东昆仑断裂带托索湖段现今形变特征及其与2021玛多地震相互作用  

Present interseismic deformation along the Tuosuo Lake segment of the East Kunlun fault zone and its interaction with the 2021 Madoi earthquake

作　　者：李少为 许文斌[1] 李志伟[1] 刘小鸽 冯光财[1] 方楠 陈志丹 江坤 谢磊 LI ShaoWei;XU WenBin;LI ZhiWei;LIU XiaoGe;FENG GuangCai;FANG Nan;CHEN ZhiDan;JIANG Kun;XIE Lei(School of Earth Science and Information Physics,Central South University,Changsha 410083,China)

机构地区：[1]中南大学地球科学与信息物理学院,长沙410083

出　　处：《地球物理学报》2023年第12期4928-4943,共16页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(42174023);国家重点研发计划课题(2022YFB3903602)资助。

摘　　要：东昆仑断裂带作为孕育强震和协调青藏高原内部构造变形的大型走滑断裂带,其现今震间闭锁情况与运动学特征一直备受关注.前人通过野外地质考察以及传统大地测量技术初步厘定了东昆仑断裂带的长期滑动速率,但受限于观测台站的空间分布,难以得到精细化的东昆仑断裂带托索湖段及其次级断裂的现今运动特征.本文利用覆盖东昆仑断裂带托索湖段2015—2021年Sentinel-1升降轨数据获取了高空间分辨率的沿断层走向震间形变速率场,结合螺位错模型和马尔科夫链蒙特卡洛方法反演得到了该段断裂现今精细化的震间滑动速率和闭锁状态.研究结果表明,东昆仑断裂带托索湖段处于断层锁定状态,闭锁深度分布在8~29 km区间,断层深部滑动速率分布在6~9 mm·a^(-1)范围内.最后,本文基于库仑应力变换探讨了2021玛多地震与东昆仑断裂带的相互作用,发现东昆仑断裂带震间运动对玛多地震无明显应力加载作用,而玛多地震却促进了东昆仑断裂带花石峡至阿尼玛卿山南缘、玛沁—玛曲段的应力积累,其潜在地震危险性值得关注.As a large sinistral strike-slip fault that breeds continental strong earthquakes and coordinates the internal tectonic deformation of the Tibetan Plateau,the current interseismic locking and kinematic characteristics of the East Kunlun fault zone have always attracted much attention.The long-term slip rates of the East Kunlun fault zone are preliminarily determined by field geological surveys and traditional geodetic techniques.However,due to the sparse distribution of observation stations,it is difficult to obtain the refined movement characteristics of the Tuosuo Lake segment of the East Kunlun fault zone and its secondary faults.In this paper,the high spatial resolution interseismic deformation velocity field is generated using Sentinel-1 images covering the Tuosuo Lake segment of the East Kunlun fault zone from 2015 to 2021.The refined interseismic slip rate and locking state of the fault in the Tuosuo Lake segment are inverted based on the screw dislocation model using the Markov chain Monte Carlo method.The results show that the Tuosuo Lake segment of the East Kunlun fault zone is in the state of fault locking,the locking depth is in the range of 8~29 km,and the long-term slip rate of the fault is in the range of 6~9 mm·a^(-1).Finally,we discuss the interaction between the 2021 Madoi earthquake and the East Kunlun fault zone based on the Coulomb stress criterion.We find that the interseismic activity of the East Kunlun fault zone has no obvious stress loading effect on the Madoi earthquake,but the Madoi earthquake promotes the stress accumulation in the East Kunlun fault zone from Huashixia to the southern margin of Animaqing Mountain and the Maqên-Maqu section.The seismic hazard of these segments deserves further attention.

关 键 词：玛多地震 东昆仑断裂带 滑动速率 库仑应力 INSAR 

分 类 号：P315[天文地球—地震学] P228[天文地球—固体地球物理学]