2022年1月2日宁蒗M_(S)5.5地震序列重定位与发震构造分析  

Relocation and seismogenic structure analysis of the M_(S)5.5 Ninglang earthquake sequence on January 2,2022

作　　者：王光明 吴中海[2] 刘昌伟 张天宇 彭关灵 Wang Guangming;Wu Zhonghai;Liu Changwei;Zhang Tianyu;Peng Guanling(Yunnan Earthquake Agency,Kunming 650224,China;Institute of Geomechanics,Chinese Academy of Geological Science,Beijing 100081,China)

机构地区：[1]云南省地震局,中国昆明650224 [2]中国地质科学院地质力学研究所,中国北京100081

出　　处：《地震学报》2022年第4期581-593,共13页Acta Seismologica Sinica

基　　金：国家自然科学基金(U2002211);2022年度震情跟踪定向工作任务(2022010105);地震科技星火计划(XH20054Y);云南省地震局“地震机理与孕震环境研究”创新团队项目共同资助。

摘　　要：2022年1月2日云南省丽江市宁蒗县发生M_(S)5.5地震。采用地震编目系统提供的此次地震的震相到时数据,使用双差定位方法对此次宁蒗M_(S)5.5地震序列进行重新定位,获得了694次地震的高精度相对位置。重定位后的地震空间分布显示:此次地震序列呈NNE至近NS向分布,与震源机制解的节面Ⅱ走向(191°)一致,主震位于地震序列南段;地震序列主体活动区长约11 km,宽约6 km,余震主要分布在4—11 km的深度范围内;地震序列在深度剖面上呈现出两组倾向不同的活动分支,其中东侧分支与震源机制解节面Ⅱ的倾角(81°)一致。此外,本次地震还可能触发了邻区的局部断裂活动。综合分析认为,2022年宁蒗M_(S)5.5地震的发震构造应该是NNE至近NS向兼具正断层分量的左旋走滑断层,倾向为WNW,倾角约为81°,其活动性质与震源区已知的活动断层均不一致。尽管本次宁蒗M_(S)5.5地震序列发生在2012年宁蒗—盐源M_(S)5.7地震序列的北侧,但是两次地震序列的发震断层并不相同。库仑应力反演结果显示,2012年宁蒗—盐源M_(S)5.7地震对本次宁蒗M_(S)5.5地震的发生具有促进作用。On January 2,2022,a M_(S)5.5 earthquake occurred in the Ninglang County,Lijiang City,Yunnan Province.Using the P and S phase arrival data of this M_(S)5.5 earthquake provided by the Seismic Catalogue System,the high-precision relative positions of 694 earthquakes in Ninglang M_(S)5.5 earthquake sequence are obtained by using the double difference relocation algorithm.In general,the relocations reveal a 11 km-long,linear NNE-NS seismicity trend concentrating in the 4—11 km depth range,which is consistent with the NNE nodal plane(191°)of the mainshock focal mechanism solution.The mainshock is located in the southern segment of the earthquake sequence.The earthquake sequence shows two groups of active branches with different tendencies on the depth profiles,in which the east branch is consistent with the dip angle of the nodal planeⅡ(81°)of the mainshock focal mechanism solution.In addition,the earthquake may have triggered local fault activity in the adjacent area.According to the comprehensive analysis,the seismogenic structure of the M_(S)5.5 Ninglang earthquake sequence should be a NNE-NS trending left-lateral strike-slip fault,with normal component,and the fault plane dips to the WNW at 81°angle.The properties of the seismogenic fault are not completely consistent with any mapped faults in this area.Although the M_(S)5.5 Ninglang earthquake sequence is located to the north of the M_(S)5.7 Ninglang-Yanyuan earthquake sequence in 2012,they have different seismogenic structures.The result of Coulomb failure stress shows that the M_(S)5.7 Ninglang-Yanyuan earthquake in 2012 promoted the occurrence of the M_(S)5.5Ninglang earthquake.

关 键 词：2022年宁蒗M_(S)5.5地震 2012年宁蒗—盐源M_(S)5.7地震 双差定位法 永宁断裂 古鲁—岩瓦断裂 

分 类 号：P315.31[天文地球—地震学]