2020年7月12日河北唐山M5.1地震破裂方向性快速测定  

Rapid Determination of Rupture Directivity of the Tangshan M5.1 Earthquake, 12 July 2020 in Hebei Province

作　　者：杨彦明[1] 范强 王磊[1] 黄瑞滨[1] 贾君鹏 贾彦杰 YANG Yanming;FAN Qiang;WANG Lei;HUANG Ruibin;JIA Junpeng;JIA Yanjie(Earthquake Agency of Inner Mongolia Autonomous Region,Huhhot 010010,China;National Field Observation and Research Station for Giant Deposits and Earthquake Disasters in Hebei Hongshan,Longyao 055350,China;Hebei Earthquake Agency,Shijiazhuang 050021,China)

机构地区：[1]内蒙古自治区地震局,呼和浩特010010 [2]河北红山巨厚沉积与地震灾害国家野外科学观测研究站,河北邢台055350 [3]河北省地震局,石家庄050021

出　　处：《华北地震科学》2023年第4期92-101,共10页North China Earthquake Sciences

基　　金：内蒙古自治区地震局局长基金重点项目(2022(ZD)JP01);中国地震局地震预测开放基金(XH23077D);中国地震局“监测、预报、科研三结合”课题(3JH-202301040);内蒙古自治区自然科学基金(2023MS04012)。

摘　　要：基于区域数字地震台网波形数据,利用gCAP反演方法获得2020年7月12日唐山M5.1地震的最佳震源机制解节面Ⅰ:走向150°、倾角76°、滑动角-14°,节面Ⅱ的走向243°、倾角76°、滑动角-166°,矩震级MW5.01;采用空间格点搜索算法,获得本次地震矩心的空间坐标为(39.668°N,118.295°E,18 km);根据相关学者对震源机制解的研究成果,计算得到中心震源机制解和标准差,表明震源机制解较为稳定、可靠;使用基于几何学H-C方法进行地震破裂方向性快速测定,显示节面Ⅱ为发震断层面。综合震源区地质构造、余震序列的空间分布和烈度等震线分布特征进行验证,最终推断此次地震断层面为节面Ⅱ,唐山-古冶断裂是发震断层,震源机制解显示以右旋走滑为主,该地震是在深、浅构造共同控制下发生的应力释放事件,属于唐山断裂带强烈活动的响应。Using the recorded waveform from the Regional Seismic Networks,the focal mechanism solution of the Tangshan M5.1 earthquake that occurred on July 12,2020,in Hebei Province was investigated by the gCAP method.The strike,dip,and slip of the first nodal plane are 150°,76°,and 14°,respectively,those of the second nodal plane are 243°,76°,and-166°,and the moment magnitude is MW 5.01.The results show that the centroid position is 39.668°N,118.295°E,and the depth is 18 km using the grid search method in the 3D vicinity of the hypocenter.The result's robustness was investigated by determining the center of several focal mechanisms of the same earthquake and their standard deviations.The resolved focal mechanism is stable.Preliminary results show the second nodal plane is inferred to be the fault plane by hypocenter-centroid methods for quick identification of an earthquake fault plane.For validating the results,combining the characteristic of geologic structure in the seismic source area,and the space distribution of aftershock sequence and isoseismal line of intensity,we conclude that the second nodal plane is inferred to be the seismogenic fault plane,and the Tangshan-Guye fault is the seismogenic structure.The mainshock source mechanism exhibits that its main characteristic is a dextrorotation strike-slip mechanism.We deduced that the earthquake may indicate the process of stress release controlled by deep and shallow structures,which is a powerful seismic activity of the Tangshan fault zone.

关 键 词：唐山M5.1地震 震源机制解 破裂方向 发震构造 唐山断裂带 

分 类 号：P315.3[天文地球—地震学]