave propagation using seismic
waveform data recorded at Broad Band Ocean Bottom Seismometers (BBOBSs) in the Northwest Pacificfrom 2010 to 2014. They determined travel times of the Po/So waves using an auto-picking algorithm
based on an AR model, and estimated the average velocities of the Po/So waves between sources andstations. The average velocities of the Po/So waves traveling in the Northwest Pacific show clear variations
as a function of azimuth, as follows:
VPo = 8.25 + 0.20 cos2(x − 153),
VSo = 4.71 + 0.04 cos2(x − 159).
The magnitudes of the anisotropy for Po and So waves velocities are 2.4% and 0.8%, respectively, which aresmaller than the results of previous studies for Pn and Sn waves [Shimamura, 1984; Shinohara et al., 2008].
The fast direction is parallel to the past spreading direction of oceanic crust as estimated from magnetic
anomalies [Nakanishi et al., 1992], which is roughly consistent with the previous studies [Shimamura,
1984; Shinohara et al., 2008].
In this study, we conduct Finite Difference Method (FDM) simulation of seismic wave propagation. We
compare calculated and reported azimuthal anisotropy of the Po/So waves propagation and discuss themechanism, which should be relating to the generation and evolution of the oceanic lithosphere.

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*S21-P-06
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

The shear-wave splitting in the crust and the upper mantle around the Bohai
Sea, North China* Yutao SHIInstitute of Earthquake Science, China Earthquake Administration, Beijing, China
Bohai Sea area is a significant area with intense deformation in the eastern North China Craton, whereexperienced thermotectonic reactivation and destruction during the Late Mesozoic–Cenozoic. In order toinfer the distribution of local stress and the deep geodynamic process in North China, this study detects
first-order seismic anisotropy in the crust and upper mantle beneath Bohai Sea area. We collected local
earthquakes within ML4.0 around Bohai Sea area and teleseismic events with magnitude greater thanMs5.5 between August 2007 to July 2012 by shear-wave splitting system analysis method and the gridsearching method of the minimum tangent energy to measure the anisotropic parameter. The total 535
local shear-wave and 726 XKS splitting measurements were obtained from stations involving permanentregional seismograph networks and a temporary seismic network. The dominant orientation of local shearwave splitting in the curst is nearly East-West, which suggests the direction of local maximum compressive
stress around the Bohai Sea area. The nearly North-South orientation of polarization caused by structure
anisotropy was obtained at some stations, which located at the Tan-Lu fault belt and Zhang-Bo seismic belt.
The average polarization of XKS-splitting is 87.4o from north to east. The average time-delays of XKSsplitting range from 0.54 s to 1.92 s, it suggests possibly about 60 km to 210 km thickness of theanisotropic layer. The measured results indicate the upper mantle anisotropy beneath Bohai Sea area, eventhe eastern of North China, is mainly driven by asthenospheric mantle flow from the subduction of the
Pacific plate. From the complicated anisotropic characteristics in this study, we infer that there might bemultiply complex mechanism in the crust and upper mantle around the Bohai sea area.

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*S21-P-07
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Effects of random heterogeneity in the upper mantle on apparent radialanisotropy* Kazunori Yoshizawa 1) 2) , Yunao Xu 2) , Takashi Furumura 3)
Faculty of Science, Hokkaido University, Japan 1) , Graduate School of Science, Hokkaido University, Japan
2), Earthqake Research Institute, The University of Tokyo, Japan 3)
Recent progress in seismic tomography and numerical simulations of seismic wave propagation haverevealed the nature of heterogeneity and anisotropy in the upper mantle on a variety of scales. Surface
wave tomography at lower frequency (5-50 mHz) have shown strong radial anisotropy with faster SH wave
speeds than SV in the asthenosphere, particularly in the fast drifting oceanic and continental plates (e.g.,
Nettles & Dziewonski, 2008; Yoshizawa, 2014). Also, the existence of rapid vertical change of anisotropic
properties has been found in continental lithosphere (Yoshizawa & Kennett, 2015), whose depth coincides
well with the enigmatic Mid-Lithosphere Discontinuity from receiver functions.
At higher frequency (-10Hz), recent observations of scattered body waves require the existence ofhorizontally elongated small-scale heterogeneity in the lithosphere (e.g., Kennett & Furumura, 2008, 2013).
The effects of such small-scale heterogeneities (correlation distance of kilometer-scale) have generally been
ignored in surface wave propagation, whose wavelength is about several hundred kilometers. Such smallscale heterogeneity can, however, cause non-negligible influence on surface-wave phase speeds bychanging the effective rigidity of the media and generating “apparent" radial anisotropy (SH>SV).
In this study, we investigate the effects of small-scale heterogeneity on the long-period surface waves
through numerical experiments with normal mode calculations as well as 2-D finite-difference method
simulations incorporating finely quasi-laminated heterogeneity in the upper mantle. We calculated
dispersion curves using a bunch of 1-D velocity profiles including random heterogeneity in the upper
mantle. The results suggest that the fine-scale heterogeneity makes the phase speeds of Rayleigh-wave
slower, while those of Love-wave faster to some extent, generating apparent radial anisotropy, even though
no effect of anisotropy is imposed on the velocity profiles.

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*S21-P-08
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Constraints on lithospheric mantle and crustal anisotropy in the NoMelt
area from an analysis of long-period seafloor magnetotelluric data
* Tetsuo Matsuno 1) 2) , Rob. Evans 3)
Kobe Ocean Bottom Exploration Center, Kobe University, Kobe, Japan 1) , Earthquake Research Institute,
The University of Tokyo, Tokyo, Japan 2) , Department of Geology and Geophysics, Woods Hole
Oceanographic Institution, Woods Hole, Massachusetts, USA 3)
Despite strong anisotropy seen in analysis of seismic data from the NoMelt experiment in 70 Ma Pacificseafloor, a previous analysis of coincident magnetotelluric (MT) data showed no evidence for anisotropy inthe electrical conductivity structure of either lithosphere or asthenosphere. We revisit the MT data and use
1D anisotropic models to demonstrate the limits of acceptable anisotropy within the data. We construct 1Dmodels by varying the thickness and the degree of anisotropy within the lithosphere, and conduct a seriesof tests to investigate what types of electrical anisotropy are compatible with the data. We find thatelectrical anisotropy is possible in a sheared and/or hydrous mantle within the lower-lithosphere (60-90
km depth). The data are not compatible with pervasive electrical anisotropy in the crust. Causes ofanisotropy within the highly resistive upper and mid-lithosphere, as seen seismically, are not expected tocause measurable impacts on MT response.

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*S21-P-09
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Upper Mantle and Crustal Structure of Sino-Korean and Yangtze Block from
Onshore-Offshore Wide-angle seismic surveys* Lihua Liu , Tianyao Hao , Chuanchuan Lyu , Qingyu You , Ya Xu
Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
By combination with other geophysical data, setting active source onshore-offshore wide-angle seismic
survey lines in the Bohai Sea, Shandong peninsula and the south Yellow Sea can help us reveal the deep
structure of Sino-Korean and Yangtze block, determine the block boundary, obtain the tectonic structure
characteristics of the conjuncture of the blocks. In 2010 and 2011 onshore-offshore surveys along two lines
in the Bohai area were carried out, these two lines revealed the P-wave velocity (Vp) structure of upper
mantle and crust of Sino-Korean. In 2013, another line was carried out, which started from the Bohai Sea
area and ended in the south Yellow Sea. By using first arrival tomography and ray-tracing modelingmethod, we got the Vp structure from Sino-Korean block to Yangtze block. Considering these three lines
together, we found that the block boundary is marked by great deep fault zone, the Vp structure is very
different from each other on the two sides of the fault zone. The north of Muping-Jimo fault zone belong to
Sino-Korean block, where there is no large-scale undulance of Moho. The south of Qingdao-WulianRongcheng fault zone belong to Yangtze block, the thickness of crust is about 32km and the lateral velocitychanges smaller than Sino-Korean block. The areas between these two fault zones belong to the suturezone of these two blocks, where the structure is much more complicated. We can find that there is a large
scale high velocity zone in the upper crust beneath the Qianliyan uplift and a large scale low velocity zone
in the middle crust beneath the Sulu orogenic belt, and the Moho depth increasing from south to north instep plunging, which suggests the process of combination of Sino-Korean and Yangtze block.

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*S21-P-10
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Shallow Moho along the failed rift on the coast of Japan Sea beneath
Japanese Islands* Makoto Matsubara 1) , Hiroshi Sato 2)
NIED, Tsukuba, Japan 1) , ERI, UTokyo, Tokyo, Japan 2)
The Mohorovicic discontinuity (Moho) is defined on the basis of an abrupt increase in seismic velocity
within the lithosphere observed using seismic refraction and receiver function analysis methods worldwide.
Moho depth varies regionally and remains a fundamental parameter of crustal structure. This study
presents a new method of mapping the Moho using a 3D seismic tomography model. A zone of highvelocity gradient is treated as the Moho because the tomographic method cannot clarify discontinuities.
Maximum lower crust/minimum upper mantle P-wave velocities in Japan are known to be 7.0 km/s and 7.5
km/s, respectively. The small residual between isovelocity surfaces of 7.0 km/s and 7.5 km/s corresponds
to the high velocity gradient. The best constrained Moho is where the isovelocity surfaces are close
together, and under much of Japan, the residual is less than 6 km and rarely larger than 10 km apart. We
selected an isovelocity surface of 7.2 km/s as a representative Moho ‘proxy' beneath Japanese Islands.
Our resulting Moho map beneath Japan is consistent with existing regional Moho models that wereobtained by controlled-source seismic investigations.
The Moho varies from shallow (25-30 km) to deep (> 30 km), and this variability is related to the structural
evolution of the Japanese islands: the opening of the Sea of Japan back-arc, ongoing arc-arc collisions atthe Hidaka and Izu collision zones, ongoing back-arc extension in Kyushu, and a possible failed back-arc
extensional event of Mesozoic age (Matsubara et al., 2017). The Moho along the failed rifts on the Japan
Sea side beneath the central Honshu Island is shallow since the high-V lower crust exists there.
Reference:
Matsubara et al. (2017) Configuration of the Moho discontinuity beneath the Japanese Islands derived fromthree-dimensional seismic tomography, Tectonophysics, in press, doi:10.1016/j.tecto.2016.11.025.

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*S21-P-11
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Spatial distribution of the Crust-Mantle boundary in colliding andsubducting Izu-Bonin-Mariana Arc beneath Japan using Receiver Function
analysis* Sawako Kinoshita 1) , Kiwamu Nishida 2) , Toshihiro Igarashi 2) , Yosuke Aoki 2) , Minoru Takeo 2)
Geological Survey of Japan, AIST 1) , Earthquake Research Institute, University of Tokyo 2)
Izu-Bonin-Mariana Arc (IBM) is the intraoceanic arc resulting from a subduction of the Pacific Plate (PAC)
beneath the Philippine Sea Plate (PHS). The arc has a length of about 2800 km between the Sagami Bay inJapan and Guam (e.g. Stern et al., 2003). IBM collides with the Honshu island at the Izu collision zone andsubducts beneath the Eurasian and the Okhotsk plate to the north. The P-wave velocity structure along andacross IBM which has yet reached the collision zone revealed a thickened with a width of about 25-30 km(Kodaira et al. 2007). Kinoshita et al. (2015) found a distinct velocity boundary at depths of 40–50 km
using the receiver function (RF) analysis below regions where IBM is subducting. They interpreted that thisboundary represents the boundary between the crust and the uppermost mantle of the IBM. Furthermore,they supposed the IBM does not subduct to a depth of about 100 km as estimated by tomography. The
purpose of this study is to understand the crustal and upper mantle structure of subducting PHS and IBM.
To address this, we conduct an inversion analysis of RFs and investigate the seismic structure of the
subducting IBM including the distribution of the crust-mantle boundary. In RF inversions, there is a tradeoff between the depth of the velocity boundary and the average velocity over the boundary, so we jointly
inverted for the velocity structure from receiver functions and dispersion curves of surface waves. Our
results are characterized by the following features: 1) The IBM crust is as deep as 40 km below the Izu
peninsula. 2) The crust-mantle boundary of IBM discontinuous in the eastern part, whereas continuous in
the western part, representing a different style of collision of IBM between the western and eastern part.

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*S21-P-12
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Seismological evidence of slab dehydration based on a high-resolution
receiver function image of the subducting Philippine Sea plate beneathwestern Shikoku, southwest Japan* Katsuhiko Shiomi , Tetsuya Takeda , Tomotake Ueno
NIED, Tsukuba, Japan
In the Nankai region, southwest Japan, low-frequency earthquakes (LFEs) are very active at the down-dip
limit of the megathrust source region. To reveal the spatial relationship between underground structure and
LFE activity, we newly constructed high-resolution receiver function (RF) profiles of the subducting
Philippine Sea (PHS) slab and overriding continental plate. In this study, we installed 30 short-period
seismographs in western Shikoku for one year. The survey line was aligned in the NNW-SSE, orthogonal to
iso-depths of the slab, and it was passed through above one of the dominant LFE clusters. We applied the
RF analysis to not only these temporal stations but also nine NIED Hi-net/F-net stations near the survey
line. To enhance converted phase amplitudes at a dipping oceanic Moho (OM), we excluded the RFs
estimated from earthquakes located in the up-dip direction (SSE) of our survey line. We clearly confirmed
the existence of the north dipping OM and the continental Moho (CM) from the profiles. The OM was lying
at 30 km depth beneath the Pacific coastline, and inclined to the north with dip of 7-degree. In the northernpart of the survey line, the flat CM was located at 30 km depth. At the area where the OM reached 40 km
depth, the CM became shallow to the south and gradually unclear. the precisely detected LFEs were
distributed to the deep extension of the upper boundary of the PHS slab. The harmonic analysis of RFs
implied anisotropic rocks existence just above the OM only at the north of LFE zone. The pressure andtemperature there corresponds to the condition for phase transition from blueschist to eclogite withdehydration. Our observation implies that water dehydrated from the oceanic crust rises to the inter-plates,
and it causes the LFEs.
Acknowledgements: This study was partially supported by JSPS KAKENHI Grant Number JP16H06475.

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*S21-P-13
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Estimation of global crustal model uncertainty using geostatistical analysis
Wolfgang Szwillus 1) , Walter D. Mooney 2) , * Jorg Ebbing 1)
Kiel University, Kiel, Germany 1) , USGS, Menlo Park, USA 2)
Active seismology provides the best tool to estimate the thickness and seismic velocity of the crust.
However, seismic experiments are mostly constrained to profiles and hence do not provide spatiallycomplete coverage. Passive seismology can complement active seismology, but is often adversely affectedby sparse station coverage, especially on a global scale. As a result, models of crustal properties are basedon a form of interpolation, which leads to smoothing and might not reproduce the true crustal structure.
This has for example consequences if such models are used to estimate upper mantle densities by strippingof a crustal density structure from the gravity field. The residual gravity field reflects both possible density
anomalies in the mantle and the errors in the crustal density model.
Here, we make use of a global database of active seismological data acquired over the last 60 years andexplore how interpolation is affecting the attainable accuracy of crustal models and compare our resultswith previously published global crustal models. Our interpolation method is based on Kriging andprovides uncertainties in addition to the gridded values. This uncertainty translates differently to nearsurface gravity and satellite gravity gradients, which allows to evaluate the uncertainties compared to
uncertainties by velocity-density conversion and to define strategies for global inversion.

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*S21-P-14
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Three-Dimensional Seismic Velocity Models of P and S Waves BeneathWestern Part of Java, Indonesia from Double-difference Tomography* Shindy Rosalia 1) , Sri Widiyantoro 2) , Andri Dian Nugraha 2)
Geophysical Engineering Study Program, Faculty of Mining and Petroleum Engineering, Institut Teknologi
Bandung, Bandung, Indonesia 1) , Global Geophysical Research Group, Faculty of Mining and Petroleum
Engineering, Institut Teknologi Bandung, Bandung, Indonesia 2)
Western part of Java is located in active subduction zone where the Indo-Australian plate is subductedunder the Eurasian plate. In this study, double-difference tomography has been applied to obtain 3D
velocity structures of P and S waves beneath the western part of Java. We have used regional earthquake
waveform data taken from the Meteorological, Climatological, Geophysical Agency (BMKG) of Indonesia
network from south of Sumatra to central Java. We have re-picked P and S arrival times from about 800
events in the period from April 2009 to December 2015. We have also used additional arrival time data of
BMKG catalog for period from January to July 2016. We have selected events which have azimuthal gap <210 degrees, magnitude > 3, and number of phases > 8. Double-difference tomographic imaging using
these data gives a clear velocity structure beneath the western part of Java, especially in the volcanic arc
area, i.e. below Mount Anak Krakatau, Mount Salak complex and southern mountains complex in West
Java. We observed low velocity anomalies of P and S waves and high Vp/Vs under the volcanoes at depth
interval of 80-100 km that may indicate hot partial melting ascending from subducted slab beneath thevolcanic arc.

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*S21-P-15
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Heterogeneous structure beneath fault zones of the 2016 Kumamoto
earthquake* Megumi Kamizono 1) , Satoshi Matsumoto 1) , Yusuke Yamashita 2) , Manami Nakamoto 3) , Masahiro
Miyazaki 2) , Shin-ichi Sakai 4) , Yoshihisa Iio 2) , Group for urgent joint seismic observation of the 2016
Kumamoto earthquake 1)
Kyushu University, Fukuoka, Japan 1) , Kyoto University, Kyoto, Japan 2) , National Institute of Polar
Research,Tokyo, Japan 3) , The University of Tokyo, Tokyo, Japan 4)
The 2016 Kumamoto earthquake occurred in April 2016. The first earthquake (M6.5) occurred at 21:26(JST) on April 14th. The main shock (M7.3) occurred at 1:25 (JST) on April 16th. The mechanism of thisearthquake has a tension axis approximately in the north-south direction and strike-slip fault type.
Furthermore, in the Beppu-Haneyama fault zone, located in northeastern part of Kumamoto, induced
earthquake (M5.7; reference value) occurred at 01:25 (JST) on April 16th. In this area, there are mainly two
active fault zones which are the Futagawa fault zone and Hinagu fault zone. Aso volcano exists in thenortheastern part of Kumamoto prefecture, the end of the Futagawa fault zone and it erupted after main
shock. The 2016 Kumamoto earthquake is characterized in that the range of seismic activity is very wideand vigorous aftershock activity.
Because the network of seismic stations (58 offline and 13 online seismic observation points) were
deployed by Group for urgent joint seismic observation of the 2016 Kumamoto earthquake from April 15,
many data of active seismicity were obtained.
We analyzed data of aftershock of the 2016 Kumamoto earthquake. We estimated background structure bycomparing the observed envelope with theoretical curve based on multiple scattering model. As a result,
there are heterogeneity in the western part of the Hinagu fault zone and beneath the Aso volcano.
As a future task, by comparing the observed envelope with the theoretically expected curve we will
estimate the distribution of scatterers based on travel time of the ripples.

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*S21-P-16
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Tectonic Tremor in northern Central Range, Taiwan* Wei-Fang Sun 1) , Cheng-Horng Lin 2) 3) , Yi-Heng Li 4) , Wen-Yen Chang 1) 3)
National Dong Hwa University, Hualien, Taiwan 1) , Academia Sinica, Taipei, Taiwan 2) , National Center for
Research on Earthquake Engineering, Taipei, Taiwan 3) , Industrial Technology Research Institute, Hsinchu,
Taiwan 4)
Triggered and ambient tectonic tremor has been observed in the Island of Taiwan, an active and obliquecollision between the Eurasian and the Philippine Sea plates. A few triggered tremor sources have beenfound in norther Central Range but no further details have been reported. Different from regularearthquakes, deep tremor is difficult to detect and locate across a sparse seismic network due to its nonimpulsive, low-amplitude property. In this study, we combine four seismic networks operated by different
institutes, containing seismic data from tens of broadband and short period stations for average station
spacing less than 10 km. We manually detect tectonic tremor through continuous data from 2013 to 2015.
For triggered tremor, we examine waveform within 1,200 s after distant earthquakes, epicentral distancemore than 1,000 km and magnitude more than 7.5, and 120 s after local earthquakes, epicentral distanceless than 100 km and magnitude more than 5.0. We assume tremor only has clear S-wave, use waveform
envelope to identify S-wave arrivals, and locate triggered tremor by hypo71. For ambient tremor, we
manually check continuous data for extracting tremor events lasting longer than 3 minutes, and apply thesame procedure to locate them. Combining the spatiotemporal distributions of the two types of tectonic
tremor and local earthquakes, we further discuss the possible mechanism for interactions between
earthquakes and tectonic tremor.

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*S21-P-17
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Three dimensional resistivity structure in the source reason of SSEs in Boso
peninsula, Central Japan* Midori Hayakawa 1) , Mao Okuda 1) , Toru Mogi 1) , Kotaro Sugano 1) , Naoki Koizimi 2) , Katsumi Hattori 2) ,Chie Yoshino 2) , Han Peng 2) , Hao Chen 2)
Hokkaido University, Sapporo, Japan 1) , Chiba University, Chiba, Japan 2)
We carried out MT surveys in the Boso peninsula (Chiba, Central Japan) to investigate the resistivity
structure in the source region of the slow slip events that have occurred at least five times within 20 years.
The MT data contaminated by large artificial noise and DC trains showed near field effect at the frequency
band below 1Hz. To avoid the local noise, in addtions to the conventional remote reference method, we
attempted to apply the independent component analysis (ICA). ICA is one of the multivariate analysis
methods and complicated mixing data can be separated into all underlying sources without knowing thesesources or the way that they are mixed.
We applied the ICA method to improve horizontal magnetic components in MT data. Two components ICA,
using both the data observed in Boso area and the noise free magnetic data observed in Esashi, Sawauchi
or Kakioka Magnetic Observatory, was applied for each magnetic component. After the ICA processing, theapparent resistivity and phase were computed by the BIRRP method developed by Chave and Thomson(2004). By this processing, we obtained gentle change and the phases take non-zero values. This result
meant that some parts of the noise components such as near field noise were removed.
After obtained the reasonable apparent resistivity and phase, we tried to discuss the 3D resistivity structureusing the improved data and discussed the structures in relation to geological structure and the presenceof fluid. We estimated 3D resistivity structure using ModEM (Egbert and Kelbert, 2012) . This area issurrounded by the sea and we especially payed attention to effects of the sea. In addition, conductive
sedimentary layers widely cover at the shallower depth in this area and the resolution of deeper structure isdiminished. We discussed improving of the 3D resistivity structure model under these difficult conditions.

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*S21-P-18
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Crustal structure across the central Ganga foreland basin bymagnetotellurics* A Manglik , L Adilakshmi , S Thiagarajan , M Suresh
CSIR-National Geophysical Research Institute, Hyderabad, India
The Ganga basin, a foreland basin of the Himalayan collision belt, formed due the flexure of the Indian
plate, consists of a thick pile of sedimentary sequence especially in its northern part. Hydrocarbon
exploration activities provided the details of the basin architecture and lithologies. However, the structureof the underlying Indian plate is largely unknown despite its important role in influencing the Himalayan
tectonics. We acquired MT data along a 285 km long profile at average station spacing of 6 - 8 km acrossthe central Ganga basin to delineate the crustal structure. The profile passes over the sedimentary cover ofthe basin but at the southern end it covers a part of the exposed Bundhelkhand massif. MT impedance
tensors were estimated in 0.001 – 1000 Hz frequency band and decomposed into TE and TM modes by
distortion and decomposition analyses. These datasets were jointly inverted along with the Hz data toobtain a geoelectric model of the crustal structure. The results reveal significant variations in thesubsurface structure. In the southern segment, the model yields three highly resistive blocks, thesouthernmost of which correlates with the Bundelkhand craton and extends down to about 150 km while
the remaining two blocks are of smaller dimension and buried under the sediments. Based on these results,
we infer that the lithosphere of the Bundhelkhand craton is at least about 150 km thick, which is contrary
to some previous results suggesting thin lithosphere for the Indian shield. Further, the Bundelkhand craton
extends far north of its earlier demarcated position but buried under 0.5 to 1 km thick sediment cover. At
the northern end of the profile, an electrically conductive crustal structure has been delineated. In thisregion, we have earlier reported the presence of thick sedimentary sequence. Thus, our results suggest ahighly heterogeneous crustal architecture of the Indian plate in the central Ganga foreland basin.

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*S21-P-19
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Three-Dimensional resistivity structure beneath Payao Fault zone: biggest
earthquake in Thailand (5 may 2014)* Songkhun Boonchaisuk 1) , Puwis Amatyakul 2) , Tawat Rung-Arunwan 3) , Sutthipong Noisagool 2) 5) ,Weerachai Siripunvaraporn 2) 4)
Geoscience division, Mahidol University, Kanchanaburi campus Sai Yok/ Kanchanaburi, Thailand 1) ,Department of Physics, Faculty of Science, Mahidol University, 272 Rama 6 Road, Rachatawee, Bangkok,
Thailand. 2) , Curl-E Geophysics Co., Ltd., 85/87 Nantawan Village, Uttayan-Aksa Road, Salaya,Phutthamonthon, Nakornpathom, Thailand. 73170 3) , ThEP Center, Commission on Higher Education, 328,
Si Ayutthaya Road, Rachatawee, Bangkok, Thailand. 4) , eEarthquake Research Institute, University ofTokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan 5)
Payao Fault zone (PYFZ) is mostly aligned in north-south direction with the length about 90 km cover thearea of Chiang Rai, Payao and northern part of Lampang province, Northern Thailand. Base on hazard mapof Thailand, this area was classified as risk zone. On May 5, 2014, The biggest earthquake in Thailand withmagnitude 6.5 was occurred at Mae Lao district, Chiang Rai province. There were also thousand
aftershocks in PYFZ. More than 3500 buildings and a road was damaged. Most of the earthquakes were
occurred in the area between two majors fault: the NE-SW-trending Mae Lao Fault Zone and N-S-trending
Pan Fault Zone. The focal depth of main shock and major aftershocks were reported at varies depth. The
focal mechanisms of main shock and after shock with high magnitude are also reported. However, there are
no deep crustal structure in this area. The deep resistivity structure could improve the understanding fault
mechanism, geology and tectonic in PYFZ. In order to reveal the PYFZ structure, Magnetotelluric (MT) datafrom 31 stations as well as a remote reference site at Kanchanaburi province (600 km apart) was installed
during February and May 2015. Full impedance tensor with tipper were then inverted to obtain the 3D
resistivity structure by using WS3DINV-MPI program. Interesting structures can be observed. Shallow
resistivity structure vary from place to place and corresponds quite well with the surface geology. There areis conductor beneath Mae Lao segment (MLS) near the seismogenic zone. The conductor might play animportant rule for the 5 May 2014 earthquake and its sequence. It was interpreted as high interconnectedaqueous fluid content zone. The fluid in pre-exiting fault, MLS, can reduce the maximum fictional strength
resulting the main shock and aftershocks.

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*S21-P-20
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S21. L
ithospheric structure

Estimation of electrical anisotropy in the oceanic upper mantle from seafloor
magnetotelluric array data
* Tetsuo Matsuno 1) 2) , Kiyoshi Baba 2) , Hisashi Utada 2)
Kobe Ocean Bottom Exploration Center, Kobe University, Kobe, Japan 1) , Earthquake Research Institute,
The University of Tokyo, Tokyo, Japan 2)
Electrical anisotropy in the oceanic upper mantle could provide important clues on mantle structure anddynamics if it is confirmed from observational data. Seafloor magnetotelluric (MT) data are useful toestimate electrical anisotropy in the oceanic upper mantle, but should be carefully treated partly because
maximum anisotropic signal may not be so large (half an order of magnitude in electrical conductivity) andthere is always trade-off between intrinsic anisotropic effects and effects of a large-scale lateralheterogeneity including bathymetric variations and coast effects. One promising method to estimate
electrical anisotropy from seafloor MT array data is first to obtain a 1-D isotropic model through iterative
correction for bathymetric distortion, and then to estimate anisotropy as deviations from the 1-D isotropic
model. We first investigate the performance of this method through a series of synthetic modeling using
plausible 1-D anisotropic models for the Normal Oceanic Mantle project area in the northwestern Pacific.
The synthetic modeling includes forward modeling using the 1-D anisotropic models with and withoutbathymetry and inversion with iterative bathymetric correction to data produced from the 1-D anisotropic
models underlying a 3-D real bathymetry. After the synthetic test, we apply the method to an observational
array data obtained during the Normal Oceanic Mantle project in the northwestern Pacific. We will show
and discuss results of the application in the presentation.

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*S22-1-01
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S22. L
ithosphere structure and dynamics: Plate boundary deformation at lithospheric scale

GPS Space Geodesy in Colombia, South America: Velocities and theconstruction of the Eastern Cordillera of the Colombian Andes* Hector Mora-Paez 1) , Dave Mencin 2) , Peter Molnar 2) , Hans Diederix 1) , Leonardo Cardona-Piedrahita 1) ,Yuli Corchuelo 1) , Juan-Ramon Pelaez-Gaviria 1)
Colombian Geological Survey, Space Geodesy Research Group, Bogota, Colombia 1) , Department of
Geological Sciences, Cooperative Institute for Research in Environmental Sciences (CIRES), University ofColorado, USA 2)
Tectonic and volcanic activity in northwestern South America is directly related to the interaction of theSouth America, Nazca, Cocos and Caribbean plates, and the smaller North Andean, Maracaibo, Choco andPanama blocks. In Colombia, the GeoRed network is a dedicated GNSS network for geodynamic studies
installed by the Colombian Geological Survey. For this work, using GPS data from nine CGPS sites andtwenty campaign sites, a GPS velocity profile across the northeast-trending Eastern Cordillera of Colombia
are estimated and compared with results from previous studies based on paleobotanical derived elevations.
The geodetic velocities show oblique convergence at 8.8 ± 1.7 mm/yr, consisting of 8.0 ± 1.7 mm/yr ofright-lateral strike-slip shear along the mountain range, and 3.7 ± 0.3 mm/yr of shortening. From this, weconclude the following: first, relative movement of the regions east and west of the Eastern Cordillera
includes a large fraction of right-lateral shear; second, the convergence rate, the component of velocities
west of the Eastern Cordillera relative to those east of it and perpendicular to the trend of the belt is only
~4 mm/yr; and third, at the northeast end of the Eastern Cordillera, shortening is essentially perpendicular
to the local trend of the belt, and the highest mountain elevations lie in this region. The strike-slip shear
corroborates geologic work suggesting such movement both southwest and northeast of the range. Given
the ~200-km width of the Eastern Cordillera, to accommodate ~ 100-150 km of crustal shortening, which
has been inferred from balanced cross sections and is implied by recent estimates of crustal thickness,would require ~25-40 Myr of shortening at 4 mm/yr or a complex velocity history. From our results, we canconclude that the present-day GPS velocities are inconsistent with the inference, based on paleobotanicalobservations, that the Eastern Cordillera rose 1500-2500 m since 3-6 Ma.

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*S22-1-02
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S22. L
ithosphere structure and dynamics: Plate boundary deformation at lithospheric scale

LITHOSPHERIC STRUCTURE IN THE NORTHWEST SOUTH AMERICA
FROM RECEIVER FUNCTIONS ANALYSIS* Carlos Alberto Vargas Jimenez 1) , Gaspar Monsalve 2) , Faustino Blanco 1) , Esteban Poveda 3)
Universidad Nacional de Colombia at Bogota 1) , Universidad Nacional de Colombia at Medellin 2) ,Universidade Federal do Rio Grande do Norte at Natal, Brazil 3)
We have combined seismological data of the National Seismological Network of Colombia for estimating
the P to S and S to P receiver functions beneath Colombia and adjacent regions to make a first orderapproximation of the thickness of the crust and the Lithosphere-Asthenosphere Boundary (LAB) in the NW
South America. An iterative time-domain deconvolution process was carried out and then a move-out
correction with a time-depth conversion using seismograms of distant earthquakes recorded at broadband
stations. P to S receiver functions reveal a relatively thin crust in northern Colombia, with a thickness thatroughly varies between 25 and 39 km, with an increase from NW to SE. S to P receiver functions were used
to estimate lithospheric thickness, yielding values between 65 and 110 km, also increasing from NW to SE.
Lithospheric thickness beneath an oceanic island in the Caribbean is 80 km, whereas for the Ecuador andColombia Trench is 65 km and around 100 km for the Panama Arc. The transition to the continent isassociated with an increase in LAB depth, where it can reach 110 km, with no significant differencesamong terranes and tectonic blocks.
These results are consistent with the ideas of flat subduction beneath the Colombian Caribbean coast,
where a relatively thin continental crust, which gradually thickens toward the SE, is on top of a shallowly
subducting Caribbean Plate; the obtained LAB likely represents the base of the oceanic plate beneath thecontinental crust. The Caldas tear structure may correspond to the southern limit of this plate, where the
Nazca plate, appears to subduct with an angle of 34 degrees. This scenario is also consistent with recent
observations of teleseismic travel time residuals, which suggest a relatively cold upper mantle, as well as
seismic reflection and gravity data.

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*S22-1-03
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S22. L
ithosphere structure and dynamics: Plate boundary deformation at lithospheric scale

Arc-arc collision structure in the southernmost part of the Kuril trench
region -Results from integrated reanalyse* Takaya Iwasaki 1) , Noriko Tsumura 2) , Tanio Ito 3) , Hiroshi Sato 1) , Eiji Kurashimo 1) , Naoshi Hirata 1) ,Kazunori Arita 4) , Katsumi Noda 5) , Akira Fujiwara 5) , Susumu Abe 6) , Shinsuke Kikuchi 6) , Kazuko Suzuki
7)

ERI, the University of Tokyo, Tokyo, Japan 1) , Graduate School of Science, Chiba University, Chiba, Japan2), Heisei Teikyo University, Tokyo, Japan 3) , The Hokkaido University Museum, Hokkaido University,
Sapporo, Japan 4) , JGI, Inc., Tokyo, Japan 5) , JAPEX, Tokyo, Japan 6) , Schlumberger Ltd., Tokyo, Japan 7)
The oblique subduction of the Kuril plate is generating a unique tectonic environment in the southernmost
part of the Kuril trench area. The Kuril forearc started to collide against NE Japan Arc from the east at thetime of middle Miocene to form the Hidaka collision zone (HCZ) in the central part of Hokkaido, Japan. Our
integrated reinterpretation for several seismic reflection/refraction experiments revealed detailed and new
structural features within the HCZ.
In the southern part of the HCZ, the crustal delamination associated with the collision was clearly imaged
by applying CRS/MDRS method to the seismic reflection data (Tsumura et al., 2014). Namely, the upper
22-23 km crust of the Kuril arc is obducted along the Hidaka Main Thrust (HMT), while the lower part ofthe crust is descending down to reach the subducted Pacific plate.
In the northern part of the HCZ, such delamination structure as obtained in the southern HCZ is not clearly
seen. The most important finding in this region is a clear image of the NE Japan arc crust descending
eastward to a depth of about 40 km under the hinterland side. Our refraction/ wide-angle reflection
analysis revealed the strong dipping reflectors with a velocity contrast of 0.5-1 km/s at depths of 10-35 km
just west of the HMT. The obduction of the upper Kuril crust starts at a deeper crustal level of at least 27-30
km and more easterly (~20 km) of the HMT as compared with the case in the southern HCZ. If themetamorphic rocks outcropped east of the HMT are the same crustal materials shallower than 22-23 km
depth as in the case of the southern HCZ, the deeper crustal portion originally situated at 23-27~30 km
depth must exist in the western side of the present HMT. The very strong and deep reflectors found west of
the HMT might result from the mixture of these middle/lower crustal (high velocity) materials of the Kuril
arc and upper crustal (low velocity) materials of the NE Japan arc.

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*S22-1-04
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S22. L
ithosphere structure and dynamics: Plate boundary deformation at lithospheric scale

Bookshelf faulting in Iceland: Characteristic of oblique rifts and unstabletransforms* Pall Einarsson
Institute of Earth Sciences, University of Iceland, Reykjavik, Iceland
Oblique and immature plate boundaries are frequently characterized by complicated fault patterns, whichmakes their seismogenic potential and seismic hazard difficult to assess. The structure of the plateboundaries in Iceland is relatively complex. Two of the plate boundary segments are highly oblique to theover-all plate velocity vector between the North America and Eurasia Plates, i.e. the Reykjanes Peninsula
and the Grimsey oblique rifts. They contain both volcanic systems and seismogenic strike-slip faults.
Oblique spreading leads to extensive volcanism and large earthquakes, a combination that is otherwise
uncommon in Iceland. The fissure swarms of individual volcanic systems contain normal faults andfissures, arranged en echelon along the plate boundary. The fissure swarms fade out as they extend into theplates on either side. Overprinting this pattern of volcano-tectonic structures are sets of parallel, transversly
striking transcurrent faults that generate the largest earthquakes in the zones, up to M 6.5. Their surface
expressions are en echelon fracture arrays and push-up structures. The distance between them varies from
0.5 to 5 km, and together they form a bookshelf-type fault system taking up the shear component of platemovements across the oblique rift zones.
The interaction of the Iceland hotspot with the mid-Atlantic plate boundary leads to frequent ridge jumps
by rift propagation and the formation of temporary microplates between the propagating and receding rifts.
At present, the Hreppar Microplate is bounded by a transform zone, the South Iceland Seismic Zone, that is
the source of many of the most damaging earthquakes in the history of Iceland, up to M 7. The earthquakes
occur on many parallel strike-slip faults that are perpendicular to the zone, i.e. by bookshelf faulting. It is
postulated that bookshelf faulting is one of the characteristics of unstable or immature plate boundaries.

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*S22-1-05
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S22. L
ithosphere structure and dynamics: Plate boundary deformation at lithospheric scale

Potential for coincident megathrust and crustal earthquakes - an additional
component of seismic hazard* Kevin Furlong , Matthew Herman
Penn State University, University Park, PA USA
The Mw 7.8 Kaikoura,N.Z. earthquake presents two distinct characteristics to geophysical observers.
Seismologically the earthquake is dominantly a megathrust event, apparently part of the southernmost
segment of the Hikurangi subduction zone. Field observations show numerous surface rupturing fault
segments, many of which show substantial surface offset. This presents the earthquake science community
with a dilemma - is the earthquake a megathrust event and the surface faulting a byproduct or is the event
primarily restricted to upper plate strike-slip (+ some thrust) faulting? Although seismological analyses
indicate some strike-slip-like behavior in the initial and latter stages of the rupture (perhaps as much as 1/3of the moment), most teleseismic analyses require significant thrust faulting consistent with rupture of the
subduction megathrust. Thus it appears that there were synchronous megathrust and crustal faulting
events. Similar situations potentially exist along other megathrust systems. Our model that reconciles thesetwo concurrent deformational events includes an inter-seismic period of strain/slip-deficit accumulation
along the megathrust plate interface. Co-seismically, crustal deformation conditions are changed by: (a)reduction of fault-normal stresses acting on the crustal faults, and (b) the decoupling of the upper-plate
faults from their base (the underlying subducting slab). These effects combine to decouple the faults fromtheir underlying foundation and significantly change the Coulomb stress conditions acting on the faults,
allowing appropriately oriented crustal faults to slip concurrent with the megathrust rupture.

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*S22-P-01
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S22. L
ithosphere structure and dynamics: Plate boundary deformation at lithospheric scale

Cenozoic rifting and crustal dynamics controlled by Variscan paleoplateboundaries in the mantle lithosphere* Vladislav Babuska , Jaroslava Plomerova , Helena Munzarova
Institute of Geophysics, Czech Academy of Sciences, Prague, Czech RepublicStudies of seismic anisotropy with the use of teleseismic data recorded during the last two decades atdense networks of temporary and permanent stations provided basis for modelling large-scale fabric of thelithosphere–asthenosphere system of Variscan massifs in Europe. Inferences from differently oriented
seismic anisotropy image the massifs as mosaics of different microplates that roughly correspond tomapped crustal tectonic units. The mantle lithosphere preserves fossil olivine fabrics of individual domainsof the massifs formed before their assembly. Changes of the anisotropy orientation related to boundaries of
the tectonic units document rigidity of their mantle lithosphere and a long memory of the coherent olivine
fabrics (Babuska and Plomerova, Gondwana Res. 2013). A distinct mantle boundary between the
Saxothuringian (ST) unit in the north and the Tepla–Barrandian (TB) and Moldanubian (MD) units in thesouth, in case of the Bohemian Massif (BM) in central Europe, witnessed a Saxothuringian oceanic
subduction followed by a continental collision of the microplates. The suture resulting from the ST/TB
collision served as a major Variscan exhumation channel of the HP–UHP rocks. Also the central part of the
Cenozoic Eger Rift with a characteristic graben structure developed above this mantle suture. Unlike the
HP–UHP rocks exhumed along the ST/TB suture, the Late Cretaceous and Cenozoic volcanic products
within the BM follow the broader rim of the ST mantle lithosphere that extends outside of the ST/TB suture(Plomerova et al., G-Cubed 2016). We suggest that younger tectonic and volcanic processes imprinted in
the crust are often related to rejuvenated paleo-boundaries in the uppermost mantle. The deep boundariesof the mantle lithosphere domains can be sharp or diffused, depending on how well the microplates werewelded into the continental plates.

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*S22-P-02
IASPEI Symposium / IASPEI06. Tectonophysics and Crustal Structure / S22. L
ithosphere structure and dynamics: Plate boundary deformation at lithospheric scale

Thermomechanical modeling of tectonic inversion at the ocean-continent
boundary of the North African margin (Algeria): possible initiation of
subduction* Abdelkarim Yelles Chaouche 1) , Carole Petit 2) , Laetitia Le Pourhiet 3) , Lamine Hamai 1) 2) , Abdesalam
Abtout 1)
Centre de Recherches en Astronomie, Astrophysique et Geophysique, Alger, Algeria 1) , Cote d'Azur
University, CNRS, OCA, IRD, Geoazur, Nice, France 2) , Pierre et Marie Curie University, CNRS, UPMC,
ISTeP, Paris, France 3)
While ocean subduction is one of the most important processes of plate tectonics, the understanding of
how and where it begins is still being debated (eg. Gerya, 2011). Northern Algeria is currently undergoing aslow compression deformation due to the ongoing African-Eurasian convergence, as evidenced by active
seismic activity recorded both on land and at sea (Yelles et al., 2006). The Algerian margin can thus
represent a transitional step between the parameters of active and passive margin (Jolivet et al., 2006).
Wide-angle seismic profiles data and The isostatic anomaly models show signs of active or recent
compressive deformation along this margin in isostatic desequilibrium. (Hamai et al., 2015). From theseobservations, two questions: I) What rheological and thermal parameters control the location ofcompressive deformation at the margin toe? II) Are these parameters suitable for long-term evolution ofthis margin into a mature subduction zone?
we use the thermo-mechanical code pTatin (May et al., 2014) to test the effect of thermal and rheologicalparameters on the tectonic inversion of a passive margin characterized by a hot young oceanic areaadjacent to a colder continental zone. We consider olso a transition zone (OCT) of 20 km wide between
oceanic lithosphere and continental lithosphere, which can be either of oceanic or continental affinity. This
OCT can be either vertical or diving towards the continent. Finally, we test the effect of a smooth thermal
gradient between the ocean and the continent and a clear vertical line between oceanic and continental
geotherms.
Our results indicate that tectonic inversion may evolve towards subduction, when the transition zone
plunges towards the continent or towards an indentation of the lower continental crust by the oceanic
lithosphere when the transition zone is vertical. In both cases, the strain localization in the margin toe
occurs only when it is sufficiently heated by the adjacent ocean area.

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*S23-1-01
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Education and Outreach to Foreign Residents Living in Japan- theImportance and Roles of Multicultural Society Coordinators in Creating
Systems for Disaster Risk Management Education for Foreign Residents.
* Akiyoshi KIKUCHI 1) 2) 3)
Keiko University, Kanagawa, Japan 1) , Sendai Tourism, Convention and International Association 2) , The
Institute of Multicultural Society Professionals 3)
With the increase in the number of foreign residents, Japanese local governments are faced with the task of
implementing policies to support them. Establishing disaster risk management policies for foreign residents
is one of the most significant points in local government agenda because Japan must confront threats ofoccurring natural disasters like earthquakes. As a Multicultural Coordinator I have focused on developing
disaster risk management education for foreign residents since 2006. Foreign residents are usually notfamiliar with basic knowledge for disaster risk management or have fewer opportunities to learn disasterrisk management because of their limited Japanese proficiency. Therefore it is highly effective and efficient
to hold multi-lingual disaster risk management sessions directed solely at foreign residents. On the other
hand, it is also necessary to hold disaster risk management sessions where Japanese and foreign residents
can communicate with each other in various ways. The first reason to hold these sessions is because theability to provide multi-lingual information in the aftermath of a disaster will be inevitably limited. And
second reason to hold these sessions is because these sessions will boost visibility of foreign residents in
the host society which will lead mutual support during a disaster. In the other words, these two kinds ofsessions are mutually complementary. The role of the Multicultural Society Coordinator is to create thesystem in which the foreign residents can learn self-help and mutual assistance in their local societies inJapan.

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*S23-1-02
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Global Dynamic Exposure and the OpenBuildingMap - Communicating Risk
and Involving Communities* Danijel Schorlemmer 1) 4) , Thomas Beutin 1) , Naoshi Hirata 2) , Max Wyss 3) , Fabrice Cotton 1) , Karsten
Prehn 1)GFZ German Research Center for Geosciences, Potsdam, Germany 1) , Earthquake Research Institute,
University of Tokyo, Japan 2) , International Centre for Earth Simulation Foundation, Geneva, Switzerland 3), Universiy of Southern California, Los Angeles, USA 4)
The substantial reduction of disaster risk and live losses, a major goal of the Sendai Framework by theUnited Nations Office for Disaster Risk Reduction (UNISDR) requires a clear understanding of the
dynamics of the built environment and how it affects the life of communities in case of natural disasters.
These dynamics are best understood and captured by local communities, following two of the guiding
principles UNISDR formulated: "empowerment of local authorities and communities" and "engagementfrom all of society". Moreover, communities that participate in risk assessments increase theirunderstanding of efficient risk mitigation measures. Our Global Dynamic Exposure model and its technicalinfrastructure build on the involvement of communities in a citizen-science approach. Simultaneously, it
helps educating community members in the risks they are facing and how they can prevent losses of lives.
We are employing a crowd-sourced exposure capturing using OpenStreetMap (OSM), an ideal foundation
with already more than 200 million building footprints (growing by ~100'000 per day), and a plethora of
information about school, hospital, and other critical facilities. Besides relying on the very active OSM
community, we are providing a tailored building capture tool for mobile devices, facilitating simple and fastbuilding property capturing for OSM. With our OpenBuildingMap system, we are harvesting OSM byprocessing every building in near-realtime. We are collecting exposure and vulnerability indicators fromexplicit data (e.g. hospital locations), implicit data (e.g. building shapes), and semantically derived data, i.e.
interpretation applying expert knowledge, and translate them into building classifications (e.g. EMS98).
With our tools, interested communities can capture their exposure and analyze how natural disaster willaffect them. It helps communicating risks down to the community level and provides the means to involvecommunities to mitigate risks.

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*S23-1-03
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

The research of risk communication using Probabilistic Seismic Hazard
Maps* Tosei Nagamatsu 1) , Satoko Oki 1) , Sumire Hirota 2)
Keio University, Tokyo, Japan 1) , Tokyo City University, Tokyo, Japan 2)[Problems]
From 1995, the “Probabilistic Seismic Hazard Maps" (PSHM) has been published every year. This is a
distribution map showing the probability of ground motions larger than shindo 6- occurring within 30
years. The purpose of this map is clearly stated as follows; “It is for the public to properly recognize therisk of the ground motion and to promote their disaster awareness and preparation". However, there is no
existing research evaluating this map from the perspective of public's better awareness and preparation.
We therefore conducted a research measuring the impacts and efficiency of this map.
[Method of Analysis]
Two social surveys were conducted in 2014 and 2015. We first categorized the participants into 3 types
according to the probability (High/Middle/Low), and randomly assigned to 4 groups; 1) seeing no maps, 2)seeing PSHM, 3) seeing global hazard map alone, 4) seeing both global hazard map and PSHM. Then wemeasured their risk perception of large earthquakes, fear, and behavioral intentions to prevent damage.
[Result]
High region participants showed statistically significant improvement in their risk perception and fear byseeing PSHM. Those of Middle region showed no change both in risk perception and fear. For the case of
Low region participants, they reduced risk perception and fear by seeing PSHM, which is completely the
opposite effect to the purpose of the hazard map.
Another important result is that participants did not intend to prepare more against disaster even in theHigh region.
Summarizing above, PSHM could improve risk perception only to those live in high probability area, but do
not contribute to the behavioral intention for disaster preparation. Those live in low probability area worsen
their risk perception by seeing PSHM, while large earthquakes may occur anywhere in Japan. Contrary to
its purpose and expectation, PSHM resulted in not a good communication for public's disaster preparation.

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*S23-1-04
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety"L'Aquila Trial" is a trial of science?
* Kazuki Koketsu 1) , Satoko Oki 2) , Alessandro Amato 3) , Andrea Cerase 4)
Earthquake Research Institute, University of Tokyo, Tokyo, Japan 1) , Faculty of Environment andInformation Studies, Keio University, Kanagawa, Japan 2) , Instituto Nazionale di Geofisica e Vulcanologia,
Rome, Italy 3) , Universita la Sapienza di Roma, Rome, Italy 4)
In the article of Stucchi et al. (SRL, 87, 591-596, 2016), the authors wrote: “All the above cannot but lead
one to the conclusion that this was indeed also a trial of scientists and that science was purposely brought
into the trial." The prosecution against the defendants consists of a matter of science and a matter ofcommunication. In the Reasons for Judgement ("Motivazione") of the first trial, seventy pages are devoted
to the matter of science as written in Stucchi et al., whereas 375 pages of its fifth chapter are mostly
devoted to the matter of communication. Noting that the title of this chapter is Causal Relationship ("Nessodi Causalita"), therefore, even in the first trial, more emphasis was put to the matter of communication than
to the matter of science. In the sentence document of the second trial (388 pages in total), only 2 pages are
devoted to the matter of science. In spite of this situation, at the stage of the prosecution, it was complained
to the world that science of earthquake was accused and a campaign was carried out against theaccusation. However, this campaign made the families of victims furious because the campaign stressed theimpossibility of earthquake prediction while the families' fury was focused on bad communication of the
defendants, which they believed to be a main cause of victims' deaths and injuries.
In addition, the article did not mention the responsibility of media, except for the TV journalist who madethe “glass of wine interview" and broadcasted it without permission. However, a Japanese documentary
program for the L'Aquila Trial showed that another TV station and a newspaper reported the content of theinterview in the next morning as it was announced by the scientist defendants. These TV stations andnewspaper should be the most responsible for the bad communication. The most important lesson learned
from the L'Aquila Trial is that scientists must carefully follow reports released by media on their activities.

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*S23-1-05
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

InSight/SEIS@Mars Educational program : Sharing the Seismic Discovery ofMars with a International Network of classes* Philippe Lognonne 1) 2) , Jean Luc Berenger 3) , Anne Sauron 4) , Paul Denton 5) , Diane Carrer 2) , Fatima
Moujdi 3) , John Taber 6) , Tammy K Bravo 6) , Jane Houston Jones 7) , Philippe Labrot 1) 2) , Domenico
Giardini 4) , William. B. Banerdt 7) , Jean Michel Martinuzzi 8)
Institut de Physique du Globe de Paris-Sorbonne Paris Cite, F 1) , Universite Paris Diderot, Paris, F 2) ,Education Nationale, Nice, F 3) , ETHZ, Zurich, CH 4) , British Geological survey, Nottingham, UK 5) , IRIS,
Washington, DC, USA 6) , Jet Propulsion Laboratory, Pasadena, USA 7) , Centre National d'Etudes Spatiales,
Paris, F. 8)
The InSIght mission will deploy in 11/2018 a suite of geophysical instruments, including 3 axis Very Broad
Band Seismometer, 3 axis Short Period Seismometer, 3 axis Flux gate Magnetometer, Heat flow probe,
geodetic beacon, infrasound/microbarometer, wind sensors and cameras. As for all NASA missions,children and teenagers will be associated to the K12 InSight program, part of it being associated to the
SEIS instrument.
SEIS@Mars Educational project will lead SEIS educational activities and will transmit SEIS data to a
network of several hundred of middle and high schools worldwide, associated to existing “seismo(graph)at school" programs in the United States (https://www.iris.edu/hq/sis), France (www.edusismo.org)
Switzerland (www.seismoatschool.ethz.ch) and United Kingdom (http://www.bgs.ac.uk/schoolseismology/).
The mission website (http://insight.jpl.nasa.gov) and the SEIS web sites (https://insight.oca.eu/, http://seis-insight.eu ) will provide online educational resources.
If the data transmission to SEIS@schools will be automatic after their release by the NASA Planetary Data
System, earlier transmission will be made after mid 2019 through the integration of selected schools to theproject activities: the selected classrooms will perform the same activities as the project scientists. They
will have the chance to process rapidly the proprietary data in order to identify MarsQuake(s) and will willsubmit requests to the team in charge of processing all requests in order to get the high frequencies events.
These schools will fully be associated to the InSight/SEIS discoveries and this will allow the students toperform scientific analysis almost at the same time as the international "professional" seismologists.
Although Mars is expected to be less geologically violent than Earth, students with the mission data will beable to perform comparison with Earth and therefore to better understand the difference between ourplanet and other terrestrial planets.

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*S23-2-01
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Action research towards effective disaster risk communication* Katsuya YAMORIKyoto University, Kyoto, Japan
Action research is one of the characteristic methods in social science. Action research must always take thesubtle and complex texture of specific social phenomena into consideration when addressing issues of apractical field. Doing so makes action research more collaborative compared with standard empirical social
science: collaboration between outsiders (e.g., researchers) and insiders (e.g., local people), collaboration
among researchers representing different disciplines (e.g., between seismologists and psychologists), andcollaboration between quantitative analyses which provide overall and general trends, and qualitative,
which capture more individual and specific phenomena. I will introduce one example of action researchthat incorporates both qualitative and quantitative approaches and is applied to the field of disaster risk
communication. An App called “Nige Tore," which means “evacuation training," was developed in theaftermath of the 2011 East Japan Earthquake and Tsunami. The “Nige Tore" provides information such as
tsunami hazard maps and the lead times before a predicted tsunami arrives at a specific location. During adrill, the “Nige Tore" records user location, evacuation route, and speed through GPS-equipped
smartphones. It gives information about whether the individual participant can successfully escape to asafe place from different starting locations and via different routes. The development of “Nige Tore" drills
has facilitated meaningful dialogues between developers and users. Research to date has validated theability of “Nige Tore" functions to facilitate community members' motivation for quick evacuation, and to
facilitate the integration of contributions from different stakeholders to co-establish tsunami risk
communication system.

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*S23-2-02
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Extension of school education for disaster prevention actions overhouseholds –a case study of Mashima Elementary SchoolTakao Iinuma 1) , * Satoko Oki 2) , Risa Yamazaki 2) , Shun Tagami 3)
Keio University, Graduate School of Media and Governance 1) , Keio University, Faculty of Environment
and Information Studies 2) , Keio University, Faculty of Policy Management 3)
After Great East Japan earthquake, the significance of education for disaster prevention is confirmed
further and improvement of current education is highly required at every school. On the other hand,countermeasures against disaster at each household depend on the awareness of parents and so the levelof preparedness resulted in large variation compared to that of schools. This represents a severe problem
for protecting children's lives because they spend more time at home than at a school. Therefore, education
for disaster prevention at school should be designed to have effects over school kids' parents.
This research will discuss a case study of Mashima Elementary School, located in Nagano prefecture. At
this school, disaster prevention education was carried out in the means of action research beginning in July
2015 and going into the academic year of 2016. The practice aimed at not only empowering children to
save their own lives, but for them to influence their families in taking preventive measures. In particular,
the practice consisted of delivering disaster prevention lectures once or twice a year, distributing
newsletters every month, and using the newsletters to facilitate monthly disaster prevention classes. As aresult, the execution rate of people taking actions such as securing their furniture, significantly increased
from approximately 10% to 50%.
This study also indicates its academic significance as it reveals a crucial point of consideration in analyzing
results of continuously conducted quantitative research on the same subjects of research. Furthermore,through these interviews carried out on guardians, 20 different factors that may serve as catalysts inencouraging people to actively take part in disaster prevention activities, were discovered. It proved thatwhen empowering people to take action, simply threatening them of risks related to earthquakes isinsufficient, but that the effects of these catalysts must be optimized.

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*S23-2-03
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

An Analysis on The Effects of the Implementation of Short Drills in Taking
an Educational Approach to Disaster Prevention - A Case Study of Shirahata
Elementary School* Risako Tokoro , Tosei Nagamatsu , Mitsuhiro Matsumoto , Nobutomo Obata , Satoko Oki
Keio University, Tokyo, JapanThe occurrence and aftermath of the 2011 Great East Japan Earthquake revealed the significance of taking
an educational approach to disaster prevention. Despite the urgency for improvements in taking suchapproaches, many schools have yet to change.
This research will discuss a case study of Shirahata Elementary School, located in the City of Yokohama.
The research began in June 2016, aiming at practicing and implementing effective measures of disasterprevention education. One of the measures of particular focus was the “short drill;" a drill developed as analternative to conventional evacuation drills lacking in effectiveness. In the short drill, students are divided
into two groups and are required to observe each other in reacting to the Early Earthquake Warning.
Afterwards, upon the teacher's facilitation, students are to give constructive feedback to each otherregarding their actions taken throughout the drill. The short drills were designed to nourish students'
abilities in making appropriate judgments that would lead to protecting their lives at the event of a disaster.
As such, they were conducted intensively in varying situations during a short time period.
As a result of the implementation, various changes suggesting the effectiveness of the short drills wereobserved in both the students and teachers. Not only did they become faster in carrying out evacuation
procedures, but also displayed the ability to make highly reasoned judgments for their actions.
The utmost goal is for society as a whole to be well prepared for coming disasters. In the presentation, we
would like to discuss the effects of the implementation of short drills and by doing so, the presentation will
aim at identifying how the empowerment of children through the short drill may achieve this goal.

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*S23-2-04
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Adapting the disaster knowledge for the local context – Practices of Tsunami
disaster education in Zihuatanejo city, Mexico* Genta NAKANO , Katsuya YAMORIKyoto University, Uji, Japan
1. Introduction
Disaster education held at school is often given by experts such as researchers (so-called outsiders). On theother hand, the educational contents need to fit with the local context. Because decontextualized education
risked learners as, for example, responding earthquake with “drop-cover-hold" was not necessarilyadequate under the circumstances of vulnerable buildings of Nepal. Hence, this study analyzes the processof adapting the knowledge given by the author (as expert) for the locality, through the tsunami disastereducation for school teachers in two schools of Zihuatanejo city, Mexico.
2. Background of the study area
Zihuatanejo in the west coast of Mexico was historically affected by tsunamis due to the subduction zone
known as Guerrero gap. Thus, local administration requested schools to plan for tsunami evacuation.
However, the measures were not taken. In this study, two schools which were located in potential tsunami
inundation zone were selected and the author intervened to facilitate the evacuation planning.
3. Contents of the education
Two seminars were given to each school. First seminar was to explain the mechanism of earthquake andtsunami and their histories in Zihuatanejo. Second seminar adopted workshop style. Firstly, basics ofdesigning the evacuation route such as “less possibility of road blockage after earthquake" was explained
and workshop was held dividing teachers into small groups. Teachers discussed the appropriate evacuationroute and shared among teachers afterwards.
4. Analysis and conclusion
Discussed route by teachers were quicker to evacuate and less risk of blockage than the routes which local
administration indicated in both schools. Moreover, one school implemented tsunami evacuation drill byteachers' initiatives. Through the observation of workshops, teachers connected the knowledge from expert
with the knowledge from local community. This resulted in designing the evacuation route which fit withlocal context.

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*S23-2-05
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Consideration of the challenges of residents with special needs in tsunami
prone area in Japan through implementing indoor tsunami evacuation drills* Takashi Sugiyama , Katsuya Yamori
Kyoto University, Kyoto, Japan
After the Great East Japan Earthquake, the needs of Tsunami evacuation drills have been increasing, andvarious ways of tsunami evacuation drills were developed. Moreover, almost all of the drills developed were
implemented outdoor, which train people to move to evacuation sites safety. Survivors needed about 17 to
19 minutes for indoor preparation before evacuation when the Great East Japan Earthquake occurred.
However, there were limited numbers of tsunami evacuation drills carried out indoor. The indoor tsunami
evacuation is defined as the drills implemented for people to evacuate safely inside their home, such as
moving from a bedroom to an entrance where is safer and easier to escape when needed. Therefore, thisresearch examines the indoor tsunami evacuation drills to verify effects of the drills in Kuroshio town,
Kochi prefecture, Japan. Participants were selected in the area. This research focused on elderly residents
who were reported to have fewer opportunities to participate in general evacuation drills carried out in thearea. As a result, the participants were able to arrive at the entrance within two minutes. However, it wascharacteristic that the speed of moving from one place to another varied by participants and it wasobserved that some participants needed more time to get up from a chair or bed before moving. This study
proved the limit of top-down approach in disaster risk communication due to various needs of participantsin disaster situation. Gathering information such as participants' residential environment or individual
needs in disaster beforehand enables more effective disaster communication during the evacuation drills.
Especially, this bottom-up approach used in this research was observed to be meaningful to motivate
elderly residents to prepare for disaster, as the approach is interactive and more inclusive. After theevacuation drills, the participants were observed to have better ownership in disaster risk reduction.

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*S23-P-01
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Resilience Science for Resilient Society-Real time monitoring, Simulation
research, Disaster education -Real time monitoring, Simulation research,
Disaster education -Real time monitoring, Simulation research, Disastereducation on Resilience Science * Yoshiyuki Kaneda , Kazuhito Fujisawa , Chikako Isouchi
Kagawa University, Kagawa, Japan
In Japan and many countries, destructive earthquakes and Tsunamis have occurred frequently.
For early earthquake and tsunami detection, the real time monitoring using ocean floor observatories iseffective. DONET1 and DONET2 are in operation and being under constructing around the Nankai troughseismogenic zone SW of Japan, respectively. These systems have multi kinds of sensors such as theaccelerometer, broadband seismometer, pressure gauge, difference pressure gauge, hydrophone andthermometer for earthquakes and tsunamis monitoring. DONET1 and DONET2 with 51 observatories will
be deployed along the Nankai Trough SW of Japan by the end of March 2016.
Otherwise, to estimate damage of earthquakes and to have images of earthquake and tsunamis,
advanced simulation researches are important and indispensable.
Furthermore, we recognize recovers/ revivals are very important and difficult. In Tohoku area damaged bylarge tsunamis, recovers/revivals have been under progressing after over 6 years passed
after the 2011 Tohoku Earthquake. Therefore, we have to prepare the pre plan before next destructive
disasters such as the Nankai trough mega thrust earthquake.
For Resilient Society, Resilience Science including many kinds of fields such as Science, Engineering,
Medical and Social Science are significant and indispensable.
Finally, this Resilience Science will contribute to cultivation of human resources.
We will explain the Resilience Science for Resilient Society.

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*S23-P-02
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Outreach Programs for school children in India* Srinagesh D 1) , Satoko Oki 2) , Rajendar Chadha 1)
CSIR-NGRI, Hyderabad 1) , Keio University, Tokyo 2)
The need of the hour is to encourage people to take preventive measures against disasters and also,
empower the individuals to take appropriate measures in an event of emergency to save their lives. The
approach adopted by scientists is to disseminate intangible information on the up-to date seismologicalknowledge. However, this is not sufficient as it is repeatedly proved that knowledge alone does not haveenough impact on individuals behavioural aspects. Our challenge is to bridge the gap between knowledge
and practice by designing an effective Disaster Preparedness Education Program. This should beapplicable to other regions in the world, even with different geological, socio-economic and cultural
backgrounds. A pragmatic and new approach has to be adopted which are community based understandingof disaster risks and personal empowerment to take preventive actions. In this presentation, the goodpractices and lessons learned from various case studies in disaster preparedness in Japan, were
implemented to Indian scenario by holding workshops jointly by CSIR-NGRI, India, ERI, Tokyo and Keio
University Japan at Jawahar Navodaya schools in the Lesser Himalayan Region in North India, under an
Indo-Japan collaborative DISANET project Also, we carried forward this program by adopting twin
approaches in Uttar Pradesh, Uttarkhand, Jharkhand and Rajasthan where our broad band seismologicalstations are in operation at Jawahar Navodaya Schools under different scientific programs allowed us todisseminate information on earthquakes and essentials of safety required during an earthquake throughexamples and empowering the school children for translating knowledge into personal empowerment toundertake preventive actions during disaster.

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*S23-P-03
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

How do disaster museums communicate with the visitors?
* Hideyuki Shiroshita , Yuto Oka
Kansai University, Takatsuki, Japan
Disaster education is usually understood as knowledge transfer from experts on DRR to non-experts.
However, several preceding studies pointed out this fixed relationship make the non-experts dependent on
the expert. On the other hand, it is also argued that collaboration between experts and non-experts isneeded to improve the standard of disaster management. In order to tackle this problem, the fixed
relationship between experts and non-experts should be changed.
There are thus far 122 disaster education museums in Japan. If the above mentioned fixed relationship is
also applied to the museums, there would be no interaction between the museums and the visitors. In orderto evaluate current situation of the interaction at the disaster museums in Japan, a questionnaire survey
has been carried out. Visitors' feedback has been taken as an example of method of communication
between the museums and the visitors. As the result, it is revealed that 57.6% of the respondent museums
have at least one method that realise interaction between the museums and the visitors. In addition, it isalso revealed that 22.4% of the respondents collaborate with volunteers. This can be understood as anothermethod of mutual communication.

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*S23-P-05
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

How to Facing Disasters? The Meanings of Game-based Disaster Education
Tools* FUHSING LEE , KATSUYA YAMORIKyoto University,Kyoto,Japan
After Japan experienced the 1995 Hanshin earthquake and the 2011 Tohoku earthquake, they realized that
it is important to learn to help themselves rather than rely on government. However, to build empowerment
for facing disaster is still a challenge in communities. The one-way transfer approach in tradition makes
people to remember the right answer but sometimes leads ineffective results. To counter these problems,
we developed the game- based tools of improving two-way dialogue between the public, stakeholders anddecision-makers.
In this study, we have conducted two game-based disaster education tools in fields. The one is a card gamecalled “Crossroad “, which is designed to have players make decisions when faced with difficult choices
under disaster situations. In this study, we also asked players to create their own “Crossroad" for sharing
their disaster experiences. The other one is a smartphone application called “Nigetore", which is apersonal tsunami evacuation drill, it shows success or not when players finished their drills.
For evaluating the achievements of this two games, we analyzed the dialogues between the players andstakeholders when we held the “Crossraod workshop" and “ Nigetore drill “ in Japan, from 2015-2017.
We found out that through “Crossroad", people in communities who concreated their problems
communicated to each other and shared the variety views. Through “Nigetore drill", people understood
the tsunami hazard and considered the tsunami risk by themselves. More importantly, during playing thistwo games, people share their “conflicts" and try to find another idea together. This process makes people
face disaster actively. In conclusion, this study showed a two-way approach for local communities to shapedecision-making and set the agenda.

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*S23-P-06
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Effects of Disaster Structural Understanding on Residents' Behavioral
Intention against Disaster -Case of Kanto Tohoku Heavy Rainfall
Disaster(2015)* Hideyuki KOBAYASHI 1) , Atsushi TANAKA 2)
Meiji University, Tokyo, Japan 1) , The University of Tokyo, Tokyo ,Japan 2)This research aims to reveal effects of disaster structural understanding on Residents' behavioral intention.
In recent studies, some disaster researches which are based on Behavioral Intention Model (Fishbein &Ajzen, 1975; Ajzen, 1991) pointed out that people don't evacuate from disaster at an early stage of disasterdeveloping process.
Tanaka et al.(2013) suggested that this tendency is caused by disaster fragmented understanding and weshould change to disaster structural understanding about disaster developing process. Disaster structural
understanding consider cause and effect relationship about some serial events which compose disasterdeveloping process. If we learn this relationship between events, we can anticipate what will happen by aformer event or information under disaster developing process. But, recent studies have remained raise
this hypothesis and haven't revealed effects of disaster structural understanding on Residents' behavioral
intention.
The author surveyed residents' disaster structural understanding about river flood and their actions against
disaster in Kinugawa river flood caused by Kanto-Tohoku Heavy Rainfall disaster (2015) by a questionnaire
survey for three hundred internet monitor in seven towns as disaster impacted area. All towns are riversideof the Kinugawa River and were at risk of this disaster.
After surveyed, the author categorized respondents for three groups corresponding to their disasterstructural understanding level, as high-level, middle-level and law-level. Results show that high-level andmiddle-level groups get a little disaster information earlier than law-level group. The result of increasing
behavioral intention is similar to getting disaster information.
The author suggests that disaster structural understanding is useful for increasing behavioral intention
against disaster. We should adopt it to education of disaster prevention.

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*S23-P-07
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Practices of the disaster prevention education that incorporated thenecessity of the kindergarten and nursery school* Nobuyuki Yamada 1) , Kaoru Choji 2)
University of Teacher Education Fukuoka, Munakata, Japan 1) , Wakayama University, Wakayama, Japan 2)
We have been performing the practical educations for the earthquake disaster prevention childcare atvarious kindergartens and nurseries in Japan. Based on these activities, we present the results of thedisaster prevention education for infants at some kindergartens and nursery schools in the Osaka andWakayama prefecture, Japan, and the questionnaire findings for their parents and childcare worker after
the practice. These cities are the one of the area where the outbreak of the large-scale disaster caused by
the strong ground motion and the tsunami are driven apprehensive in the near future. Therefore, to grasp
the situation around of the kindergarten for disaster mitigation is an aim of this study. Based on thepractice result of the disaster prevention childcare in such a kindergarten, we are going to improve theearthquake disaster mitigation education for the infants.

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*S23-P-08
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

The Nicoya, Costa Rica, Mw=7.6 Earthquake :A very successful experienceof Scientific and Community organization and Preparation* Shusuke IRABU 1) , Marino Protti 2) , Victor Gonzalez 2) , Douglas Salgado 3)
Japan International Cooperation Agency, Tokyo, Japan 1) , Volcanological and Seismological Observatory of
Costa Rica, National University of Costa Rica, Heredia, Costa Rica 2) , Costa Rica National Emergency
Commission, San Jose, Costa Rica 3)
On October 5th, 2012 a magnitude Mw=7.6 earthquake expectably occurred under the Nicoya peninsula in
NW Costa Rica. In spite of its large magnitude with maximum Intensity VIII of MMI recorded, and its onland occurrence, this earthquake left no casualties directly caused by its shaking and very little damage wasproduced. Given the occurrence of large earthquakes in this segment of the subduction zone in 1853, 1900
and 1950, a dense geodynamic control network of seismic and geodetic instruments was installed, over a
decade before, to capture the incoming large earthquake. Geoscientists kept the population informed of theseismic potential of the region; the mass media was fundamental in getting this information to every cornerof the peninsula. As the stress was building up and this network was recording it, an outreach strategy toprepare the population was carried out by Japanese and Costa Rican emergency planners, together withgeoscientists. This initiative was part of the BOSAI project which focused on dissemination of geoscientificresult to public in earthquake prone area, an International Cooperation project co-funded by the Japan
International Cooperation Agency and the Costa Rica Emergency Commission. As a result of thissuccessful experience geoscientists and emergency officials gained recognition and trust from the public.

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*S23-P-09
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Minna de Honkoku: online transcription project of historical earthquake
documents* Yasuyuki Kano 1) , Yuta Hashimoto 1) , Ichiro Nakanishi 1) , Junzo Ohmura 2) , Tama Amano 1) , Tomoyo
Kuba 1) , Haruno Sakai 1) , Kazuyuki Ito 1) , Yoko Odagi 1) , Makiko Nishikawa 3) , Haruo Horikawa 4) , Kazuya
Mizushima 1) , Ryoichi Yasukuni 5) , Munehisa Yamamoto 6)
Kyoto University, Kyoto, Japan 1) , Bukkyo University, Kyoto, Japan 2) , International Research Center forJapanese Studies, Kyoto, Japan 3) , National Institute of Advanced Industrial Science and Technology,
Tsukuba, Japan 4) , Sumitomo Historical Archives, Kyoto, Japan 5) , Foundation of the Kamoagatanushi Clan,
Kyoto, Japan 6)
We have launched Web-based transcription project “Minna de Honkoku" in January, 2017. The URL is
https://honkoku.org/. “Minna de Honkoku" is also the name for Web application to realize this onlinetranscription project. The study of historical earthquake is based on historical documents. In Japan, almost
all of the documents are written in Kuzushi-ji. Kujzushi-ji is writing style used before ~1900. Since the style
is different from that of modern Japanese, transcription is necessary to use the historical documents as data
for earthquake research. Catalogs of historical records such as "New collection of materials for the historyof Japanese earthquakes" has been published and used for earthquake research. Although huge number ofhistorical documents survives, the majority of the documents left untranscribed. We loaded 114 historical
documents included in the Ishimoto correction in Earthquake Research Institute Library, the University ofTokyo. We planned to start the transcription project with historical document describing past earthquakes
on "Minna de Honkoku," although the application can be used for any type of historical document. "Minnade Honkoku" consists of viewer of document image and vertical (Japanese-style) editor for transcription.
Users can input transcribed texts viewing its image. The ranking of words transcribed is displayed to keep
motivation of users. The edit history and online bulletin board are implemented to enhance communication
between users. The application is inked to Kuzushi-ji Learning Application, KuLA developed by Osaka
University. Transcription has been completed for 29 documents out of total 114 documents in 3 weeks.
Total number of inputted character is about 700,000. To finish the transcription of 114 earthquake-related
historical document is the main goal of the project. In addition, the Web-based project may attract people
who are not interested in local earthquake history and natural disaster.

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*S23-P-10
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

ENGINEERING GEOLOGICAL APPROACHES TO DEAL WITH
GEOHAZARD ASSESSMENT IN SEISMIC TERRITORIES* Mario Luigi Rainone 1) , Giovanna Vessia 1) , Carla Weaver 2)"G. d'Annunzio" University of Chieti-Pescara, Italy 1) , Department of Geological Sciences, California State
University, Long Beach (CA) 2)
The Engineering geological studies carried out in seismic territories are mainly focused on the assessmentof co-seismic hazards. They consist on the following issues: 1)Site effects due to strong motion seismic
events; 2)Liquefaction potential calculation and its numerical prediction; 3)Dynamic characterization ofsoil and rock mass behavior through lab and in situ experimental campaigns; 4)Seismically induced
landslides in soil slopes. Several approaches and methods can be used to tackle the preceding issues
commonly taking place contemporarily at a site. Thus, at those sites where strong earthquakes (with Local
Magnitude ML>5) occur multiple hazard scenarios must be considered, according to the recent
experiences developed in 2009 L'Aquila earthquake, 2010 Canterbury earthquake and 2012 Emilia
Romagna earthquake. For addressing these types of studies multiple types of tools must be performed boththrough experimental and numerical approachesGeophysicists, geologists, geotechnical engineers areneeded to combine expertise and scientific knowledge to contribute to understanding the complex
interdependency among simultaneous effects induced by natural phenomena, such as the elastic wave
propagation from seismic sources placed in the crust.In this contribution, the first issue of the list is
considered. Local seismic response is strongly affected by the surface geo-lithological characters andgeometrical setting of sediments overlapping the seismic “bedrock" (Vessia and Russo 2013,
D'Intinosante and Vessia 2014). This is especially true in “near field areas" (Vessia et al. 2011, Vessia etal. 2016) that is the main character of the Italian Strong Motion seismic events causing heavy economic
losses and several casualties. As an example, the case study of Casentino district (L'Aquila province, Italy)
is hereafter considered to show how multidisciplinary tools are combined within engineering geologicalapproaches to draw amplification maps at urban scales.

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*S23-P-11
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

Integrated Probabilistic Tsunami Hazard Assessment against possible
tsunamis along Nankai Trough, Sagami Trough, and Japan Trench* Kenji HIRATA 1) , Hiroyuki FUJIWARA 1) , Hiromitsu NAKAMURA 1) , Masaki OSADA 1) , Tsuneo OHSUMI, Nobuyuki MORIKAWA 1) , Shin'ichi KAWAI 1) , Takahiro MAEDA 1) , Hisanori MATSUYAMA 2) ,Nobuhiko TOYAMA 2) , Tadashi KITO 2) , Yo'ichi MURASHIMA 3) , Yasuhiro MURATA 3) , Takuya INOUE 3) ,Ryu SAITO 3) , Shin'ichi AKIYAMA 4) , Mariko KORENAGA 4) , Yuta ABE 4) , Norihiko HASHIMOTO 4) ,Tomoya HAKAMATA 4)
NIED,Tsukuba,Japan 1) , OYO,Tsukuba,Japan 2) , KKC,Tokyo,Japan 3) , CTC,Tokyo,Japan 4)
1)

Last years, we presented regional Probabilistic Tsunami Hazard Assessments (PTHAs) for three coastal
zones along Nankai Trough, Sagami Trough, and Japan Trench (Hirata et al., 2014, 2015, AGU; Hirata et al.,2016, SSJ). In three PTHAs, our procedures are follows; (i) we consider all possible earthquakes in the
future, including those that the Headquarters for Earthquake Research Promotion (HERP) of Japanese
Government already assessed. (ii) We construct a set of Characterized Earthquake Fault Models (CEFMs),
for all the possible earthquakes(Toyama et al., 2014, JpGU; Korenaga et al., 2014, JpGU). (iii) For all the
CEFMs, we compute tsunamis by solving a nonlinear long wave equation, using FDM, including runup
calculation, over a nesting grid system with a minimum grid size of 50 meters. (iv) Finally, we gather excessprobabilities for variable tsunami heights, calculated from all the CEFMs, at every observation point along
the coastal zone to get PTHA. We incorporated aleatory uncertainties inherent in tsunami simulation andearthquake fault slip heterogeneity in the integration process(Abe et al., 2014, JpGU).
In this study, we integrate three of the regional PTHAs calculated from all possible earthquakes along
Nankai Trough, Sagami Trough, and Japan Trench to get a nationwide PTHA. We will make two kind of theprobabilistic tsunami hazard map; one is “Present-time hazard map" under an assumption that earthquake
occurrence basically follows a renewal process based on BPT (Brownian Passage Time) distribution. The
other is “Long-time averaged hazard map" under an assumption that earthquake occurrence follows astationary Poisson process. A Present-time hazard map, showing the probability that the tsunami height will
exceed 5 meters at coastal points in next 30 years (starting at 1st January, 2016), suggests high possibility
over 50% along the southern coasts of Shikoku to Tokai region, perhaps due to contribution from the next
Nankai earthquake.

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*S23-P-12
IASPEI Symposium / IASPEI07. Education and Outreach / S23. Geoscience andsociety

What was the difference of local people between the 2016 Kumamoto
earthquake in Japan and the 2009 L'Aquila earthquake in Italy?
* Megumi Sugimoto 1) 2) , Silvia Peppoloni 3) , Yandejia Song 1)
Kyushu University, Fukuoka, Japan 1) , International Association for Promoting Geoethics in Japan,
Fukuoka, Japan 2) , International Association for Promoting Geoethics, Roma, Italy 3)
Japan Meteorological Agency said smaller earthquake will be happen before the main shock of the 2016
Kumamoto earthquake in 14th April. Italian seismologists and officers were found guilty in 2012 for saying
it was safe before the main shock of the 2009 L'Aquila earthquake. Experts mistook foreshocks for main
shocks in the 2016 Kumamoto earthquake in Japan and the 2009 L'Aquila earthquake in Italy, however
local chose different actions. We will introduce analysis of questionnaires survey from local in ourpresentation.
In addition, we point out following six for important lessons for future disaster education:
1. Teachers should inform students “Seismology has taught us a lot, but there is still a lot we don't know.
Earthquake prediction is not impossible today." in disaster education program.
2. It is difficult for human beings to predict events beyond their experience. We need disaster education tolearn living lessons in public schools.
3. It is necessary for students to practice of better decision to survive by themselves through disastereducation program.
4. It is difficult for human beings to make use of lessons from disasters in other countries because of an
instinct for self-preservation that makes them think disasters seldom occur to them and they can survive ifthey occur. We have to try to learn from living lessons of the world.
5. It is difficult for human beings to pass down living lessons to future generations over decades. Teachers
should introduce both good and bad lessons to students from cases in the world.
6. Human beings usually underestimate the danger because they tend to make judgments based on theirown experience. On the other hand, experts tend to avoid risk communication to people for fearing
spreading panic. We have to doubt information underestimated.
We introduce new activities as a step forward in International Association for Promoting Geoethics. We
translate UNESCO English disaster handbook including lessons in Italian and Chinese.

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*S24-1-01
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Thermal properties of mud-dominant sediment from the Joetsu Basin in theeastern margin of the Japan Sea* Shusaku Goto 1) , Makoto Yamano 2) , Sumito Morita 1) , Toshiya Kanamatsu 3) , Akihiro Hachikubo 4) ,Satsuki Kataoka 5) , Manabu Tanahashi 6) , Ryo Matsumoto 6)
National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan 1) , The University ofTokyo, Tokyo, Japan 2) , Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan 3) ,Kitami Institute of Technology, Kitami, Japan 4) , Kobe University, Kobe, Japan 5) , Meiji University, Tokyo,
Japan 6)
Thermal properties (thermal conductivity, heat capacity, specific heat, and thermal diffusivity) of marine
sediment are important parameters for estimating the flow of fluid and heat in sediment and modelingthermal structure below the seafloor. Although many thermal conductivity data on marine sediment havebeen accumulated, there are relatively few studies on heat capacity, specific heat, and thermal diffusivity ofmarine sediment. In this study, we measured thermal conductivity and heat capacity for mud-dominant
sediment recovered from the Joetsu Basin in the eastern margin of the Japan Sea by applying the dualneedle probe method. We also measured physical properties (bulk density and porosity) for the muddominant sediment. Thermal diffusivity and specific heat of the sediment were calculated from themeasured physical and thermal properties. Using the measured thermal properties of the sediment, we
propose empirical formulae for the relationships between thermal diffusivity and thermal conductivity, andheat capacity and thermal conductivity for the sediment in the Joetsu Basin. These relationships aredifferent from those for mud-dominant sediment in the eastern flank of the Juan de Fuca Ridge presented
in previous work. We suggest that the differences of the relationships between these areas are derived froma difference in mineral composition, probably mainly in the amount of quartz, between the sediments inthese areas. This study was financially supported by the MH21 Research Consortium for Methane Hydrate
Resources in Japan.

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*S24-1-02
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Laboratory measurements of rock thermal conductivity and diffusivity bytransient divided bar and pulsed needle probe methods
Thue S. Bording , Soeren B. Nielsen , * Niels Balling
Department of Geoscience, Aarhus University, Aarhus Denmark
For the determination of terrestrial heat flow and regarding any aspect of subsurface thermal modelling,accurate information on rock thermal properties is of vital importance. Several methods are available forlaboratory measurements of thermal conductivity, while fewer are available for thermal diffusivity, andaccurate determinations are not straightforward. We have revisited the classical divided bar and needle
probe methods with methodological improvements to measure thermal conductivity and volumetric heat
capacity simultaneously, and thereby also thermal diffusivity. The divided bar technique is generalised tothe transient case (Bording et al. 2016) and for the needle probe, we apply a pulsed mode. For bothmethods, measured temperature history is fitted by numerical finite element forward modelling, and sample
properties are determined using inverse Monte Carlo analysis. This methodology provides a robust
framework for deriving sample thermal properties with associated uncertainty estimates.
A series of synthetic tests were performed, and both techniques were applied for laboratory measurementsof various materials including different rock samples. The transient divided bar provides excellent
reproducibility and high accuracy. For conductivity the obtained uncertainty may be reduced to 1–3 percent, and for diffusivity to about 3–5 per cent. The main uncertainty originates from the presence ofthermal contact resistance across the internal interfaces in the bar, and they need to be minimized. The
pulsed needle probe yields equally accurate values for thermal conductivity. The determination of highquality values of thermal diffusivity requires a dense sampling of the temperature rise function at earlytimes and a very good contact between probe and sample material.
Bording, T. S., Nielsen, S. B. and Balling, N., 2016. The transient divided bar method for laboratory
measurements of thermal properties. Geophys. J. Int., 207, 1446–1455.

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*S24-1-03
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Thermal petrophysics in application to hydrocarbon reservoir investigations:
Current state of art* Yuri Popov 1) , Evgeny Popov 1) , Evgeny Chekhonin 1) , Denis Gorobtsov 2)
Skolkovo Institute of Science and Technology, Moscow, Russia 1) , Russian State Geological Prospecting
University, Moscow, Russia 2)
Methods and instruments for rock thermal property measurements developed recently and applied ingeothermics have obtained evolution and wide application in investigations of conventional andunconventional hydrocarbon reservoirs. The optical scanning technique provided development of a new
thermal core logging method with continuous non-contact non-destructive high-resolution (0.2-2 mm)
profiling all full sized core samples along a well. The detailed thermal core logging data provide a wellfounded selection of full sized core samples for preparation of core plugs that are studied (1) with a special
optical scanning technique at dry state and after their saturation with brine and oil, and (2) with special
instruments at elevated temperature and pressure. The additional measurements of the rock thermal
properties are performed on small pieces of broken cores with the optical scanning technique if necessary.
The measurements on frozen rock samples are possible. Determination of elastic wave velocities, acoustic
anisotropy, natural radioactivity, density, total organic carbon, porosity, the thermal properties of rockmineral matrix have became possible from the data inferred from the thermal core logging due tocorrelations established between the rock thermal properties and other rock properties. Combination ofthermal core logging and standard petrophysical logging data has allowed determination of geomechanicalparameters – Young's modulus, Poisson's ratio, unconfined compressive strength, etc. – from the newthermal core logging technique results and correlations established. The rock matrix thermal properties canbe determined from the thermal core logging as well as from the measurements on core plugs. The results
are being applied for basin and petroleum system modeling, hydrodynamic modeling thermal methods of
EOR, geomechanical and geochemical modeling, detailed characterization of geological structure ofhydrocarbon reservoirs.

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*S24-1-04
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

A new probabilistic framework to estimate the information content ofindustrial bottom-hole temperature data: A case study using the Australian
OzTemp dataset* Marcus Haynes
Australian National University, Canberra, Australia
The industrial drilling for petroleum and minerals resources can provide extensive datasets of bottom-holetemperature (BHT) measurements. These represent a primary source of data for understanding the thermal
state of the crust. Unfortunately, they are of notoriously low and varied quality. A new framework istherefore presented here to deal with these uncertainties in a probabilistic manner. The framework focuseson two major components of BHT uncertainties; provenance uncertainties, those related to measurement
errors and subsequent correction, and intrinsic uncertainties, those related to data rounding and data entry
error. By building an appreciation for the uncertainties inherit in BHT measurements, we are able toestimate the information provided by each datum on the true subsurface temperature.
A compilation of international, data-driven studies is used to identify the broad range of biases inherit inuncorrected BHT measurements, as well as the precision of corrected, drill string test, and equilibrium BHT
measurements. To identify the degree and magnitude of data-rounding, a novel approached is developed
based on a logical appraisal of the statistical characteristics expected of an unadulterated dataset.
Deviations from these expectations reveal the scope of human intervention in the raw data. Synthetic
testing suggests that it is possible for this method to accurately estimate both the degree and magnitude ofpotential data-rounding errors in BHT datasets.
Finally, the framework is applied to examine OzTemp, the Australian industrial BHT dataset. The results
identify data rounding to the nearest 5* and 10*C, as well as to the nearest 2*, 5* and 10*F. Individual
probability density functions can be created to describe the uncertainty between any BHT datum and thetrue virgin rock temperature. This framework thereby enables higher levels of precision and accuracy in theinterpretation and analysis of BHT measurements than has been previously achieved to date.

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*S24-1-05
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

In-Situ Optical Scanning* David Sauer , Moh'd Amro , Steffen Wagner , Frederick Rose
Technical University Bergakademie Freiberg, Freiberg, Germany
Knowledge about the thermal conductivity of rock is essential for accurate design of geothermal plants.
Thermal conductivity can be measured in situ, with low precision and coarse spatial resolution, or in alaboratory, where samples are subject to altered conditions and represent only limited sections of theborehole. We developed and evaluated a new technology involving fast, high-resolution and high precision
scanning of in-situ thermal conductivity within boreholes. The prototype demonstrated the feasibility of thetechnology for shallow geothermic wells, with an accuracy of 10%.
The probe is designed for use in open-hole areas of a well. It is fixed and adjusted by a packer system,
which consists of fixing, measuring, and centralizing packers (outer casing). Optical sensors are placed in
an inner casing in the measuring packer. Pneumatic inflation of the measuring packer purges liquid/mudfrom the measuring interval; thus, optical scanning is possible in mud filled boreholes. Optical scanning is
operated parallel to the borehole axis. A laser heats up the foil of the measuring packer from the inner side,and the heat is transferred to the rock formation by conduction. The laser moves with constant velocity
along the profile. An infrared camera and triangulation tool are mounted at a fixed distance to the laser, sothat the surface structure and corresponding thermal tail of the wall are scanned. Subsequent dataprocessing leads to the thermal conductivity of the borehole. The probe algorithm enables automatic
measurements and corrects for profile and packer rubber foil effects.
Prospecting, the technology can be used in intermediate and deep wells. Furthermore the theories
according to Prof. Yuri A. Popov can be applied to measure thermal diffusivity and anisotropy. The toolshows that a tomographic thermal conductivity scanning with shallow penetration depth is possible. Thus, afilter cake and layers of altered rock can be distinguished from original rock.

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*S24-2-01
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

The structure of free thermal convection flows in water filled boreholeinferred from a laboratory experiment* Dmitry Demezhko , Bogdan Hatskevich , Mansur Mindubaev
Institute of Geophysics, UB RAS, Yekaterinburg, Russia
One of the main methods of geothermics is temperature measurements in water filled boreholes.
Development of modern equipment provides high accuracy, stability, spatial and temporal resolution oftemperature measurements and significantly expands the geological applications of borehole temperaturedata. However, the capabilities of these applications often cannot be fully realized due to the effect of freethermal convection (FTC) of the liquid in the wells. The non-stationary character of FTC leads totemperature variations, which represent a significant source of errors in conducting high-precision
temperature measurements.
A new experimental lab method for studying the structure of FTC flows in conditions approached to theborehole's one has been developed. The methods based on infrared thermography of temperature
anomalies appearing on the outer walls of the vertical water-filled ceramic pipe, where conditions of FTC
are maintained. Upward flow of air from the toroidal heater produces temperature gradient on the outerwall of the pipe. The experiments have shown that when the critical Rayleigh number is slightly exceeded(Ra = 290 - 1000) the flows of thermal convection constitute a system consisting of 2 - 4 helical jets,
rotating around a vertical axis. At inner pipe's diameter of 20 mm the helical pitch varies from 140 to 300
mm. Angular velocity of rotation increases from 4 E-3 to 25 E-3 rad/s while Rayleigh number grows from
290 to 1000.

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*S24-2-02
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Geothermal field under development: monitoring using unmanned aerial
vehicle (UAV)* Sergey Cherkasov 1) , Anvar Farkhutdinov 2) , Arbi Shaipov 3)
Vernadsky State Geological Museum of RAS (SGM RAS) 1) , Bashkir State University (BSU) 2) , Grozny State
Oil Technological University (GSOTU) 3)
Development of a geothermal reservoir requires a system of wells, pipelines and pumping equipment.
Management and monitoring of such system is quite complicated, so, in 2016, a Geoscan 201 unmanned
aerial vehicle (UAV) equipped with regular and infrared imaging cameras was used for a survey of the
Khankala geothermal field (Chechen Republic, Russia). The reservoirs of the geothermal field are being
exploitated with a number of old wells and a newly built (2015) doublet and Khankala Heat Geothermal
Plant (KHGP). The survey's goals were: (a) – to locate the leaks of the old wells and pipelines, (b) – tocompare an environmental impact of KHGP with and without reinjection of the geothermal fluid, and (c) –to evaluate a capacity of UAV-based monitoring methods for geothermal sites. As a result of the survey: (a) 13 thermal anomalies have been allocated in the area of about 10 sq.km. Analysis of the anomalies
facilitated determination of their sources: fire, pipelines, leaking wells, etc., which was confirmed by aground check; (b) – temporal and spatial parameters of the heat pollution originated from KHGP without
the fluid's reinjection have been evaluated; and (c) - a high potential of UAV surveys for environmental andtechnological monitoring of geothermal fields under exploitation, and/or development have been revealed.
The evaluation of the heat pollution has been studied on the basis of two UAV surveys executed withdifferent regimes of the KHGP's exploitation. As a side effect, possibilities of using the plant as anexperimental stand should be underlined taking into count high-level KHGP technologies facilitating the
doublet, heat-exchangers, and the regime of the whole geothermal loop management.

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*S24-2-03
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Determination of formation equilibrium temperature and geothermal
gradient from temperature measurements in production wells drilled in oil
and gas fields
Rim Valiullin 1) , Ayrat Ramazanov 1) , * Guzel Vakhitova 1) , Ruslan Akchurin 1) , Yuri Popov 2)
Bashkir State Univ., Ufa, Russia 1) , Skoltech, Moscow, Russia 2)
Several ways to determine the parameters of geothermal field according to the temperature measured in
the wellbore are known. One of them is the measurement of temperature along the borehole of special
wells (control, piezometric). There is a way based on the registration of non-stationary temperature in theborehole after drilling. The idea of the third method consists of the reservoir fluid flowing temperature isrecorded as a function of time during the well test. All these methods have known disadvantages and they
can be used only in a small number of wells on the interested oilfields.
We have proposed a method of determining the equilibrium temperature of rocks and geothermal gradientfrom the measured temperature distribution in the producing wells. These measurements are carried out inlarge numbers on the being developed oil and gas fields. If the well has a sufficiently long sump (forproducers it is more than 10 meters), then near the bottom there is zone with undisturbed geotherm.
Rocks equilibrium temperature in this range can be determined with a predetermined accuracy by solving
the inverse problem with regard to the speed of device movement and the thermal inertia of sensor. CFD
modeling, laboratory experiments and analysis of downhole measurements made it possible to investigate
the influence of confounding factors: conductive heat transfer from the working reservoir, a metal casing,free heat convection in the borehole on the distribution of temperature in the sump. Algorithm forcorrecting the measured temperature along the wellbore is developed. Data on the vertical variation of thethermal properties are used to restore the equilibrium temperature of the rocks outside the borehole sumpinterval. The paper presents practical examples of using the developed method for the determination of therocks' equilibrium temperature, geothermal gradients and deep heat flux on the Russian oilfields.

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*S24-2-04
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Long-term measurement of 1m-depth geo-temperature and its relationshipwith ambient temperature change* Osamu Matsubayashi 1) , Sachio Ehara 2)
National Institute of Advanced Industrial Science and Technology 1) , Institute for Geothermal Information2)

It was in 1951 that a group of geophysicists working on hotsprings completed a very good compilation of
1m-depth subsurface temperature data through four seasons at many locations in Japan. After a long timeof lack of such kind of data, a new project has been put forward by Ehara in 2012 to restart systematic
measurements of geo-temperature at 1m-depths with a standardized simple thermometer system, intending
to observe the long-term change of earth's surface temperature and to look into the evidence of global
warming as well as that of heat-island phenomena in the Japanese territory. Within the Kanto Plain area
where the latter effect is considered the strongest in the world, we have currently 8 stations for long-term
measurement.
The focus of this paper is to examine the change of geo-temperature at 1m-depth as time-series, trying toestimate the thermal property of each measurement site from the relationship between the geo-temperaturechange at 1m-depth and its major thermal driving force, i.e., ambient atmospheric temperature. Its
mathematical formulation has been given in textbooks on geothermics. We can see a clear correspondence
between the time-series of 1m-depth geo-temperature which we really observed and that of daily averaged
air temperature at the same location, with a certain delay-time. Based on the delay-time and also theamplitude attenuation, we estimate the Effective Thermal Diffusivity (ETD) of the materials beneath theground surface using the Angstrom method. By picking up variation components having periods of 10 to 20
days, the estimated ETD values range from 3.5 to 7.0 E-7 m**2/s. For longer-period components, such as
the annual variation, our observation duration up to now might not be long enough yet. The obtained
values of ETD, as well as those of annual mean 1m-depth geo-temperature derived from our work, would
also be useful in other studies of geothermics, like the inversion of past climatic change based on deep
borehole observation.

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*S24-2-05
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Long-term observations of pressure, temperature and flow rate for deep-sea
hydrothermal fluid at the middle Okinawa Trough.
* Yuka Masaki , Tatsuo Nozaki , Masayuki Watanabe , Tomokazu Saruhashi , Masanori Kyo , Noriaki Sakurai, Takahiro Yokoyama , Keita Akiyama , Lena Maeda , Hidenori Kumagai
JAMSTEC, Kanagawa, JapanThe middle Okinawa Trough locating along the Ryukyu-arc has several active seafloor hydrothermal fields.
Cruise CK16-01 by D/V Chikyu targeted the Iheya-North and Noho hydrothermal fields to comprehend subseafloor geological structure and polymetallic mineralization. In this cruise, we installed the Kuroko
cultivation apparatus that can monitor fluid pressure, temperature and flow rate of the artificialhydrothermal vent.
In February 2016 during Cruise CK16-01, two Kuroko cultivation apparatuses equipped with P/T sensor,
flowmeter and load cell were installed at Holes C9017B and C9024A. In January 2017 during Cruise
KR16-17 , two cultivation cell parts including sensors were recovered by ROV Kaiko Mk-IV and R/V Kairei .
In this study, we report long monitoring data of hydrothermal fluid for more than 10 months at two deepsea artificial hydrothermal vents.
Hole C9017B at the Noho site, fluid temperature was constant for 5 months from the beginning of the cell
deployment. Then, temperature became decreasing from 75 to 40oC gradually. The day and monthly
periodic transition of temperature (the amplitude was ca. 0.3 - 0.5oC) induced by tidal wave was found.
Among such periodicity, high temperature peaks coincided with low pressure peaks. Drilling operation atHole C9017A which is 10 m away from Hole C9017B during Cruise CK16-05 in November 2016 would
have influenced subseafloor hydrology and induced sudden temperature and pressure drops.
Hole C9024A at the Iheya-North site, pressure, temperature and flow rate also changed periodically withtidal wave, and maximal and minimal points of flow rate were concurrent with those of temperature. The
maximum temperature reached 308oC, which is similar to the value obtained from the ROV thermometer(311oC) at the Iheya-North field. The average flow rate of hydrothermal fluid was ca. 300 L/min and, 9 days
later, flow rate became zero, suggesting that the impermeable minerals sealed top of the cultivation
apparatus.

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*S24-P-01
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Thermal properties of sedimentary rocks for the Tarim Basin, northwest
China* Shaowen Liu 1) 2) , Xianglan Li 1) 2) , Changge Feng 1) 2)
Nanjing University, Nanjing, China 1) , Key Laboratory of Coast and Island Development, Nanjing
University, Nanjing, China 2)
Thermal properties of rocks are essential parameters for investigating geothermal regime of thesedimentary basins, also playing an important role in hydrocarbon and geothermal energy resources
assessment. Tarim Basin that locates at northwest China, just north of the Tibet Plateau, has shown greathydrocarbon resource potential, and is the ongoing target for industry exploration. However, systematic
measurement of thermal properties of sedimentary rocks for the Tarim Basin is still rare, making theunderstanding of thermal regime of this basin not well. Herein we collected 114 samples of sedimentaryrocks from this basin and measured their complete thermal properties. Our results show that the ranges(and means) of the thermal conductivity, radiogenic heat production, and specific heat capacity are from1.000 to 3.000W/m.K (2.446 W/m.K), 0.027 to 2.500 HPU (1.210 HPU), and 0.75 to 1.10 kJ/ (kg.K) (0.863
kJ/ (kg.K)), respectively. The calculated volumetric heat (or thermal) capacity and thermal diffusivity fallwithin the ranges from 1.61 to 2.79 MJ/ (cubic meters·K) (2.26 MJ/ (cubic meters·K)) and from 0.22 to 3.05
unit (1.11 unit), respectively. In addition, it is found that these thermal properties show great differences invarious lithologies; even within the same lithology, the values scatter much. This indicates that the thermal
properties cannot be used to distinguish lithology alone in practice. The thermal conductivity increases
with increasing burial depth and stratigraphic age, suggestive of the influence of change in porosities onthermal conductivity. The specific heat capacity increases with the elevated temperature from 40 to 100
degree Celsius. Furthermore, strong contrast in thermal properties between salt and other common
sedimentary rocks would obviously distort subsurface temperature pattern, which should be taken into
consideration in basin modelling.

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*S24-P-02
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Repeated borehole temperature logs: climate or anthropogenic impact?
* Vladimir Cermak , Petr Dedecek , Jan Safanda , Milan Kresl
Institute of Geophysics, Czech Academy of Sciences, Prague, Czech RepublicMore than two decades of the activities of the Borehole Climate Observatory of the Institute for Geophysics
in Prague clearly proved that the local urban climate gets substantially warmer by more than 2 K since1993. A 150 m deep borehole, part of the observatory, has been repeatedly logged since then to trace thecorresponding time changes in the subsurface temperature field. Transient components of the individuallogs yielded by the functional space inversion (FSI) indicated a strong impact of the down penetrating(climate) warming. Its magnitude exceeded 1.3 deg.C at 20 m below the ground surface and reached 0.7
deg.C at 40 m and 0.15 deg.C at 80 m within years 1993 through 2016. The individual temperature logs
were inverted into ground surface temperature (GST) histories, compared with the history yielded by asimultaneous inversion of all obtained logs. Their variations were confronted with the results of the surface
air temperature monitoring as well as with the records of the nearby meteorological station. Special
attention was paid to the analysis the surface temperature offset, the difference between the near surface
air temperature and the “skin" surface temperature. The monitored ground surface temperature series
were further used as the forcing function to model the corresponding temperature-depth distribution andthe resulting time-variable geothermal models were compared with the measured data. It was proved thatthe observed warming must have been sizeably affected by the terrain alternations and by an effect of newbuilding erected nearby. Some 30-40 per cent of the observed warming can be attributed to the humanactivities in the direct vicinity.

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*S24-P-03
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Determination of formation equilibrium temperature from unsteady
temperature measurements in wells under drilling
Ruslan Akchurin 1) , * Ayrat Ramazanov 1) , Rim Valiullin 1) , Yuri Popov 2)
Bashkir State Univ., Ufa, Russia 1) , Skoltech, Moscow, Russia 2)
The temperature distribution recorded in wells corresponds to the equilibrium temperature distribution
only the measurements were performed in shut-in wells. In practice the temperature measurements areusually performed in scientific, control, piezometric and idle production wells. To determine theequilibrium temperature of rocks after well drilling completion it is necessary to wait for a long time before
the well reaches shut-in state that is possible in very rare cases only.
We have proposed a method of determining the equilibrium temperature of rocks from the unsteady
temperature recording within some time interval in a well at drilling breaks or after drilling completion.
Determination of the equilibrium temperature is based on the solution of the inverse problem using thedeveloped simulator. The simulator allows to calculate the model temperature distribution in drilling
wellbore, provides accounting for spatial variations in rock thermal properties and allows to take into
account the history of parameter during the well drilling, such as drilling speed, flow rate and temperature
variations of the mud at the wellhead. Recording the temperature variation T(t) in the borehole at aparticular depth H versus impermeable zones after drilling completion and comparing it with the model
temperature Tm(t), calculated using the simulator for different functions of the equilibrium temperature
TG(H), allows to determine the equilibrium temperature of the rocks. The mathematical model developed
provides modeling the temperature distribution during the drilling process. Results of the sensitivity studyof the model describe the model sensitivity to the uncertainties in the input data. The calculations of theformation equilibrium temperature from the unsteady temperature data recorded in the well after the
drilling completion were performed.

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*S24-P-04
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Temperature and heat-flow calculations: about the benefit of well-log based
thermal-conductivity profiles
Sven Fuchs 1) , Niels Balling 2) , * Andrea Foerster 1)
GFZ German Research Centre for Geosciences, Potsdam, Germany 1) , Aarhus University, Aarhus, Denmark2)

The calculation of temperature and heat-flow-density profiles in boreholes requires reliable values of rockthermal conductivity with depth. We developed a new approach for the indirect determination of thermal
conductivity from standard geophysical well logs, which massively enlarges the available databases ofsubsurface rock conductivities beyond the usual drill core measurements. This approach results in a new
set of predictive equations which overcomes the common limitation of empirical equations to specific rocktypes or to the region for which they were originally developed.
The new set of prediction equations is universally applicable for all major types of sedimentary rocks(clastics, carbonates and evaporites) and allows calculating continuous thermal-conductivity profiles fromdifferent combinations of standard geophysical well-logs (i.e. density, hydrogen index, sonic interval transit
time, gamma-ray response, photoelectric factor). The combination of three to five well-log parameters
results in absolute predictions uncertainties of <15% on a synthetic test data set and of <20% on
benchmark laboratory data (Fuchs et al., 2015). However, mean values for geological formations upscaled
from laboratory data can be fitted by well logs with uncertainties of approx. 5-7%.
Based on borehole conductivity profiles from various boreholes, we demonstrate the calculation oftemperature and heat-flow profiles with absolute errors <3 degC compared to measured temperature logs
along boreholes of several kilometers length.

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*S24-P-05
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Geotherms of the continental crust: ambiguity from experimental P–T
correction to thermal conductivity* Andrea Foerster , Sven Fuchs , Ben Norden , Hans-Juergen Foerster
GFZ German Research Centre for Geosciences, Potsdam, Germany
Calculation of geotherms, reflecting steady-state heat conduction, is dependent on surface heat flow, thecompositional model of the crust, and its thermo-physical properties, such as thermal conductivity (k) andradiogenic heat production (H). Available global geotherms are afflicted with uncertainties associated withthe simplification of the crustal model, e.g. from dividing the crust into an upper and a lower crust. Here we
address uncertainty in geotherm construction that arises from ignoring the mandatory correction of k forpressure (P) and temperature (T). For this purpose, published P-T relations derived from laboratory
experiments up to T of 800 degC and performed with physical-contact methods are applied in geotherm
calculation, considering different crustal models. The single P and T correction equations are used in a
combined approach. The generalized conceptual geotherm model discussed here considers a surface heatflow of 60 mW/m² and a 35 km-thick crust consisting of a 16 km-thick granitic upper crust (k 3.0 W/m/K; H
1.5 microW/m³) and a granulitic lower crust (k 2.6; H 0.45), which is a scenario used in pioneering works
on global geotherms in the 1980s and 1990s. P-T relations applied to k are those developed for typicalupper crustal (granitic) and lower crustal (granulitic) rock types. Using those rock-specific relations, T at
the Moho would amount to 570+/-15 degC. This Moho T is higher by 40 degC compared to earlier work inwhich some generalized P-T relation to k is applied (Chapman, 1986; Chapman & Furlong, 1992). The
difference to Moho T uncorrected for k is more substantial, on the order of 80 degC. Results imply that thecrust is warmer if experimental results on P-T relations to k are considered in geotherm parameterization.
The difference between corrected and uncorrected geotherms become more serious for higher surface heatflow and for compositionally more diverse, i.e. closer-to-reality crust, and may well exceed 100 degC.

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*S24-P-06
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Thermal conductivity variation of granites at elevated temperatures* Labani Ray , N. Narshimha Naidu , Varun Kumar , Nishu Chopra
CSIR-National Geophysical Research Institute, Hyderabad
The knowledge of the downward variation of thermal conductivity (TC) within Earth's interior is an
important key parameter to estimate the sub-surface temperature distribution accurately. The depth wise
variation is dominantly controlled by temperature and to less extent by the pressure. In the present study,
we have measured thermal conductivity (TC) variation with temperature for 20 granite rocks from the
Bundelkhand craton (BC), central India, one of the oldest cratons in the Indian shield. The BC
predominantly consists of granites and gneisses, covering 80% of its areal extent. In this craton, granites
exhibit three different varieties based on their geochemical composition.
Measurements are carried out in the laboratory using a steady-state apparatus (guarded heat flow meter,
DTC-300) in the temperature range 25 to 300 oC. Thermal conductivity is measured at an interval of 25 oC
between 25 and 100 oC and 50oC between 100 and 300 oC. Studied temperature range corresponds to aupper to middle crustal scenario. We found that for the three varieties of the granites, TC at room
temperature varies between 2.3 and 3.4 W/m/K whereas TC at 300 oC varies between 1.9 and 2.2 W/m/K.
Drop in thermal conductivity in the studied temperature range is significant (10 to 30%) for the all types of
granite rocks. Also, this variations in TC are distinctly different among all the three varieties of granites.
Moreover, within each type of granite, the drop in TC with temperature is dependent on their TC at room
temp. Thus, the observed large variation in thermal conductivity with temperature indicates that thesystematic study of thermal conductivity variation with temperatures for granites is essential for precise
estimation of the sub-surface thermal regime.

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*S24-P-07
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

FEATURES OF THE TEMPERATURE RECOVERY IN WELL AFTER STOPOF INJECTION/PRODUCTION IN CASE OF RESERVOIR WITH
HUDRAULIC FRACTURING
Artyom Sharipov 1) 2) 3) , * Ramil Sharafutdinov 1) 2) 3) , Rim Valiullin 1) 2) 3) , Ayrat Ramazanov 1) 2) 3)
Bashkir State University 1) , Ufa 2) , Russia 3)
At the present time problem of temperature field changes in reservoir with hydraulic fracturing is very
interesting. The knowledge of the geothermal temperature distribution is very important for interpretationof temperature. For this reason, analysis of temperature recovery process after stop of injection/production
in case of reservoir with hudraulic fracturing is necessary. In this work analysis of temperature recovery
process are made using numerical modelling. Modelling of temperature changes are made with consideringof Joule-Thomson and adiabatic expansion effects, convective and conductive heat transfer. The influenceof the length, width of fracture on temperature recovery process are studied. It is shown that the presenceof a hydraulic fracture in the formation reduces the recovery time of the temperature in the well.

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*S24-P-08
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

ACQUISITION OF INTEGRATED PETROPHYSICAL DATA FROMTHERMAL CORE LOGGING AND THERMAL CORE PLUGINVESTIGATION FOR USINSKOYE HEAVY OIL FIELD
Evgeny Popov 1) , * Yuri Popov 1) , Evgeny Chekhonin 1) , Egor Savelev 1) , Ekaterina Nozdryakova 1) , Irina
Gurbatova 2)
Skolkovo Institute of Science and Technology 1) , PermNIPIneft, LCC Lukoil-Engineering 2)
The integrated approach to investigations of the Usinskoye heavy oil field (Timano-Pechora province,
Russia) was applied. A continuous high-resolution profiling of rock thermal properties (thermal
conductivity, volumetric heat capacity, thermal anisotropy coefficient) on all cores (more than 3 000
samples) recovered from two wells was combined with (1) the thermal property measurements on standard
core plugs (1x1“, more than 300 samples) in four core plug states successively (as-received state, dry,brine- and oil-saturated samples), and (2) processing the thermal property data jointly with the standard
petrophysical logging data. The optical scanning technique was used for all thermal measurements on fullsized cores and core plugs. The results of high-resolution thermal profiling allowed detailing the porosity
variations up to scale of 5 mm. Variations of rock mineralogical composition were defined more accuratelyfrom inverse problem solution. Possibilities to determine detailed vertical variations in elastic wave
velocities and rock density were established and used for estimation of rock geomechanical parameters
and their detailed variations along the wells. The data inferred from thermal core logging and thermal
measurements on core plugs provided detailed variations in the thermal properties of rock matrix along thewells. The data are necessary for basin and petroleum system modeling, study of formation geologicalstructure, modeling heat and mass transfer processes in reservoirs at thermal methods of enhanced oil
recovery, development of technologies for heavy oil recovery, geomechanical modeling, interpretation oftemperature monitoring data during the reservoir heating and heavy oil production.

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*S24-P-09
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S24. M
ethods and instruments of experimental geothermics – Application and recent evolution

Effect of water saturation on the electrical impedance and elastic wave
velocity of geothermal reservoir rocks* Kazuki Sawayama 1) , Keigo Kitamura 2) , Yasuhiro Fujimitsu 1)
Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan 1) , International Instituteof Carbon Neutral Energy Research, Kyushu University, Fukuoka, Japan 2)
The estimation of underground water saturation is essential in geothermal fields, particularly for anenhanced geothermal system (EGS). Recently, electromagnetic exploration using magnetotellurics (MT)
has been applied to the geothermal fields for estimating water saturation. However, the relationshipbetween the electrical impedance obtained through this method and the water saturation in the reservoir
rock has not been well known. Our goal is to elucidate this basic relationship via laboratory experiments. In
the fluid-flow test, at first, reservoir rock samples were filled with nitrogen gas, which emulates thesuperheated steam observed in the geothermal fields. Then, brine was injected into the samples and its
injection pressure was increased and decreased to vary the water saturation in the samples. During thetest, water saturation, permeability, electrical impedance (at a frequency of 10m-100K Hz) and elastic wave
velocity were measured. As a result of fluid-flow test on andesite (Makizono lava formation, Japan), theelectrical impedance dramatically decreased from 100K to 1K Ω because of the brine injection. This
remarkable change could be due to the replacement of pre-filled nitrogen gas with the brine. After the brine
injection, the electrical impedance decreased with increasing injection pressure (small changes in water
saturation) by up to 40%. In the pressure-decreasing phase, the electrical impedance increased withdecreasing injection pressure and this electrical impedance was smaller than that observed in the pressureincreasing phase (up to 27%). However, the P-wave velocity was almost constant (less than 1%) at that time.
These results indicate that the electrical impedance varied with small changes in water saturation in thepressure-decreasing phase, whereas P-wave velocity did not show any variations. In other words, thissuggests that electrical impedance could be sensitive to minor changes in water saturation compared with
P-wave velocity.

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*S25-1-01
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S25. D
evelopment and application of geothermal databases

Reference framework for crustal geotherms, with constraints based onseismic data for the lower crust* Valiya Hamza 1) , Carlos Alexandrino 2)
National Observatory, Rio de Janeiro, Brazil 1) , Univeristy of VJM, Teofilo Otoni, Brazil 2)
In the present work, we consider the possibility of setting up a reference framework for crustal geotherms,
as a useful tool in comparative studies of heat flow in different tectonic settings. The essence of theprocedures for crustal geotherms has already been discussed in many of the earlier geothermal studies, but
its implications for setting up a global framework has not so far been explored. Geotherms considered in
the present work are based on analytical solution to the standard heat conduction problem in stratified
media, coupled with empirical relations between seismic velocities and temperatures at the crust-mantle
interphase. Iterative trial and error methods has been employed in establishing successful coupling. A
major advantage of this approach is that estimates of deep crustal temperatures may be obtained that are
relatively free from the perturbing effects of petrological complexities in the upper crust. It also minimizes
uncertainties in downward extrapolation of main model parameters. Results of initial tests, carried out for
selected sites in stable continental settings, are found to be in broad agreement with indirect estimates oftemperatures obtained in deep crustal studies. Another major aspect of this new approach is that it allows
estimation of crustal temperatures and mantle heat flow that has connecting links with seismic data, which
is useful in comparative evaluation of geotherms across different tectonic settings. The reference frame
works for geotherms could serve as a useful supplement to existing IHFC database.

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*S25-1-02
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S25. D
evelopment and application of geothermal databases

Thermal data beneath in and around Japan: What we know and do not yet
know* Akiko Tanaka
Geological Survey of Japan, AIST, Tsukuba, Japan
Surface heat flow provides important constraint on the thermal and chemical evolution of the Earth.
General pattern of heat flow distribution in and around Japan had been revealed by the early 1970s, andheat flow data have been continuously updated and improved by adding data. However, the number of heatflow data is limited and spatially very inhomogeneous. To provide an attempt at a higher resolution map ofheat flow, thermal conductivities are measured using sampled cores and used from existing and newly
collected data. Also since we have published a CD-ROM “Geothermal Gradient and Heat Flow Data in andaround Japan" [Tanaka et al., 2004], new data are provided. We plan to update the database including
thermal properties.
Meanwhile, there exist many indicators that are proxies for quantifying the thermal structure. One of thepromising indicators is the cut-off depth of shallow seismicity. Several studies have been conducted toassess the inverse correlation between the cut-off depth and heat flow, since it has attributed primarily tothe temperature. Another indicator is the depth of magnetic sources based on spectrum analysis ofmagnetic anomaly data. This analysis is still controversial, however, good correlation between estimateddepths of crustal magnetic sources and heat flow suggests that this depth may reflect the broad averagetemperature. We address the advantages and limitations of each data and method.

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*S25-1-03
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S25. D
evelopment and application of geothermal databases

Mapping the continental surface temperature of Australia: the surface
boundary condition for conductive thermal models* Marcus Haynes 1) , Frank Horowitz 2) , Malcolm Sambridge 1) , Ed Gerner 3) , Graeme Beardsmore 4)
Australian National University, Canberra, Australia 1) , Cornell University, Ithaca, United States of America
2), Geoscience Australia, Canberra, Australia 3) , Hot Dry Rocks Pty Ltd, Melbourne, Australia 4)
The mean crustal surface temperature represents an important boundary condition for many geothermal
studies. This boundary is particularly important to help constrain the information provided by bottom-holetemperature measurements made in mineral and petroleum boreholes, many of which are shallow innature, observing relatively small changes in temperature from surface to depth. Onshore, this boundary
represents the mean land-surface temperature. A mean land-surface temperature map of the Australiancontinent has therefore been produced from 13 years of MODIS satellite imagery, for the period
2003-2015. The map shows good agreement with independent methods of estimating average land-surface
temperature, including borehole surface-temperature extrapolation and long-term, near-surface groundmeasurements. The MODIS-based method provides spatially continuous estimates (1km pixels) of landsurface temperature and can be employed in regions free from seasonal ground cover of snow. Offshore,
this boundary represents the mean sea-floor temperature. A mean sea-floor temperature map of the region
surrounding the Australian continent has therefore been produced from models of pelagic temperaturedata. The mean thermocline observed through each pixel in these models is extrapolated to sea-floor depth.
The use of pelagic temperature models also enables spatially continuous temperature estimates (1/8
degree pixels on-shelf, 1/2 degree pixels across the abyssal plain), that will be applicable throughout theworld's oceans. When examined in the context of an extensive real-world bottom-hole temperature dataset,the new maps diminished thermal gradient values up to 10% compared to previous methods.

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*S25-1-04
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S25. D
evelopment and application of geothermal databases

Energy Budget of the Global Lands in the Course of Recent Climate Change* Shaopeng Huang 1) 2)
Xi'an Jiaotong University, Xi'an, Shaanxi, China 1) , University of Michigan, Ann Arbor, Michigan, USA 2)
Ground surface temperature variation imposes transient perturbation to the steady state of the thermal fieldof the uppermost crustal layer, hence, impacts the energy flux across the ground surface. In this regard,
continental lithosphere is an important regulator of the energy budget of global climate system. Greatefforts have been devoted to detect and attribute the heat content changes of the global oceans andatmosphere. Less well understood is the extent of subsurface warming of the global lands. I examined theannual heat content change of the continental landmasses over the period from 1850 to 2015 based on
meteorological records. Result shows that the rocks beneath 30% of the globe has absorbed 19 ZJ (10^21
Joules) of thermal energy since the beginning of the 20th century global climate warming, more than twice
as much thermal energy as the entire atmosphere has absorbed. The calculated subsurface temperature
anomalies are consistent in general with the anomalies recorded in more than 1000 borehole profiles of
the global database of borehole temperatures for climate reconstruction. I further extended the analysis toYear 2100 under three climate scenarios: a business as usual scenario of continuation of the recent
warming trend, a climate stabilization scenario with ground surface temperature maintaining at the current
state, and an energy freeze scenario of halting the ground surface energy flux. If the observed global
warming trend over the 25 year period (1991-2015) is to continue at 2.89K/100a, an additional 51 ZJ ofheat will be trapped underground by the end of the 21st century. Even if the global surface temperature is
to stabilize at the current state throughout the rest of the 21st century, the continental landmasses willcontinue to acquire over 15 ZJ extra energy from the atmosphere. An overall 0.72 K cooling at the global
ground surface between 2016 and 2100 is required to avoid further heating of the continents.

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*S25-1-05
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S25. D
evelopment and application of geothermal databases

Development of geothermal studies in Uzbekistan* Irina Sidorova
Institute of Geology and Geophysics, Tashkent, Uzbekistan
A high variability of Heat Flow Density (HFD) is typical for the territory of Uzbekistan. The statistics showthat the HFD changes in a wide range from 18 mW/m2 (the site Karamurum in the Central Kyzylkum) to
207 mW/m2 (well Jarkamar in NW Ferghana). Several zones with a thermal flow as high as 100 mW/m2
are distinguished in the SW spurs of the Gissar and Surkhandarya depression. In the Central Kyzylkum,
there are 60 points for the determination of HFD, mainly in ore deposits. The limits of changes in the HFDvalues vary from 18 (site Karamurun) to 90 mW/m2 (deposit Muruntau). Geothermal data such as
terrestrial heat flow, temperature gradient and rock thermal properties as thermal conductivity, heat
capacity and radiogenic heat production rate of rocks have been investigated by the author (patent Heat
Flow_DataBase BGU00339Uz).Laboratory studying of thermophysical properties of rocks. In our laboratory
during long-term develop study of thermophysical properties of rocks. On the base of obtained data andraster pictures of distribution of elements in the sample, received on microanalyzer JXA-8800R JEOL thecomputer program PercolationCheck (the patent DGU 01170Uz) intended for calculation of percolation –high thermal conductivity process in rocks has been developed.

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*S25-P-01
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S25. D
evelopment and application of geothermal databases

Temperature and heat flux changes at the base of Laurentide Ice Sheetinferred from geothermal data (evidence from province of Alberta, Canada)* Dmitry Demezhko 1) , Anastasia Gornostaeva 1) , Jacek Majorowicz 2) , Jan Safanda 3)
Institute of Geophysics UB RAS, Yekaterinburg, Russia 1) , Department of Physics, University of Alberta,
Edmonton, Canada 2) , Geophysical Institute, AS CR, Prague, Czech Republic 3)
Using a previously published temperature log of the 2363 meter-deep borehole Hunt well (Alberta, Canada)
and the results of its previous interpretation, the new reconstructions of ground surface temperature (GST)and surface heat flux (SHF) histories for the last 30 ka have been obtained. Two ways to adjust thetimescale of geothermal reconstructions are discussed, namely the traditional method based on the a priori
data on thermal diffusivity value, and the alternative one including the orbital tuning of the surface heat
flux and the Earth's insolation changes. It is shown that the thermal regime of the Earth's surface in thearea during the last glacial cycle was formed under the influence of a number of factors. These include theorbital related insolation changes, thermomechanical properties of the Ice Sheet, deglaciation, formation of
glacial lakes and their subsequent draining. Still, the insolation remains the main factor which determines
the behavior of the other factors through a complex system of climate feedbacks.

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*S25-P-02
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S25. D
evelopment and application of geothermal databases

Evaluating methods and uncertainties in the inversion of downholetemperature data for palaeoclimate studies, Australian examples* Sandra McLaren , Roger Powell
University of Melbourne, Melbourne, Australia
Downhole temperature data have been used for many years to try and understand variations in ground andair surface temperature in the geological past. The inference of ground surface temperature histories from
borehole temperature data is an ill-posed inverse problem that can be approached via a range of numericalmethods, broadly divisible into (1) regularisation and (2) Bayesian techniques. Inversion results are
dependent on the method chosen and the details of the implementation, as well as the geologicalconstraints built into the inversion. A number of authors have compared different approaches exploring, forexample, the impact of variations in geological and geophysical parameters such as borehole depth anduncertainties in measured thermal data on inversion results. We add to this body of work looking at thesensitivity of different inversions of realistic synthetic temperature data. On the basis of this, we invert realtemperature data collected from two purpose-drilled and well-characterised boreholes in southeastern
Australia: Tynong-1, southeast of Melbourne (total depth of 400m) and Stavely-07, in western Victoria (total
depth of 500m). Results suggest that inversion may result in over-interpretation of the data and that it may
be difficult to distinguish equally plausible temperature histories.

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*S25-P-03
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S25. D
evelopment and application of geothermal databases

A geothermal resource assessment based on GIS analysis of multiple
parameters for the Guanzhong Basin, NW China
Yilei Xu 1) , Tingting Ke 1) , * Shaopeng Huang 1) 2) , Ruyang Yu 1) , Xiaoyin Tang 1)
University of Xi'an Jiaotong University, Xi'an, Shaanxi, China 1) , University of Michigan, Ann Arbor,
Michigan, USA 2)
The Guanzhong Basin, also known as Weihe Basin, in Shaanxi Province of NW China is a Cenozoic allusive
basin of graben origin. It is situated between the Qinling Mountain on the south and Beishan Mountain on
the north with an area of about 36,000 km^2. The basin is rich in low to medium temperature geothermal
fluids. There are currently about 200 geothermal wells in this basin, tapping hot water mainly from four
aquifers at the depths between 400 and 4000 m. Data from multiple sources such as heat flow, boreholetemperature, geological structure and stratum, earthquake catalog, crustal electrical structure, remotesensing imagery, and socioeconomic data are assembled into a GIS platform to facilitate better assessmentsof resource, demand and application potential. Heat flow within the basin varies in the range of 62-80
mW/m^2, with a mean of 71 mW/m^2 which is substantially higher than the regional mean. Based on
geological structure, the basin can be divided into six uplift/depression segments. Geothermal resource isfound to be most enriched in the Xi'an Depression where the maximum Cenozoic sedimentary thickness
reaches 7,000 m. Light to moderate earthquake epicenters are concentrated along the boundaries of the
uplift-depression boundaries. With a population of over 8.5 million, the Xi'an - Xianyang area is the mostpopulated and economically developed area in the basin. The abundant geothermal resource is coincidedwith high demand for renewable energy to sustain the economic and social development in this area. Our
analysis shows that geothermal resource can play an increasingly important role in the socio-economic andenvironmental development of the Guanzhong Basin in general, and Xi'an – Xianyang area in particular.

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*S25-P-04
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S25. D
evelopment and application of geothermal databases

Terrestrial Heat flow and 1D Geoelectric Model of the Baiyinchagan Sag,
Erlian Basin, Northern China* Jiong Zhang 1) , Rao Fu 1) , Yongshui Zhou 5) , Yi Wang 3) , Di Hu 3) , Yinhui Zuo 4) , Shaopeng Huang 1) 2) ,Xiaoyin Tang 1) , Ruyang Yu 1)
Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China 1) , Department of Earthand Environmental Sciences, University of Michigan, Ann Arbor, US 2) , Institute of Geology andGeophysics, Chinese Academy of Scinece 3) , Chengdu College of Geology, Chengdu, China 4) , Sinopec
Zhongyuan Oilfield, Puyang, China 5)
The Baiyinchagan Sag is located in the western margin of the Erlian Basin, a Mesozoic rift basin in thecollision suture zone of the Siberian Plate and North China Craton in northwest Inner Mongolia in northern
China. Here we report preliminary analysis of new heat flow measurements in four deep boreholes andmagnetotelluric soundings at these borehole sites. Subsurface temperature gradient varies from 35.6 to
45.4 degrees per kilometer in the selected boreholes between the depths from 200 to 2150 m. Thermal
conductivities of 36 sedimentary and metamorphic rock samples fall in the range of 0.93-4.03 W/m/K. The
mean of the measured heat flow values is 76 mW per suquare meter. Our new heat flow measurements are
consistent with the recent report of Zuo et al. (2016, 75 mW per suquare meter), but substantially greaterthan the estimates of 43-66 mW per suquare meter registered for the Erlian Basin in the fourth edition of
the Chinese heat flow data compilation (Jiang et al., 2016). One-dimensional Occam's inversion of themagnetotelluric sounding data shows that the uppermost 4 km layer of the rocks are low in electric
resistivity (<100 Ωm), likely due to the fluid in the porous strata. A high resistance (>2000 Ωm) layer islocated at the depth of 7-20 km. We are in the process of constructing the thermal structure of thelithosphere for the Baiyinchagan Sag based on the new measurements and other relevant geological andgeophysical data. The geodynamic and petroleum resource implications of the lithospheric thermal
structure will be discussed, and the results will be presented at the meeting.

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*S26-1-01
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Shallow crustal heat flow and heat production inversion* Marcus Haynes 1) , Rhys Hawkins 1) , Malcolm Sambridge 1) , Graeme Beardsmore 2)
Australian National University, Canberra, Australia 1) , Hot Dry Rocks Pty Ltd, Melbourne, Australia 2)
Understanding the heat flowing from the Earth is fundamental to understanding the nature of the crust.
Previous attempts to analyse the surface heat flow across the Australian continent have typicallyinterpolated the sparse available data points. These studies inherently make the assumption that lateral
distance between heat flow determinations is sufficiently short to act as a proxy for changes in theestimated rate. However, the variations apparent in the data suggest that such an assumption cannot hold.
Surface heat flow estimates can be regarded as the sum of heat flowing from several source components.
The observation of linear heat flow provinces suggested that, over large distances, the heat production at
the surface of the crust provides a first-order constraint on surface heat flow rates. Regardless of thephysical mechanisms behind these patterns, this seemed to suggest that the remaining heat flow
component, commonly referred to as ‘reduced heat flow', exhibits large wavelengths of variation that are,in general, more amenable to spatial interpolation over large distances.
We approach heat flow inversion as regression problem. The reduced heat flow signal is regressed fromsurface heat flow determinations, where upper crustal heat production provides a purely-additive noise thatmasks the coherence of the reduced heat flow signal. We use a transdimensional-tree Markov Chain Monte
Carlo model to regress reduced heat flow across the Australian continent. Our prior beliefs about the heatproduction in the upper crust, informed by surface geochemical measurements, enable the twocomponents of surface heat flow to be probabilistically separated. In this format, the noise modelled in our
regression can be recovered and represents the total inferred heat production for the shallow continental
crust. This method is applied to the Australian surface heat flow dataset, and the results and theiruncertainties are presented.

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*S26-1-02
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Magma underplating at crust mantle interphase as the source of anomalous
heat flow in passive continental margins* Valiya Hamza , Fabio Vieira
National Observatory, Rio de Janeiro, Brazil
Analysis of global heat flow data points to the existence of narrow belts of relatively high heat flow (>60mW/m2) along several segments of the passive continental margins. These belts are confined between
zones of low to normal heat flow, present in adjacent stable segments of continental and oceanic crust.
Available data on the width of the heat flow anomaly (range of 100 to 300km) precludes thermal refraction
effects. Hence, we consider release of heat by sources located at the base of transitional crust as the likely
mechanism. Model studies were carried out to examine the nature of magma underplating. The results
indicate that an underplating episode at a depth of 20km, occurring 2Ma back in time, is capable ofaccounting for the observed heat flow anomaly. It is argued that weak “tectonic bonding" between
continental and oceanic segments of the lithosphere and ductile nature of mantle at the contact zones
allow lateral flow of magma at the base of the crust. This mechanism seems to be an end-member case ofdifferential stretching, in which extension is limited mostly to the sub-crustal layer. However, these need
not necessarily produce intrusive or volcanic activity in overlying strata. We advent the hypothesis that
passive flow of mantle material at the base of transitional crust is responsible for much of the micro-seismic
activity at shallow depths along continental margins. Results of model studies also reveal that a
combination of thermal maturity indices and palinspastic reconstructions of sedimentary strata may be
used to constrain estimates of the duration of underplating events. Analysis of data for continental marginof Brazil point to the occurrence of two successive underplating events: a recent short-period one toaccount for the observed heat flow anomaly and an older long-period one for boosting thermal maturity
indices to levels compatible with the occurrence of extensive oil fields.

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*S26-1-03
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Two-dimensional thermal modeling associated with subduction of thePhilippine Sea plate beneath southern Kyushu, Japan* Nobuaki Suenaga 1) , Shoichi Yoshioka 1) 2) , Takumi Matsumoto 3)
Research Center for Urban Safety and Security, Kobe University, Jpan 1) , Department of Planetology,
Graduate School of Science, Kobe University, Japan 2) , National Research Institute for Earth Science andDisaster Resilience 3)
There is a non-volcanic region sandwiched between the Aso and Kirishima volcanic zones in southern
Kyushu, Japan. Several characteristic seismic events were identified around there; Postseismic slips were
found associated with the two Hyuga-nada earthquakes (M6.6), which were interplate earthquakes that
occurred on October 19 and December 3, 1996. Tectonic tremors were observed around the mantle wedge
corner beneath the Pacific coast of Miyazaki prefecture. To investigate the cause of these events, we
performed 2-D box-type time-dependent thermal modeling in southern Kyushu. We set a profile to passthrough the regions in the plate convergence direction where tectonic tremors and postseismic slips wereidentified. To constrain calculated temperature structure, we used surface heat flow data. In our model, we
considered the subduction history of the Philippine Sea (PHS) plate, and changed the age of an ocean floor
and subduction velocity along the profile at each time step. To explain the observed low heat flow above
the mantle wedge corner, we introduced a low viscosity layer at the plate boundary. It became difficult for
mantle flow to intrude into the mantle wedge corner, by incorporating the low viscosity layer, and surface
heat flow above there became lower than that without it. As a result, the temperature range of the uppersurface of the subducting PHS plate where postseismic slip associated with the 1996 Hyuga-nada
earthquake on December 3 occurred became approximately 300 degree. Interplate temperature where
tectonic tremors occurred beneath Miyazaki prefecture ranges from 400 to 500 degree. We also estimatedthe dehydration process along the profile and used the phase diagram of hydrous MORB in the oceanic
crust. As a result, blueshist transformed into lawsonite blueshist in the postseismic slip region, andlawsonite blueshist transformed into lawsonite eclogite in the active region of tectonic tremors.

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*S26-1-04
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Reconstruction of recent 6Ma thermal structure seaward of updip limit ofNankai seismogenic zone off Kumano inferred from IODP NanTroSEIZE
geothermal data and time-dependent numerical model* Masataka Kinoshita 1) , Eiichiro Araki 2) , Toshinori Kimura 2) , Achim Kopf 3) , Demian Saffer 4) , Sean
Toczko 2)
Earthquake Research Institute, Univ. Tokyo 1) , JAMSTEC 2) , MARUM, Univ. Bremen 3) , Pennsylvania State
University 4)
Understanding the slip behavior of the seismogenic faults in subduction zones requires accurate estimateson the present & past thermal structures. To depict the thermal history, we need to know the tectonics andthermal regime of the Philippine Sea plate (PHS), which may have stopped subduction until ~6MaBP, andrestarted afterwards. Our purpose here is to test if such subduction tectonics can affect the ‘present'
thermal regime.
During the IODP NanTroSEIZE expeditions, we deployed 2 borehole observatories containing 5
thermistors. In 2012, the first one was deployed at Site C0002 above the updip limit portion of megathrust,and the temperature and heat flow at ~900 m below seafloor is determined as 38 degC and 57 mW/m2,
respectively. In 2016, we deployed the second one at Sites C0010 across the shallow megasplay fault zone.
Thermistors are located between ~400 mbsf (crossing the fault zone) and 562.72 mbsf, and the temperature
at 562.7 mbsf is 26.7 degC. With core thermal conductivity data, average heat flow is determined as ~60
mW/m2. It is slightly higher than nearby Site C0004 (54 mW/m2). It may be attributed either to pore fluid
flow or transient phenomena (e.g., burial due to thrust faulting).
Using these heat flow data, a thermal evolution model around the updip zone of Nankai seismogenic zone
is constructed for 2 end-member models; subduction of 12Ma-old Shikoku Basin (SB) started at 6MaBP, vs.
subduction of 5Ma-old SB continued since 13MaBP. We found that two end-member models (subduction
has been continuous vs. it started 6MaBP) are very similar and impossible to discriminate to each other.
We also found that the thermal structure at 6-3MyBP can be different from the present one. In that case theaccretionary prism evolution, as reconstructed through paleo-thermometry, may need reconsideration.

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*S26-1-05
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Numerical Simulation of the Geothermal Effect of the Millennium Eruptionof the Changbaishan Tianchi (Mt. Paektu) Volcano at Sino-North Korean
Border* Wentao Duan 1) , Ting Ke 1) , Shaopeng Huang 1) 2) , Xiaoyin Tang 1)
Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China 1) , Department of Earthand Environmental Sciences, University of Michigan, Ann Arbor, US 2)
The eruption of the Changbaishan Tianchi Volcano (CTV, also known as Mt. Paektu Volcano) in around
1000AD ejected about 100 cubic kilometers peralkaline rhyolites. It was one of the largest explosive
eruptions in the world over the last 10,000 years. Volcanic eruptions are associated with a vast amount ofheat being carried from the greater interior to shallower depths by magmatism. Therefore, volcanic areas
are generally rich in geothermal resource. Numerical simulation is an effective means not only in the
research of thermo-tectonic evolution of the lithosphere, but also in the assessment of geothermal energy
potential in a volcanic area. Here we simulate the thermal effects of the magmatism with ANSYSWORKBENCH, a finite-element simulation software platform that has been widely used in engineering
thermophysics, but so far rarely applied in a geothermal research. Based on the latest geothermal,
petrological and geophysical data, we construct two conceptual models to simulate the thermal effects of
the CTV Millennium Eruption. Petrological studies indicate that the erupted CTV rhyolites were derived
from the upper-middle crust at depths of about 10-15 km; whereas recent magnetotelluric sounding andanalysis of Advanced Land Observing Satellite PALSAR data suggests that the magma chamber is located in
the upper crust beneath the depth of around 8 km. Consequently, our two conceptual models represent theupper crust and upper-middle crust magma chamber scenarios, respectively. Simulation result shows thatin either case, the conductive thermal diffusion of the magma activity of the CTV Millennium eruption 1 kyr
ago is restrained within the range of 500 meters from the intruded magma column. This might be part of
the reason for the lack of widespread hydrothermal activities in the CTV area.

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*S26-2-01
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Heat flow distribution along the Nankai Trough floor correlated with thecrustal structure of the incoming oceanic plate* Makoto Yamano 1) , Yoshifumi Kawada 2) , Mikiya Yamashita 3)
The University of Tokyo, Tokyo, Japan 1) , Tohoku University, Sendai, Japan 2) , JAMSTEC, Yokohama,Japan 3)
Detailed heat flow measurements conducted on the floor of the Nankai Trough, near the trench axis,
revealed that the heat flow distribution significantly varies along the trough. The variation appears to becorrelated with the spreading history of the incoming Philippine Sea plate (Shikoku Basin). In the central
part of the trough (between 134.5 and 136 degE), the youngest part pf the Shikoku Basin formed byspreading in the NE-SW direction, heat flow is highly variable and the average is much higher than thevalue estimated from the seafloor age. In the older parts of the basin formed by E-W spreading with a faster
rate, located on the east and on the west of the central part, heat flow is nearly normal and less scattered.
Other geophysical data, e.g., seismicity, crustal thickness, and basement topography, also vary significantly
around the spreading direction boundaries. It suggests that the crustal structure changes across theboundaries associated with differences in the spreading direction and rate. The high average heat flow inthe central part of the trough floor can be attributed to heat transport along the plate interface by fluid
circulation through a permeable layer in the subducted oceanic crust (Spinelli and Wang, 2008). The
permeability structure of the crust may be different between the central part and the older, eastern andwestern parts, resulting in difference in intensity and/or pattern of fluid circulation, and thus the observed
contrasting heat flow. The high variability of heat flow in the central part may also be related to the crustal
structure. In the central part, characterized by large basement relief, there is a negative correlation between
heat flow and sediment thickness; higher heat flow on basement highs, whereas no apparent correlation isfound in the eastern and western parts. These findings indicate that the crustal structure of the Shikoku
Basin has a large influence on the temperature distribution along the plate interface.

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*S26-2-02
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Modelling three-dimensional hydrothermal heat transport around the
Nankai Trough* Yoshifumi Kawada 1) , Makoto Yamano 2) , Xiang Gao 3)
Tohoku University, Sendai, Japan 1) , The University of Tokyo, Tokyo, Japan 2) , Chinese Academy of
Science, Qingdao, China 3)
To understand the behaviour of mega-thrust earthquakes, estimating temperature structure of the
subduction zone is a key issue. The Nankai Trough, with a lot of heat flow data, is one of the best regions
for this purpose. The major features of the available data are high heat flow (more than twice that expectedfrom thermal models with the corresponding plate age) at the Muroto area, moderately high heat flow (atmost 1.5 times that expected from thermal models) at the Kumano area (150 km east of the Muroto area),
and a gradual heat flow variation between these areas with the spatial scale of ca. 50 km.
Spinelli and Wang (2008) proposed a thermal model including hydrothermal circulation to explain the highheat flow at the Muroto area. They assumed that the uppermost 500 m of the oceanic plate (usually called
aquifer) is permeable both before and after subduction. This model explains the heat flow data and gives animportant aspect that temperature at depth along the aquifer is decreased by 50 degrees Celsius.
Here we extend Spinelli and Wang's (2008) model so that the heat flow variation between the Muroto andKumano areas can be targeted. We pay attention to hydrological structure of the crust and irregular slab
geometry between these areas, which reflects paleo-spreading direction. We construct a three-dimensionalmodel including anisotropic aquifer permeability to include these features.
Results are summarised as follows. 1) Taking a high permeability entire of the areas results in pervasivehigh heat flow. 2) High permeability at the Murtoto area and low permeability at the Kumano area with asharp contrast between these areas, results in a sharp heat-flow contrast between these areas. These are
not the case. 3) We consider anisotropy in permeability, in which the Muroto area has high permeability
and the Kumano area has high permeability only in the direction parallel to the trench axis. This model can
explain the heat flow variation between these areas.

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*S26-2-03
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Curie Depth Point of the Iberian Microplate. A thermal, compositional andtectonic perspective of its evolution
Juvenal Andres 1) , Ignacio Marzan 1) , David Marti 1) , Imma Palomeras 2) , Puy Ayarza 2) , * Ramon
Carbonell 1)
CSIC-ICTJA Inst. Earth Sciences Jaume Almera 1) , Department of Geology, University of Salamanca,
Salamanca, Spain 2)
Thermal structure of the Iberian micro-plate is derived from magnetic data through the Curie-Depth Point(CDP) isotherm, which accounts for the depth at which ferromagnetic minerals become paramagnetic(~580 ºC). CDP modulates the surface heat flow through thermal conduction. Variations on the CDP
thickness translate into heat anomalies most probably due to small scale tectonics. The CDP, the CDP
derived thermal gradient with the Moho depth maps provide knowledge on the thermal regime. Within
Iberia the isotherm is located at depths of 17 to 29 km beneath surface. This isotherm is shallow offshore,
where the lithosphere is thinner. In continental Iberia, the Variscan domain reveals a deep signal, probably
linked to thickening-extension processes during the orogeny, which an extensive emplacement of granites(in the Central Iberian Arc). This resulted in a very thermally conductive crust. The CDP at the Gibraltar
Arc is consistent with the slab roll-back geodynamic model. Offshore the broad magnetization can be
accounted for by proposing serpentinization of the upper mantle. Similarly, in the Atlantic margin, a
relatively thick serpentine layer is interpreted, which is consistent with a hyperextended margin
configuration (exhumed mantle has been sampled). The Mediterranean presents generalized
serpentinitation in the Algerian Basin. Furthermore, correlations have been found between the CDP,
thermal gradient and vertical ground motion, where subsidence is related to low thermal gradient and, nullor small uplift implies high thermal gradient. (Research supports: CGL2014-56548-P, 2009-SGR-1595,
CGL2013-47412-C2-1-P)

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*S26-2-05
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Seismogenic Layer within the Crust beneath Japanese Islands on the Japan
Sea Side – application of JUICE catalog* Tomoko E. Yano , Makoto Matsubara
NIED, Tsukuba, Japan
Understanding the thickness of seismogenic layer is important parameter for the earthquake hazard
assessment because this relates to the size of earthquakes caused by the active fault. We investigated theindexes D5 and D95 as the upper and lower limits of the seismogenic layer defined as the depth above
which 5 % and 95 % of the whole crustal earthquakes occurred from the surface, respectively.
In previous study, we relocated hypocenters for 12 years between 2001 and 2012 from the NIED Hi-net
catalog (hereinafter referred as “JUICE catalog", Yano et al. 2016) for high resolution hypocenter locations(Depth ≦40 km, M≧0.0). In order to satisfy Gutenberg-Richter magnitude-frequency relation, we extracted
events with magnitude eaqual to or greater than 1.5 from the JUICE catalog. We then estimated the D5 andD95 using the same method as Matsubara and Sato (2015).
The general pattern of our results is consistent with similar studies of D10 and D90 (e.g. Matsubara andSato, 2015; Tanaka, 2004; Omuralieva et al., 2012). For example, very deep D95 lies beneath the northern
Hokkaido and northern Honshu and very shallow D95 extends along the belt-like volcanic areas. Moreover,this study enables to reveal that D5 and D95 have local variability of depth along active faults because weused the JUICE catalog, in which these hypocenters are confined into each cluster of seismicity and some
active faults.

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*S26-P-01
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Heat flow map of the Czech Republic, revisited* Petr Dedecek , Vladimir Cermak , Jan Safanda , Milan Kresl
Institute of Geophysic ASCR, Prague, Czech Republic
The existing heat flow pattern of Central Europe is reasonably well known since the late eighties. However,in recent years additional geothermal data have been accumulated which provided a certain possibility toreconsider the previous knowledge and update it. A revised version of heat flow map of the Czech Republic
is presented together with the maps of the isotherms at depths of 500, 2000 and 5000 meters. The
geothermal data were thoroughly completed with similar information available from the surrounding
countries, the paleoclimatic corrections were applied on the whole dataset. 3D numerical model based on
the additional information summarizing the results of the laboratory measurements of the radiogenic heatproduction and heat conductivity of collected rock samples was proposed to describe the crustal thermal
structure of the studied territory and allowed to delineate the potential zones for the utilization of deep
geothermal energy. The influence of the convective heat transfer on subsurface temperature field in the
discharge and recharge areas, namely in southern and western Bohemia, was briefly discussed in context
of regional heat flow density pattern.

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*S26-P-02
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Heat flow and tectono-thermal histories in cratons of China* Lijuan He
Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
There are altogether 1230 heat flow data in the continental area of China, and most of them concentrate in
the three cratons: the North China Craton, the Tarim Craton, and the Yangtze Craton. Heat flow in thesecratons displays much different characteristic., which is 42.5 mW/m2 in the Tarim Basin, 61 mW/m2 in thewestern NCC, ~64 mW/m2 in the eastern NCC, 71.2 mW/m2 in Subei Basin of the Lower Yangtze Craton,and 53.2 mW/m2 in the Sichuan Basin of the upper Yangtze Craton. In general the high heat flow locates at
the active continental block (e.g. eastern NCC) and the low heat flow at the stable craton block (e.g. Tarim).
Each of the cratons has experienced complicated evolution histories since their formation, presents distinct
thermal regime, and displays different stability. The Tarim Craton keeps its stability till now. The eastern
North China Craton has been destructed in the Mesozoic, but the western North China Craton still stable.
The stability of the Yangtze craton is a controversial issue, and the newest study believed it experienced
similar tectono-thermal events as the North China Craton and has also been destructed in the Mesozoic.
Several sedimentary basins developed in these cratons, and most of them are rich of oil-gas resources.
These basins have different formation mechanism and experienced distinct tectono-thermal evolution,
which resulted in individual thermal histories. The sedimentary basins have recorded distinct thermal
evolution of these craton. Heat flow data, together with basins' tectono-thermal histories in these cratons
may help to provide ideas for geodynamical mechanism on the craton stability/destruction, as well as
implications for hydrocarbon generation.

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*S26-P-03
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S26. E
xploring connections between heat flow and tectonics

Indications of “hot belts" along passive continental margin of Brazil
Fabio Vieira , * Valiya Hamza
Observatorio Nacional, Rio de Janeiro, Brasil
Analysis of geothermal data for the coastal sedimentary basins of eastern Brazil has revealed the existenceof an anomalous high heat flow belt along its passive continental margin. The main characteristics of thisanomaly are the geothermal gradients in excess of 30oC/km and heat flow greater than 70mW/m2. It is
confined between zones of relatively low to normal heat flow in the adjacent continental regions to the west
and stable oceanic regions to the east. The width of the belt is somewhat variable, but most of it falls within
the range of 100 to 300 km. It is relatively large in the southern (in the basins of Pelotas, Santos andCampos) and northern (basins of Potiguar and Ceara) parts, when compared with those in the central parts(basins of South Bahia, Sergipe and Alagoas). The characteristics of heat flow anomalies appear to becompatible with those produced by thermal sources at shallow depths in the upper crust. Seismicity within
the belt is relatively weak, with focal depths less than 10km for most of the events. Such observations imply
that “tectonic bonding" between continental and oceanic segments is relatively weak. Hence, it is
proposed that “passive" continental margins like that of Brazil be considered as constituting a type of plateboundary that is aseismic at sub crustal levels, but allows for escape of significant amounts of earth's
internal heat at shallow depths.

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*S27-1-01
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S27. G
eothermal energy: Ground source heat pump, hydrothermal system, and hot dry rocks

The efficiency of Borehole heat exchanger system by regional differences* Hideki Hamamoto 1) , Yuji Miyashita 2) , Philipp Blum 3) , Alexander Limberg 4) , Makoto Taniguchi 5)
Center for Environmental Science in Saitama, Saitama, Japan 1) , Hot Springs Research Institute of
Kanagawa Prefecture, Kanagawa, Japan 2) , Karlsruhe Institute of Technology, Karlsruhe, Germany 3) ,Senate Department for the Environment, Transport and Climate Protection, Berlin, Germany 4) , ResearchInstitute for Humanity and Nature, Kyoto, Japan 5)
Borehole heat exchanger (BHE) is an economically and environmentally friendly technology. Therefore, the
BHE is beginning to spread around the world. For design and deployment of the system, it is thus
important to evaluate the available subsurface heat energy through thermal response tests and/or
numerical simulations and to design appropriate systems (depth and the number of boreholes for heatexchange). Geological structures, groundwater properties, and subsurface temperatures are essential input
data for the numerical simulations. The evaluations are roughly separated to two models; wide model andlocal model.
We demonstrate the wide model at first. We illustrate a new construction method of BHE potential map
from regional geological structure and measured subsurface temperature for typical Japanese plains. Our
main target areas are central part of Kanto Plain and Obama Plain. Kanto Plain is including of Tokyo
metropolitan and Obama Plain is located in the central part of Japan and faces the Sea of Japan. We haveconducted measurements of subsurface temperatures 25 stations in central part of Kanto Plain and 4
stations in Obama Plain for the evaluation.
A part of the numerical simulations results shows that BHE efficiency increase 20 % when subsurface
temperature rise up 5 degree and the efficiency also increase 30 % when groundwater flow vary from 0 to
15 m/year. We show also the efficiency of BHE difference due to the difference of the subsurface
temperatures in the worldwide cities (example for Tokyo, Osaka, Bangkok, and Berlin).
We have also discussed an influence of subsurface warming effect on the BHE efficiency by numericalsimulations. We reveal that subsurface warming effect increase BHE efficiency of heating drive (inversely,
decrease efficiency of cooling).

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*S27-1-02
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S27. G
eothermal energy: Ground source heat pump, hydrothermal system, and hot dry rocks

Assessment of efficiency and potential of a ground source heat pump system
under geological complexity in Japan* Yoshitaka Sakata 1) , Takao Katsura 1) , Katsunori Nagano 1) , Atsunao Marui 2)
Hokkaido University, Sapporo, Japan 1) , National Institute of Advanced Industrial Science and Technology,
Tsukuba, Japan 2)This paper presents an assessment of the efficiency and the potency of a ground source heat pump system(GSHP) in Japan. This research is fundamental on the 3D geo-database which consists of over fortythousand water well drilling reports. Indicator kriging interpolation is applied to estimate the soil/rocktypes in any location. The accuracy of kriging interpolation is validated in the leave-one-out crossvalidation. The geodatabase translates the probability estimates of soil/rock types to the effective thermal
conductivity and transmissivity as matched with the in-situ measurements. The database also provides thegroundwater flow simulation results by AIST to evaluate heat advection effects in the Holocene, Pleistocene
and Neogene layers. This study performs the GSHP simulation by using the Ground Club, which wasdeveloped based on the cylindrical heat source theory to calculate ground temperatures rapidly withaccuracy. The Ground Club is also useful to assess the advection effects of groundwater flow in the multilayered formations. The assumed GSHP is composed of a commercial heat pump and a vertical boreholeheat exchanger (BHE) in a standard residence. The total external area of the residence is 313 m2 and the Uvalues are ranged from 0.46 W/m2/K in the cold region to 0.87 W/m2/K in the warm regions. The heat
demands are variable according to the hourly data of the outdoor temperatures and the insolation amounts.
In each location, the system efficiency values on a third year are estimated under different cases ofassumed BHE lengths, so that minimum lengths of BHEs for the required efficiency are determined. The
simulation is demonstrated all over the country with a grid of 0.25 km in space. The results are averaged
into a grid of 1 to 10 km in space for a national map. The map contributes to the assessment of theefficiency and the possibility of the GSHP under the regional situations of geology and groundwater inJapan.

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*S27-1-03
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S27. G
eothermal energy: Ground source heat pump, hydrothermal system, and hot dry rocks

Alternative use of subsurface energy as heat pump or groundwater* Makoto Taniguchi 1) , Hideki Hamamoto 2)
Research Institute for Humanity and Nature, Kyoto, Japan 1) , Center for Environmental Science in Saitama,
Saitama, Japan 2)
Thermal energy in subsurface environment can be used sustainably if we can manage the resources
carefully. Demands for energy to melt snow accumulated on the roads is increasing in many coastal snowy
areas in Japan. There are alternative uses of subsurface energy, and the one of them is the use ofgroundwater for melting snow, because the temperature of the groundwater is relatively higher in winterthan that of the air and river water, therefore groundwater itself is a useful heat source to melt snow.
Another way is the use of heat pump, which is the use of thermal energy in shallow subsurface for melting
snow. In this study, the effects of alternative use of subsurface energy as heat pump or groundwater havebeen analyzed by three-dimensional groundwater flow model with subsurface thermal analyses in thesnowy areas of Obama City, Fukui Prefecture, Japan.

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*S27-1-04
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S27. G
eothermal energy: Ground source heat pump, hydrothermal system, and hot dry rocks

Subsurface temperature modelling with inverse parameter optimisation* Niels Balling 1) , Soeren E. Poulsen 2) , Sven Fuchs 3) , Soeren B. Nielsen 1)
Aarhus University, Aarhus Denmark 1) , VIA University College, Horsens, Denmark 2) , GFZ German
Research Centre for Geosciences, Potsdam, Germany 3)
Focus on the utilization of geothermal energy as a sustainable energy source has resulted in extensive
geothermal exploration activities with a demand for procedures for obtaining reliable information on
subsurface temperatures and thermal resources. Subsurface thermal information is basically obtained fromtwo different sources: direct observations by measurements in boreholes and indirectly by numericalmodelling. We present a modelling methodology which ensures consistency between model temperature
predictions and measured temperatures and which provides easily updated models.
Structural and lithological information, data on rock thermal properties and current information on
borehole temperatures and heat flow are integrated into a parameterised 3D subsurface model, for which
the heat equation is solved by applying combined numerical forward modelling and inverse optimisation
methodology. A priori values of model thermal parameters, such as thermal conductivity and heatproduction, as well as background heat flow may be adjusted, within uncertainty limits, to ensure model
agreement between observed borehole temperatures and resulting model estimates. Inverse parameter
calibration is carried out by minimising an objective function comprised of a weighted sum of the squared
differences between modelled and measured temperatures.
This methodology is applied to Danish and North German sedimentary basins. The resulting thermal
models include temperature predictions in a densely spaced 3D grid of subsurface points. Temperature
information may be extracted in terms of local temperature-depth profiles, temperature maps for specified
geological horizons, such as potential geothermal reservoirs or for selected constant depths. Such models
improve our understanding of the subsurface thermal field, including sources of temperature variations andanomalies, and facilitate risk reduction by integration into regional as well as local geothermal exploration.

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*S27-1-06
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S27. G
eothermal energy: Ground source heat pump, hydrothermal system, and hot dry rocks

Magnetotelluric surveys to delineate shallow reservoir of low-enthalpy
geothermal systems in Thailand* Puwis Amatyakul 1) , Songkhun Boonchaisuk 2) , Chatchai Vachiratiencha 3) , Tawat Rung-Arungwan 3) ,Kriangsak Pirarai 4) , Aranya Fuangswasdi 4) , Weerachai Siripunvaraporn 1)
Department of Physics, Faculty of Science, Mahidol University, Bangkok, Thailand 1) , Geoscience Program,
Mahidol University, Kanchanaburi Campus, Kanchanaburi, Thailand 2) , Curl-E Geophysics Co., Ltd.,
Nakornpathom, Thailand 3) , Department of Groundwater Resources, Ministry of Natural Resources andEnvironment, Bangkok, Thailand 4)
Most of Thailand geothermal fields are classified as the low-enthalpy system which can be efficiently
utilized with the current technology for power production. The geothermal exploration assessment program
was then initiated. The deep geophysical survey is one of the major parts of the program.
Since 2014, Mahidol University incorporation with a joint venture leading by Thailand Department of
Groundwater Resources has been conducting magnetotelluric surveys on the selected geothermal fields innorthern and southern Thailand. The 3-D resistivity distribution of those fields, up to a depth of 2 km, werecarried out by a 3-D magnetotelluric inversion, WSINV3DMT, using impedance tensor and tipper data.
The obtained resistivity models support the conceptual model of the previously proposed hydrothermal
system in most of the fields. The heat source is the deep resistive granitic rocks. The derived model also
reveals the geological and fault structures acted as the fluid pathway to the surface where the hot spring
manifestation occurred. The shallow conductive structures are mapped and can be referred as thegeothermal reservoir in the formed of fluid-filled fractures in weathered granitic rocks or a clay cap formedin the sedimentary layers. The deep 1 km drilled well was then conducted in one of the fields. The core log
data coincides with the resistivity model derived from the magnetotelluric survey. The methodology
developed during the past surveys can be applied to other low-enthalpy geothermal fields and could help
accelerating the geothermal energy utilization in Thailand.

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*S27-P-01
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S27. G
eothermal energy: Ground source heat pump, hydrothermal system, and hot dry rocks

Evaluation of geothermal energy potential for heating/cooling of the Xi'an
Jiaotong University new campus in Xixian, Shaanxi, China* Tingting Ke 1) , Yilei Xu 1) , Shaopeng Huang 1) 2) , Xiaoyin Tang 1) , Wentao Duan 1)
Institute of Global Environmental Change, University of Xi'an Jiaotong University, Xi'an, Shaanxi, China 1) ,Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA 2)
The Xi'an Jiaotong University (XJTU) is an elite research university in China. It has been tasked by the
Shaanxi Provincial Government to develop its new campus as a technological innovation hub in western
China. Socioeconomically, the XJTU new campus is located in the Xixian District, a transmission zone
between Xi'an and Xianyang designated for ecological urbanization development. Geologically, it situateson the top of the Xi'an Depression of the Guanzhong Basin where geothermal resource is abundant and has
been utilized for thousands of years. More than 150 geothermal wells mostly of depths between 1000 to3000 m are currently in production in the Xi'an –Xianyang area. A preliminary energy demand analysis ofheating/cooling for the new campus based on space functionalities shows a maximum load of 179 MW
during the 4-month winter heating season from mid-November to mid-March, and 189 MW during the
2-month summer cooling time from July to August. This ongoing project is to evaluate the feasibility for
geothermal resource to meet the heating/cooling demand. Based on the data available in the literature, ageological model of the Xi'an Depression has been established. Five Cenozoic formations have been
identified as geothermal water bearing strata within the depth down to 5 km. Although the new campus
occupies an area of about 3.12 square km, we use a reservoir area of 5 square km in our resource
assessment because extraction of underground geothermal fluid does not have to be restricted within thecampus boundary. Geothermal resource of each reservoir stratum is calculated in terms of formation
thickness, porosity, and temperature data. The thermal energy reserve for the XJTU new campus isestimated to be 14900 billion Kcal. In search for an optimal and sustainable geothermal energy application
plan, we are in the process of simulating various production schemes. Results will be presented at thisconference.

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*S27-P-02
IASPEI Symposium / IASPEI08. International Heat Flow Commission / S27. G
eothermal energy: Ground source heat pump, hydrothermal system, and hot dry rocks

RINGEN - Research INfrastructure for Geothermal ENergy* Petr Dedecek 1) , Vladimir Cermak 1) , Jan Safanda 1) , Tomas Fischer 2) , Antonin Tym 2)
Institute of Geophysic ASCR, Prague, Czech Republic 1) , Faculty of Science, Charles University, Prague,
Czech Republic 2)
RINGEN (Research INfrastructure for Geothermal ENergy) is a unique research institution – first of its kindin the Czech Republic, whose hosting institution (founder) is Faculty of Science of Charles University in
Prague. The RINGEN promotes research and development in the country and offers specific services
related to the practical use of geothermal energy. Its key asset is the existence of 2.1 km deep testing
geothermal borehole PVGT-LT1 (drilled in 2006-2007) and the basic seismic monitoring network(established in 2014) allowing in-time testing. RINGEN is the Czech contribution to European and global
research and development in the area of geothermal energy, which until now has been rather limited to thecooperation of individual national research centers and/or individual researchers without the appropriatematerial and scientific background. We want to further broaden its scope to focus on induced seismicity,
detection capabilities of seismic networks, hydrogeological, geomechanical and geotechnical conditions
and on mathematical modeling of underground geothermal exchangers as well as the studies of thegeothermal properties of rocks. Among the nearest goals belongs a proposed new 4 – 5 km deep borehole
to be drilled at Litomerice area in northern Bohemia. The so far obtained RINGEN results are briefly
presented with our desire to open the RINGEN facilities to the international cooperation, research
institutions or researchers from anywhere are welcome to establish a partnership.

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