2021年云南漾濞M_(S)6.4地震序列发震构造及其与2013年洱源、2017年漾濞地震的异同  

The seismogenic structure of the 2021 Yunnan Yangbi M_(S)6.4 earthquake sequence and the difference between the Eryuan earthquake in 2013,Yangbi earthquake in 2017 and 2021

作　　者：崔华伟[1,2] 郑建常 万永革[2,3] 程宇豪 杨帆[4] 孙庆山 赵瑞 许鑫 柴光斌[6] CUI HuaWei;ZHENG JianChang;WAN YongGe;CHENG YuHao;YANG Fan;SUN QingShan;ZHAO Rui;XU Xin;CHAI GuangBin(Shandong Earthquake Agency,Jinan 250102,China;Hebei KeyLaboratory of Earthquake Dynamics,Hebei Sanhe 065201,China;Institute of Disaster Prevention,Hebei Sanhe 065201,China;Yunnan Earthquake Agency,Kunming 650224,China;Liaoning Earthquake Agency,Shenyang 110031,China;Changyi Seismic Station,Shandong Changyi 261300,China)

机构地区：[1]山东省地震局,济南250102 [2]河北省地震动力学重点实验室,河北三河065201 [3]防灾科技学院,河北三河065201 [4]云南省地震局,昆明650224 [5]辽宁省地震局,沈阳110031 [6]昌邑地震台,山东昌邑261300

出　　处：《地球物理学报》2022年第2期620-636,共17页Chinese Journal of Geophysics

基　　金：河北省地震动力学重点实验室开放基金(FZ202205);地震预测开放基金;中国地震局震情跟踪定向工作、中国地震科学实验场的地震可预测性国际合作研究(2018YFE0109700)共同资助。

摘　　要：2021年5月21日云南漾濞发生M_(S)6.4地震.为深入了解该地震的发震断层及发震构造特征,探讨其与2013年洱源与2017年漾濞地震发震构造及背景的异同,本文基于中国地震台网中心的观测报告,使用双差方法对漾濞地震序列进行重定位,并从全球矩心矩张量(GCMT)和美国地质调查局(USGS)搜集了9个震源机制解计算了震源区构造应力场,初步得到如下结论:(1)2021年漾濞地震序列呈NW-SE向展布且SE端余震数量多于NW端,余震区地壳应力不均匀释放,致使5.0级及以上地震周边余震稀少;4个5.0级及以上地震初始破裂深度大于矩心深度,推测发震断层是从断裂底部向浅部破裂.(2)发震断裂是维西—乔后—巍山断裂西南侧的未知断裂F2、F3,其走向NW-SE、倾向SW、倾角近垂直,具有右旋走滑特征.其中F2贯穿整个地震序列,长约30 km,F3主要发育在中南段,长约11 km,两条发震断层相交于地震丛集中间位置.(3)震源区构造应力场是走滑的应力机制,呈SSE向(174.57°)低倾伏角(18.79°)挤压,及SWW向(-93.65°)近水平(5.21°)拉张状态.震源区的发震构造受川滇块体与滇南块体形成的右旋走滑边界控制.(4)这3个地震均发生在川滇块体右旋走滑西南边界形成的走滑应力机制作用背景下.2013年洱源地震可能更多的受控于局部构造的垂向差异运动;2017年漾濞地震仅受到川滇块体西南边界的右旋走滑作用;2021年漾濞地震则主要受控于川滇块体西南边界的右旋走滑运动,还存在少量局部构造垂向差异运动作用.An M_(S)6.4 earthquake occurred on May 21;,2021 in Yunnan Yangbi country.In order to analyze the seismogenic fault and structure deeply,and discuss the difference of seismogenic structure and background between the 2013 Eryuan,2017 and 2021 Yangbi earthquakes.The earthquake sequence is relocated by double-difference method with the observation report from the China Earthquake Networks Center(CENC).And the tectonic stress field is calculated with nine focal mechanism solutions from the Global Centroid Moment Tensor(GCMT)catalogue and the United States Geological Survey(USGS)in seismic source region.The initial conclusions are as follow:(1)The Yangbi earthquake sequence is distributed in the direction from NW to SE.More aftershocks are located in the part of SE segment than that in NW segment of earthquake cluster.Few aftershocks occurred around the earthquakes with magnitude larger than 5.0 because of heterogeneity release of crustal stress.Initial rupture depth of four events with magnitude larger than 5.0 are deeper than their centroid depth,their rupture process of seismogenic faults are beginning from fault bottom to fault upper.(2)Two unknown faults F2 and F3 are the seismogenic faults of the Yangbi earthquake sequence,which are lying down southwestern of Weixi-Qiaohou-Weishan fault.Both of them are similar with nearly vertical dip,tending to SW direction,trending from NW to SE direction and sliding in right-lateral strike-slip.The length of F2 is about 30 km,another one(F3)is shorter with the length of nearly 11 km and intersecting with F2 fault in the middle of earthquake cluster.(3)The tectonic stress field is strike-slip regime in seismic source region.The principal compressive stress axis is tended in SSE direction(174.57°)with lower plunge(18.79°).And the principal extensional stress axis is tended in SWW direction(-93.65°)with nearly horizontal plunge(5.21°).The seismogenic structure in seismic source region is controlled by right-lateral strike-slip boundary between Sichuan-Yunnan Block and Southe

关 键 词：漾濞M_(S)6.4地震 双差重定位 震源机制解 构造应力场 发震构造异同 

分 类 号：P315[天文地球—地震学]