柴达木盆地北部2021年6月16日青海茫崖M_(S)5.8地震发震构造分析  

ANALYSIS OF THE SEISMOGENIC STRUCTURE OF THE JUNE 2021 M_(S)5.8 MANG’AI EARTHQUAKE IN NORTHERN QAIDAM BASIN

作　　者：张博譞 郑文俊 陈杰[3,4] 何骁慧[1,2] 李启雷 张冬丽 段磊[1,2,3] 陈干 ZHANG Bo-xuan;ZHENG Wen-jun;CHEN Jie;HE Xiao-hui;LI Qi-lei;ZHANG Dong-li;DUAN Lei;CHEN Gan(Guangdong Provincial Key Lab of Geodynamics and Geohazards,Sun Yat-sen University,Guangzhou 510275,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,China;State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Xinjiang Pamir Intracontinental Subduction National Observation and Research Station,Beijing 100029,China;Qinghai Earthquake Agency,Xining 810001,China;Institute of Disaster Prevention,Sanhe,Hebei 065201,China)

机构地区：[1]中山大学,地球科学与工程学院,广东省地球动力作用与地质灾害重点实验室,珠海510275 [2]南方海洋科学与工程广东省实验室(珠海),珠海519082 [3]中国地震局地质研究所,地震动力学国家重点实验室,北京100029 [4]新疆帕米尔陆内俯冲国家野外科学观测研究站,北京100029 [5]青海省地震局,西宁810001 [6]防灾科技学院,三河065201

出　　处：《地震地质》2022年第5期1313-1332,共20页Seismology and Geology

基　　金：第2次青藏高原综合科学考察研究(2019QZKK0901)资助。

摘　　要：青海茫崖M_(S)5.8地震发生在祁连山与柴达木盆地交界的部位。对于此次地震开展研究,不仅有助于理解柴达木盆地与祁连山之间的现今构造变形、应力状态及动力学过程,也将为该区未来的强震趋势预测提供依据。文中首先利用CAP方法反演得到该次地震的震源深度约为13km,震源机制解为逆冲性质。结合地表地质、卫星影像和地震反射剖面解译,认为该地震发生在冷湖逆断裂-褶皱带的东南端,发震构造可能为冷湖七号东背斜之下控制背斜生长的2条倾向相反的隐伏逆冲断裂之一。此次茫崖5.8级地震仅使冷湖七号东背斜下伏逆断层发生了部分破裂,并未破裂至地表,为典型的褶皱地震。震区发育多条第四纪活动褶皱及下伏逆断层,这些构造均具备发生M^(W)5.9~7.2地震的构造条件,并有可能因级联地震破裂而引发7级以上强震。因此,震区未来的地震危险性不容忽视。The M_(S)5.8 Mang’ai earthquake occurred in northwest Qaidam Basin on June 16,2021.There are the Santai reverse fault-fold belt,Xiaoqulin reverse fault-fold belt,Lenghu reverse fault-fold belt and Eboliang reverse fault-fold belt developed in the seismic area from north to south,which converge along the direction of the Altun Fault in the northwest and spread out in the southeast basin.As the boundary between the southern margin of Qilian Shan and the northern margin of Qaidam Basin,the Mesozoic and Cenozoic tectonic deformation is very complex.The study of seismogenic capacity and mechanism of fold-related faults in this area is beneficial to further understand the strain distribution pattern and tectonic deformation mechanism between the southern Qilian Shan and the northern margin of Qaidam Basin.This earthquake occurred in the eastern section of the NW-trending Lenghu anticline in the northwestern margin of Qaidam Basin.The focal depth of the earthquake is about 13km determined by using CAP method,and the focal mechanism solution is thrust type.The parameters of the double-couple nodal planes obtained in this paper are similar to those obtained by GFZ and USGS,respectively.Combined with surface geology,satellite images and seismic reflection profile interpretation,it is considered that the earthquake occurred in the southeast of the Lenghu reverse fault-fold belt,and the seismogenic structure may be one of two deep concealed thrust faults dipping north and south,respectively,which control the growth of the anticline under the east of Lenghu No.7 anticline.According to the position of the growth strata interpreted by the seismic reflection profile,the latest rapid deformation in the eastern section of Lenghu anticline began around the sedimentary period of the Shizigou Formation in the Late Cenozoic,and the activity has continued till now.This M_(S)5.8 Mang’ai earthquake only partially ruptured the underlying thrust fault of the east of Lenghu No.7 anticline,but did not rupture to the surface,so it was a t

关 键 词：茫崖M_(S)5.8地震 CAP方法 冷湖逆断裂-褶皱带 褶皱地震 发震构造 

分 类 号：P315.2[天文地球—地震学]