Coseismic Displacements and Surface Fractures from Sentinel-1 InSAR: 2019 Ridgecrest Earthquakes
Coseismic Displacements and Surface Fractures from Sentinel-1 InSAR: 2019 Ridgecrest Earthquakes
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DOI：
10.1785/0220190275
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发表时间：
2020-07-01
影响因子：
3.3
通讯作者：
Smith-Konter, Bridget
中科院分区：
文献类型：
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作者：
Xu, Xiaohua;Sandwell, David T.;Smith-Konter, Bridget
干涉合成孔径雷达是大陆大地震地表形变成像的重要工具。在这里，我们使用多个Sentinel-1图像展示了2019年里奇克莱斯特地震的同震位移和应变图。我们提供三种类型的干涉测量产品。(1)两个观测方向的标准干涉图提供了变形概况，可用于模拟同震滑动。(2)同震干涉图叠加的相位梯度图提供了高分辨率（类似于30米）的应变浓度和地面压裂图像，可用于指导现场调查。(3)高通滤波、叠加、解包裹相位分解为东西分量、上下分量、南北分量，用于确定断层滑动感。所得到的相位梯度图显示了300多条地表裂缝，包括Garlock断层的触发滑动。高通滤波相位的东西分量揭示了许多裂缝的走滑偏移极性（右侧或左侧）。我们发现少数裂缝具有逆背景构造应力的滑移极性。这与1999年M-w 7.1赫克托矿井破裂附近观测到的逆行滑动类似，但山脊观测的图像更完整，因为来自双哨兵1号航天器的频繁和高质量的采集。确定逆行特征是由现有断层的滑动触发的，还是由脊峰地震的应力变化引起的顺应性断层变形触发的，或者是新的库仑式断层，将需要额外的现场工作、建模和分析。
Interferometric Synthetic Aperture Radar is an important tool for imaging surface deformation from large continental earthquakes. Here, we present maps of coseismic displacement and strain from the 2019 Ridgecrest earthquakes using multiple Sentinel-1 images. We provide three types of interferometric products. (1) Standard interferograms from two look directions provide an overview of the deformation and can be used for modeling coseismic slip. (2) Phase gradient maps from stacks of coseismic interferograms provide high-resolution (similar to 30 m) images of strain concentration and surface fracturing that can be used to guide field surveys. (3) High-pass filtered, stacked, unwrapped phase is decomposed into east-west and up-down, south-north components and is used to determine the sense of fault slip. The resulting phase gradient maps reveal over 300 surface fractures, including triggered slip on the Garlock fault. The eastwest component of high-pass filtered phase reveals the polarity of the strike-slip offset (right lateral or left lateral) for many of the fractures. We find a small number of fractures that have slip polarity that is retrograde to the background tectonic stress. This is similar to observations of retrograde slip observed near the 1999 M-w 7.1 Hector Mine rupture, but the Ridgecrest observations are more completely imaged by the frequent and high-quality acquisitions from the twin Sentinel-1 spacecrafts. Determining whether the retrograde features are triggered slip on existing faults, or compliant fault deformation in response to stress changes from the Ridgecrest earthquakes, or new Coulombstyle failures, will require additional field work, modeling, and analysis.