实际地形对2010年玉树MS7.1地震动力学破裂过程及地震动特征的影响  

Influence of actual topography on the source dynamic rupture process and strong ground motion of the 2010 Yushu M7.1 earthquake

作　　者：王铭锋 李一琼[1] 俞言祥[1] Wang Mingfeng;Li Yiqiong;Yu Yanxiang(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]中国地震局地球物理研究所,中国北京100081

出　　处：《地震学报》2021年第1期57-72,共16页Acta Seismologica Sinica

基　　金：国家自然科学基金(41574051);中国地震局地球物理研究所基本科研业务费专项(DQJB19B04)联合资助。

摘　　要：基于震源动力学模型,采用曲线网格有限差分法模拟了水平自由地表及实际地形条件下2010年玉树MS7.1地震的震源破裂过程及相应的地面地震动,获取了断层面上的破裂传播过程、最终滑移量分布及峰值地面速度分布,讨论了实际地形对玉树地震破裂过程及相应地震动的影响。基于本文设定的动力学模型,模拟结果显示:断层面上的高应力降是玉树地震出现超剪切破裂传播现象的主要原因;计算区域的实际地形阻碍了由自由地表引起的超剪切破裂的产生,对断层面滑移量的分布特征及滑动速率影响较大,进而在一定程度上降低了地震动峰值,同时对地震动的分布特征产生影响,且地震动平行断层面的水平分量相对受影响更大。Based on the source dynamic models,the curved grid finite-difference method was implemented to simulate the dynamic rupture process and the resultant ground motions of the2010 MS7.1 Yushu earthquake with horizontal free surface and actual topography respectively.Then the rupture propagation,final slip distribution and distribution of peak ground velocity were obtained to investigate the effect of actual topography on the dynamic rupture process of the Yushu earthquake and the resultant strong ground motions. Based on our models,the results show that the super-shear rupture occurred during the rupture propagation process,which was mainly induced by high stress drop on fault plane. The actual topography has prevented the generation of super-shear induced by free surface and has a great influence on the final slip distribution and slip rate on fault plane,then will affect the characteristics of ground motions as well as reduce the peak values of ground motions to a certain extent. The faultparallel component of ground motion is relatively more affected. The investigation about the fault rupture dynamics will help us to understand well about the source rupture process and explain the characteristics of its strong ground motions,which is of great significance to more reasonably predict the ground motions of possible destructive earthquakes in the future.

关 键 词：震源动力学破裂 超剪切破裂 起伏地形 强地面地震动 曲线网格有限差分 

分 类 号：P315.33[天文地球—地震学]