摘要
基于中国地震科学数据中心提供的波形资料,采用gCAP方法反演2019年6月17日四川长宁M 6.0地震震源机制解以及17次M>3.5余震震源机制解,并用所得震源机制解资料反演了震源区震后构造应力场.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309°、68°和41°,节面Ⅱ的走向、倾角和滑动角分别为201°、53°和152°,矩心深度为10.7 km,矩震级为5.8,结果表明主震属于兼具有走滑分量的逆冲型地震,余震序列以逆冲型地震为主;(2)震后震源区主压应力轴方位为NEE,倾角近乎水平,主张应力轴方位为SSE,倾角接近垂直,属于逆冲型应力状态,与周边地质构造运动状态相吻合;(3)结合震源机制解特征、余震展布、等震线长轴方向以及周边地质构造特征,推测此次地震的发震断层为长宁—双河背斜北翼褶皱伴生的NW向断层,对应于主震震源机制解节面Ⅰ.
Based on the digital waveform from Data Management Centre of China National Seismic Network,the focal mechanism solutions of the 17 June 2019 Changning M 6.0 earthquake and 17 aftershocks(M>3.5)were inverted by using gCAP method.The obtained focal mechanism solutions were used to invert the post-seismic stress field in source area.The results show that:(1)the mainshock parameters are as follow,nodal planeⅠ:strike=309°,dip=68°,rake=41°;nodal planeⅡ:strike=201°,dip=53°,rake=152°,centroid depth is 10.7 km,the moment magnitude is 5.8,focal mechanisms represent that the Changning earthquake is a thrust event with strike-slip component and the aftershocks are mainly thrust events.(2)The orientation of maximum principal compressive stress axis is NEE in nearly horizontal direction;the orientation of minimum principal compressive stress axis is SSE in nearly vertical direction;the stress field in source region shows a thrust stress regime,and is consistent with the characteristics of the surrounding tectonic movement state.(3)According to the focal mechanism solution,aftershock distribution,the major axis of the isoseismals and surrounding geological structure,we infer that the seismic fault of the Changning earthquake is NW trending fault associated with North Changning-Shuanghe anticline,corresponding to nodal plane I of main shock focal mechanism.
作者
胡晓辉
盛书中
万永革
卜玉菲
李振月
HU Xiao-hui;SHENG Shu-zhong;WAN Yong-ge;BU Yu-fei;LI Zhen-yue(Institute of Disaster Prevention,Sanhe 065201,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Jiangsu Earthquake Agency,Nanjing 210014,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)
出处
《地球物理学进展》
CSCD
北大核心
2020年第5期1675-1681,共7页
Progress in Geophysics
基金
国家自然科学基金项目(41704053,41674055)
河北省地震科技星火计划(DZ20190415002)共同资助.
