Coseismic deformation field of the Jiuzhaigou MS7.0 earthquake from Sentinel-1A InSAR data and fault slip inversion
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摘要:
基于InSAR技术，利用欧空局升降轨Sentinel-1A/IW宽幅数据，获取了2017年8月8日四川九寨沟7.0级地震InSAR同震形变场，并以升降轨InSAR观测结果为约束，反演了断层滑动分布，基于三种不同接收断层计算了同震库仑应力变化.结果表明，同震形变场发生在塔藏断裂、岷江断裂和虎牙断裂交汇的三角地带，升降轨干涉位移均显示本次地震的形变场影响范围约为50 km×50 km，形变场长轴方向为NW向，升降轨观测的形变量相反，反映断层运动性质以走滑运动为主，升降轨数据观测得到的最大LOS（Line of Sight，视线向）形变量分别为~22 cm和~14 cm.非对称形变场反映出断层两侧的运动差异.反演结果显示，最大滑动量约为1 m，平均滑动角为-9°，矩震级为MW6.5，地震破裂主要集中在地下1~15 km深度范围内，但整体而言本次地震破裂较为充分，基本将该区域1973年及1976年4次> MW6.0地震的破裂空区完全破裂.考虑到塔藏断裂和虎牙断裂的运动性质，可初步判定发震断层为虎牙断裂北侧延伸分支.基于三种不同接收断层模型的同震库仑应力变化计算结果反映出该区域以应力释放为主，进一步触发较大走滑型余震的可能性不大.
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关键词:
- 九寨沟地震 /
- InSAR同震形变场 /
- 滑动分布 /
- 地震危险性
Abstract:We processed the Sentinel-1A/IW data with InSAR technology and generated the surface deformation fields caused by Jiuzhaigou MS7.0 earthquake occurred on August 8 2017. The result shows that the overall deformation field caused by this event follows the NW direction. Main deformation region is about 50 km×50 km delimited by Tazang, Minjiang and Huya faults. The maximum displacement reaches about 14 cm, and the minimum value is about 22 cm in LOS.The displacement field indicates a left-lateral strike-slip movement of seismogenic fault. Based on ascending InSAR deformation field only, we carried out the slip distribution inversion by using a fault model with single fault plane and medium dip angle.The inversion results indicate an obvious slip concentrated area located in 1~15 km in depth.The maximum slip is about 0.86 m.The moment magnitude is MW6.5, consistent with previous results from seismic data inversion provided by USGS. We can see that the rupture of this event has filled the rupture gap of four earthquakes larger than MW6.0 occurred in 1973 and 1976.The coseismic Coulomb stress change shows that the rupture has produced two stress increasing zones in the depth of 10 km, ~(3~5)×105Pa.This will increase the possibility of aftershocks in this area.A large stress decreasing zone delimited by Minjiang and Tazang fault indicates the releasing of accumulated stress before the rupture.Thus, the possibility to trigger further strong aftershocks in this region is relatively small.
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图 1
(a) 青藏高原东缘地震构造背景，(b)本次地震震中区地震构造略图
Figure 1.
(a) Tectonic setting in eastern margin of Tibetan Plateau. (b) Aftershocks distribution and tectonic setting in the epicentral area of the Jiuzhaigou earthquake
图 2
九寨沟MS7.0地震降轨同震形变场
Figure 2.
The descending coseismic interferogram (a) and deformation field (b) of MS7.0 Jiuzhaigou earthquake
图 3
九寨沟MS7.0地震升轨同震形变场
Figure 3.
The ascending coseismic interferogram (a) and deformation field (b) of MS7.0 Jiuzhaigou earthquake
图 5
基于InSAR数据反演的同震滑动分布模型
Figure 5.
Fault slip distribution from inversions constrained by InSAR
图 7
断层滑动分布反演拟合情况: (a—c)分别对应升轨InSAR数据的观测值、模拟值和残差；(d—f)分别对应降轨InSAR数据的观测值、模拟值和残差
Figure 7.
Observation, simulation and residual from ascending (a—c) and descending (d—f) InSAR data and inversion
图 8
九寨沟MS7.0地震同震库仑应力变化(接收断层为虎牙断裂本身)
Figure 8.
Coseismic Coulomb stress change caused by the Jiuzhaigou MS7.0 earthquake using the Huya fault as the receiver fault
图 9
九寨沟MS7.0地震同震库仑应力变化(接收断层为岷江断裂)
Figure 9.
Coseismic Coulomb stress change caused by the Jiuzhaigou MS7.0 earthquake using the Minjiang fault as the receiver fault
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Chen C Y, Ren J W, Meng G J, et al. 2012. Analysis of modern activity of major faults in northeast margin of Baryan-Har block. Journal of Geodesy and Geodynamics (in Chinese), 32(3):27-30. http://en.cnki.com.cn/Article_en/CJFDTOTAL-DKXB201203006.htm
Deng Q D. 2007. Map of Active Tectonics in China (in Chinese). Beijing:Seismological Press.
Deng Q D, Cheng S P, Ma J, et a1. 2014. Seismic activities and earthquake potential in the Tibetan Plateau. Chinese J. Geophys. (in Chinese), 57(7):2025-2042, doi:10.6038/cjg20140701.
Lin J, Stein R S. 2004. Stress triggering in thrust and subduction earthquakes and stress interaction between the southern San Andreas and nearby thrust and strike-slip faults. Journal of Geophysical Research, 109:B02303, doi:10.1029/2003JB002607.
Scholz C H. 1990. The Mechanics of Earthquakes and Faulting. New York:Cambridge University Press, 439.
Tang R K, Lu L K. 1981. On the seismogeological characteristics of 1976 Songpan-Pingwu earthquakes. Seismology and Geology (in Chinese), 3(2):41-47. http://en.cnki.com.cn/Article_en/CJFDTOTAL-DZDZ198102007.htm
Toda S, Stein R S, Richards-Dinger K, et al. 2005. Forecasting the evolution of seismicity in southern California:Animations built on earthquake stress transfer. Journal of Geophysical Research, 110:B05S16, doi:10.1029/2004JB003415.
Toda S, Lin J, Meghraoui M, et al. 2008. 12 May 2008 M=7.9 Wenchuan, China, earthquake calculated to increase failure stress and seismicity rate on three major fault systems. Geophysical Research Letters, 35:L17305, doi:10.1029/2008GL034903.
Wang R, Motagh M, Walter T R. 2008. Inversion of slip distribution from coseismic deformation data by a sensitivity-based iterative fitting (SBIF) method.//EGU General Assembly 2008. EGU, 10:EGU2008-A-07971.
Zhou C J. 2014. The change of stress field in margin of Bayankala block and its influence of occurrence of strong earthquakes[Ph. D. thesis] (in Chinese). Beijing:Chinese Academy of Geological Sciences.
http://cdmd.cnki.com.cn/Article/CDMD-82501-1015584763.htm Zhu H, Wen X Z. 2009. Stress triggering process of the 1973 to 1976 Songpan, Sichuan, sequence of strong earthquakes. Chinese J. Geophys. (in Chinese), 52(4):994-1003, doi:10.3969/j.issn.0001-5733.2009.04.016.
陈长云, 任金卫, 孟国杰等. 2012.巴颜喀拉块体北东缘主要断裂现今活动性分析.大地测量与地球动力学, 32(3):27-30. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=dkxb201203006&dbname=CJFD&dbcode=CJFQ
邓起东. 2007.中国活动构造图.北京:地震出版社.
邓起东, 程绍平, 马瑾等. 2014.青藏高原地震活动特征及当前地震活动形势.地球物理学报, 57(7):2025-2042, doi:10.6038/cjg20140701. http://www.geophy.cn/CN/abstract/abstract10474.shtml
唐荣昌, 陆联康. 1981. 1976年松潘、平武地震的地震地质特征.地震地质, 3(2):41-47. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=dzdz198102007&dbname=CJFD&dbcode=CJFQ
周春景. 2014. 巴颜喀拉块体边界应力场变化及其对强震发生的影响[博士论文]. 北京: 中国地质科学院.
http://cdmd.cnki.com.cn/Article/CDMD-82501-1015584763.htm 朱航, 闻学泽. 2009. 1973~1976年四川松潘强震序列的应力触发过程.地球物理学报, 52(4):994-1003, doi:10.3969/j.issn.0001-5733.2009.04.016. http://www.geophy.cn/CN/abstract/abstract1001.shtml
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