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
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
许才军,博士,教授。cjxu@sgg.whu.edu.cn
收稿:2024-12-23,
纸质出版:2025-05-05
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杨九元,许才军.InSAR观测揭示的2020年新疆于田Mw 6.3地震坡-坪状发震构造[J].武汉大学学报(信息科学版),2025,50(5):928-936.
YANG Jiuyuan,XU Caijun.Ramp-Flat Seismogenic Structure of the 2020 Yutian (Xinjiang,China) Mw 6.3 Earthquake Revealed by InSAR Observations[J].Geomatics and Information Science of Wuhan University,2025,50(5):928-936.
杨九元,许才军.InSAR观测揭示的2020年新疆于田Mw 6.3地震坡-坪状发震构造[J].武汉大学学报(信息科学版),2025,50(5):928-936. DOI:10.13203/j.whugis20240482
YANG Jiuyuan,XU Caijun.Ramp-Flat Seismogenic Structure of the 2020 Yutian (Xinjiang,China) Mw 6.3 Earthquake Revealed by InSAR Observations[J].Geomatics and Information Science of Wuhan University,2025,50(5):928-936. DOI:10.13203/j.whugis20240482
2020-06-25,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、降轨合成孔径雷达影像提取了与此次地震有关的同震及震后3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。
Objectives
2
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 Qinghai-Tibet 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
2
We first apply the ascending and descending synthetic aperture radar images of 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
2
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.
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