2022年1月23日青海德令哈M_(S)5.8地震全矩张量反演及发震构造初步分析  

Preliminary analysis of the seismogenic structure and full moment tensor inversion of the M_(S)5.8 Delingha,Qinghai earthquake on January 23,2022

作　　者：徐志国[1] 史健宇 梁姗姗[2] 李宏伟[1] 邹立晔[2] XU Zhiguo;SHI Jianyu;LIANG Shanshan;LI Hongwei;ZOU Liye(National Marine Environmental Forecasting Center,Beijing 100081,China;China Earthquake Networks Center,Beijing 100045,China)

机构地区：[1]国家海洋环境预报中心,北京100081 [2]中国地震台网中心,北京100045

出　　处：《地震工程学报》2022年第5期1128-1135,共8页China Earthquake Engineering Journal

基　　金：自然资源部“中印尼海洋与气候中心发展”项目(2029999001)。

摘　　要：基于青海和甘肃区域地震台网记录的宽频带地震波形和震相观测数据,利用近震全波形反演方法和双差定位方法分别对2022年1月23日青海德令哈M_(S)5.8地震进行全矩张量反演和地震序列重定位研究。矩张量反演结果表明主震为一次典型走滑型地震,最佳断层面节面Ⅰ走向78°、倾角88°、滑动角-22°,节面Ⅱ走向169°、倾角68°、滑动角-177°,矩心深度为9 km,矩震级为M_(W)=5.5。定位结果显示余震优势展布方向为NNW-SSE,长度约16 km,余震震源深度优势分布在7~12 km之间。综合分析表明,节面Ⅱ与余震精定位所勾勒出的断层面走向和倾向较为一致,推断NNW走向的断层面为可能发震断层面,认为德令哈地震是发生在祁连山断裂带的向W倾、倾角约为68°的右旋走滑断裂上。在印度板块向欧亚板块俯冲挤压作用下,青藏高原东北部构造块体应力不断积累,造成祁连山断裂带内断层失稳而发生此次青海德令哈M_(S)5.8地震。To investigate the source characteristics and seismogenic structure of the M_(S)5.8 Delingha,Qinghai earthquake on January 23,2022,in this study,a full moment tensor inversion and seismic sequence relocation for the earthquake was performed with the full-waveform inversion method and double-difference position method,respectively.The inversion results show that the mainshock is a typical strike-slip earthquake.The optimal fault plane solution is nodal planeⅠ:strike=78°/dip=88°/rake=-22°,nodal planeⅡ:strike=169°/dip=68°/rake=-177°.The moment magnitude is M_(W)=5.5,and the centroid depth is 9 km.The relocation results denote that the spatial distribution of aftershocks demonstrates an NNW-SSE strike,with a length of approximately 16 km,and the dominant distribution of the aftershocks’focal depth is 7-12 km.The comprehensive analysis shows that the strike and dip of the fault plane from the precise location of the aftershocks are relatively consistent with those of the nodal planeⅡ.Based on inference,the fault plane with the NNW strike is a possible seismogenic fault plane,and the Delingha earthquake occurred on the dextral strike-slip fault with a dip of about 68°in the Qilian Mountain fault zone.The Delingha M_(S)5.8 earthquake is mainly caused by the instability of the Qilian Mountain fault zone due to the continuous stress accumulation of tectonic blocks in the northeastern Qinghai-Tibet Plateau under the long-term subduction and compression between the Indian and Eurasian plates.

关 键 词：德令哈地震 震源机制 全矩张量 地震重定位 

分 类 号：P315.22[天文地球—地震学]