四川芦山2022年M_(S)6.1和2013年M_(S)7.0地震余震序列重定位及构造关系  

Relocation of the 2022 M_(S)6.1 and 2013 M_(S)7.0 earthquake sequences in Lushan,Sichuan Province,and their tectonic relationship

作　　者：张胜霞 马晓妹 尹欣欣 鞠慧超 王祖东 万文琦 ZHANG Shengxia;MA Xiaomei;YIN Xinxin;JU Huichao;WANG Zudong;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5期1223-1233,共11页China Earthquake Engineering Journal

基　　金：甘肃省地震局科技计划野外站项目(2021Y08);甘肃省青年科技基金计划(22JR5RA826)。

摘　　要：以2013年4月20日芦山M_(S)7.0地震和2022年6月1日芦山M_(S)6.1地震为研究对象,首先通过HypoDD对两次地震的主震及其余震序列进行重定位,得到精确的震源位置及空间分布,给出两次主震的震中位置和深度,以及余震区的破裂范围。其次,通过研究两次地震的余震震源时空分布和震源深度剖面,表明两次地震的主震及其余震分布在大川—双石断裂带的不同侧,但发震断层均不是该断裂带;其中2013年M_(S)7.0地震的发震断层为大川—双石断裂和大邑—名山断裂之间的龙门山前缘滑落带;而2022年M_(S)6.1地震的余震分布则位于大川—双石断裂带西北侧,发震断层为一条倾向SE的逆冲断层,经过研究分析,认为该断裂带为近NS走向,与大川—双石断裂同属龙门山前山构造体系。最后,分析两次地震的关联性,发现尽管两次地震空间位置较为接近,但由于两次地震的发震断层不同,且余震扩展方向差异明显,余震丛集也相对独立,因此认为M_(S)6.1地震是一次相对独立的地震事件。This paper studies two earthquakes that occurred in Lushan County,Sichuan Province:the M_(S)7.0 earthquake on April 20,2013,and the M_(S)6.1 earthquake on June 1,2022.First,the double-difference location method(HypoDD)was used to relocate the two main shocks and their aftershock sequences.This method provided precise hypocenters and spatial distributions,as well as the epicenter locations and focal depths of the two main shocks and the rupture ranges of the aftershock areas.By analyzing the temporal and spatial distribution of aftershocks and the focal depth profiles of the two earthquakes,we found that the main shocks and their aftershocks are distributed on different sides of the Dachuan-Shuangshi fault,which is not the seismogenic fault for either earthquake.The seismogenic fault for the M_(S)7.0 earthquake is the Longmenshan front slip zone located between the Dachuan-Shuangshi and Dayi-Mingshan faults.In contrast,the M_(S)6.1 earthquake occurs to the northwest of the Dachuan-Shuangshi fault,with its seismogenic fault dipping to the southeast.This fault is considered to strike nearly NS and is part of the Longmenshan piedmont structural system,along with the Dachuan-Shuangshi fault.Finally,the correlation analysis between the two earthquakes indicates that,although their spatial locations are close,the M_(S)6.1 earthquake is considered an independent seismic event.This is due to the differences in the seismogenic faults and the expansion directions of the two earthquakes,as well as the relatively independent clusters of their aftershocks.

关 键 词：芦山地震 余震序列 双差定位 震源位置 

分 类 号：P319.56[天文地球—固体地球物理学]