Pattern of stress change and its effect on seismicity rate caused by M_s8.0 Wenchuan earthquake

作     者：XIE ChaoDi ZHU YuanQing LEI XingLin YU HaiYing HU XiongLin 

作者机构：School of Ocean&Earth ScienceTongji UniversityShanghai 200092China Geological Survey of JapanAISTTsukuba 305-8567Japan Seismological Bureau of ShanghaiShanghai 200062China Seismological Bureau of YunnanKunming 650224China 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2010年第53卷第9期

页      面：1260-1270页

核心收录：

学科分类：07[理学] 08[工学] 

基　　金：supported by National Natural Science Founda-tion of China (Grant No. 40364001) the Construction Project of Inte-grated Deep-Well Seismic Observation System in Shanghai 

主　　题：Wenchuan earthquake optimally oriented fault Coulomb stress change seismicity rate 

摘      要：We use five published source models to calculate the Coulomb failure stress changes induced by the Ms8.0 Wenchuan earthquake, and analyze the association between stress changes and the subsequent earthquakes. Based on the analysis of uncertainties resulting from source models, we determine the stress changes on nearby faults caused by the Wenchuan earthquake. Moreover, we focus on the seismicity rate change as a function of time on every fault under the influence of stress changes. The results indicate that the spatial distributions of aftershocks correlate well with the regions where stress is calculated to increase using the related models. The largest lobes of dropped stress lie in the west and east sides of source fault. The largest lobes of increased failure stress close to southern and northern ends of the source fault extend into the whole source failure plane. In addition, another region of increased stress lies in the Wenchuan-Yingxiu zone close to the southern segment of source fault, where a large number of aftershocks have occurred. And subsequent earthquakes seem to extend to even more remote distances; therefore, this area also has a high risk of seismic hazard. We find that the positive stress changes on nearby faults imposed by the Wenchuan earthquake produce an encouraging effect on seismicity rate. The effect is most significant on the Pengxian-Guanxian fault and Qingchuan fault, the value of seismicity rate maintains two times greater than the value before the mainshock for the next hundred years on these faults, and the time needed for the aftershock rate to recover to the pre-mainshock seismicity rate can reach up to 800-900 yr. The influence is not significant on the western Qinling fault, the Longquanshan fault, the Xianshuihe fault, the Yulongxi fault, the Anninghe fault, the Minjiang fault, and the Aba fault. Compared with the seismicity rate on these faults before the mainshock, the aftershock rate is raised by less than two times, and the