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Title:: Earthquake Relocation and Seismic Tectonic Background of the 2022 Delingha M_S6.0 Earthquake Sequence

作者:: 黄浩¹; 袁伏全¹; 李丽²; 赵燕杰¹; 万玉杰¹; 马建新¹; 李启雷¹; 胡维云¹; 郭瑛霞¹; (1.青海省地震局,青海西宁 810017; 2.山西省地震局,山西太原 030021)

Author(s):: HUANG Hao¹; YUAN Fuquan¹; LI Li²; ZHAO Yanjie¹; WAN Yujie¹; MA Jianxin¹; LI Qilei¹; HU Weiyun¹; GUO Yingxia¹; (1.Qinghai Earthquake Agency,Xining 810017,Qinghai,China)(2.Shanxi Earthquake Agency,Taiyuan 030021,Shanxi,China)

Keywords:: the Delingha earthquake; earthquake relocation; focal mechanism; seismic tectonic background; Qinghai

摘要:: 2022年1月23日、3月26日和4月15日青海省德令哈市分别发生M_S5.8、M_S6.0和M_S5.4地震。采用CAP方法反演了M_S6.0地震及6次M_S≥3.7地震的震源机制解和震源矩心深度,利用双差定位方法重新定位了德令哈M_S6.0地震序列的震源位置,初步分析了德令哈M_S6.0地震序列的发震背景。震源机制结果显示,M_S6.0地震震源机制解节面Ⅰ:走向174°/倾角80°/滑动角-156°,节面Ⅱ:走向79°/倾角66°/滑动角-11°,矩心深度6 km。地震重定位结果显示,德令哈M_S6.0地震序列震中呈NS向展布、震源区北部为主体破裂区域。基于震源机制解、地震重定位结果和震源区附近局部发育NS向构造的特征,分析认为德令哈M_S6.0地震序列的发震构造为一条NS向、高倾角的右旋走滑隐伏断层。

Abstract:: A 5.8-magnitude,a 6.0-magnitude,and a 5.4-magnitude earthquake occurred respectively on Jan.23,Mar.26 and Apr.15,2022 in Delingha city of Qinghai province.We firstly inverted the focal mechanisms and the centroid depth of the source of the M_S6.0 main shock and other 6 M_S≥3.7 aftershocks by the CAP method,then we relocated the sources of the M_S6.0 earthquake sequence by the hypoDD method,and analyzed the characteristics of the focal mechanisms,the relocated source parameters and the seismogenic structure.The focal mechanism of the Delingha M_S6.0 earthquake has 2 solutions:for the first nodal plane,strike is 174°,dip is 80°,rake is -156°.For the second nodal plane,strike is 79°,dip is 66°,rake is -11°.The centroid depth is 6 km.The sources of the M_S6.0 earthquake sequence are mainly distributed in North-South direction.According to the focal mechanism,relocated source parameters,and the geological structure in the source region,the seismogenic structure of the M_S6.0 earthquake sequence is a hidden fault with high dip angel in North-South direction.