Numerical Simulation of Earthquake Dynamic Rupture along Curved/ Branched fault Segments

沿弯曲/分支断层段地震动态破裂的数值模拟

基本信息

批准号：
15607020
负责人：
FUKUYAMA Eiichi
金额：
$ 1.86万
依托单位：
National Research Institute for Earth Science and Disaster Prevention
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15607020/
关键词：
Earthquake Rupture Dynamics Boundary Integral Equation Method Initial Stress Field Constitutive law for Earthquake Faulting 境界積分方程式方初期応用力場

项目摘要

We have conducted simulations of earthquake dynamic rupture on non-planar faults using boundary integral equation method. We found that in the simulation, fault geometry, shear stress applied on the fault and fault constitutive relation are important for the computation of dynamic rupture. Based on these information, we computed the dynamic ruptures of the 2000 western Tottori earthquake, 1891 Nobi earthquake, and 1995 Kobe earthquake. For the western Tottori earthquake, assuming the preexisting fault geometry and uniform constitutive relation, we estimated the stress field around the fault, which was found to be consistent with that estimated by the stress tensor inversion. For the Nobi earthquake there has been a debate whether the buried fault slipped during the earthquake or not. To accelerate the discussion, we conducted a dynamic rupture simulation using the preexisting fault geometry and found that whether or not the buried fault slipped depends on the connectivity to the adjacent fault. Finally, we investigated the Kobe earthquake. Using the fault geometry obtained, the rupture could not propagate bi-laterally. We found that to make a bi-lateral rupture, a small strike slip fault is required just beneath the Akashi trout, which was required by the inversion analysis with GPS data at Akashi bridge. In addition, using the near-fault seismograms observed at the western Tottori earthquake and the 2002 Denali, Alaska earthquake, we showed that the slip-weakening distance is size dependent.We organized two special sessions in 2004 and 2005 American Geophysical Union Fall Meeting. And we had more than 150 abstracts in total for these sessions. We recognized that this is one of the high-lighted topics that many people are interested in. We are now preparing a book to publish the major issues in the sessions.

我们利用边界积分方程方法对非平面断层的地震动态破裂进行了模拟。我们发现，在模拟中，断层几何形状、断层上施加的剪应力以及断层本构关系对于动态破裂的计算很重要。根据这些信息，我们计算了 2000 年鸟取西部地震、1891 年浓尾地震和 1995 年神户地震的动态破裂。对于鸟取县西部地震，假设预先存在的断层几何形状和一致的本构关系，我们估计了断层周围的应力场，发现该应力场与应力张量反演估计的结果一致。对于浓尾地震，人们一直争论埋藏断层是否在地震期间发生滑动。为了加速讨论，我们使用预先存在的断层几何形状进行了动态破裂模拟，发现隐伏断层是否滑动取决于与邻近断层的连通性。最后，我们调查了神户地震。使用获得的断层几何形状，破裂不能双向扩展。我们发现，要实现双边破裂，就需要在明石鳟鱼下方有一个小的走滑断层，这是明石桥 GPS 数据反演分析所需要的。此外，利用在鸟取西部地震和2002年阿拉斯加德纳利地震中观测到的近断层地震图，我们表明滑移减弱距离与大小有关。我们在2004年和2005年美国地球物理联合会秋季会议上组织了两次特别会议。我们为这些会议总共收集了 150 多份摘要。我们认识到这是很多人感兴趣的重点话题之一。我们现在正在准备一本书来出版会议中的主要问题。