【一般講演】資源開発技術・開発機械

[3K0502-07-04] 全波形逆解析による地震の震源メカニズムの推定(発表者：修士課程)

○JANG Iktae¹、三ケ田 均¹、武川 順一¹ (1. 京都大学)

キーワード：震源メカニズム、数値実験、全波形逆解析

To ensure the safety of society from natural disasters such as earthquake and tsunami, one of the most important factors is to issue the information to the public accurately and quickly. Some countries in the world have actually had the early warning system in a practical way for disaster mitigation purposes. Estimating the earthquake source mechanism is an essential task for prompt information for disaster mitigation. The centroid-moment tensor (CMT) solution represents the stress tensor centered at the hypocenter at the break of the earthquake event. For any large events that could not be expressed only by the centered moments, it requires to express earthquake mechanism with a series of contiguous focal segments that could be obtained in the observation of aftershocks for a long time. We would like to resort to the method of full-waveform inversion (FWI) to estimate the series of contiguous focal segments without any aftershock observation to issue the mechanism of earthquakes promptly.
As the first step in this study, we investigate the applicability of FWI considering both P- and S-waves induced by an arbitrary orientation fault. To confirm the effectiveness of the proposed approach, we conduct quantitative numerical experiments based on the finite-difference method assuming a known source time function. We finally evaluate the effect of each fault parameter using the L2-norm error function. The results of this study indicate that the FWI can be used to estimate earthquake parameters such as the location of the fault plane and distribution of dislocations.