2020年新疆于田MS6.4地震发震构造研究

doi:10.12196/j.issn.1000-3274.2021.02.001

摘要/Abstract

摘要： 2020年6月26日新疆于田西昆仑地区发生M_S6.4地震, 这是继2008年M_S7.3和2014年M_S7.3两次于田地震后发生的又一次强震。判定此次地震的发震构造是进行地震解剖需要解决的一个基本问题。本文基于GIS平台与技术, 对构造地质、高分遥感、地貌地形、地震、 GPS速度场、震源机制等各种资料进行整合, 通过跨学科资料的综合分析, 对地震相关的动力学、运动学机制进行了研究, 对发震构造进行了初步的判定。此次于田地震的发生可能是2014年强震破裂段进一步向西南方向破裂的结果。地震精定位结果显示震中位于琼木孜塔格峰附近。高分遥感解译及构造地貌变形分析的结果表明极震区是一个典型的张性盆岭构造区, 发育有小型的断陷盆地和正断性质的控盆断裂。震后高分卫星影像表明在震区未发现明显的地表破裂带以及地震次生灾害。此次地震可能是由西昆仑地块与松潘—甘孜地块之间NE向构造带内张性构造体系的活动而引发的。由于构造带两侧地块的斜向拉张运动, 使得正断层、走滑断层在构造带内先后形成并且持续地、同步地活动。正断比走滑更主要一些, 其分别能够很好地适应并吸收张性纯剪切分量以及横向简单剪切分量, 从而使得构造带内正断型、走滑型地震频发, 此次于田M_S6.4地震就是在这种背景下发生的。构造区范围内的地壳自地表向深部可能存在着多层次的张性构造体系, 各个体系之间可能不具有明显的关联性。本次地震可能与地表张性构造体系关系不大, 推断是深层次张性构造体系活动的结果。

关键词: 2020年新疆于田M_S6.4地震, 发震构造, 高分遥感, 构造断块运动

Abstract: The Yutian M_S6.4 earthquake, which occurred on 26 June 2020 in West Kunlun, Xinjiang, is another strong earthquake following the 2008 M_S7.3 and 2014 M_S7.3 earthquakes. Determination of the seismogenic structure of this earthquake is a basic problem to be solved for seismic anatomy. Based on GIS platform and technology, this paper fully integrates various data such as structure geology, high-resolution remote sensing, topography, seismology, GPS velocity field and focal mechanism. The dynamic and kinematic mechanisms related to earthquakes are studied, and the seismogenic structure is preliminarily determined. The Yutian earthquake may be the result of a further southwest rupture of the ruptured segment of the 2014 strong earthquake. The results of seismic relocation show that the epicenter is located near Ulugh Muztagh. The results of high-resolution remote sensing interpretation and tectonic geomorphology deformation analysis show that the epicentral area is a typical extensional basin-ridge tectonic area, and there are small faulted basins and basin-controlling normal faults. High resolution satellite images after the earthquake showed that no obvious surface rupture zone and secondary earthquake disasters were found in the earthquake area. This earthquake may be caused by the activity of the NE-trending tectonic system in the tectonic belt between the West Kunlun block and the Songpan-Ganzi block. Due to the oblique tension movement of the blocks on both sides of the structural belt, normal faults and strike-slip faults are successively formed and continuously and synchronously faulted in the structural belt. Normal faults are more active than strike-slip faults in the area. Normal faults and strike-slip faults can well adapt to and absorb the tensile pure shear component and the lateral simple shear component respectively, so that normal faults and strike-slip earthquakes occur frequently in the tectonic belt. There may be a multi-level extensional tectonic system in the crust from the surface to the deep, and there may be no obvious correlation between the various systems. This earthquake may have little relationship with the surface tensional structural system, and it is inferred that it is the result of the activity of deep-seated tensional structural system.

Key words: The Yutian M_S6.4 earthquake in Xinjiang in 2020, Seismogenic structure, High-resolution remote sensing, Tectonic block movement

中图分类号:

P315.7

耿爽, 王林, 田勤俭, 徐岳仁, 李文巧, 袁兆德. 2020年新疆于田M_S6.4地震发震构造研究[J]. 地震, 2021, 41(2): 1-13.

GENG Shuang, WANG Lin, TIAN Qin-jian, XU Yue-ren, LI Wen-qiao, YUAN Zhao-de. Study on Seismogenic Structure of the Yutian M_S6.4 Earthquake in Xinjiang in 2020[J]. EARTHQUAKE, 2021, 41(2): 1-13.

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