青海玛多7.4级地震发震断裂继承性及新生性探讨  

Inheritance and Regeneration of Seismogenic Faults of the Maduo 7.4 Earthquake in Qinghai Province

作　　者：王运生[1] 许强[1] 赵伟华[1] 吉锋[1] 杨莹辉 黄健[1] 崔圣华 董秀军[1] 李为乐[1] WANG Yunsheng;XU Qiang;ZHAO Weihua;JI Feng;YANG Yinhui;HUANG Jian;CUI Shenghua;DONG Xiujun;LI Weile(State Key Laboratory of Geological Disaster Prevention and Geological Encironment Proteetion,Chengdu University of Techmology,Chengdu 610059,China)

机构地区：[1]成都理工大学地质灾害防治与地质环境保护国家重点实验室,四川成都610059

出　　处：《灾害学》2023年第1期57-62,71,共7页Journal of Catastrophology

基　　金：国家自然科学基金创新研究群体科学基金项目“西部地区重大地质灾害潜在隐患早期识别与监测”(41521002)。

摘　　要：2021年5月22日青海省果洛州玛多县发生7.4级强烈地震,地表破裂发育,裂缝具断续分布特征,破裂带走向自中西段的NWW到东段转为EW,最终转为NEE向。然而,目前学术界对发震断裂有不同认识,区域地质资料显示,玛多—甘德断裂、昆仑山口—江措断裂均走向NW,倾向NE,但玛多7.4级地震地表破裂在空间位置上与玛多—甘德断裂,昆仑山口—江措断裂均不甚吻合,且地震震源机制解揭示发震断裂南倾,也与昆仑山口—江措的倾向相反,地表破裂表明发震断裂应属一条走向近EW、倾向南的未出露隐伏断裂。为进一步揭示玛多大地发震断裂特征及活动机制,在野外地质调查基础上,采用LiDAR扫描、InSAR解译、地质力学分析和数值模拟方法进行深入研究。结果表明,NW向断裂(玛多—甘德断裂、昆仑山口—江措断裂)在NEE—SWW向区域应力场作用下,在左旋错动过程中于瓶颈处受阻,在江措断裂北部产生应力集中带,东段因瓶颈部位受阻,产生近EW向的新生性地表破裂,出现鱼尾式地表破裂现象,发震断裂不是玛多—甘德断裂或昆仑山口—江措断裂,而是一条走向NNW,斜切昆仑山口—江措断裂小角度相交的隐伏断层。发震断裂走向上继承了既有断裂展布,研究成果为进一步活动断裂防震设计提出了新的借鉴。On May 22,2021,a strong earthquake of Ms 7.4 occurred in Maduo County,Guoluo State,Qinghai Province.The surface rupture was developed,and the fissures had discontinuous distribution characteristics.The trend of the rupture zone moved along NWW to EW in the central and western sections to NEE at the end.However,at present,there are different opinions of seismogenic faults.Regional geological data show that the Maduo-Gander fault and the Kunlunshankou-Jiangcuo fault are NW-trending and NE-trending.However,the surface rupture of the Maduo Ms 7.4 earthquake is not very consistent with the Maduo-Gander fault and the Kunlunshankou-Jiangcuo fault in spatial position.The seismic focal mechanism solution reveals that the seismogenic fault is south-trending,which is also opposite to the Kunlunshankou-Jiangcuo trending.The surface rupture shows that the seismogenic fault should be an unexposed concealed fault which is near east-west and south-trending.In order to reveal the characteristics and active mechanism of seismic faults in Maduo,based on field geological survey,LiDAR scanning,InSAR analysis,geomechanics and numerical simulation methods are used for in-depth study.The results show that the NW-trending faults(Maduo-Gander fault,Kunlunshankou-Jiangcuo fault)are blocked at the bottleneck during the sinistral dislocation under the action of the NE-SW regional stress field,and the stress concentration zone is generated in the northern part of the Jiangcuo fault.The eastern section is blocked due to the bottleneck position,resulting in nearly EW-trending Cenozoic surface rupture and fishtail surface rupture.The seismogenic fault is not the Maduo-Gand fault or the Kunlun-Jiangcuo fault,but a concealed fault that strikes northwest and obliquely cuts the Kunlun Pass-Jiangcuo fault at small angles.Seismogenic faults inherit the distribution of existing faults in strike,and the research results provide a new reference for seismic protection design of further active faults.

关 键 词：玛多7.4级地震 发震断裂 继承性 新生性 

分 类 号：P642[天文地球—工程地质学] TU458[天文地球—地质矿产勘探] X43[天文地球—地质学] X915.5[建筑科学—岩土工程]