space geodetic tools provide early warnings for earthquakes and volcanic eruptions development of space geodetic techniques such as global navigation satellite system and synthetic aperture radar in last few decades allows us to monitor deformation of earth s surface in unprecedented spatial and temporal resolution these observations combined with fast data transmission and quick data processing enable us to quickly detect and locate earthquakes and volcanic eruptions and assess potential hazards such as strong earthquake shaking tsunamis and volcanic eruptions these techniques thus are key parts of early warning systems help identify some hazards before a cataclysmic event and improve the response to the consequent damage

quasi real time fault model estimation for near field tsunami forecasting based on rtk gps analysis application to the 2011 tohoku oki earthquake mw 9 0 1 real time crustal deformation monitoring is extremely important for achieving rapid understanding of actual earthquake scales because the measured permanent displacement directly gives the true earthquake size seismic moment mw information which in turn provides tsunami forecasting we have developed an algorithm to detect estimate static ground displacements due to earthquake faulting from real time kinematic gps rtk gps time series the new algorithm identifies permanent displacements by monitoring the difference of a short term average sta to a long term average lta of the gps time series we assessed the noise property and precision of the rtk gps time series with various baseline length conditions and orbits and discerned that the real time ephemerides based on the international gnss service igs are sufficient for crustal deformation monitoring with long baselines up to 1 000 km we applied the algorithm to data obtained in the 2011 off the pacific coast of tohoku earthquake mw 9 0 to test the possibility of coseismic displacement detections and further we inverted the obtained displacement fields for a fault model the inversion estimated a fault model with mw 8 7 which is close to the actual mw of 9 0 within five minutes from the origin time once the fault model is estimated tsunami waveforms can be immediately synthesized using pre computed tsunami green s functions the calculated waveforms showed good agreement with the actual tsunami observations both in arrival times and wave heights suggesting that the rtk gps data by our algorithm can provide reliable rapid tsunami forecasting that can complement existing tsunami forecasting systems based on seismic observations

real time reliable magnitudes for large earthquakes from 1 hz gps precise point positioning the 2011 tohoku oki japan earthquake 1 the early warning issued after the onset of the mw9 0 tohoku oki earthquake significantly underestimated its magnitude saturating 120 seconds after the earthquake began at mw8 1 here we investigate whether real time deformation data from japan s dense network of continuously recording global positioning system gps stations could have been used to provide a more reliable rapid estimate of the earthquake s magnitude and ultimately a more robust tsunami forecast we use precise point positioning in real time mode with broadcast clock and orbital corrections to give station positions every 1 s we then carry out a simple static inversion on a subset of stations to determine the portion of the fault that slipped and the earthquake magnitude unlike most previous methods our method produces estimates of seismic moment before the earthquake rupture has completed we find that the deformation data allow a robust magnitude estimate just 100 s after the earthquake onset we also investigated the density of stations required for a robust moment magnitude estimate fewer than 1 station every 100 km are needed we recommend that gps data be incorporated into earthquake early warning systems for regions at threat from large magnitude earthquakes and tsunamis

very high rate 10 hz gps seismology for moderate magnitude earthquakes the case of themw6 3 l aquila central italy event accepted for publication in journal of geophysical research copyright 2010 american geophysical union

kinematic rupture scenarios and synthetic displacement data an example application to the cascadia subduction zone scenario ruptures and ground motion simulation are important tools for studies of expected earthquake and tsunami hazards during future events this is particularly important for large mw8 and very large mw8 5 events for which observations are still limited in particular synthetic waveforms are important to test the response of earthquake and tsunami warning systems to large events these systems are not often exercised in this manner we will show an application of the karhunen loeve kl expansion to generate stochastic slip distributions of large events with an example application to the cascadia subduction zone we will discuss how to extend the static slip distributions obtained from the k l expansion to produce kinematic rupture models and generate synthetic long period displacement data at the sampling rates of traditional gnss stations we will validate the waveforms produced by this method by comparison to a displacement based ground motion prediction equation gmpe obtained from gnss measurements of large earthquakes worldwide

operational real time gps enhanced earthquake early warning moment magnitudes for large earthquakes mw 7 0 derived in real time from near field seismic data can be underestimated due to instrument limitations ground tilting and saturation of frequency amplitude magnitude relationships real time high rate gps resolves the buildup of static surface displacements with the s wave arrival assuming nonsupershear rupture thus enabling the estimation of slip on a finite fault and the event s geodetic moment recently a range of high rate gps strategies have been demonstrated on off line data here we present the first operational system for real time gps enhanced earthquake early warning as implemented at the berkeley seismological laboratory bsl and currently analyzing real time data for northern california the bsl generates real time position estimates operationally using data from 62 gps stations in northern california a fully triangulated network defines 170 station pairs processed with the software trackrt the bsl uses g larms the geodetic alarm system to analyze these positioning time series and determine static offsets and preevent quality parameters g larms derives and broadcasts finite fault and magnitude information through least squares inversion of the static offsets for slip based on a priori fault orientation and location information this system tightly integrates seismic alarm systems cisn shakealert elarms 2 as it uses their p wave detections to trigger its processing quality control runs continuously we use a synthetic hayward fault earthquake scenario on real time streams to demonstrate recovery of slip and magnitude reanalysis of the mw7 2 el mayor cucapah earthquake tests the impact of dynamic motions on offset estimation using these test cases we explore sensitivities to disturbances of a priori constraints origin time location and fault strike dip

global positioning system gps and gps acoustic observations insight into slip along the subduction zones around japan the global positioning system gps is one of the most powerful tools available for observation of earth s surface deformation in particular coseismic postseismic slow transient and interseismic deformation have all been observed globally by gps over the past two decades especially in subduction zones moreover gps acoustic techniques have been developed for practical use in the past decade allowing observation of offshore deformation immediately above slip regions here we describe the application of gps and gps acoustic observations to the detection of deformation due to plate boundary slip for interplate earthquakes as well as afterslip and slow slip events in subduction zones around japan where geodetic data coverage is particularly dense the data demonstrate temporally variable strain accumulation in the source region of the 2011 mw 9 0 tohoku oki earthquake and observation of the huge slip of the tohoku oki earthquake near the trench using gps acoustic methods has considerably advanced o

tsunami simulation using sources inferred from various measurement data implications for the model forecast model forecast applications use various models of tsunami sources inferred from different measurement data even the same type of observation data can produce substantially different tsunami source models during a real time forecast when more data are obtained during the real time analysis improved tsunami observations enable investigation of the influence of such model source variability on the final forecast using different source data sets of several events the 2010 maule chile and 2011 tohoku japan tsunamis were two recent events that provide ample observations throughout the pacific and were thus used here to study the sensitivity of different model inputs for forecasting the sources for these events were derived using the following three different methods 1 real time or post event inversion of tsunameter water level data 2 prediction of sea floor deformations via analysis of seismic wave forms and application of a finite fault model and 3 prediction of sea floor deformation using real time gps data for the march 11 2011 tohoku tsunami two examples of each method are used while for the february 27 2010 maule event only one tsunameter inversion and one finite fault model method were used due to a much more limited data set observed data from the deep ocean assessment and reporting for tsunamis dart network japan gps buoys and select tide gauges across the pacific were compared with forecasts to assess the sensitivity of these three methods using root mean square error analysis we divided the analysis by the type of data and the distance from the source this sensitivity analysis showed that increasing the resolution of a tsunami source model does not necessarily improve tsunami forecast quality even in the near field instead the findings suggest that when forecasting coastal impact defining the overall energy characteristic of a tsunami source may be more important than refining small source details source models based on direct tsunami observations are better at reproducing a tsunami signal this finding is not very surprising but has implications for tsunami forecasting and warning operations

a methodology for near field tsunami inundation forecasting application to the 2011 tohoku tsunami existing tsunami early warning systems in the world can give either one or a combination of estimated tsunami arrival times heights or qualitative tsunami forecasts before the tsunami hits near field coastlines a future tsunami early warning system should be able to provide a reliable near field tsunami inundation forecast on high resolution topography within a short time period here we describe a new methodology for near field tsunami inundation forecasting in this method a precomputed tsunami inundation and precomputed tsunami waveform database is required after information about a tsunami source is estimated tsunami waveforms at nearshore points can be simulated in real time a scenario that gives the most similar tsunami waveforms is selected as the site specific best scenario and the tsunami inundation from that scenario is selected as the tsunami inundation forecast to test the algorithm tsunami inundation along the sanriku coast is forecasted by using source models for the 2011 tohoku earthquake estimated from gps w phase or offshore tsunami waveform data the forecasting algorithm is capable of providing a tsunami inundation forecast that is similar to that obtained by numerical forward modeling but with remarkably smaller cpu time the time required to forecast tsunami inundation in coastal sites from the sendai plain to miyako city is approximately 3 min after information about the tsunami source is obtained we found that the tsunami inundation forecasts from the 5 min gps 5 min w phase 10 min w phase fault models and 35 min tsunami source model are all reliable for tsunami early warning purposes and quantitatively match the observations well although the latter model gives tsunami forecasts with highest overall accuracy the required times to obtain tsunami forecast from the above four models are 8 min 9 min 14 min and 39 min after the earthquake respectively or in other words 3 min after receiving the source model this method can be useful in developing future tsunami forecasting systems with a capability of providing tsunami inundation forecasts for locations near the tsunami source area

long period ground motion prediction equations for moment magnitude estimation of large earthquakes in japan we developed long period 5 30 s ground motion prediction equations gmpes for peak ground velocities pgvs and peak ground displacements pgds for crustal interplate and intraplate earthquakes we used strong motion data from kik net downhole stations located in layers with shear wave velocities equal to or greater than 2000 m s the data set consisted of 20 earthquakes of 6 m w 9 1 that occurred in and around japan including the 2011 tohoku earthquake two stage regression analyses were performed to derive the long period gmpes we fitted the data with bilinear regression lines bending at m w 7 5 although additional factors such as focal depth and earthquake type were found to enhance the fitting with the observed data the developed equations indicated that long period pgvs and pgds are larger for crustal earthquakes than for interplate and intraplate earthquakes the attenuation coefficients indicated that long period pgvs and pgds increase with increasing depth we estimated the moment magnitude by fitting the observed pgvs and pgds in the 5 30 s period range with the long period gmpes we obtained estimates of the magnitudes of 23 earthquakes recorded by kik net downhole accelerometers and the results were consistent with the moment magnitudes obtained from the global centroid moment tensor project the described method was proven useful for estimating the moment magnitude of great earthquakes offering the potential for rapid estimation of moment magnitude if information from the source area is available

near field tsunami models with rapid earthquake source inversions from land and ocean based observations the potential for forecast and warning computation of tsunami models in the region adjacent to large earthquakes immediately after rupture initiation remains a challenging problem limitations of traditional seismological instrumentation in the near field and concern by tsunami modelers regarding the nonuniqueness of source inversions and the use of indirect observations have in the past been hurdles for such efforts employing near field data from the mw 9 0 2011 tohoku oki data we test source models obtained from newly developed algorithms and multisensor data we demonstrate the ability of such source models determined from land based coseismic data from the combination of gps and strong motion sensors to forecast near source tsunamis we also demonstrate that rapid ingestion of offshore shallow water 100 1000 m wave gauge data substantially improves the earthquake source and tsunami forecast to assess the success of such tsunami models we rely on detailed comparisons to 2000 tsunami survey measurements collected after the event we argue that deployments of shallow water wave gauges coupled with land based geophysical sensors can in the future provide enough information to issue timely and accurate forecasts of tsunami intensity immediately or shortly after rupture initiation of large earthquakes

source inversion of w phase speeding up seismic tsunami warning w phase is a long period phase arriving before s wave it can be interpreted as superposition of the fundamental first second and third overtones of spheroidal modes or rayleigh waves and has a group velocity from 4 5 to 9 km s 1 over a period range of 100 1000 s the amplitude of long period waves better represents the tsunami potential of an earthquake because of the fast group velocity of w phase most of w phase energy is contained within a short time window after the arrival of the p wave at a distance of 50 w phase energy is contained within 23 min after the origin time which is the distinct advantage of using w phase for rapid tsunami warning purposes we use a time domain deconvolution method to extract w phases from the broad band records of global seismic networks the bandwidth of w phase is approximately from 0 001 to 0 01 hz and we bandpass filter the data from 0 001 to 0 005 hz in most cases having extracted w phase from the vertical component records we perform a linear inversion using a point source to determine mw and the source mechanism for several large earthquakes including the 2004 sumatra andaman earthquake the 2005 nias earthquake the 2006 kuril is earthquake and the 2007 sumatra earthquake w phase inversion yields reliable solutions and holds promise of the use of w phase for rapid assessment of tsunami potential

shallow dynamic overshoot and energetic deep rupture in the 2011 mw 9 0 tohoku oki earthquake strong spatial variation of rupture characteristics in the moment magnitude mw 9 0 tohoku oki megathrust earthquake controlled both the strength of shaking and the size of the tsunami that followed finite source imaging reveals that the rupture consisted of a small initial phase deep rupture for up to 40 seconds extensive shallow rupture at 60 to 70 seconds and continuing deep rupture lasting more than 100 seconds a combination of a shallow dipping fault and a compliant hanging wall may have enabled large shallow slip near the trench normal faulting aftershocks in the area of high slip suggest dynamic overshoot on the fault despite prodigious total slip shallower parts of the rupture weakly radiated at high frequencies whereas deeper parts of the rupture radiated strongly at high frequencies

a new seismogeodetic approach applied to gps and accelerometer observations of the 2012 brawley seismic swarm implications for earthquake early warning 1 the 26 august 2012 brawley seismic swarm of hundreds of events ranging from m1 4 to m5 5 in the salton trough california provides a unique data set to investigate a new seismogeodetic approach that combines global positioning system gps and accelerometer observations to estimate displacement and velocity waveforms first in simulated real time mode we analyzed 1 5 hz gps data collected by 17 stations fully encircling the swarm zone at near source distances up to about 40 km using precise point positioning with ambiguity resolution ppp ar we used a reference network of north american gps stations well outside the region of deformation to estimate fractional cycle biases and satellite clock parameters which were then combined with ultrarapid orbits from the international gnss service to estimate positions during the brawley seismic swarm next we estimated seismogeodetic displacements and velocities from gps phase and pseudorange observations and 100 200 hz accelerations collected at three pairs of gps and seismic stations in close proximity using a new tightly coupled kalman filter approach as an extension of the ppp ar process we can clearly discern body waves in the velocity waveforms including p wave arrivals not detectable with the gps only approach for earthquake magnitudes as low as mw 4 6 and significant static offsets for magnitudes as low as mw 5 4 our study shows that gps networks upgraded with strong motion accelerometers can provide new information for improved understanding of the earthquake rupture process and be of critical value in creating a robust early warning system for any earthquake of societal significance

seismology speed and size of the sumatra earthquake we now have a clearer picture of the seismic features of last year s gigantic event our seismological results reveal that indonesia s devastating sumatra andaman earthquake on 26 december 2004 was 2 5 times larger than initial reports suggested second only to the 1960 chilean earthquake in recorded magnitude they indicate that it slowly released its energy by slip along a 1 200 km fault generating a long rupture that contributed to the subsequent tsunami now that the entire rupture zone has slipped the strain accumulated from the subduction of the indian plate beneath the burma microplate has been released and there is no immediate danger of a similar tsunami being generated on this part of the plate boundary although large earthquakes on segments to the south still present a threat

constraining shallow slip and tsunami excitation in megathrust ruptures using seismic and ocean acoustic waves recorded on ocean bottom sensor networks abstract great earthquakes along subduction zone plate boundaries like the 2011 magnitude 9 0 tohoku oki japan event deform the seafloor to generate massive tsunamis tsunami wave heights near shore are greatest when excitation occurs far offshore near the trench where water depths are greatest and fault slip is shallow the tohoku event featuring over 30 m of slip near the trench exemplifies this hazard unfortunately the rupture process that far offshore is poorly constrained with land based geodetic and even most seafloor deformation measurements and seismic inferences of shallow slip are often nonunique here we demonstrate through dynamic rupture simulations of the tohoku event that long period guided waves in the ocean specifically leaking oceanic p wave modes known as pl waves can resolve the shallow rupture process and tsunami excitation near the trench with predicted pressure changes of 0 1 1 mpa along most of the seafloor landward of the trench and periods of several seconds these pl waves should be observable with ocean bottom pressure sensors and or seismometers with cabled sensor networks like those being deployed offshore japan and in other subduction zones these waves could be used to rapidly quantify shallow slip and near trench seafloor uplift and improve local tsunami early warning systems

localized fault slip to the trench in the 2010 maule chile mw 8 8 earthquake from joint inversion of high rate gps teleseismic body waves insar campaign gps and tsunami observations the 27 february 2010 mw 8 8 maule earthquake ruptured 500 km along the plate boundary offshore central chile between 34 s and 38 5 s establishing whether coseismic fault offset extended to the trench is important for interpreting both shallow frictional behavior and potential for tsunami earthquakes in the region joint inversion of high rate gps teleseismic body waves interferometric synthetic aperture radar insar campaign gps and tsunami observations yields a kinematic rupture model with improved resolution of slip near the trench bilateral rupture expansion is resolved in our model with relatively uniform slip of 5 10 m downdip beneath the coast and two near trench high slip patches with 12 m displacements the peak slip is 17 m at a depth of 15 km on the central megathrust located 200 km north from the hypocenter and overlapping the rupture zone of the 1928 m 8 event the updip slip is 16 m near the trench another shallow near trench patch is located 150 km southwest of the hypocenter with a peak slip of 12 m checkerboard resolution tests demonstrate that correctly modeled tsunami data are critical to resolution of slip near the trench with other data sets allowing but not requiring slip far offshore large interplate aftershocks have a complementary distribution to the coseismic slip pattern filling in gaps or outlining edges of large slip zones two clusters of normal faulting events locate seaward along the plate motion direction from the localized regions of large near trench slip suggesting that proximity of slip to the trench enhanced extensional faulting in the underthrusting plate

the diversity of large earthquakes and its implications for hazard mitigation with the advent of broadband seismology and gps significant diversity in the source radiation spectra of large earthquakes has been clearly demonstrated this diversity requires different approaches to mitigate hazards in certain tectonic environments seismologists can forecast the future occurrence of large earthquakes within a solid scientific framework using the results from seismology and gps such forecasts are critically important for long term hazard mitigation practices but because stochastic fracture processes are complex the forecasts are inevitably subject to large uncertainty and unexpected events will continue to surprise seismologists recent developments in real time seismology will help seismologists to cope with and prepare for tsunamis and earthquakes combining a better understanding of earthquake diversity with modern technology is the key to effective and comprehensive hazard mitigation practices

linear and nonlinear computations of the 1992 nicaragua earthquake tsunami numerical computations of tsunamis are made for the 1992 nicaragua earthquake using different governing equations bottom frictional values and bathymetry data the results are compared with each other as well as with the observations both tide gauge records and runup heights comparison of the observed and computed tsunami waveforms indicates that the use of detailed bathymetry data with a small grid size is more effective than to include nonlinear terms in tsunami computation linear computation overestimates the amplitude for the later phase than the first arrival particularly when the amplitude becomes large the computed amplitudes along the coast from nonlinear computation are much smaller than the observed tsunami runup heights the average ratio or the amplification factor is estimated to be 3 in the present case when the grid size of 1 minute is used the factor however may depend on the grid size for the computation

aseismic slow slip on an inland active fault triggered by a nearby shallow event the 2008 iwate miyagi nairiku earthquake mw6 8 1 using gps observations we have detected an aseismic slip event on the intraplate dedana fault that was triggered by the iwate miyagi nairiku earthquake mw6 8 13 jun 2008 utc on a nearby but separate fault the observations cannot be satisfactorily explained in terms of either viscoelastic relaxation or poroelastic rebound and we cannot explain the observed displacement time series without presuming that aseismic slip occurred on the dedana fault this slip was likely triggered by the mainshock stress change the detection of future such aseismic slip events on intraplate faults is likely to require denser geodetic networks than are currently in operation but is important for fully characterizing the seismic hazard associated with intraplate earthquakes

paleoflood analysis of an alluvial channel in the south central great plains black bear creek oklahoma abstract late holocene floodplain of the black bear basin in north central oklahoma was chronologically developed based upon slackwater deposition and radiocarbon dating of associated paleosols major paleoflood events occurred 3590 80 yr bp and 1150 100 yr bp assumptions developed for application in semi arid bedrock channels were tested and modified maximum accumulation of slackwater deposits were located some 400 m up tributaries rather than at the intersection of the mouths of present day tributary junctions these sites represent the intersection with tributaries during the extreme widths of floods on an alluvial floodplain physically tracing slackwater units up tributaries was possible in some cases 8 km an accurate estimate of flood stage was determined by measuring up terrace perpendicular to the tributary during floods aggradation and degradation of the main channel were insignificant because the broad floodplain is the most impacted feature in an alluvial setting the preflood landscapes determined from paleosol elevations were recreated to estimate the manning roughness coefficients and paleoflood discharges the hec 2 water surface profile hydrologic engineering center 1982 determined that paleodischarges of 4391 cm in 3590 bp and 8782 cm in 1150 bp emplaced the slackwater deposits along the tributaries of black bear creek

modeling the rupture process of the 2003 september 25 tokachi oki hokkaido earthquake using 1 hz gps data received 10 september 2004 accepted 3 october 2004 published 3 november 2004 1 high rategpshasthepotentialtorecoverbothdynamic and static displacements accurately we analyze 1 hz gps data recorded during the 2003 tokachi oki earthquake the 1 hz gps displacement waveforms show good agreement with integrated accelerometer records except for low frequency noise that are inherently present in integrated seismic records the gps waveforms were inverted to model the spatio temporal evolution of the fault slip during the rupture the slip is found to propagate downdip in the subduction zone with largest moment release 50 km northwest of the hypocenter the region of largest slip agrees in general with traditional seismic studies indicating that 1 hz gps can be used for finite fault studies the 1 hz gps slip model shows clearer contrast with afterslip distributions than those inferred from strong motion data possibly because 1 hz gps is more sensitive to cumulative slip distribution index terms 1294 geodesy and gravity instruments and techniques 7209 seismology earthquake dynamics and mechanics 7212 seismology earthquake ground motions and engineering citation miyazaki s k m larson k choi k hikima k koketsu p bodin j haase g emore and a yamagiwa 2004 modeling the rupture process of the 2003 september 25 tokachi oki hokkaido earthquake using 1 hz gps data geophys res lett 31 l21603 doi 10 1029 2004gl021457

sediment transport modeling of multiple grain sizes for the 2011 tohoku tsunami on a steep coastal valley of numanohama northeast japan abstract the grain size distribution of a tsunami deposit may have a correlation with the tsunami inundation process and further with the tsunami source characteristics we test this hypothesis using thickness and grain size distribution data of the 2011 tohoku tsunami deposit in numanohama coast iwate prefecture japan here we build and validate a tsunami sediment transport model that can simulate deposit thickness and grain size distribution our numerical model has three layers parent bed deposit bed and suspended load layers the two bed layers contain information about the grain size distribution this numerical model can handle a wide range of grain sizes from 0 063 4 to 5 657 mm 2 5 the grain size distributions at 12 sample points along a 900 m transect from the beach through a marsh and up to the inundation limit are used to validate the tsunami sediment transport model we adopt a reference tsunami source model that can well reproduce the observed tsunami run up heights ranging from 16 to 35 m along the steep valley during the 2011 tsunami the simulated sand thickness distribution along the transect is consistent with the observed thickness ranging from 3 to 23 cm the computed net erosion and deposition suggest that most of the sand deposit was originated from the near shore the shapes of the simulated grain size distributions represented by their sorting skewness kurtosis and mean at most of the sample sites are similar to the observations the differences between the observed and simulated peak of grain size distributions are less than 1 to evaluate the sensitivity to the tsunami source model we test five tsunami scenarios which are modified from the reference source model while the tsunami scenario with 120 of the reference amplitude can also reproduce the thickness and grain size distribution the scenarios with amplitudes smaller than 80 of the reference or with wave periods shorter than 50 of the reference source model underestimate the thickness and cannot reproduce the grain size distributions our simulation results suggest that it is possible to estimate tsunami wave amplitude and wave period from sediment deposit thickness and grain size distribution data

detection of ground motions using high rate gps time series monitoring surface deformation in real time help at planning and protecting infrastructures and populations manage sensitive production i e seveso type and mitigate long term consequences of modifications implemented we present rt shake an algorithm developed to detect ground motions associated with landslides sub surface collapses subsidences earthquakes or rock falls rt shake detects first transient changes in individual gps time series before investigating for spatial correlation s of observations made at neighbouring gps sites and eventually issue a motion warning in order to assess our algorithm on fast seconds to minute large from 1cm to meters and spatially consistent surface motions we use the 1hz geonet gnss network data of the tohoku oki mw9 0 2011 as a test scenario we show the delay of detection of seismic wave arrival by gps records is of 10 seconds with respect to an identical analysis based on strong motion data and this time delay depends on the level of the time variable noise nevertheless based on the analysis of the gps network noise level and ground motion stochastic model we show that rt shake can narrow the range of earthquake magnitude by setting a lower threshold of detected earthquakes to mw6 5 7 if associated with a real time automatic earthquake location system

earth s free oscillations excited by the 26 december 2004 sumatra andaman earthquake at periods greater than 1000 seconds earth s seismic free oscillations have anomalously large amplitude when referenced to the harvard centroid moment tensor fault mechanism which is estimated from 300 to 500 second surface waves by using more realistic rupture models on a steeper fault derived from seismic body and surface waves we approximated free oscillation amplitudes with a seismic moment 6 5 10 22 newton meters that corresponds to a moment magnitude of 9 15 with a rupture duration of 600 seconds the fault rupture models represent seismic observations adequately but underpredict geodetic displacements that argue for slow fault motion beneath the nicobar and andaman islands

long period surface motion of the multi patch mw9 0 tohoku oki earthquake we show that it is possible to capture the oscillatory ground motion induced by the tohoku oki event for periods ranging from 3 to 100s using precise point positioning ppp we find that the ground motions of the sedimentary basins of japan were large respectively 0 15m s and 0 15m s2 for velocity and acceleration even for periods larger than 3s we compare geodetic observables with a ground motion prediction equation gmpe designed for japan seismicity and find that the spectral acceleration sa is well estimated for periods larger than 3s and distances ranging from 100 to 500km at last through the analysis of the displacement attenuation plots we show that the 2011 tohoku oki event is likely composed of multiple rupture patches as suggested before by time reversal inversions of seismic data

existence of interplane earthquakes and neutral stress boundary between the upper and lower planes of the double seismic zone beneath tohoku and hokkaido northeastern japan abstract using data from the recently constructed nationwide dense seismic network we determined the hypocenters and focal mechanisms of many intermediate depth intraslab earthquakes within the pacific slab beneath northeastern japan the results show that in addition to the upper and lower planes of the double seismic zone a considerable number of intraslab earthquakes also occur between the two planes this interplane earthquake activity is not homogeneously distributed in space being high beneath eastern hokkaido and the fore arc regions of southeast and central tohoku the focal mechanisms of the interplane earthquakes tend to be of the down dip compressional type dc in tohoku and the hokkaido corner but down dip tensional type de in eastern hokkaido upper plane earthquakes are characterized by dc type stress while lower plane earthquakes are de type in both tohoku and eastern hokkaido the existence of interplane earthquakes enables estimation of the position of the neutral plane between the upper plane dc stress and the lower plane de stress we did so by applying stress tensor inversions to focal mechanism data obtained in the present study and japan meteorological agency jma data the results show that the neutral plane is located about 22 km beneath the upper plate interface beneath tohoku but only about 10 km beneath the upper surface beneath eastern hokkaido this difference in the location of the neutral plane may be due to the difference in buoyancy force exerted by the less dense metastable olivine wedge that is a result of the oblique plate subduction beneath hokkaido comparison of large intraslab earthquakes beneath the two regions shows that their aftershock areas are limited by the neutral plane suggesting that large earthquake ruptures are confined to either the dc or de stress field and do not go beyond the neutral plane

tsunami forecast by joint inversion of real time tsunami waveforms and seismic or gps data application to the tohoku 2011 tsunami correctly characterizing tsunami source generation is the most critical component of modern tsunami forecasting although difficult to quantify directly a tsunami source can be modeled via different methods using a variety of measurements from deep ocean tsunameters seismometers gps and other advanced instruments some of which in or near real time here we assess the performance of different source models for the destructive 11 march 2011 japan tsunami using model data comparison for the generation propagation and inundation in the near field of japan this comparative study of tsunami source models addresses the advantages and limitations of different real time measurements with potential use in early tsunami warning in the near and far field the study highlights the critical role of deep ocean tsunami measurements and rapid validation of the approximate tsunami source for high quality forecasting we show that these tsunami measurements are compatible with other real time geodetic data and may provide more insightful understanding of tsunami generation from earthquakes as well as from nonseismic processes such as submarine landslide failures

a rapid estimation of near field tsunami runup many efforts have been made to quickly estimate the maximum runup height of tsunamis associated with large earthquakes this is a difficult task because of the time it takes to construct an accurate tsunami model using real time data from the source it is possible to construct a database of potential seismic sources and their corresponding tsunami a priori however such models are generally based on uniform slip distributions and thus oversimplify the knowledge of the earthquake source here we show how to predict tsunami runup from any seismic source model using an analytic solution that is specifically designed for subduction zones with a well defined geometry i e chile japan nicaragua and alaska the main idea of this work is to provide a tool for emergency response trading off accuracy for speed the solutions we present for large earthquakes appear promising here runup models are computed for the following the 1992 mw 7 7 nicaragua earthquake the 2001 mw 8 4 peru earthquake the 2003 mw 8 3 hokkaido earthquake the 2007 mw 8 1 peru earthquake the 2010 mw 8 8 maule earthquake the 2011 mw 9 0 tohoku earthquake and the recent 2014 mw 8 2 iquique earthquake the maximum runup estimations are consistent with measurements made inland after each event with a peak of 9 m for nicaragua 8 m for peru 2001 32 m for maule 41 m for tohoku and 4 1 m for iquique considering recent advances made in the analysis of real time gps data and the ability to rapidly resolve the finiteness of a large earthquake close to existing gps networks it will be possible in the near future to perform these calculations within the first minutes after the occurrence of similar events thus such calculations will provide faster runup information than is available from existing uniform slip seismic source databases or past events of premodeled seismic sources

using 1 hz gps data to measure deformations caused by the denali fault earthquake the 3 november 2002 moment magnitude 7 9 denali fault earthquake generated large permanent surface displacements in alaska and large amplitude surface waves throughout western north america we find good agreement between strong ground motion records integrated to displacement and 1 hertz global positioning system gps position estimates collected 140 kilometers from the earthquake epicenter one hertz gps receivers also detected seismic surface waves 750 to 3800 kilometers from the epicenter whereas these waves saturated many of the seismicinstruments in the same region high frequency gps increases the dynamic range and frequency bandwidth of ground motion observations providing another tool for studying earthquake processes

the 2014 m w 6 0 napa earthquake california observations from real time gps enhanced earthquake early warning recently progress has been made to demonstrate feasibility and benefits of including real time gps rtgps in earthquake early warning and rapid response systems most concepts however have yet to be integrated into operational environments the berkeley seismological laboratory runs an rtgps based finite fault inversion scheme in real time this system g larms detected the 2014 mw 6 0 south napa earthquake in california we review g larms performance during this event and 13 aftershocks and present rtgps observations and real time modeling results for the main shock the first distributed slip model and magnitude estimates were available 24 s after the event origin time which after optimizations was reduced to 14 s 8s s wave travel time 6 s data latency g larms solutions for the aftershocks that had no measurable surface displacements demonstrate that in combination with the seismic early warning magnitude m w 6 0 is our current resolution limit

near field tsunami forecasting from cabled ocean bottom pressure data 1 we propose a method for near field tsunami forecasting from data acquired by cabled offshore ocean bottom tsunami meters obtms in real time we first invert tsunami waveforms recorded at obtms to estimate the spatial distribution of initial sea surface displacements in the tsunami source region without making any assumptions about fault geometry and earthquake magnitude then we synthesize the coastal tsunami waveforms from the estimated sea surface displacement distribution to improve the reliability of the tsunami forecasting we use updated obtm data to repeat the forecast calculation at 1 min intervals we tested our method by simulating the 1896 sanriku tsunami earthquake which caused a devastating tsunami with maximum runup height of 38 m along the pacific coast of northeastern japan instead of real obtm records proxies were used the simulation demonstrated that our method provided accurate estimations of coastal arrival times and amplitudes of the first peak of the tsunami more than 20 min before the maximum amplitude wave reached the coastal site nearest to the source we also applied the method to real data of a small tsunami that was caused by a local earthquake and successfully forecasted the tsunami at coastal tide stations we found that accuracy of our estimated coastal tsunami amplitudes can be affected by the spatial relationship between the tsunami source and the offshore observation stations our numerical simulation showed that even more accurate tsunami amplitude forecasts would be achieved by deployment of additional offshore stations separated by a distance comparable to the trench parallel length of the tsunami source

fast determination of earthquake magnitude and fault extent from real time p wave recordings s u m m a r y this work is aimed at the automatic and fast characterization of the extended earthquake source through the progressive measurement of the p wave displacement amplitude along the recorded seismograms we propose a straightforward methodology to quickly characterize the earthquake magnitude and the expected length of the rupture and to provide an approximate estimate of the average stress drop to be used for earthquake earlywarning and rapid response purposes we test the methodology over a wide distance and magnitude range using a massive japan earthquake accelerogram data set our estimates of moment magnitude source duration length and stress drop are consistent with the ones obtained by using other techniques and analysing the whole seismic waveform in particular the retrieved source parameters follow a self similar constant stress drop scaling median value of stress drop 0 71 mpa for the m 9 0 2011 tohoku oki event both magnitude and length are underestimated due to limited available p wave time window ptws and to the low frequency cut off of analysed data we show that in a simulated real time mode about 1 2 seconds would be required for the source parameter determination of m 4 5 events 3 10 seconds for m 6 7 and 30 40 s for m 8 8 5 the proposed method can also provide a rapid evaluation of the average slip on the fault plane which can be used as an additional discriminant for tsunami potential associated to large magnitude earthquakes occurring offshore

pre computed tsunami inundation database and forecast simulation in pelabuhan ratu indonesia we built a pre computed tsunami inundation database in pelabuhan ratu one of tsunami prone areas on the southern coast of java indonesia which can be employed for a rapid estimation of tsunami inundation during an event the pre computed tsunami waveforms and inundations are from a total of 340 scenarios ranging from 7 5 to 9 2 in moment magnitude scale mw including simple fault models of 208 thrust faults and 44 tsunami earthquakes on the plate interface as well as 44 normal faults and 44 reverse faults in the outer rise region using our tsunami inundation forecasting algorithm neartif we could rapidly estimate the tsunami inundation in pelabuhan ratu for three different hypothetical earthquakes the first hypothetical earthquake is a megathrust earthquake type mw 9 0 offshore sumatra which is about 600 km from pelabuhan ratu to represent a worst case event in the far field the second hypothetical earthquake mw 8 5 is based on a slip deficit rate estimation from geodetic measurements and represents a most likely large event the third hypothetical earthquake is a tsunami earthquake type mw 8 1 which often occurs south of java we compared the tsunami inundation maps produced by the neartif algorithm with results of direct forward inundation modeling for the hypothetical earthquakes the tsunami inundation maps produced from both methods are similar for the three cases however the tsunami inundation map from the inundation database can be obtained in much shorter time 1 min than the one from a forward inundation modeling 40 min these indicate that the neartif algorithm based on pre computed inundation database is reliable and useful for tsunami warning purposes this study also demonstrates that the neartif algorithm can work well though the earthquake source is located outside the area of fault model database because it uses a time shifting procedure for the best fit scenario searching

dispersion and nonlinear effects in the 2011 tohoku oki earthquake tsunami this study reveals the roles of the wave dispersion and nonlinear effects for the 2011 tohoku oki earthquake tsunami we conducted tsunami simulations based on the nonlinear dispersive equations with a high resolution source model the simulations successfully reproduced the waveforms recorded in the offshore deep sea and focal areas the calculated inundation area coincided well with the actual inundation for the sendai plain which was the widest inundation area during this event by conducting sets of simulations with different tsunami equations we obtained the followings insights into the wave dispersion nonlinear effects and energy dissipation for this event although the wave dispersion was neglected in most studies the maximum amplitude was significantly overestimated in the deep sea if the dispersion was not included the waveform observed at the station with the largest tsunami height 2 m among the deep ocean stations also verified the necessity of the dispersion it is well known that the nonlinear effects play an important role for the propagation of a tsunami into bays and harbors additionally nonlinear effects need to be considered to accurately model later waves even for offshore stations in particular including nonlinear terms rather than the inundation was more important when precisely modeling the waves reflected from the coast

detection of arbitrarily large dynamic ground motions with a dense high rate gps network 1 we describe the detection of teleseismic surface waves from the 3 november 2002 mw 7 9 denali fault earthquake in alaska with a dense network of 1 hz gps stations in southern california about 3900 km from the event relative horizontal displacements with amplitudes in excess of 15 mm and duration of 700 seconds agree with integrated velocities recorded by nearby broadband seismometers with an rms difference of 2 3 mm the displacements are derived from independent 1 hz instantaneous positions demonstrating that a gps network can provide direct measurements of arbitrarily large dynamic and static ground horizontal displacements at periods longer than 1 s and amplitudes above 2 mm with an inherent precision signal to noise that improves indefinitely with amplitude without clipping and in real time high rate real time gps networks can enhance earthquake detection and seismic risk mitigation and support other applications such as intelligent transportation and civil infrastructure monitoring

tfish rapid rapid improvement of near field tsunami forecasting based on offshore tsunami data by incorporating onshore gnss data we have developed a new algorithm that improves near field tsunami forecasting based on offshore tsunami data soon after an earthquake by incorporating real time onshore global navigation satellite system gnss data in our algorithm called tfish rapid tsunami forecasting based on inversion for initial sea surface height real time automatic detection method for permanent displacement 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 our algorithm can be applicable to arbitrary types of large tsunamigenic earthquakes when the static displacements are substantial enough to be detected at onshore gnss stations we retrospectively applied our algorithm to the 2011 mw 9 0 tohoku earthquake and demonstrated its ability to provide information about disastrous tsunamis approaching wide areas along the near field coast furthermore arrival times and wave heights of large amplitude short period tsunamis affecting specific near field coasts can be predicted at least 5 min before the actual tsunami arrivals

the utility of gnss for earthquake early warning in regions with sparse seismic networks abstract real time global navigation satellite systems gnss data are on their way to being well integrated into earthquake early warning eew systems the strength of gnss data lies in the resolution of large dynamic and static displacements because of the limits in precision gnss data alone cannot resolve small ground displacements due to for instance p waves therefore their use is currently limited to refining early warnings with more precise earthquake characteristics such as magnitudes or ground motion predictions here we analyze 1 hz global positioning system gps data from the 24 january 2016 m w 7 1 iniskin earthquake which ruptured 125 km under cook inlet in alaska to motivate the inclusion of gnss derived s wave measurements into the trigger algorithms of eew systems in regions lacking dense early warning instrumentation networks we derive a relationship between earthquake depth and distance to help determine whether gnss s wave observations could expedite warnings to specific locations because the iniskin earthquake was deep by the time the s wave reached the surface the p wave had already been observed over a wide region limiting the potential for unique contributions from gnss data to this event for the same earthquake occurring near the surface however s waves derived from gnss data have the potential to increase the warning time regardless of the depth the iniskin earthquake is an excellent example of the utility of gnss in rapidly assessing the magnitude improving predictions of ground shaking and estimating the area of impact for the earthquake

the value of real time gnss to earthquake early warning gnss based earthquake early warning eew algorithms estimate fault finiteness and unsaturated moment magnitude for the largest most damaging earthquakes because large events are infrequent algorithms are not regularly exercised and insufficiently tested on few available datasets we use 1300 realistic time dependent synthetic earthquakes on the cascadia megathrust to rigorously test the geodetic alarm system solutions are reliable once six gnss stations report static offsets which we require for a first alert median magnitude and length errors are 0 15 0 24 units and 31 40 for the first alert and 0 04 0 11 units and 7 31 for the final solution we perform a coupled test of a seismic geodetic eew system using synthetic waveforms for a mw8 7 scenario seismic point source solutions result in severely underestimated pga geodetic finite fault solutions provide more accurate predictions at larger distances thus increasing warning times hence gnss observations are essential in eew to accurately characterize large out of network events and correctly predict ground motion

millimeter level ultra long period multiple earth circling surface waves retrieved from dense high rate gps network abstract high rate gps networks have proven to be capable of continuously recording strong ground motion which is valuable for studying earthquake rupture processes and seismic hazard mitigation previous studies of high rate gps usually resolved dynamic ground displacements of some major seismic phases stronger than a few millimeters in this study we explore the feasibility of retrieving much weaker ground motions sub millimeter in long duration records by stacking high rate gps network we processed data of the 2011 tohoku oki earthquake recorded by more than 600 high rate gps stations of the plate boundary observatory pbo and analyzed kinematic displacement results with seismic array methods from these high rate gps seismograms we identified abundant seismic phases not only including clear body waves such as multiple s waves s ss sss ssss traveling along minor major great circle arc and ssssss beyond 360 degrees but also the r1 r5 rayleigh waves and g1 g6 love waves some of which travel around the earth multiple times many of these seismic phases have not been reported by previous high rate gps studies the group velocity dispersion curves extracted from multiple earth circling love waves of high rate gps are consistent with those of broadband seismic records in the period from 150 to 600 s which can sample the mantle structure down to top of the lower mantle thus important for understanding interaction between upper mantle and lower mantle so the dense high rate gps networks should be useful for deep mantle research as an additional valuable dataset with the development of multi system gnss and the more precise modeling of error sources high rate gnss data should have great potential for accurately detecting more geodynamic processes with much wider bandwidth in geoscience studies

merging tsunamis of the 2011 tohoku oki earthquake detected over the open ocean 1 tsunamis often travel long distances without losing power and severely devastate some coastal areas while leaving others with little damage this unpredictable situation has been a major challenge for accurate and timely tsunami forecasting to facilitate early warning and possible evacuations of affected coastal communities without disturbing the lives of others here we show evidence from satellite altimetry observations of the 2011 tohoku oki earthquake induced tsunami that sheds light on this issue three satellites observed the same tsunami front and for the first time one of them recorded a tsunami height about twice as high as that of the other two model simulations based on the gps derived earthquake source and constrained by measurements of seafloor motions near the hypocenter confirm that the amplified tsunami is one of several jets formed through topographic refraction when tsunamis travel along ocean ridges and seamount chains in the pacific ocean this process caused the tsunami front to merge as it propagates resulting in the doubling of the wave height and destructive potential in certain directions we conclude that the potential of merging tsunamis should be emphasized in mapping tsunami hazards and assessing risk levels at key coastal facilities

regard a new gnss based real time finite fault modeling system for geonet the short period seismometer based magnitude saturation problem especially for events with magnitude 8 can be improved by a real time global navigation satellite system gnss positioning technique which has enabled rapid estimation of a finite fault model for a large earthquake without any saturation a new real time fault modeling system based on the gnss earth observation network geonet is developed and is under experimental operation in japan in this paper we present the newly developed system regard the real time geonet analysis system for rapid deformation monitoring which consists of real time gnss positioning automatic detection of coseismic displacement by the event and quasi real time finite fault model inversion routines the performance of the automatic event detection system is tested through experimental real time operation based on geonet data for two months furthermore we also test the reliability of the finite fault model inversion routines using real raw gnss data observed for past large earthquakes the 2003 tokachi oki earthquake moment magnitude mw 8 3 the 2011 tohoku earthquake mw 9 0 and the 2011 off ibaraki earthquake mw 7 7 a simulated 1707 hoei type nankai trough earthquake mw 8 7 is also tested the real time experimental operation shows that real time gnss positioning is precise enough to detect all the tested earthquakes and the inversion results demonstrate that the regard can reliably estimate the earthquake size and its extent within 3 min after the origin time these results suggest that the regard system will complement the seismometer based magnitude determination system

real time gnss seismology using a single receiver summary high rate gnss has attracted increasing attention and numerous applications in geohazard monitoring and early warning in this paper we investigate three current existing singlereceiver approaches for real time gnss seismology comparing their observation models for equivalence andassessingtheimpactofmainerrorcomponents weproposesomerefinements to the variometric approach and especially consider compensating the geometry error component by using the accurate initial coordinates before the earthquake to eliminate the drift trend in the integrated coseismic displacements after careful corrections of satellite ephemeris ionospheric delay tropospheric delay and geometry errors the refined variometric approach andthetemporalpointpositioning tpp methodhaveequivalentmathematicalmodelwiththe converged precise point positioning ppp we evaluated the precision of the variometric and tpp approaches with various error correction schemes and duration time using numerous data sets and demonstrated that few centimetres accuracy of coseismic displacements is achievable even for 20 min interval we applied these single receiver approaches to process 1 hz gps data collected from the tohoku oki earthquake mw 9 0 2011 march 11 in japan to capture coseismic displacement and further inverted the obtained displacement fields for fault slip distribution and moment magnitude comparisons of the results obtained using the refined variometric approach and tpp as well as the converged ppp displayed very good consistence both in coseismic displacements within few centimetres and in the slip distribution patterns and moment magnitudes

simple and reliable finite fault solutions for large earthquakes using the w phase the maule m w 8 8 and tohoku m w 9 0 earthquakes 1 we explore the ability of w phase waveform inversions to recover a first order coseismic slip distribution for large earthquakes to date w phase inversions for point sources provide fast and accurate moment tensor solutions for moderate to large events we have applied w phase finite fault inversion to seismic waveforms recorded following the 2010 maule earthquake mw 8 8 and the 2011 tohoku earthquake mw 9 0 firstly a w phase point source inversion was performed to assist us in selecting the data for the finite fault solution then we use a simple linear multiple time window method accounting for changes in the rupture velocity with smoothing and moment minimization constraints to infer slip and rake variations over the fault our results describe well the main features of the slip pattern previously found for both events this suggests that fast slip inversions may be carried out relying purely on w phase records

trench normal variation in observed seafloor displacements associated with the 2011 tohoku oki earthquake 1 seafloor geodetic measurements using the gps acoustic technique just above the rupture area of the 2011 tohoku oki earthquake revealed strong trench normal variation in the horizontal crustal displacement associated with the earthquake one set of observations at a site only 50 km away from the trench yielded the most trench ward data ever reported with an accuracy better than 1 m it showed a coseismic displacement of up to 31 m whereas another set of observations 100 km away from the trench showed a 15 m displacement these horizontal data as well as vertical data from pressure gauges and tsunami observations strongly indicate that the seismic slip reached the trench they are also likely to contribute quantitatively to further investigations that reveal the coseismic behavior of the frontal wedge of the overriding plate in the source region along the japan trench

rapid modeling of the 2011 mw 9 0 tohoku oki earthquake with seismogeodesy 1 rapid characterization of finite fault geometry and slip for large earthquakes is important for mitigation of seismic and tsunamigenic hazards saturation of near source weak motion and problematic integration of strong motion data into displacements make this difficult in real time combining gps and accelerometer data to estimate seismogeodetic displacement waveforms overcomes these limitations by providing mm level three dimensional accuracy and improved estimation of coseismic deformation compared to gps only methods we leverage collocated gps and accelerometer data from the 2011 mw 9 0 tohoku oki japan earthquake by replaying them in simulated real time mode using a novel approach to account for fault finiteness we generate an accurate centroid moment tensor solution independently of any constraint on the slab geometry followed by a finite fault slip model the replay of gps and seismic data demonstrates that robust models could have been made available within 3 min of earthquake initiation

ability of 1 hz gps data to infer the source process of a medium sized earthquake the case of the 2008 iwate miyagi nairiku japan earthquake 1 we demonstrate the ability of 1 hz global positioning system gps data to infer a medium sized m6 class earthquake source process through an inversion study of the 2008 iwate miyagi nairiku japan earthquake m 6 9 1 hz gps waveforms for this earthquake are compared and show good agreement with strong motion waveforms ground motions are well recorded at a sufficient number of gps stations in and around source region allowing us to perform waveform inversion using 1 hz gps data only the 1 hz gps inversion result shows fairly good agreement with a joint inversion of geodetic and strong motion data such as the seismic moment mw 6 9 cumulative slip distribution and rupture propagation such agreements demonstrate that 1 hz gps is able to infer the dynamic features of the rupture process as well as permanent or static slip even for a m6 class medium sized earthquake

investigating carbonate platform types multiple controls and a continuum of geometries abstract current classifications of carbonate platforms use depositional gradient as the main criterion for separating systems into two end member types ramps and flat topped platforms ftps however many examples do not conform to this simple classification to investigate why this is and to better understand probable controls on platform development we have used a series of 2d numerical forward model runs to investigate how sediment production diffusional sediment transport and other controls such as tectonic subsidence antecedent topography and relative sea level oscillation interact to determine platform geometry modeling results reaffirm that rates of down dip sediment transport relative to rates of autochthonous production are a critical factor in maintaining a ramp profile in stable cratonic settings under a constant rate of relative sea level rise type of carbonate production versus water depth curve for example euphotic versus oligophotic is not a significant control in our model cases both euphotic and oligophotic production profiles produce ftps when diffusion coefficients are low relative to production rates and ramps when diffusion coefficients are relatively high these results suggest a continuum of platform types ranging from transport dominated low gradient systems at one end of the spectrum to in situ accumulation dominated systems at the other a system may be transport dominated because high energy processes are able to break down and transport even bound sediment or because carbonate factories produce only sediment that is easily transportable under even low energy conditions time evolution is also probably important initially low gradient systems will in the absence of sufficiently high sediment transport rates tend to evolve towards high gradient flat topped steep margined platforms many observed or inferred platform geometries are therefore likely to be transient forms and this could complicate interpretation investigating how basin bathymetry and style of subsidence control platform geometry suggests that in transport dominated systems strata simply drape the underlying topography and that pre existing breaks of slope and differential fault subsidence are a stronger control on platform geometry in in situ accumulation dominated systems rotational subsidence tends to create transport dominated systems during rotation as the topographic gradient increases and transport rate increases and outpaces in situ production rate relative sea level oscillations tend to move the locus of sediment production laterally along any slope present on the platform distributing the sediment accumulation across the whole width of the platform suppressing progradation and steepening and so favoring development of low gradient systems based on all these results we suggest that a simple cutoff classification into ramp and flat topped platform types can still be useful in some circumstances but a more meaningful approach may be to describe and predict platform strata in terms of a multiple dimension platform parameter space containing a continuum of geometries controlled by sediment production sediment diffusion coefficient antecedent topography differential subsidence effects relative sea level oscillations and perhaps other as yet unappreciated controls

instantaneous geodetic positioning at medium distances with the global positioning system we evaluate a new method of global positioning system gps data analysis called instantaneous positioning at spatial scale lengths typical of interstation spacings in a modern crustal motion network this method is more precise and versatile than traditional gps static and kinematic processing of multi epoch batches of data the key to instantaneous positioning is the ability to resolve integer cycle phase ambiguities with only a single epoch of dual frequency phase and pseudorange data rendering receiver cycle slips irrelevant we estimate three dimensional relative coordinates and atmospheric zenith delay parameters independently every 30 s over a 12 week period for baseline distances of 50 m 14 km and 37 km horizontal precision of a single epoch coordinate solution is about 15 mm and vertical precision is about 7 8 times worse removing that component of each time series which repeats with a period of exactly 1 sidereal day and thus manifests signal multipath reduces the scatter by about 50 in all components solution averaging of the high frequency time series can be performed using any number of measurement epochs to further improve coordinate precision we demonstrate that the daily coordinates estimated with instantaneous positioning are more precise by 20 50 per coordinate component than those estimated with 24 hour batch processing spectral analysis of the single epoch solutions indicates that the flicker noise characteristic of gps time series observed in lower frequency bands also affects gps solutions in the frequency band 0 01 mhz to 10 mhz we argue that the flicker noise is induced by tropospheric effects since modern gps receivers are capable of observing at frequencies as high as 10 hz our technique significantly overlaps and complements the frequency band of broadband seismology and benefits other research areas such as earthquake geodesy volcanology and gps meteorology

high rate coseismic displacements from tightly integrated processing of raw gps and accelerometer data high rate gps and seismic sensors are mutually contributing to seismological applications for capturing earthquake induced coseismic displacements in this study we propose an approach for tightly integrating gps and strong motion data on raw observation level to increase the quality of the derived displacements the performance of the proposed approach is demonstrated using 5 hz high rate gps and 200 hz strong motion data collected during the el mayor cucapah earthquake m w 7 2 2010 april 4 in baja california mexico the new approach not only takes advantages of both gps and strong motion sensors but also improves the reliability of the displacement by enhancing gps integer cycle phase ambiguity resolution which is very critical for deriving displacements with highest quality

seismic and tsunami wave propagation of the 2011 off the pacific coast of tohoku earthquake as inferred from the tsunami coupled finite difference simulation abstract the 2011 tohoku earthquake m 9 0 caused significant hazards including strong ground motion coseismic ground deformation and tsunamis for a deeper understanding of these phenomena we conducted a large scale parallel computer simulation by means of the finite difference method fdm with newly developed tsunami coupled equations of motion this method is based on the equations of motion for an elastic medium treating seawater as elastic material having zero s wave velocity tsunami waves are included by taking into account gravity and their equilibrium with the pressure gradient an effective method of fdm simulation using the state of the art massively parallelized k computer is also studied with the use of a 3d layered velocity structure that includes topography and bathymetry basement structure moho depth and plate boundaries and use of the appropriate source rupture model based on joint inversion of seismic waves and geodetic observations the simulated seismic waves demonstrate anomalous seismic wave propagation by the thick 3d basin structure inland we also found that the sea column acts as a strong absorber of seismic waves for shallow up dip slip on the ocean side coseismic deformation and tsunamis are dynamically generated in this simulation tsunami attacks on the subsided pacific coast are simulated without any additional assumptions we also modeled the tsunami and seismic records of ocean bottom pressure gauges above the fault because sea bottom tsunami and seismic observation is powerful but very complex recording both seismic and tsunami waves the use of these coupled numerical simulations has great potential for resolving complex source fault rupture processes in a 3d heterogeneous structure online material mpeg movies of fault slip seismic wave propagation seafloor and ground displacement and tsunamic propagation

rapid determination of earthquake magnitude using gps for tsunami warning systems 1 the 26 december 2004 sumatra earthquake mw 9 2 9 3 generated the most deadly tsunami in history yet within the first hour the true danger of a major oceanwide tsunami was not indicated by seismic magnitude estimates which were far too low mw 8 0 8 5 this problem relates to the inherent saturation of early seismic wave methods here we show that the earthquake s true size and tsunami potential can be determined using global positioning system gps data up to only 15 min after earthquake initiation by tracking the mean displacement of the earth s surface associated with the arrival of seismic waves within minutes displacements of 10 mm are detectable as far away as india consistent with results using weeks of data after the event these displacements imply mw 9 0 0 1 indicating a high tsunami potential this suggests existing gps infrastructure could be developed into an effective component of tsunami warning systems

near field tsunami inundation forecast using the parallel tunami n2 model application to the 2011 tohoku oki earthquake combined with source inversions to contribute to tsunami early warning systems we investigated the currently achievable speed of tsunami inundation simulations on a parallel computer as well as the benefits of high resolution and faster than real time inundation predictions we found that a 5 m resolution inundation simulation can be 75 times faster than real time requiring only 1 5 min to overview the inundation situation in sendai city for the 2011 tohoku tsunami we developed a novel parallel tsunami model based on the well known tunami n2 model and achieved 9 17 tera floating point operations per second flops on 9469 cpu cores the present model can accurately hindcast the observed inundated regions of the 2011 tohoku tsunami using tsunami source estimations of the tfish and tfish rapid algorithms which can be instantly derived from real time observation data the present high resolution predictions can provide clear images of imminent hazards disasters and can provide guidance for appropriate evacuation actions

real time high rate co seismic displacement from ambiguity fixed precise point positioning application to earthquake early warning 1 nowadays more and more high rate real time gps data become available that provide a great opportunity to contribute to earthquake early warning eew system in terms of capturing regional surface displacements as an independent information source useful for promptly estimating the magnitude of large destructive earthquake in our study we demonstrate the performance of the real time ambiguity fixed precise point positioning ppp approach using 5 hz gps data collected during el mayor cucapah earthquake mw 7 2 4 april 2010 the ppp based displacements show to agree with accelerometer based displacement at centimeter level the key for successfully obtaining high precision displacements is the efficient ambiguity resolution ppp with ambiguity fixing can result in correct permanent co seismic offsets and correct recovery of moment magnitude and fault slip inversion at levels comparable to post processing

temporal point positioning approach for real time gnss seismology using a single receiver 1 high rate global navigation satellite systems gnss has an increasing number of applications in geohazard monitoring gnss derived displacements can provide important information for magnitude estimation and fault slip inversion which is critical for seismic and tsunamigenic hazard mitigation in this paper we propose a new approach to quickly capture coseismic displacements with a single gnss receiver in real time the new approach can overcome the convergence problem of precise point positioning and also avoids the integration process of the variometric approach using the results of the 2011 tohoku oki earthquake it is demonstrated that the proposed method can provide accurate displacement waveforms and permanent coseismic offsets at an accuracy of few centimeters and can also reliably recover the moment magnitude and fault slip distribution