Source characteristics of the mainshock and aftershocks of the 2019 Changning earthquake sequence:Implications for fluid effects  

作　　者：Kun DAI Yong ZHENG Rumeng GUO Jianqiao XU 

机构地区：[1]School of Physics,Huazhong University of Science and Technology,Wuhan 430074,China [2]Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences,Wuhan 430071,China [3]State Key Laboratory of Geological Processes and Mineral Resources,School of Geophysics and Geomatics,China University of Geosciences,Wuhan 430074,China

出　　处：《Science China Earth Sciences》2023年第6期1321-1333,共13页中国科学（地球科学英文版）

基　　金：supported by the high-performance computing platform TS10000 of the School of Geophysics and Geomatics,China University of Geosciences(Wuhan);supported by the National Natural Science Foundation of China(Grant Nos.42274082,42030108,41874053);Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(Grant No.162301132637).

摘　　要：The 2019 M_(S)6.0 Changning earthquake occurred in the tectonically stable Sichuan Basin,where the epicenter and its adjacent areas are important shale gas and salt mine production fields,resulting in hot debates on whether the seismogenic mechanism of the 2019 Changning earthquake is related to human activities.As source characteristics and fluid pressure can provide important constraints on whether an earthquake is induced,weinvestigate the seismogenic mechanisms of the mainshock and 9 MW≥4.0 aftershocks.In overall,the mainshock and the majority of the aftershocks are characterized by relatively shallow focal depths(1‒4 km)and significant non-double-couple(non-DC)components.However,the mainshock and the aftershocks differ in two aspects:(1)the compensated-linear-vector-dipole components dominate the non-DC components of the mainshock,whereas the isotropic components dominate the most aftershocks;(2)the fluid overpressure of the mainshock is over 30 MPa,whereas the fluid overpressure of the most aftershocks is less than 10 MPa.Thus,we propose that the mainshock is triggered by weakened fault strength with long-term fluid injection,and that its large non-DC components are associated withcomplex rupture processes.Comparatively,the aftershocks may be triggered by postseismic stress transfer by combining the Coulomb failure stress changes in the poroelastic medium.Our results highlight the possible role of fluid in the occurrence of the Changning earthquake sequence.

关 键 词：The 2019 Channing earthquake Induced earthquakes Non-double-couple components Focal depths Poroelasticity 

分 类 号：P315.33[天文地球—地震学]