摘要
基于云南和四川区域地震台网的数字地震观测资料,采用矩心矩张量反演方法,结合断层失稳参数,对2022年1月2日发生在云南宁蒗的M_(S)5.5地震的震源机制和发震构造进行研究.结果显示,宁蒗M_(S)5.5地震破裂过程由两个在时间和空间上独立的子地震组成:较大子地震M_(major)占总地震矩的74.7%,矩震级为M_(W)5.2,较小子地震M_(minor)占总地震矩的25.3%,矩震级为M_(W)4.9,二者均为典型的正断层地震.断层失稳参数分析显示,M_(major)震源机制解中的节面I对应的断裂,即走向NW、倾向NE的永宁断裂推测其为主发震断裂.较大余震的震源机制解表明,主震激发了震中区附近的次级断裂的活动.研究认为,2022年宁蒗M_(S)5.5地震是在区域构造应力场的作用下,永宁断裂继2012年6月24日宁蒗—盐源M_(S)5.7地震后,沿NW方向进一步扩展的结果,反映出该断裂在过去十年中持续积累应力并发生破裂的构造演化特征.
Based on digital seismic data from the regional seismic networks of Yunnan and Sichuan,this study investigates the focal mechanism and seismogenic structure of the M_(S)5.5 Ninglang earthquake that occurred on January 2,2022,using centroid moment tensor inversion combined with fault instability parameter.The results show that the rupture process consisted of two spatially and temporally distinct sub-events.The larger sub-event(M_(major))accounted for 74.7% of the total seismic moment with a moment magnitude of M_(W)5.2,while the smaller sub-event(M_(minor))contributed 25.3% with a moment magnitude of M_(W)4.9.Both sub-events exhibit typical normal faulting characteristics.Fault instability parameter analysis indicates that nodal plane I of the M_(major)focal mechanism corresponds to a NW-striking,NE-dipping fault,consistent with the Yongning fault,which is inferred to be the primary seismogenic fault.The focal mechanisms of the larger aftershocks suggest that the mainshock triggered seismicity on secondary faults near the epicentral area.The results suggest that the 2022 Ninglang M_(S)5.5 earthquake was a continuation of the NW-trending rupture of the Yongning fault under the regional tectonic stress field,following the Ninglang-Yanyuan M_(S)5.7 earthquake on June 24,2012.This reflects a structural evolution characteristic involving sustained stress accumulation and repeated rupture along the fault over the past decade.
作者
刘俊清
张宇
蔡宏雷
张雪冰
王光明
陈兆新
LIU JunQing;ZHANG Yu;CAI HongLei;ZHANG XueBing;WANG GuangMing;CHEN ZhaoXin(School of Geomatics and Prospecting Engineering,Jilin Jianzhu University,Changchun 130119,China;Jilin Earthquake Agency,Changchun 130117,China;School of Earth Sciences,Institute of Disaster Prevention,Sanhe Hebei 065201,China;Yunnan Earthquake Agency,Kunming 650224,China)
出处
《地球物理学报》
北大核心
2025年第9期3433-3445,共13页
Chinese Journal of Geophysics
基金
吉林省科技发展计划项目(YDZJ202501ZYTS476)资助.
