2021年5月21日云南漾濞MS6.4地震: 一次破裂在隐伏断层上的浅源走滑事件

杨九元, 温扬茂, 许才军. 2021. 2021年5月21日云南漾濞MS6.4地震: 一次破裂在隐伏断层上的浅源走滑事件. 地球物理学报, 64(9): 3101-3110, doi: 10.6038/cjg2021P0408
引用本文: 杨九元, 温扬茂, 许才军. 2021. 2021年5月21日云南漾濞MS6.4地震: 一次破裂在隐伏断层上的浅源走滑事件. 地球物理学报, 64(9): 3101-3110, doi: 10.6038/cjg2021P0408
YANG JiuYuan, WEN YangMao, XU CaiJun. 2021. The 21 May 2021 MS6.4 Yangbi (Yunnan) earthquake: A shallow strike-slip event rupturing in a blind fault. Chinese Journal of Geophysics (in Chinese), 64(9): 3101-3110, doi: 10.6038/cjg2021P0408
Citation: YANG JiuYuan, WEN YangMao, XU CaiJun. 2021. The 21 May 2021 MS6.4 Yangbi (Yunnan) earthquake: A shallow strike-slip event rupturing in a blind fault. Chinese Journal of Geophysics (in Chinese), 64(9): 3101-3110, doi: 10.6038/cjg2021P0408

2021年5月21日云南漾濞MS6.4地震: 一次破裂在隐伏断层上的浅源走滑事件

  • 基金项目:

    国家重点研发计划(2018YFC1503604,2019YFC1509204),国家自然科学基金(41721003,41974004)资助

详细信息
    作者简介:

    杨九元, 男, 1990年生, 博士研究生, 主要从事大地测量反演与构造形变研究.E-mail: 2018102140006@whu.edu.cn

    ; 温扬茂, 男, 1982年生, 副教授, 主要从事构造大地测量研究.E-mail: ymwen@sgg.whu.edu.cn

    通讯作者: 许才军, 男, 1964年生, 长江学者特聘教授, 主要从事地球物理大地测量等方面研究.E-mail: cjxu@sgg.whu.edu.cn
  • 中图分类号: P315, P228

The 21 May 2021 MS6.4 Yangbi (Yunnan) earthquake: A shallow strike-slip event rupturing in a blind fault

More Information
  • 2021年5月21日,在中国云南省大理州漾濞县发生了MS6.4地震.该地震震中位于川滇菱形块体西部边缘的维西—乔后—巍山断裂附近.作为该区域过去45年以来发生的最大地震,快速的灾害反应及震源参数反演将为防震减灾提供重要的帮助.由于未搜集到与此次地震地表破裂相关的报告,这次地震的发震断层目前仍难以确定.本文利用哨兵1A/B卫星的合成孔径雷达干涉(InSAR)数据获得了与此次地震相关的同震形变,并反演了这次事件的断层几何参数及详细的滑动分布.反演结果显示:破裂断层以右旋走滑运动为主,兼有少量的正断分量;滑动主要分布在2到12 km深度范围内,在约7 km深度处滑动达到最大,约为0.64 m.破裂断层浅部0到2 km范围内滑动的缺失揭示了一个重要的滑动亏损区,该区域很可能被震后余滑及震间浅部滑动所弥补.通过对反演结果、余震序列和局部断层构造特性的综合分析,认为此次地震可能破裂在维西—乔后—巍山断裂的隐伏分支断层或一个独立的未知的隐伏主断层上.计算的同震库仑应力变化表明维西—乔后—巍山断裂的巍山盆地段北端、维西—乔后—巍山断裂的玉狮场—乔后段最南端及洱源—弥渡断裂的中段北端具有较高的破裂风险.

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  • 图 1 

    (a) 青藏高原及相邻区域的构造背景;(b)川滇地区的构造背景;(c)2021年漾濞地震区域构造背景

    Figure 1. 

    (a) Tectonic setting of the Tibetan Plateau and its adjacent areas, (b) Tectonic setting of the Sichuan-Yunnan region, (c) Regional tectonic setting of the 2021 Yangbi earthquake

    图 2 

    (a) 和(d)分别为2021年漾濞地震升轨99和降轨135的同震干涉条纹图;(b)和(e)为对应的同震视线向位移;黑色曲线代表以2 cm为间隔的同震形变等值线;(c)和(f)为对应的降采样数据

    Figure 2. 

    (a) and (d) are the ascending track 99 and descending track 135 coseismic interferograms, respectively, (b) and (e) are the corresponding coseismic line-of-sight displacement; the black curved lines represent the contours of each 2 cm coseismic deformation, (c) and (f) are the corresponding downsampled data

    图 3 

    (a) 蒙特卡罗分析的均匀断层面几何参数;(b)非线性反演中断层宽度与滑动量的关系;(c)不同倾角和平滑因子的log(ξ+ψ)函数的等值线图

    Figure 3. 

    (a) Geometric parameters for the uniform fault plane from the Monte-Carlo analysis. (b) The relationship between fault width and slip during the nonlinear inversion. (c) Contour map of log(ξ+ψ) with different dip angles and smoothing factors

    图 4 

    (a) 2021年漾濞地震投影到地表的同震滑动分布模型;(b)沿走向和倾向投影的同震滑动分布模型;(c)沿图(a)中剖线AB的地形及断层结构

    Figure 4. 

    (a) Surface projection of coseismic distributed slip model of the 2021 Yangbi earthquake. (b) The projection of coseismic distributed slip model along strike and dip directions. (c) Topography and fault structure along the profile AB in figure (a)

    图 5 

    (a) 和(d)分别为升轨99和降轨135的同震观测形变;(b)和(e)为对应的模拟数据;(c)和(f)为残差;(g)、(h)和(i)分别为沿剖线CD、EF和GH的同震形变

    Figure 5. 

    (a) and (d) are the observed coseismic displacements for the ascending track 99 and descending track 135, respectively. (b) and (e) are the corresponding modeled data. (c) and (f) are the residuals. (g), (h) and (i) are coseismic displacements along the profile CD, EF and GH, respectively

    图 6 

    2021年漾濞地震引起的附近断层同震库仑应力变化

    Figure 6. 

    Coseismic Coulomb stress changes in the nearby faults induced by the 2021 Yangbi earthquake

    表 1 

    2021年漾濞地震震源参数

    Table 1. 

    Source parameters of the 2021 Yangbi earthquake

    地震机构 经度(°) 纬度(°) 走向(°) 倾角(°) 滑动角(°) 长(km) 宽(km) 深度(km) 滑动量(m) 震级(MW)
    USGS 100.012 25.765 135 82 -165 - - 9 - 6.1
    GCMT 100.02 25.61 315 86 168 - - 15 - 6.1
    GFZ 99.92 25.73 319 88 -165 - - 17 - 6.0
    CENC 99.87 25.67 - - - - - 8 - 6.4*
    均匀滑动模型 99.934 25.644 139 81 -170 12.4 8.7(固定) 6 0.46 6.0
    注:带*符号表示MS震级;均匀滑动模型中深度为破裂面中心点到地表的深度.
    下载: 导出CSV

    表 2 

    用于生成同震形变的SAR数据信息

    Table 2. 

    Details of SAR data used for coseismic deformation

    卫星 轨道 参考日期 重复日期 垂直基线(m) 入射角(°) 方位角(°)
    哨兵1A/B 升轨99 20210520 20210526 -23.5 36.8 -10.7
    哨兵1A 降轨135 20210510 20210522 -50.9 41.6 -169.7
    下载: 导出CSV
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收稿日期:  2021-07-09
修回日期:  2021-07-30
上线日期:  2021-09-10

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