2023年10月24日甘肃肃北Ms5.5地震震源机制及发震构造  

The Focal Mechanism Solution and Seismogenic Structure of the Subei Ms 5.5 Earthquake in Gansu on October 24th,2023

作　　者：张潇 李振月 郭祥云[2] 崔华伟[3] 盛书中 王甘娇 米梓菲 徐仁义 ZHANG Xiao;LI Zhenyue;GUO Xiangyun;CUI Huawei;SHENG Shuzhong;WANG Ganjiao;MI Zifei;XU Renyi(School of Geophysics and Measurement-control Technology,East China University of Technology,Nanchang 330013,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Shangdong Earthquake Agency,Jinan 250014,China;Jiangxi Earthquake Agency,Nanchang 330036,China)

机构地区：[1]东华理工大学地球物理与测控技术学院,南昌330013 [2]中国地震局地球物理研究所,北京100081 [3]山东省地震局,济南250014 [4]江西省地震局,南昌330036

出　　处：《华北地震科学》2024年第2期51-58,共8页North China Earthquake Sciences

基　　金：国家自然科学基金项目(41704053,42364005);东华理工大学博士科研启动基金(DHBK2019084)。

摘　　要：收集到青海和甘肃区域地震台网记录的宽频带地震波形和震相观测数据,利用ISOLA近震全波形方法对2023年10月24日甘肃肃北Ms5.5地震进行矩张量反演,得到震源机制解和矩心深度;通过双差定位方法获得地震序列精定位结果和时空分布特征,并结合该地区构造背景对发震构造进行分析。获得肃北Ms5.5地震震源机制解参数为:节面Ⅰ的走向、倾角和滑动角为170°、73°和108°,节面Ⅱ的走向、倾角和滑动角为300°、24°和42°,震源矩心深度为4km;重定位后,此次地震序列震中集中分布在长约22km、宽约10km的区域内,地震丛集的优势方向为NNW-SSE向。通过对震源机制解、定位结果、区域构造背景等进行分析,推测震源机制解节面Ⅰ为发震断层面,此次地震为发生在隐伏断层上的一次逆冲兼有走滑型地震事件,发震断裂与周边主要断裂的性质一致。This article collected broadband seismic waveform and phase data recorded by the Qinghai and Gansu regional seismic networks.The focal mechanism solution and centroid depth of the Subei Ms5.5 earthquake in Gansu on October 24th,2023 were obtained by performing centroid moment tensor inversion with ISOLA software.The precise hypocenter results and spatio-temporal distribution characteristics of the earthquake sequence were obtained through the double-difference relocation method,and an analysis of the seismogenic structures was conducted based on the structural background of the area.The focal mechanism solution parameters of the Subei Ms5.5 earthquake are as follows:the strike,dip and slip angles of nodal plane I are 170°,73°and 108°,respectively.The strike,dip and slip angles of nodal plane II are 300°,24°and 42°,respectively.The main shock centroid depth is 4 km.After relocation,the epicenter of the earthquake sequence was concentrated in a region about 22 km long and 10 km wide,and the dominant direction of the earthquake cluster was NNW-SSE.Based on the analysis of focal mechanism solution,relocation results and regional tectonic background,we infer that the focal mechanism solution plane I is the seismogenic fault plane,and the earthquake is a predominantly thrust faulting with strike-slip event occurring on the hidden fault,and the seismogenic fault has the same property as the surrounding major faults.

关 键 词：震源机制 全矩张量 肃北地震 发震构造 地震重定位 

分 类 号：P315.33[天文地球—地震学]