摘要
2022年9月5日四川泸定县发生M6.8级强震,震中位于鲜水河断裂东南末端,野外地质调查初步结果显示本次地震并未发现明显的地表破裂迹象.本文基于震后科考GNSS流动观测和震中周边连续站观测资料,解算并提取震中90 km范围内31个测站的静态水平向同震位移.结果显示:GNSS同震形变场空间分布呈现明显的左旋走滑特征,观测到的最大水平向同震位移达23 cm,震中距50 km范围内同震位移量普遍大于1 cm.基于GNSS观测资料反演得到的同震滑动分布显示泸定地震地表破裂主要集中在磨西至田湾之间,主破裂深度2~8 km,最大滑动量~1.96 m,地震矩9.25×10^(18)N·m,对应矩震级M_W6.6.静态库仑应力结果显示本次地震增强了震源破裂区周边活动断层的库仑应力,并触发了大量余震,余震主要发生在库仑应力增强区域.结合震间闭锁分布、历史地震及库仑应力变化,我们认为未来需要密切关注与磨西断裂交接的安宁河、大凉山断裂以及康定—磨西段的地震危险性.
On September 5, 2022, a M6.8 earthquake occurred in Luding county, Sichuan Province. The epicenter is located at the southeastern end of the Xianshuihe fault. The preliminary results of field geological investigation show that no obvious surface rupture caused in this earthquake. We obtain the static horizontal coseismic displacements within 90 km of the epicenter at 31 survey-mode and continuously operated GNSS stations. The deformation pattern measured by GNSS is agreement with the left-lateral strike slip faulting mechanism. The maximum horizontal coseismic displacement observed by GNSS reaches 23 cm, and the GNSS stations within 50 km of the epicenter records coseismic offsets generally over 1 cm. The optimal coseismic slip model derived from GNSS data shows that the surface rupture mainly concentrated between Moxi town to Tianwan township. The coseismic slip concentrates at depths of 2~8 km, with the maximum slip of 1.96 m. The estimated seismic moment is 9.25×1018 N·m, corresponding to MW6.6. The earthquake has enhanced the Coulomb stress on the fault planes around the periphery of the source rupture area, and a large fraction of aftershocks occurred in the region where Coulomb stress increased. Considering the interseismic coupling ratio, historical earthquake ruptures and Coulomb stress variations, it is worth paying more attentions on seismic hazards of Anninghe fault, Daliangshan fault and Kangding—Moxi segment of the Xianshuihe fault in near future.
作者
余建胜
赵斌
董培育
刘刚
刘成利
徐锐
陈正松
黄功文
房立华
熊维
王明明
林牧
聂兆生
乔学军
YU JianSheng;ZHAO Bin;DONG PeiYu;LIU Gang;LIU ChengLi;XU Rui;CHEN ZhengSong;HUANG GongWen;FANG LiHua;XIONG Wei;WANG MingMing;LIN Mu;NIE ZhaoSheng;QIAO XueJun(Institute of Seismology,China Earthquake Administration,Wuhan 430071,China;Key Laboratory of Earthquake Geodesy,China Earthquake Administration,Wuhan 430071,China;Center of Space Research,Institute of Geophysics and Geomatics,China University of Geoscience,Wuhan 430074,China;Sichuan Earthquake Agency,Chengdu 610041,China;Geodetic Data Processing Centre of Ministry of Natural Resources,Xi'an 710054,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第3期1022-1036,共15页
Chinese Journal of Geophysics
基金
中国地震局星火计划(XH21020,XH20038)
湖北省自然基金(2021CFB508)
国家自然科学基金(42074116,42174113,42074015,41731072,42304005)
中国地震局地质研究所基本科研业务专项(IGCEA1824)共同资助。
关键词
泸定地震
GNSS
同震位移
滑动分布
库仑应力变化
Luding earthquake
GNSS
Coseismic displacement
Slip distribution
Coulomb stress changes
