• ISSN 2097-1893
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2020年尼玛MW6.3地震同震及震后断层滑动特征

刘洋 张宇 温扬茂 杨九元

引用本文: 刘洋,张宇,温扬茂,杨九元. 2023. 2020年尼玛MW6.3地震同震及震后断层滑动特征. 地球与行星物理论评(中英文),54(0):1-10
Liu Y, Zhang Y, Wen Y M, Yang J Y. 2023. Coseismic and postseismic fault slip characteristics of the 2020 MW6.3 Nima earthquake. Reviews of Geophysics and Planetary Physics, 54(0): 1-10 (in Chinese)

2020年尼玛MW6.3地震同震及震后断层滑动特征

doi: 10.19975/j.dqyxx.2022-078
基金项目: 国家自然科学基金资助项目(41874011,41974004,41404007)
详细信息
    通讯作者:

    刘洋(1984-),男,副教授,主要从事InSAR数据处理与地学解释的研究. E-mail:Yang.Liu@sgg.whu.edu.cn

  • 中图分类号: P228, P315

Coseismic and postseismic fault slip characteristics of the 2020 MW6.3 Nima earthquake

Funds: Supported by the National Natural Science Foundation of China (Grant Nos. 41874011, 41974004, 41404007)
  • 摘要: 2020年尼玛MW6.3地震发生在青藏高原羌塘块体依布茶卡地堑北部. 震中区域地质构造、地形地貌复杂,近场地面观测台站、数据较少. 合成孔径雷达干涉测量(Interferometric Synthetic Aperture Radar, InSAR)技术具有全天侯、大范围、高空间分辨率等监测优势,能够弥补近场地面形变观测的不足. 然而,已有研究对该次地震发震断层、同震及震后断层滑动特征的观点存在差异,且仅采用运动学模型提取震后断层余滑特征. 本文利用哨兵1号(Sentinel-1)卫星升、降轨合成孔径雷达(Synthetic Aperture Radar, SAR)影像和差分干涉测量技术提取该次地震不同视角的同震形变场,基于弹性半空间位错模型反演地震同震断层几何及滑动分布,采用应力驱动的震后余滑模型对震后断层滑动进行建模分析,并且探讨了地震发震断层及断裂带摩擦属性特征. 结果表明,升、降轨InSAR同震形变场在震中区域连续光滑、整体呈NNE-SSW走向,断层南东侧区域形变均较为显著且沿视线向以下降为主. 同震断层破裂以正断为主,兼有左旋走滑分量,走向角为31.43º,倾角为45.79º,同震断层滑动主要位于地下3.58~10.75 km,最大滑动量为1.33 m,矩震级为MW6.33. 应力驱动的震后余滑模型能够较好地解释尼玛MW6.3地震近6个月的InSAR震后形变场,震后余滑主要发生在同震断层显著滑动区域南西段的上侧、下侧及南西侧,最大值为47.2 cm. 尼玛MW6.3地震发震断层可能为位于依布茶卡—日干配错断裂中部、倾向SEE的正断层,发震断裂带摩擦属性可能非均匀.

     

  • 图  1  (a)尼玛MW6.3地震区域的主要构造特征,黑色实线表示断裂,红色震源球表示来自美国地质调查局(USGS)、全球矩心矩张量(GCMT)的地震震源机制解,蓝色方框表示SAR观测范围;(b)黑色方框表示图(a)中显示的区域

    Figure  1.  (a) Major tectonic characteristics of the MW6.3 Nima earthquake zone. Black solid lines represent faults. Red beach balls represent focal mechanisms from the United States Geological Survey (USGS) and Global Centroid Moment Tensor (GCMT). Blue boxes represent the Synthetic Aperture Radar (SAR) observation coverages. (b) Black box indicates the region shown in (a)

    图  2  尼玛MW6.3地震InSAR同震形变场、基于同震断层滑动分布模型的拟合及残差形变场,(a)、(d)、(g)对应于升轨012;(b)、(e)、(h)对应于降轨121;(c)、(f)、(i)对应于降轨019. 蓝色实线表示本文确定的同震断层滑动分布模型地表迹线

    Figure  2.  Interferometric Synthetic Aperture Radar (InSAR) coseismic deformation field of the MW6.3 Nima earthquake, as well as fitted and residual deformation fields based on the coseismic fault slip distribution model. (a), (d), and (g) are for ascending track 012; (b), (e), and (h) are for descending track 121; and (c), (f), and (i) are for descending track 019. Blue lines denote the surface traces of the coseismic fault slip distribution model determined in this study

    图  3  (a)同震断层滑动分布,绿色箭头表示滑动方向;(b)同震断层滑动分布误差

    Figure  3.  (a) Coseismic fault slip distribution. Green arrows denote the slip direction; (b) Coseismic fault slip distribution error

    图  4  (a)尼玛MW6.3地震InSAR震后形变场(数据来自于Yang et al., 2022),黑色、紫色实线分别表示几何模型1、2的地表迹线,虚线方框表示计算拟合残差的空间范围;基于震后断层余滑分布模型的拟合及残差形变场,(b)、(c)对应于几何模型1,(d)、(e)对应于几何模型2

    Figure  4.  (a) InSAR postseismic deformation field of the MW6.3 Nima earthquake (data from Yang et al., 2022). Black and purple solid lines denote the surface traces of geometric modes 1 and 2, respectively. Dashed box denotes the spatial coverage of the fitted residual calculation. Fitted and residual deformation fields based on the postseismic fault afterslip distribution model. (b) and (c) are for geometric mode 1; (d) and (e) are for geometric mode 2

    图  5  不同震后余滑模型参数对应的拟合残差RMS. (a)几何模型1($ \varphi =0.2 $);(b)几何模型2($ \varphi =0.4 $). 黑色圆圈表示较优模型参数

    Figure  5.  Root Mean Square (RMS) values of fitted residual corresponding to different postseismic afterslip model parameters. (a) is for geometric mode 1 ($ \varphi =0.2 $); (b) is for geometric mode 2 ($ \varphi =0.4 $). Black circles denote the preferred model parameters

    图  6  应力驱动的震后断层余滑分布. (a)几何模型1;(b)几何模型2. 空白区域表示滑动分布集中后的同震断层显著滑动区域

    Figure  6.  Stress-driven postseismic fault afterslip distribution. (a) is for geometric mode 1; (b) is for geometric mode 2. Blank areas denote the significant slip areas of coseismic fault after concentrating the slip distribution

    表  1  尼玛MW6.3地震震源参数

    Table  1.   Source parameters of the MW6.3 Nima earthquake

    经度/纬度/(º)长度/km顶深/底深/km走向/倾角/(º)滑动角/滑动量/[(º)/m]地震矩/(1018 N·m)/MW
    USGS 86.86/33.14 11.5a) 20/61 −91/- -/6.27
    GCMT 86.87/33.10 16.8a) 10/48 −88/- -/6.4
    Gao等(2022)b) 13.1 28.8/49.4 −78.6/1.2 -/6.28
    Hu等(2022)b) 12.6 31.3/51.6 −70.5/2.63 -/6.3
    冀宗童等(2021)b) 12.3 28.4/48.3 −81.34/1.06 3.59/6.3
    李承涛等(2021)b) 13.2 30.41/49.52 −71.27/1.47 -/6.3
    Li等(2021)b) 28/48 −87/- -/6.4
    梁世川等(2022)b) 12.38 207/33.1 −96.31/2 -/-
    Yang等(2022)b) 13.2 30/48.3 −80.2/1.2 -/6.3
    本研究c) 86.827/33.209 12.81 4.68/9.32 31.43/45.79 −75.77/1.22 3.03/6.29
    0.001/0.001 0.11 0.07/0.06 0.42/0.42 0.92/0.04 0.02/0.002
    a) 矩心深度;b) 均匀滑动模型结果;c) 基于均匀滑动模型反演确定的震源参数,下面行的数值表示上面行对应参数值的误差
    下载: 导出CSV

    表  2  干涉像对参数

    Table  2.   Parameters of the interferometric pairs

    轨道升、降轨主影像日期辅影像日期时间基线/d空间基线/m
    012升轨2020-07-182020-07-3012−84.9
    121降轨2020-07-142020-07-2612108.8
    019降轨2020-07-132020-07-251243.9
    下载: 导出CSV
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  • 收稿日期:  2022-12-11
  • 录用日期:  2023-01-15
  • 修回日期:  2023-01-11
  • 网络出版日期:  2023-02-02

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