日本地球惑星科学連合2018年大会

講演情報

[JJ] ポスター発表

セッション記号 S (固体地球科学) » S-SS 地震学

[S-SS13] 地震予知・予測

2018年5月24日(木) 10:45 〜 12:15 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:馬場 俊孝(徳島大学大学院産業理工学研究部)

[SSS13-P04] Determining Magnitude of Large Earthquake in Japan using Seismic Stations in China

*Qiang Yao1Dun Wang1 (1.State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan, Hubei 430074, China)

キーワード:real-time, large earthquakes, back-projection

Rapid determination of earthquake magnitude is of importance for estimating shaking damages, and tsunami hazards. However, due to the complexity of source process, it is still a challenge for great earthquakes to accurately estimate magnitude in minutes after origin time. A recent example is the 2011 M 9 Tohoku, Japan earthquake.
Here we determine the magnitudes of eleven M ≧7.0 (USGS) shallow earthquakes that occurred in and around Japan from 2008 to 2016, using seismic data recorded in China and across the global. The magnitude is estimated by considering P-wave maximum displacement of global stations and source duration derived from back-projection using dense seismic stations in China.
The results agree well with the Mw estimated from W-phase inversion, with a standard deviation of 0.19, and suggest that the magnitudes can be accurately estimated in 3 to 9 min after origin times of earthquakes, depending on the epicenter distances to seismic stations in China. For the case of the 2011 M 9 Tohoku, Japan earthquake, the magnitude is estimated as to be 9.1, 9.0, 8.8, 8.9 at 3, 5, 7, 9 min after the origin time, respectively.
We use station corrections derived from nearby earthquakes to perform back-projection. The final source durations don’t show significant variations, demonstrating that the magnitude of earthquake can be estimated with the pre-stored database of station corrections. Therefore, we propose to build an automated system for determining magnitude of large earthquake in and around Japan using real-time seismic data in China and across the global, for disaster mitigation right after a damaging earthquake, especially when dealing with the tsunami evacuation and emergency rescue.