InSAR观测揭示的2023年甘肃积石山Ms 6.2地震发震构造

Seismogenic Fault Structure of the 2023 Jishishan (Gansu) MS 6.2 Earthquake Revealed by InSAR Observations

  • 摘要: 2023年12月18日,在中国甘肃省临夏州积石山县发生了一次Ms 6.2地震。作为该区域自地震观测记录以来发生的最大地震,此次事件的发生为深入理解区域发震构造及破裂行为提供了宝贵的机会。本文利用哨兵1A卫星的合成孔径雷达干涉测量(Interferometric Synthetic Aperture Radar,InSAR)数据提取了此次地震的同震地表形变,并调查了该地震的发震断层结构。大地测量反演结果显示:西南倾和东北倾发震断层模型均能较好地拟合同震InSAR观测数据。通过对余震序列、区域断层构造特性和同震干涉图的综合分析,研究认为此次地震破裂在东北倾的发震断层上,可能为拉脊山南缘断裂的一个隐伏分支断层。同震库仑应力变化表明拉脊山北缘断裂东分支断层中段、拉脊山南缘断裂东分支断层南段和西秦岭北缘断裂西段具有较高的地震危险性。

     

    Abstract: Objectives: On 18 December 2023, an MS 6.2 earthquake struck the Jishishan County, Linxia Prefecture, Gansu Province, China. As the largest earthquake to hit this region since seismic record, the occurrence of the 2023 Jishishan earthquake provides a race opportunity to improve our understanding of the seismogenic structure and rupture behavior of the regional active fault. Methods: In this study, we utilize Sentinel-1A Interferometric Synthetic Aperture Radar data to extract the coseismic surface deformation associated with this earthquake and investigate the seismogenic fault structure. Results and conclusions: Geodetic inversion result shows that both the SW-dipping and NE-dipping fault models can fit the coseismic InSAR observations better. By a joint analysis of the aftershocks, regional fault kinematics and coseismic interferograms, we infer that the 2023 Jishishan earthquake ruptured the NE-dipping seismogenic fault, which may be a buried branch fault belonging to the LJSF. Coseismic Coulomb stress changes indicate a high seismic risk at the middle segment of the eastern branch fault of the LJNF, the southern segment of the eastern branch fault of the LJSF and the western segment of the XLNF.

     

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