2021年青海玛多M_(W)7.4地震GNSS同震形变场及其断层滑动分布  

2021 Qinghai Madoi M_(W)7.4 earthquake coseismic deformation field and fault-slip distribution using GNSS observations

作　　者：王迪晋[1,2] 王东振 赵斌[1,2] 李瑜 赵利江[4] 王阅兵 聂兆生 乔学军 王琪 WANG DiJin;WANG DongZhen;ZHAO Bin;LI Yu;ZHAO LiJiang;WANG YueBing;NIE ZhaoSheng;QIAO XueJun;WANG Qi(Institute of Seismology,China Earthquake Administration,Wuhan 430071,China;Key Laboratory of Earthquake Geodesy,China Earthquake Administration,Wuhan 430071,China;China Earthquake Networks Center,Beijing 100045,China;The Integrated Survey Center of Qinghai Province for Geographic Information and Natural Resources,Xining 810001,China;Institute of Geophysics and Geomatics,China University of Geosciences,Wuhan 430074,China)

机构地区：[1]中国地震局地震研究所,武汉430071 [2]中国地震局地震大地测量重点实验室,武汉430071 [3]中国地震台网中心,北京100045 [4]青海省地理信息与自然资源综合调查中心,西宁810001 [5]中国地质大学(武汉)地球物理与空间信息学院,武汉430074

出　　处：《地球物理学报》2022年第2期537-551,共15页Chinese Journal of Geophysics

基　　金：国家自然科学基金(41731071,41874018,42074116,42074015,42130101)共同资助。

摘　　要：2021年5月22日青海玛多M_(W)7.4地震作为发生在巴颜喀拉块体内部的一次强震,再次引起了人们对该地区地震活动性的强烈关注.本文基于震后GNSS流动观测和区域连续GNSS站资料,解算了106个站点的同震形变及其中17个站点的高频形变波形.同震形变场显示玛多地震具有典型的左旋走滑特征,GNSS观测到的最大同震位移达到1.2 m.GNSS与InSAR数据相符度较高,GNSS提供了准确的近场形变信息.基于GNSS同震形变场,本文反演了断层滑动分布,并计算了发震断层上产生的库仑应力变化.结果表明,发震断层的滑动破裂存在多个凹凸体,破裂分段特征明显且出露地表,与野外地表破裂考察和余震分布吻合,主体破裂位于断层面0~10 km的浅部区域,最大滑动量达到4.6 m,地震矩1.63×10^(20)N·m,矩震级为M_(W)7.4;发震断层上静态库仑应力增加区域与余震分布具有一致性,说明余震主要是由静态库仑应力加载而触发的.On May 22,2021,a M_(W)7.4 event stroke Qinghai Madoi in Bayan Har massif,attracting attention on the seismic activities in this area.Based on a campaign-mode observation after the event and data from the regional continuous GNSS stations,this paper obtained coseismic displacements of the Madoi earthquake in 106 GNSS sites and high-frequency seismic waveforms in 17 continuous GNSS sites of them.The GNSS coseismic displacement field shows that the Madoi earthquake is a typical left-lateral strike-slip event and the maximum coseismic displacement observed by GNSS is 1.2 m.GNSS and InSAR observations are consistent with each other and the details of near-field deformation can be shown by the GNSS observation.Based on the GNSS coseismic displacements,we carried out an inversion for the coseismic slip distribution of the Madoi earthquake and then calculated the Coulomb stress changes on the seismogenic fault induced by the event.The inversion results show that there are several asperities on the fault,and the fault ruptured to the ground surface.The results are consistent with field surface rupture report and aftershock distribution.Coseismic slip is concentrated at the depth of 0~10 km,and the maximum slip is up to 4.6 m.The inverted seismic moment is 1.63×10^(22)N·m,corresponding to M_(W)7.4.Areas of increased Coulomb stress roughly cover aftershock distributions,demonstrating that aftershocks were mainly triggered by the load of static Coulomb stress.

关 键 词：玛多地震 GNSS观测 同震位移场 滑动分布 

分 类 号：P315[天文地球—地震学]