Strong earthquake clustering around the eastern Tibetan Plateau after the 2008 MW7.9 Wenchuan earthquake

作     者：Duyuan XU Jie XIAO Jiankun HE Weimin WANG Duyuan XU;Jie XIAO;Jiankun HE;Weimin WANG

作者机构：Key Laboratory of Continental Collision and Plateau UpliftInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China CAS Center for Excellence in Tibetan Plateau Earth SciencesChinese Academy of SciencesBeijing 100101China College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China 

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

年 卷 期：2020年第63卷第7期

页      面：999-1012页

核心收录：

学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学] 0704[理学-天文学] 

基　　金：supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA20070302) he National Natural Science Foundation of China(Grant Nos.41674104&41274064) the 13th Five-year Informatization Plan of Chinese Academy of Sciences(Grant No.XXH13505-06)。 

主　　题：Earthquake clustering Viscoelastic stress triggering Finite element modeling Wenchuan earthquake Eastern Tibetan Plateau 

摘      要：After the 2008 M_W7.9 Wenchuan earthquake,the eastern Tibetan Plateau experienced a series of M_W6.0 earthquakes,including the 2013 M_W6.6 Lushan,2014 M_W6.1 Kangding and 2017 M_W6.5 Jiuzhaigou events.Based on available constraints,we build a three-dimensional viscoelastic finite element model to calculate Coulomb failure stress caused by these strong earthquakes.In this model,the geometry and slip vector of the initial rupture zone of each earthquake are used to better evaluate the earthquake-related stress projection.Considering reasonable ranges of viscosities for the crust and upper mantle in different tectonic units,numerical results show that after the Wenchuan earthquake,the coseismic Coulomb failure stress change at the hypocenters of the subsequent earthquakes increased to approximately+0.012–+0.040,+0.01–+0.03,and+0.008–+0.015 MPa,respectively.With viscoelastic relaxation of the lower crust and upper mantle,the Coulomb failure stress change at the hypocenters of these earthquakes accumulated to about+0.014–+0.042,+0.016–+0.036,and+0.003–+0.007 MPa just before their occurrence.This suggests that the Wenchuan earthquake indeed triggered or hastened the occurrence of the Lushan,Kangding and Jiuzhaigou events,supporting that strong earthquake clustering around the eastern Tibetan Plateau could be related to stress interaction between the seismogenic faults.Besides,~94%and^6%of the stress increase around(and before the occurrence of)the Kangding earthquake were contributed by the Wenchuan event and the Lushan event,respectively;the positive Coulomb failure stress change at the Jiuzhaigou earthquake hypocenter was related to coseismic slip partitioning of the Wenchuan earthquake.This means that stress interaction among the earthquakes could be controlled by the combined effect of stress of the previous events and by the complexity of earthquake ruptures.Thus,in researches on the earthquake-triggering mechanism,special attentions should be paid on both details of the rupture model and multiple factors of previous earthquakes.