SSS24-01

Room:A06

Time:May 27 09:00-09:15

Prediction of ground shaking from shaking itself: application of numerical shake prediction method for various frequency
HOSHIBA, Mitsuyuki1∗ ; AOKI, Shigeki2
1

Meteorological Res. Inst., JMA, 2 Japan Meteorological Agency

Many of the present Earthquake Early Warning (EEW) systems quickly determine the hypocenter and magnitude, and thenpredict strengths 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, a new concept was proposed for EEW,
in which the distribution of the present wavefield is estimated precisely in real time (real-time shake mapping) by applying a data
assimilation technique, and then the future wavefield is predicted time-evolutionally by simulation of seismic wave propagation(Hoshiba and Aoki, 2014). Information on the hypocenter location and magnitude are not necessarily required in the method;
instead physical processes are simulated from the precisely estimated present condition. The method is called ”numerical shakeprediction” by analogy to ”numerical weather prediction” in meteorology. In this presentation, we will apply the numerical shakeprediction method to the 2011 Tohoku Earthquake and the 2004 Mid-Niigata Earthquake (Mw 6.7) for not only frequency bandof seismic intensity (that is, around 1 Hz (period of 1 s)) but also for various bands such as around 0.3 Hz (3 s) and 0.15 Hz (6s). We will show that low frequency waves were trapped in the Kanto basin while high frequency waves passed by, and that thenumerical shake prediction method is applicable even for low frequency of around 0.15 Hz in case of prediction of near future.
Keywords: Earthquake Early Warning, Real-time prediction of earthquake ground motion, Numerical shake prediction, long
period ground motion

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SSS24-02

Room:A06

Time:May 27 09:15-09:30

Consideration of site amplification and data stability of OBS for magnitude estimation ofearthquake early warning
HAYASHIMOTO, Naoki1∗ ; HOSHIBA, Mitsuyuki1 ; NAKAMURA, Takeshi2
1

Meteolorogical Research Institute, 2 JAMSTEC

In Japan, large-scale ocean bottom seismographs (OBSs) network, such as DONET and DONET2 (JAMSTEC) and S-net(NIED), are now under construction to make use of those data for real-time monitoring, and it is expected to utilize those systems
for Earthquake Early Warning (EEW). However, since OBSs are installed on unconsolidated sedimentary layer, the installation
environment of OBSs may be different from that of land stations.
Site amplification of OBS is one of the important factors. Magnitude of EEW (Meew ) at Tonankai OBS estimated from maximum displacement amplitudes of three component vector waveforms was generally larger than Mj by about 0.6 because of site
amplification of OBS (Hayashimoto and Hoshiba, 2013). Similar amplification is also found at DONET (JAMSTEC, Nakamura
et al . (2014)). From the relative site amplification factor of OBS estimated from spectral ratio in frequency domain, it is foundthat amplification of horizontal component is remarkably larger than that of vertical component at less than 1 Hz.
Stability of OBS data exposed strong shaking is also essential factor. Yamamoto et al . (2004) pointed out that one of OffKushiro OBS (JAMSTEC) was rotated about 5 degree by strong ground motion during the 2003 Tokachi-oki earthquake of
Mjma8.0. The inclination of OBS causes baseline offset change in acceleration waveform on the gravitational acceleration component. We investigate the characteristics of OBS data during strong shaking at the Off-Kushiro OBSs, and it is found that theacceleration offsets are larger on the horizontal component (perpendicular to the cable line) than the other horizontal component(along the cable line). Furthermore, it is found that the S-wave H/V ratio for strong motion at OBS has typical features of nonlinear response, which is similar with that of land stations.
In this presentation, we discuss influence for EEW magnitude estimation. To avoid their influence, we will propose a newstable magnitude estimation method by using vertical component.
Acknowledgement: The strong ground motion acceleration waveform data used in this study were obtained from the Japan
Meteorological Agency (JMA) network, DONET and Off-Kushiro OBS of the Japan Agency Marine-Earth Science and Technology (JAMSTEC), K-NET and KiK-net of the National Research Institute for Earth Science and Disaster (NIED).
Keywords: Ocean Bottom Seismograph, Earthquake Early Warning, Site amplification, Inclination angle, Non-linear response,
Magnitude estimation

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SSS24-03

Room:A06

Time:May 27 09:30-09:45

A Method to Identify Multiple Concurrent Events and its Application
TAMARIBUCHI, Koji1∗
1

JMA

The extremely active seismicity after the 2011 off the Pacific Coast of Tohoku Earthquake caused serious issues for the automatic hypocenter determination such as the Earthquake Early Warning (EEW) system in Japan. Because multiple earthquakes
shook distant seismometers within a short period of time, the system misidentified a large earthquake shook them.
To solve this problem, Liu and Yamada (2014) proposed a likelihood function suitable for classifying multiple concurrent
earthquakes, which uses amplitude information. Tamaribuchi et al. (2014) developed the concept, named Integrated Particle
Filter method (IPF), using maximum amplitudes together with P-wave arrival times, B-delta method, and principal component
analysis. This method can avoid false alarms in the case of multiple concurrent events, including aftershocks of the 2011 off the
Pacific coast of Tohoku Earthquake.
In this study, I applied this method to deep earthquakes such as occurred at Southern sea of Okhotsk (M7.3, 654km depth).
The current system issued a warning because estimation of the earthquake was inland and shallow using only P-wave arrival
times on the first alert. In this case, the IPF method can avoid the inaccurate warning taking into account the B-delta method aswell as P-wave arrival times.
In addition, I developed the IPF method for smaller earthquakes such as JMA catalog. This method uses P- and S-wave arrival
times and maximum amplitude integrally. I applied this method for some swarms and aftershocks activity, including the earthquake at Northern Nagano Prefecture on 22 October, 2014. In this case, this method can detect more than 1,700 events within 24
hours, although the current system could detect only 250 events.
I think it is useful to grasp seismic activities in real time. These methods, including for EEW and for JMA catalog, will deploy
in the next our system.
References:
Liu and Yamada, 2014, BSSA, 104-3, 1111-1121.
Tamaribuchi et al., 2014, Zisin2, 67, 41-55.

Keywords: Automatic hypocenter determination, Earthquake Early Warning, JMA catalog

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SSS24-04

Room:A06

Time:May 27 09:45-10:00

P and S wave identification filter for the on-site seismic alarm
HORIUCHI, Shigeki1∗
1Home Seismometer Corporation

1. Introduction
S wave average amplitude is about 5 times larger than that of P wave. Onsite warning system measures P wave amplitude orreal-time shaking intensity and estimates that of S wave. In a case when an onsite warning system is not able to discriminate
S wave arrivals and estimates S wave amplitude using observed S wave data instead of P wave, estimated S wave amplitude
becomes five times larger in average than the observed value. Damaging earthquakes except for those in the subduction zones
occur in areas within about 30km and their (S-P) times are less than 3 or 4 seconds. Therefore, it is important to develop atechnique to discriminate S wave arrival within a short time from S wave onset. The present study propose a filter which makes
possible to identify S wave arrival within a short time from its onset.
2. P and S wave identification filter
It is well known that 1) The amplitude of the vertical component is large at P wave arrival and horizontal component at S wave
arrival, 2) The dominant frequency of the S wave is longer than that of P wave. We propose the following filters for identifying
the P and S waves.
F (t) = {bZ (t) -NS (t) -EW (t)} -c {V (t) -rA (t)} (1)Where, Z (t), NS (t) and EW (t): running means of absolute value of vertical, NS and EW components, V (t) and A(t); runningmean of the absolute value of the three component seismograms and their derivative by time, b, c , and r are constants. b, c andthey are put to be 2.0, 0.3 and 0.0. In a case P wave onset is measured, b and r are re-defined using about one second of data after
P wave arrival so that the first and the second terms in (1) become 0.
The first term of Equation (1) corresponds to the amplitude variation of the vertical and horizontal components. If the verticalcomponent becomes dominant at P wave arrival, it becomes positive and becomes negative if the horizontal component dominants
at S wave arrival. The second term corresponds to the change in the dominant frequency. The value becomes negative by the low
frequency S wave arrival.
3. Result
We used waveform data with seismic intensity larger than 5 lower recorded by K-NET, NIED to examine the effectiveness ofthe present P and S wave discrimination filter. The plot of the outputs of the filter together with observed waveforms shows thatfilter outputs for almost all seismograms become negative at S wave arrivals and their absolute values are several times larger
than amplitudes of P wave or P wave coda. We conclude that the present filter is effective for the development of accurate on-site
alarm system. We also concluded that this filter is effective for the automatic P and S wave arrival time picking in periods justafter a large earthquake when the aftershock activity is extremely high and difficult to distinguish between P and S wave.

Keywords: Onsite Alrm, P and S wave identification filter, H/V change, frequency change, intensity estimation, Automatic
hypocenter location

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SSS24-05

Room:A06

Time:May 27 10:00-10:15

How to utilize the information acquired by home seismometers spread across JapanNAITO, Shohei1∗ ; NAKAMURA, Hiromitsu1 ; AZUMA, Hiroki1 ; FUJIWARA, Hiroyuki1 ; FUJIMAKI, Shizuko2 ;KAWANO, Tsubasa2 ; KACHI, Masaaki2
1

National Research Institute for Earth Science and Disaster Prevention, 2 A2 Corporation

1. Introduction
The Japan Meteorological Agency has started the practical service of Earthquake Early Warining (EEW) system since 2007.
But, because of limitations imposed by station spacing and the determination and transmission of earthquake source parametersin real-time, the automatic system cannot issue an EEW to areas within 30 km of the earthquake parameters [Horiuchi et.al(2009)]. So, Horiuchi et.al (2007) pointed out that by spread of home seismometer, the receiving unit of EEW equipped with a
CPU and memory, the extra addition of cheap seismometer and A/D converter, we would have over 10 times of the number ofthe current seismic stations, also we can get more rapid warning information near focal areas.
Yamamoto et.al (2007) also issued about the development of the home seismometer, an inexpensive, compact and user-friendly
EEW intelligent system based upon a MEMS accelerometer. Besides, Nakamura et.al (2008) reported about demonstration test
in house to observe seismic signal and noise. Furthermore, Horiuchi et.al (2008) developed a function in the home seismometerto discriminate seismic signal from noise event. Moreover, A2 Corporation have been provided the EEW information service fora price by utilization of the home seismometer and these research achievements.
In this study, we issue about the number of the adoption of home seismometers, also consider how to utilize the informationacquired by them.
2. Diffusion of home seismometers
At the point of 2014, 7 years have passed since the first release, there are approximately 4,000 home seismometers in Japan.
The distribution of locations are heterogeneous. The urban areas located around Kanto, Osaka, and Noubi Plain are densely
installed. On the other hand, there are many sparse installed areas in a thinly populated area such as island or mountain.
3. Utilize the information acquired by home seismometers
For the purpose of estimating seismic damages and delivering information with a high degree of accuracy, we have been
provided data recorded when approximately 8,700 earthquakes happens from A2 Corp. Meanwhile, we have to take into account
how to utilize these data because they have considerable variation factors, for example, soil conditions, building structures,settings, surrounding noises.
For an experiment, Figure 1 shows a plot of JMA intensity versus epicentral distance using a number of seismic waves recordedby home seismometers and K-NET / KiK-net stations. Each data have nearly consistent tilt, but home seismometers show higher
dispersion.
In consideration of these dispersion, it will be possible to utilize data recorded by home seismometer by using of interpolate
K-NET and KiK-net data. So, we are going to research about the way to decrease these dispersion, and think about the way toutilize data for the purpose of estimating detailed seismic damaged areas and delivering information in real time.
Reference
Shigeki Horiuchi et.al: Home Seismometer Spread Plan, JPGU, 2007.
Shigeki Horiuchi et.al: Home seismometer for earthquake early warning, Geophysical Research Letters, Vol.36 No.5. L00B04,
2009.
Shunroku Yamamoto et.al: Making of home-seismometer and its performance, JPGU, 2007.
Hiromitsu Nakamura et.al: Measurement performance of Home-seismometer and its demonstration test in house, JPGU, 2008.
Shigeki Horiuchi et.al: Development of a function in the home seismometer to discriminate seismic signal from noise event(2),JPGU, 2008.

Keywords: Home Seismometer, EEW, MEMS

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SSS24-05

Room:A06

Time:May 27 10:00-10:15

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SSS24-06

Room:A06

Time:May 27 10:15-10:30

Improvement of the single-station EEW algorithms for railways
YAMAMOTO, Shunroku1∗ ; IWATA, Naoyasu1 ; NODA, Shunta1 ; KORENAGA, Masahiro1
1

Railway Technical Research Institute

The present earthquake early warning system for railways adopts a single-station approach which has functions of a S-wave
warning that is issued by threshold excess of acceleration and a P-wave warning that is issued by analyzing the P-wave initial
phase, in order to control trains as rapid as possible during earthquakes. To improve accuracy and rapidity of the P-wave warning,
here we proposed upgraded P-wave warning using the new algorithms developed recently.
Major upgraded points are as follows, 1) P-wave detection, 2) epicentral distance estimation, 3) back-azimuth estimation, 4)
magnitude estimation and 5) noise discrimination. For improving P-wave detection, we re-determined the STA/LTA parameters
so as to be able to detect seismic motions growing very slow, and we also introduced the level trigger logic which simply monitors
threshold excess to make the trigger performance more reliable. For enhancing the performance of estimating epicentral distanceand back-azimuth, we introduced the C-∆ method (Yamamoto et al., 2012) and the variable time window method (Noda et el.,2012) which improve the accuracy of estimation by 12% and 28% respectively. Further we re-defined the relation between thecoefficient C and epicentral distance. For upgrading magnitude estimation, we introduced acceleration magnitude which is directly determined from observed acceleration. Since it is confirmed that the peak amplitude of seismic motions averagely appears
faster in acceleration than in displacement, faster estimation can be possible by using acceleration for magnitude estimation. To
improve the noise discrimination performance, we developed the new algorithm using frequency information of the input signal(Iwata et al., 2014).
Improvement of the P-wave warning is expected by using those upgraded algorithms. A prototype seismometer has beendeveloped and tested in the field to evaluate its performance.

Keywords: Earthquake Early Warning, P-wave, Single-station method

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SSS24-07

Room:A06

Time:May 27 10:30-10:45

Improvement of the discrimination algorithm between train-induced vibrations from seismic motions for EEW
IWATA, Naoyasu1∗ ; YAMAMOTO, Shunroku1 ; KORENAGA, Masahiro1
1

Railway Technical Research Institute

When the safety of railway facilities and running vehicles are threatened by large shakings of ground motions during earthquakes, railway operators stop trains as soon as possible (Nakamura, 1996; Ashiya et al., 2007; Yamamoto and Tomori, 2013).
To stop trains rapidly, it is effective to utilize the P-wave whose propagation velocity is faster than the S-wave. At present thewarning systems which estimate the epicenter location and the seismic magnitude using the initial P-wave information in several
seconds are in operation to stop the trains (Odaka et al., 2003; Iwahashi et al., 2004).
It is necessary to discriminate clearly between the seismic motions and the train-induced vibrations regarding seismographs installed along railways, because the feeble vibrations are used typically to estimate the seismic parameters from the initial P-wave.
The seismographs now in use are implemented with the algorithm to discriminate the train-induced vibrations from the seismic
motions using the component ratio of amplitudes (Sato and Nakamura, 2005). In this study, we proposed the new discriminationindex taking account of frequency characteristics and evaluated the discrimination performance. Further, we developed the new
discrimination algorithm using the combination of the current and the proposed indices (Iwata et al., 2014).
The improvement of the warning reliability during earthquakes is expected by using the proposed method.

Keywords: earthquake early warning, seismic motion, train-induced vibration, noise discrimination, algorithm

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SSS24-08

Room:A06

Time:May 27 11:00-11:15

Real-time Earthquake Magnitude Estimation by the GEONET real-time processing system: REGARD
KAWAMOTO, Satoshi1∗ ; MIYAGAWA, Kohei1 ; SATO, Yudai1 ; NISHIMURA, Takuya2 ; OHTA, Yusaku3 ;HINO, Ryota3 ; MIURA, Satoshi3 ; TODORIKI, Masaru4
1

Geospatial Information Authority of Japan, 2 Disaster Prevention Research Institute Kyoto University, 3 Graduate School of Science, Tohoku University, 4 The University of Tokyo Interfaculty Initiative in Information Studies
The recent development of Global Navigation Satellite Systems (GNSS) and communication infrastructures provides real-time
displacement data. The data enables the real-time estimation of coseismic fault model for large earthquake, which is free from thesaturation problem found for seismic data. The obtained moment magnitude (Mw) constrains the size of a subsequent tsunami,
thus it potentially improves tsunami warning systems that rely only on the seismic data.
Geospatial Information Authority of Japan (GSI) and Tohoku University have jointly developed a real-time analysis systemin the Japan’s national GNSS network, GEONET: the Real-time GEONET Analysis system for Rapid Deformation monitoring(REGARD). The goal is to estimate the magnitude and finite fault models for large earthquake in real-time. Currently the system
involves about 1300 GNSS stations, RAPiD algorithm (Ohta et al., 2012) for automatic event detections, and two real-time fault
modeling routines: a single rectangular fault modeling routine and a slip distribution fault modeling routine.
We evaluate the two fault modeling procedures for the 2003 Tokachi-oki earthquake, the 2011 Tohoku earthquake and the 1707
Hoei type Nankai trough earthquake in the real-time situations. The real-time waveform data for the Nankai trough earthquake
are based on the simulation (Todoriki et al., 2013). Furthermore, we also evaluate the past large earthquakes using the publishedfinite fault models (Sato et al., 1989) and the maximum class tsunamigenic earthquake models used to predict the potential
tsunami inundation area in each prefecture.
Both routines gave magnitudes with high variance reduction for the 2003 Tokachi-oki earthquake and the 2011 Tohoku earthquake within 3 minutes. However, only the slip distribution model provided reasonable magnitude for the simulated Nankai
trough earthquake. On the other hand, the single rectangular fault modeling routine was unstable to model the Nankai troughearthquakes. This implies the fault rupture is too heterogenic to approximate with a single rectangular fault for the future Nankai
trough earthquake, and should adopt the slip distribution for the robustness.
Keywords: GEONET, Real-time analysis, RTK-GPS, Fault model inversion

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SSS24-09

Room:A06

Time:May 27 11:15-11:30

An Attempt of Using of Earthquake Prompt Reports for Dispatching Health and Medical
Support TeamISHIMINE, Yasuhiro1∗
1

National Institute of Public Health

I will talk about an attempt to develop an information tool for supporting the activities of health and medical assistant teams
during earthquake disasters by using the damage estimation based on the earthquake prompt reports. Japan has built up aframework for dispatching assistant teams such as DMATs to rescue victims as soon as large scale disaster occurs on the basis of
the lessons learned from previous devastating disasters due to earthquakes and some other natural hazards. However, rescue inmostly affected areas might be delayed because of the absence of information. The rapid estimation of the numbers of damagedbuildings and injured people based on the real-time information such as earthquake prompt reports has a potential to provide theindication for the effective support with efficient usage of limited resources. I will present a fundamental design of an information
tool for the above purpose.
Keywords: Earthquake Prompt Report, Rescue, Health and Medical Support, DMAT

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