2020年云南巧家M5.0地震震源机制解与震源区应力场研究  

Study on the Focal Mechanism of the 2020 Qiaojia M5.0 Earthquake and the Stress Field in the Epicentral Area

作　　者：杨帆 盛书中 胡晓辉 崔华伟[4] YANG Fan;SHENG Shu-zhong;HU Xiao-hui;CUI hua-wei(Yunnan Earthquake Agency,Kunming 650224,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;University of Science and Technology of China,Hefei 230026,China;Shandong Earthquake Agency,Ji’nan 250102,China)

机构地区：[1]云南省地震局,云南昆明650224 [2]东华理工大学地球物理与测控技术学院,江西南昌330013 [3]中国科学技术大学,安徽合肥230026 [4]山东省地震局,山东济南250102

出　　处：《地震》2021年第4期93-105,共13页Earthquake

基　　金：国家自然科学基金项目(41704053)。

摘　　要：基于国家测震台网数据中心提供的波形资料,采用gCAP方法反演2020年5月18日云南巧家M5.0地震及研究区域51次地震震源机制解,并收集研究区域震源机制解50个。采用网格搜索法反演区域构造应力场,并对研究区域采用不同划分进行应力场反演。获得以下结论:①主震震源机制解节面Ⅰ的走向、倾角和滑动角分别为175°、67°和-19°,节面Ⅱ的走向、倾角和滑动角分别为273°、73°和-156°,矩震级为4.97,矩心深度为8.8 km。表明主震属于兼具逆冲分量的走滑型地震;②震后区域应力场主压应力轴方位为NWW,倾角接近水平,主张应力轴方位为NNE,倾角接近水平,属于走滑型应力状态,与周边地质构造运动状态相吻合;③对研究区域采用不同划分所得应力场结果相差不大,表明该区域应力场比较稳定,受深大断裂带和震源机制解类型影响较小。Based on the digital waveform from Data Management Centre of National Seismic Network,the focal mechanism solutions of the May 18,2020 Yunnan Qiaojia M5.0 earthquake and 51 historical earthquakes in the focal area were inverted by using gCAP method,and collect 50 focal mechanism solutions in the study area.Wan’s grid search method is used to invert the tectonic stress field in the seismic source area,and the study area is divided into different divisions for stress field inversion.The results show that:①the mainshock parameters are as follow,nodal plane I:strike=175°,dip=67°,rake=-19°;nodal planeⅡ:strike=273°,dip=73°,rake=156°,the moment magnitude is 4.97,centroid depth is 8.8 km,focal mechanisms represent that the Qiaojia earthquake is a strike-slip event with thrust component.②The orientation of maximum principal compressive stress axis is NWW in nearly horizontal direction;the orientation of minimum principal compressive stress axis is NNE in nearly horizontal direction;the stress field in source region shows a strike-slip stress regime.③The stress field results obtained from the division of different regions are not much different,indicating that the stress field in this region is relatively stable,and is less affected by the type of deep and large faults and focal mechanism solutions.

关 键 词：2020年巧家M5.0地震 震源机制解 应力场 

分 类 号：P315.7[天文地球—地震学]