Sentinel-1影像约束下的东昆仑断裂带玛沁—玛曲段现今地壳变形特征  

Present-day crustal deformation of the Maqên-Maqu segment in the East Kunlun Fault zone revealed by Sentinel-1 images

作　　者：温扬茂[1,2,3] 方志斌 贺克锋 杨九元 熊露雲 许才军 WEN YangMao;FANG ZhiBin;HE KeFeng;YAGN JiuYuan;XIONG LuYun;XU CaiJun(School of Geodesy and Geomatics,Wuhan University,Wuhan 430079,China;Key Laboratory of Geospace Environment and Geodesy,Ministry of Education,Wuhan 430079,China;Key Laboratory of Geophysical Geodesy,Ministry of Natural Resources,Wuhan 430079,China)

机构地区：[1]武汉大学测绘学院,武汉430079 [2]地球空间环境与大地测量教育部重点实验室,武汉430079 [3]自然资源部地球物理大地测量重点实验室,武汉430079

出　　处：《地球物理学报》2023年第11期4517-4532,共16页Chinese Journal of Geophysics

基　　金：国家自然科学基金(41774011,41974004,4213000045)资助。

摘　　要：东昆仑断裂带是青藏高原北部一条活跃的大型左旋走滑活动断裂,其东段滑动速率呈自西向东递减的特征;东段的玛沁—玛曲段被认为是地震破裂空段,存在发生大震的可能.本文首先处理2014—2021年间覆盖东昆仑断裂带玛沁—玛曲段的Sentinel-1卫星升、降轨影像,获得该区域近7年的视线(Line-of-sight,LOS)向形变速率场;然后,联合GPS速度场解算该区域的三维形变速率场和应变率场;最后,对玛沁—玛曲段的应变率积累、滑动速率和形变模式进行分析.结果表明:(1)该区域地壳变形表现为整体向东运动的特征,LOS向和东西向形变速率在玛沁—玛曲段南北两侧存在明显的梯度,且沿断裂带自西向东逐渐减小;(2)玛沁—玛曲段上的阿尼玛卿山和西贡周断层交汇区附近具有显著的应变率积累,同时这两处距上次地震的离逝时间已非常接近其地震复发间隔,表明这两个区域具有较高的地震危险性;(3)玛沁—玛曲段的滑动速率自阿尼玛卿山向东分别为6.0±0.2 mm·a^(-1)、5.6±0.2 mm·a^(-1)、3.9±0.2 mm·a^(-1)和3.5±0.2 mm·a^(-1),意味着东昆仑断裂带东段的滑动速率在距离断裂带最东端至少300 km处的阿尼玛卿山附近就已经开始缓慢递减;(4)玛沁—玛曲段附近的次级块体表现出顺时针旋转的刚性运动特征,符合书斜构造模型,即青藏高原东北部的侧向挤出产生的区域变形由东昆仑断裂带和周缘次级断裂的左旋走滑及其断裂带最东端的地壳缩短共同吸收调节.The East Kunlun fault zone(EKF)is a large active left-lateral strike-slip fault in the northern Tibetan Plateau.The slip rate of the eastern segment of the EKF decreases from west to east.The Maqên-Maqu segment(MMS)located in the eastern EKF is recognized as a seismic rupture gap,exhibiting high potential for the occurrence of strong earthquakes.In this study,ascending and descending Sentinel-1 images of the MMS in the EKF were firstly adpoted to determine the interseismic Line-of-sight(LOS)deformation velocity field during 2014—2021 using the Interferometric Synthetic Aperture Radar(InSAR)technique.Then,both three-dimensional velocity deformation and strain rate fields of the MMS were calculated from the integration of GPS and InSAR.Finally,the strain rate accumulation,slip rate,and deformation characteristics of the MMS were discussed.The results are shown as follows:(1)The crustal deformation of the studied region is generally characterized by the eastward motion,and there is an obvious gradient zone between the two sides of the MMS in the LOS and east-west velocities,which decrease from west to east along the MMS.(2)The Anyemaqen Mountain region and Xigongzhou intersection zone have remarkable strain rate accumulation,and the current elapsed time since the last event is very close to the recurrence interval of the characteristic earthquakes,which indicates relatively high seismic risk.(3)Slip rates along the MMS from the Anyemaqen Mountain region to the east are 6.0±0.2 mm·a^(-1),5.6±0.2 mm·a^(-1),3.9±0.2 mm·a^(-1) and 3.5±0.2 mm·a^(-1),respectively,showing that the long-term slip rate of the EKF likely decreases slowly near the Anyemaqen Mountain,which is at least 300 km from the eastern termination of the EKF.(4)The sub-blocks around the MMS exhibit clockwise rigid rotation,which is consistent with the bookshelf model,namely the regional deformation caused by oblique extruction of the northeastern Tibetan Plateau is accommodated and regulated by the left-lateral strike-slip of both the EKF and th

关 键 词：东昆仑断裂带 时序InSAR 三维形变速率场 应变率场 滑动速率 

分 类 号：P228[天文地球—大地测量学与测量工程]