甘肃积石山6.2级地震序列重定位及分析  

Relocation and analysis of the Jishishan M_(S)6.2 earthquake sequence in Gansu Province

作　　者：鞠慧超 张元生 秦满忠 刘白云 尹欣欣 高鹏 焦煜媛 杜建清 孙长青 蒲举 张卫东 万文琦 JU Huichao;ZHANG Yuansheng;QIN Manzhong;LIU Baiyun;YIN Xinxin;GAO Peng;JIAO Yuyuan;DU Jianqing;SUN Changqing;PU Ju;ZHANG Weidong;WAN Wenqi(Gansu Lanzhou Geophysics National Observation and Research Station,Lanzhou 730000,Gansu,China;Gansu Earthquake Agency,Lanzhou 730000,Gansu,China)

机构地区：[1]甘肃兰州地球物理国家野外科学观测研究站,甘肃兰州730000 [2]甘肃省地震局,甘肃兰州730000

出　　处：《地震工程学报》2024年第4期918-923,共6页China Earthquake Engineering Journal

基　　金：甘肃省地震局科技发展基金(KY2203003)。

摘　　要：利用甘肃数字地震台、预警台、流动台三网数据,对2023年12月18日甘肃省积石山6.2级地震余震序列进行震相分析,并采用双差定位法和遗传算法对序列进行重定位。截至2024年1月10日,共分析余震约600个,Pg和Sg震相约15000条,较同期测震台网增加震相4000多条。重定位中,双差方法得到的地震数目为余震总数的70%;在此基础上,使用遗传算法对速度和震源位置进行联合反演,要求每个地震至少有3个台站的震相记录,共使用4828条Sg波和Pg波到时差数据,最终获得余震序列中577个地震的重定位结果,测得主震震源深度为15.2 km。结果显示,余震震中主要沿地表破裂走向分布,其深部近似呈对冲断层形态分布,在空间上余震展布存在明显的边界,可能存在滑脱面。重定位结果可为认识该区复杂的断裂活动及构造背景提供参考依据。Leveraging the data recorded by the Gansu digital seismic,early warning,and moving stations,we analyzed the seismic phases of the aftershock sequence of the Jishishan M_(S)6.2 earthquake.Subsequently,employing the double-difference location method and a genetic algorithm,it relocated the analyzed sequence.Accordingly,until January 10,2024,we analyzed approximately 600 aftershocks and 15000 Pg and Sg phases,marking an excess of>4000 seismic phases over those analyzed by the seismic network during the same period.During relocation,the double-difference location algorithm recorded earthquakes amounting to 70%of the total number of aftershocks.Considerably,a joint inversion of the velocity and focal location was conducted using the genetic algorithm,requiring the phases of each earthquake to be recorded by at least three stations.Finally,the relocation results of 577 earthquakes in the aftershock sequence were obtained based on arrival time differences between 4828 Sg and Pg waves.Moreover,the focal depth of the main shock was measured to be 15.2 km.Results revealed that the epicenters of aftershocks were predominantly distributed along the surface rupture trend,while a thrust fault appeared within the deep section.The distribution of aftershocks in space presented a distinct boundary,indicating the possibility of a detached surface.Overall,these relocation results offer insights into the complex fault activity and tectonic background of this area.

关 键 词：积石山地震 地震定位 双差定位法 遗传算法 

分 类 号：P315.2[天文地球—地震学]