2018年11月26日台湾海峡M_S6.2地震发震构造研究  

Seismogenic structure of the M_S6.2 Taiwan strait earthquake on 26 November,2018

作　　者：王小娜[1,2,3] 叶秀薇[1,2,3] 黄元敏[1] 王力伟[1,2,3] WANG XiaoNa;YE XiuWei;HUANG YuanMin;WANG LiWei(Guangdong Earthquake Agency,Guangzhou 510070,China;CEA Key Laboratory of Earthquake Monitoring and Disaster Mitigation Technology,Guangdong Earthquake Agency,Guangzhou 510070,China;Guangdong Provincial Key Laboratory of Earthquake Early Warning and Safety Diagnosis of Major Projects,Guangdong Earthquake Agency,Guangzhou 510070,China)

机构地区：[1]广东省地震局,广州510070 [2]广东省地震局中国地震局地震监测与减灾技术重点实验室,广州510070 [3]广东省地震局广东省地震预警与重大工程安全诊断重点实验室,广州510070

出　　处：《地球物理学报》2019年第12期4673-4683,共11页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目（41604055,41676057）;广东省科技计划项目（2017B030314082）;地震科技星火计划项目（XH18034Y）资助

摘　　要：本文利用福建省地震台网、广东省地震台网和台湾“中央”气象局17个台的宽频带记录,使用CAP方法反演了2018年11月26日台湾海峡M S6.2地震震源机制解,得到节面1走向/倾角/滑动角为89°/82°/-173°,节面2走向/倾角/滑动角为358°/84°/-7°,最佳拟合深度14 km,矩震级5.8.使用双差定位获取了94个M L2.0以上地震的精定位结果,结果显示,主震位于北纬23.36°,东经118.62°,震源深度10.43 km.根据小震分布和构造应力场反演得到余震断层面走向和倾角分别为88°和60°.研究认为,台湾海峡6.2级地震发震构造为近EW向的台湾浅滩断裂,受南海板块张裂拉伸发育而成,孕震过程中有东山隆起东缘断裂的参与,推测在菲律宾板块对欧亚板块NW-SE向挤压碰撞背景下,近EW向的台湾浅滩断裂与近NS向的东山隆起东缘断裂交接部位属于强度薄弱区,最终产生高倾角右旋走滑错动而引发地震,余震主要沿台湾浅滩断裂分布.Based on the broadband record of 17 stations from Fujian seismic network,Guangdong seismic network and Taiwan Central Weather Bureau,We obtained the focal mechanism of the M S6.2 earthquake with the“Cut and Paste”(CAP)method,The results show that the best-fit moment magnitude and focal depth are M W5.8 and 14 km respectively.One nodal plane of the best double couple solution of the mainshock is 89°,82°and-173°for strike,dip and rake angles respectively,while the other nodal plane is 358°,84°and-7°.We also obtained 94 relocated events by applying double-difference location method.The hypocenter of the mainshock is 23.36°N,118.62°E with the focal depth of 10.43 km.According to the distributions of earthquake sequence and tectonic stress field,the synthetical fault plane of aftershocks is 88°and 60°for strike and dip angle respectively.The research suggests that,the seismogenic structure of the M S6.2 Taiwan strait earthquake is Taiwan shoal fault,this fault with near E-W trending is formed due to the tension rifting of South China Sea subplate.Under the background of collision and compression in NW direction between Philippine plate and Eurasian plate,the Taiwan shoal fault and the Dongshan uplift Eastern fault intersect in the seismic area,which reduces the frictional strength of the faults.Under the continuous pushing of the Philippine plate,a right-lateral strike-slip dislocation with high dip angle occurred in the Taiwan shoal fault,which triggered the M S6.2 earthquake,then the aftershocks distribute along the Taiwan shoal fault.

关 键 词：台湾海峡M S6.2地震 震源机制解 双差定位 台湾浅滩断裂 

分 类 号：P315[天文地球—地震学]