2022年泸定Mw 6.6地震InSAR同震形变与滑动分布

Coseismic Deformation and Slip Distribution of the 2022 Luding Mw 6.6 Earthquake Revealed by InSAR Observations

  • 摘要: 2022-09-05,青藏高原东缘的鲜水河断裂上发生了泸定Mw 6.6地震,该地震是鲜水河断裂上40年来发生的最大地震,研究该地震的运动学和同震破裂模式对理解青藏高原东缘构造形变机制和评估鲜水河断裂以及安宁河断裂的地震危险性具有重要意义。利用Sentinel-1和ALOS-2卫星雷达影像,采用合成孔径雷达干涉技术获取了泸定地震的同震形变场,进而基于弹性半空间的位错模型,确定了本次地震发震断层的几何参数和滑动分布。结果表明,泸定地震是一次典型的左旋走滑事件,发震断层西倾,倾角约为72°,走向沿NNW-SSE方向,约为167°;断层破裂主要集中在0~10 km深度,最大滑动发生在约5.8 km深度,约为2.23 m;同震释放的地震矩约为8.74×1018 N·m,相当于矩震级Mw 6.59。通过对震后光学影像解译,发现此次地震诱发的滑坡多集中分布在发震断层西侧,该现象与余震主要集中在断层西侧的结果相一致,可认为是地震上盘效应的体现。

     

    Abstract:
      Objectives  On 5th September 2022, an Mw 6.6 earthquake struck Luding and it is the largest earthquake on the Xianshuihe fault, Eastern Tibet in the past 40 years. It is of great significance for investigating the tectonic activity and assessing future seismic hazards in the region.
      Methods  In this study, we used Sentinel-1 and ALOS-2 synthetic aperture radar (SAR) images to retrieve coseismic surface displacements and then to determine the fault geometry parameters and slip distribution with a dislocation model in an elastic half-space.
      Results  The results show that the 2022 Luding Mw 6.6 earthquake is a left-lateral sliding event with a maximum surface displacement of 15 cm and 21 cm for the Sentinel-1 and ALOS-2 radar images, respectively. The fault ruptured along an NNW-SSE strike, and westward at a dip of 72°. The slip was concentrated at depths of 4-12 km with a maximum fault slip of 2.23 m occurring at a depth of 5.8 km.
      Conclusions  By analyzing the distribution of the coseismic landslides interpreted by optical images, we found that the coseismic landslides were mainly located on the west side of the fault, which is consistent with the aftershock distribution and can be considered due to hanging wall effects.

     

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