2021年5月22日青海玛多M7.4地震余震重新定位与断层面参数拟合  

THE RESEARCH ON RELOCATION AND FAULT PLANE SOLUTION AND GEOMETRIC MEANING OF THE MADUO M7.4 EARTHQUAKE ON 22 MAY 2021

作　　者：刘白云 赵莉 刘云云 王文才 张卫东 LIU Bai-yun;ZHAO Li;LIU Yun-yun;WANG Wen-cai;ZHANG Wei-dong(Gansu Earthquake Agency,Lanzhou 730000,China;State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Gansu Provincial Research Center for Conservation of Dunhang Cultural Heritage,Dunhuang 736200,China;China Tower Co.,LTD Gansu Branch,Lanzhou 730000,China;Xinjiang Excellent Engineering Project Management Co.,Ltd.,Urumqi 841100,China)

机构地区：[1]甘肃省地震局,兰州730000 [2]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 [3]甘肃省敦煌文物保护研究中心,敦煌736200 [4]中国铁塔股份有限公司,甘肃省分公司,兰州730000 [5]新疆卓越工程项目管理有限公司,乌鲁木齐841100

出　　处：《地震地质》2023年第2期500-516,共17页Seismology and Geology

基　　金：中国地震局地震预测研究所基本科研业务专项(2017IESLZ02);甘肃省科技重点研发计划项目(22YF7FA079);地震动力学国家重点实验室开放基金(LED2020B01);甘肃省敦煌文物保护研究中心开放课题(GDW2021YB13)共同资助。

摘　　要：文中基于青海和周边地震台网72个台站以及震后布设的12个流动观测台站于2021年5月22—27日记录的青海玛多M7.4地震主震及1 357次余震资料,使用双差地震定位法重新对余震位置进行了修定,获得了1 289次余震修定后的震源位置。重新定位后,余震基本沿昆仑山口-江错断裂呈NWW向线性分布,震源深度由重新定位前主要集中于5~10km变为在5~15km深度范围内相对均匀地分布。根据重新定位后的余震分布特点并参考地质断层及现场考察的地震破裂带展布情况,依据成丛地震发生在断层附近的原则,选取了6个矩形区域内重新定位后的震源信息,联合采用模拟退火与高斯-牛顿算法反演获得了每个区域断层面的详细参数。结果表明,主干断裂为长约146km、总体走向为285°~290°的高倾角大型左旋走滑兼逆冲断裂。重新定位还显示,主干断裂东、西两侧有分叉现象,可能是大地震发生时期由于复杂的应力分配导致触发并新产生2条分支断裂,断裂整体显示为树形。西侧分支走向为306°,与主干断裂相交,夹角为21°。东侧分支走向近EW,与主干断裂的东段相连。At 2:04 on May 22,2021,an earthquake of M7.4 occurred in Maduo County,Golog Prefecture,Qinghai Province,with the focal depth of 17 kilometers,the epicenter at 34.59°N and 98.34°E.This earthquake was the largest after the Wenchuan earthquake in China.The epicenter of the earthquake is 38km away from Maduo county seat and 385km from Xining,the provincial capital.The earthquake caused some houses to collapse and some damage to roads in the epicenter.But due to the sparse population in the epicenter area,the earthquake did not cause casualties.Seismologist believe that the earthquake is the result of the continuous activity of the boundary fault of the Bayankala block,which is geographically located in the north of the Qinghai-Tibet Plateau and is the hub for the transformation of the direction of the crustal movement of the plateau.In recent years,many destructive earthquakes occurred inside the block.This earthquake is another strong earthquake after the M7.1 Yushu earthquake in Qinghai in 2010.According to the analysis of this earthquake briefing,the fault zone that induced this earthquake is speculated to be the Maduo-Gande fault zone or the Kunlun Mountains Pass-Jiangcuo fault zone.In order to find out which fault is the seismogenic structure and the distribution of the seismogenic structure of this earthquake,we relocated the dense earthquakes by double-difference method based on the data of 1357 aftershocks in the Maduo M7.4 earthquake area recorded by 72 fixed stations of the digital seismic network of Gansu and its adjacent seismic network and 12 portable seismographic stations during the May 22 to May 27,and obtained the source parameters for 1289 earthquakes.The accurately located small earthquakes distribute along both sides of the Kunlun Mountains Pass-Jiangcuo Fault,which is NNW-trending obviously.It shows that the seismogenic structure of this earthquake is the Kunlun Mountains Pass-Jiangcuo Fault,rather than the Maduo Gande Fault as considered previously by some scholars.This is consistent with the

关 键 词：双差定位 玛多M7.4地震 断层面解 发震构造 

分 类 号：P315.2[天文地球—地震学]