Spatio-temporal variation and focal mechanism of the Wenchuan M_S8.0 earthquake sequence

作     者：Wanzheng Cheng Zhiwei Zhang Xiang Ruan 

作者机构：Earthquake Prediction Institute Earthquake Administration of Sichuan Province Chengdu 610041 China 

出 版 物：《Earthquake Science》 (地震学报（英文版）)

年 卷 期：2009年第22卷第2期

页      面：109-117页

核心收录：

学科分类：0709[理学-地质学] 0819[工学-矿业工程] 07[理学] 070801[理学-固体地球物理学] 0707[理学-海洋科学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0815[工学-水利工程] 0816[工学-测绘科学与技术] 0813[工学-建筑学] 0814[工学-土木工程] 0825[工学-航空宇航科学与技术] 0704[理学-天文学] 

基　　金：supported by National Key Basic Research 973b National Scientific Technology Support Plan (2006BAC01B02-01-01) 

主　　题：Wenchuan earthquake strong aftershock spatio-temporal variation focal mechanism solution 

摘      要：Based on abundant aftershock sequence data of the Wenchuan Ms8.0 earthquake on May 12, 2008, we studied the spatio-temporal variation process and segmentation rupture characteristic. Dense aftershocks distribute along Longmenshan central fault zone of NE direction and form a narrow strip with the length of 325 krn and the depth between several and 40 km. The depth profile （section of NW direction） vertical to the strike of aftershock zone （NE direction） shows anisomerous wedgy distribution characteristic of afiershock concentrated regions; it is related to the force form of the Longmenshan nappe tectonic belt. The stronger aftershocks could be divided into northern segment and southern segment apparently and the focal depths of strong aftershocks in the 50 km area between northern segment and southern segment are shallower. It seems like ＇to be going to rupture＇ segment. We also study focal mechanisms and segmentation of strong aftershocks. The principal compressive stress azimuth of aftershock area is WNW direction and the faulting types of aftershocks at southern and northern segment have the same proportion. Because afiershocks distribute on different secondary faults, their focal mechanisms present complex local tectonic stress field. The faulting of seven strong earthquakes on the Longmenshan central fault is mainly characterized by thrust with the component of right-lateral strike-slip. Meantime six strong aftershocks on the Longmenshan back-range fault and Qingchuan fault present strike-slip faulting. At last we discuss the complex segmentation rupture mechanism of the Wenchuan earthquake.