Inverse Method for Static Stress Drop and Applicationto the 2011 Mw9.0 Tohoku-Oki Earthquake
Inverse Method for Static Stress Drop and Applicationto the 2011 Mw9.0 Tohoku-Oki Earthquake
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静应力降反演方法及其在2011年Mw9.0东北冲地震中的应用
DOI：
10.1002/2017jb014871
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Yongen Cai
中科院分区：
文献类型：
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作者：
Zhoumin Xie;Yongen Cai
地震应力降是研究地震机制的基本参数。一般都是通过断层错动震源模型或地震矩来间接预测，断层上应力变化的反演还没有得到应有的重视。在这项研究中，我们提出了一个有限元方法来反演断层上的应力降，所观察到的同震变形的约束。该模型可自动预测断裂终止和断层位移。将该方法应用于2011年Mw9.0 Tohoku-Oki地震，我们发现断层由两个凸起组成，最大剪应力分别为11.7和10.1 MPa。预测的最大水平和垂直位移的上盘在日本海沟分别为55.2和10.8米，与观测结果吻合良好。主震和主震后29分钟的Mw7.9级余震的预测总静态矩分别为4.48 × 1022和1.46 × 1021 Nm，对应的矩震级分别为Mw9.0和Mw8.0，与美国地质调查局观测确定的Mw9.0和Mw7.9的结果也非常吻合。
Seismic stress drop is a fundamental parameter for the investigation of earthquake mechanism. In general, it is indirectly predicted by fault slip based on the dislocation source model or seismic moment; inversion for the stress change on faults has not received the deserved attention. In this study, we propose a finite element method to invert the stress drop on fault, constrained by the observed coseismic deformation. Rupture termination and displacement on fault are automatically predicted from the model. Applying the method to the 2011Mw9.0 Tohoku‐Oki earthquake, we find that the fault consists of two asperities with maximum shear stress drops of 11.7 and 10.1 MPa, respectively. The predicted maximum horizontal and vertical displacements on the hanging wall at the Japan Trench are 55.2 and 10.8 m, respectively, in good agreement with observation. The predicted total static moments of the mainshock and theMw7.9 aftershock, 29 min after the mainshock, are 4.48 × 1022and 1.46 × 1021Nm, corresponding to moment magnitudes ofMw9.0 andMw8.0, respectively, again in excellent agreement with the observationally determinedMw9.0 andMw7.9 by the U.S. Geological Survey.