2021年日本福岛县冲地震的震源破裂过程分析——基于采用经验格林函数方法的波形反演  

Rupture process of the 2021 Fukushima-ken Oki earthquake estimated from waveform inversion with empirical Green’s functions

作　　者：吴双兰 野津厚 長坂陽介 WU Shuanglan;NOZU Atsushi;NAGASAKA Yosuke(Port and Airport Research Institute,Kanagawa 239-0826,Japan)

机构地区：[1]港湾空港技術研究所,日本神奈川県239-0826

出　　处：《世界地震工程》2021年第2期1-12,共12页World Earthquake Engineering

基　　金：港湾空港技術研究所基础研究项目(1A-191-B)资助。

摘　　要：利用中小震作为经验格林函数,选取0.2~2.0 Hz频段的强震数据进行波形反演,获得了2021年福岛县冲地震的破裂过程。结果表明:该地震的破裂主要集中在断层面距离震源约25 km的区域内,沿震源向东北延伸约5 km,向西南延伸约20 km;在该区域内,识别出两个滑动量集中的区域,均分布在距离震源约15 km西南侧,主要滑动量集中区域最大滑动量约3.2 m,深度基本与震源一致;次要滑动量集中区域略比主要滑动量集中区域浅约18 km。该震源模型对应矩震级M_(w)7.3,破裂速度为2.4 km/s。通过选择不同的中小震组合进行波形反演,结果对该震源模型特性无显著影响,揭示了该震源模型的稳健性;基于该震源模型合成反演分析中未使用的强震观测台站强震动,获得的合成波形与观测波形有很好的相关性,充分证明了该震源模型时空特征的可靠性。The rupture process and generation mechanism of strong ground motions of the 2021 Fukushima-ken Oki earthquake were investigated through waveform inversions of strong-motion data in the frequency range of 0.2~2.0 Hz using empirical Green’s functions(EGFs).The results indicate that,the main rupture area of this earthquake was within 25 km from the hypocenter.In this region,two large slip regions,were identified:the primary one with the maximum slip of 3.2 m was located~15 km southwest of the hypocenter,and the secondary one was centered~18 km shallower than the primary large slip region.A rupture velocity of 2.4 km/s was identified.Furthermore,the robustness of the source model was examined through additional waveform inversions with different combinations of EGF events.Additionally,using the estimated slip model,we synthesized strong motions at stations that were not used in the inversion analyses;the synthetic waveforms were consistent well with the observed waveforms,illustrating the validity of the major spatiotemporal characteristics of the slip model.

关 键 词：2021年福岛县冲地震 破裂过程 经验格林函数 波形反演 强震动 

分 类 号：P315[天文地球—地震学]