InSAR观测揭示的2020年新疆于田Mw 6.3地震坡-坪状发震构造

杨九元; 许才军

doi:10.13203/j.whugis20240482

InSAR观测揭示的2020年新疆于田Mw 6.3地震坡-坪状发震构造

杨九元¹,
许才军^2,3, ,

1 华北水利水电大学测绘与地理信息学院, 河南郑州, 450046;
2 武汉大学测绘学院, 湖北武汉, 430079;
3 地球空间环境与大地测量教育部重点实验室, 湖北武汉, 430079

基金项目:

国家自然科学基金（42304007,42130101）。

详细信息

作者简介:
杨九元，博士，讲师，主要从事大地测量反演与构造形变研究。jyyang@whu.edu.cn

通讯作者:
许才军，博士，教授。cjxu@sgg.whu.edu.cn

中图分类号: P237
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出版历程

Ramp-flat Seismogenic Structure of the 2020 Yutian (Xinjiang， China) MW 6.3 Earthquake Revealed by InSAR Observations

YANG Jiuyuan¹,
XU Caijun^2,3, ,

1 College of Surveying and Geo-informatics, North China University of Water Resources and Electric Power, Zhengzhou 450046, China;
2 School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China;
3 Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan 430079, China

摘要

摘要: 2020年6月25日，以左旋走滑运动为主要特征的青藏高原西北缘阿尔金断裂带西南部发生了一次MW 6.3浅源正断地震，为深入理解该区域的发震构造及地震成因提供了宝贵机会。基于Sentinel-1A卫星的升、降轨SAR影像提取了与此次地震有关的同震及震后三个月的地表形变。同震反演结果表明该地震成核于一条倾角56°的埋深于地下3～11 km深度的正断层，而进一步的震后形变分析揭示震后余滑孕育于一条倾角76°的浅部断层结构。该地震浅部震后余滑和深部同震滑动精细刻画出一条坡-坪状发震断层结构。通过综合分析区域地形地貌、活动断裂分布与特性、历史地震和反演结果，推断此次于田地震的发生归因于走滑边界断裂控制的阶分区内拉张应变能的释放。
- 青藏高原西北缘 /
- 于田地震 /
- InSAR /
- 坡-坪状断层
Abstract: Objectives:On 25 June 2020, a shallow MW 6.3 normal-faulting earthquake struck the southwestern segment of Altyn Tagh fault in the northwest margin of Tibetan Plateau, which is characterized by left-lateral strike-slip motion. This earthquake offers a rare opportunity to understand the seismogenic structure and seismogenesis in the region. Methods:In the paper, we first apply the ascending and descending SAR images of the Sentinel-1A satellite to extract the coseismic and the first three months postseismic surface deformation related to the earthquake. Then, we utilize the coseismic and postseismic observations to invert for the detailed coseismic slip and postseismic afterslip of the earthquake, respectively. Results and conclusions:Coseismic inversion result reveals that the earthquake nucleated on a moderate-angle (a dip of 56°) normal fault buried at a depth of 3 to 11 km while further postseismic analysis uncovers that afterslip propagates in the shallow fault structure with a dip of 76°. The shallow postseismic afterslip and deep coseismic slip of the earthquake finely image a ramp-flat seismogenic fault structure. According to a joint analysis of the regional geology geomorphology, active fault distribution and kinematics, historical earthquakes and the inversions, we conclude that the occurrence of the Yutian earthquake may be attributed to the release of extensional stress in a stepover zone controlled by the bounding strike-slip faults.
- Northwest margin of Tibetan Plateau /
- Yutian earthquake /
- InSAR /
- Ramp-flat fault