Co- and Early Postseismic Deformation Due to the 2019 Ridgecrest Earthquake Sequence Constrained by Sentinel-1 and COSMO-SkyMed SAR Data
Co- and Early Postseismic Deformation Due to the 2019 Ridgecrest Earthquake Sequence Constrained by Sentinel-1 and COSMO-SkyMed SAR Data
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DOI：
10.1785/0220190299
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发表时间：
2020-02
影响因子：
3.3
通讯作者：
Kang Wang;R. Bürgmann
中科院分区：
文献类型：
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作者：
Kang Wang;R. Bürgmann
2019 年里奇克莱斯特地震序列导致了南加州莫哈韦沙漠以北广阔的东加州剪切带的一系列共轭断层破裂。地震周围全球导航卫星系统（GNSS）站的平均间距为20-30公里，不足以约束地震的破裂细节。在这里，我们使用 Sentinel-1 和 COSMO-SkyMed (CSK) 合成孔径雷达数据来导出与 Ridgecrest 地震序列相关的高分辨率同震和早期震后表面变形。从 Sentinel-1 和 CSK 数据得出的视距 (LoS) 干涉合成孔径雷达位移与 GNSS 测量结果非常吻合。最大同震位移发生在 Mw 7.1 震中附近，估计断层偏移约为 4.5 m，位于西北走向的断裂处。 CSK 数据的像素跟踪分析还显示，Mw 6.4 前震可能在第二个西北走向的断层带上出现约 1 m 的急剧表面偏移，该断层带位于主破裂以东约 2-3 公里处。在 Mw 6.4 事件期间，该断层段缺乏明显的表面位移，这表明该断层可能已破裂两次，并且在 Mw 7.1 主震期间发生了更明显和更浅的滑动。 Sentinel-1 和 CSK 数据都揭示了 2019 年 Ridgecrest 地震序列后明显的震后变形。主震约 2 个月后，Mw 7.1 震中附近的累积震后形变沿卫星视距达到约 5 厘米。观察到的断层附近的震后变形表明了后滑和孔隙弹性回弹。我们以各种数据格式提供本研究中得出的数据，这对于研究该地震序列的广大社区很有用。
The 2019 Ridgecrest earthquake sequence ruptured a series of conjugate faults in the broad eastern California shear zone, north of the Mojave Desert in southern California. The average spacing between Global Navigation Satellite System (GNSS) stations around the earthquakes is 20–30 km, insufficient to constrain the rupture details of the earthquakes. Here, we use Sentinel-1 and COSMO-SkyMed (CSK) Synthetic Aperture Radar data to derive the high-resolution coseismic and early postseismic surface deformation related to the Ridgecrest earthquake sequence. Line of sight (LoS) Interferometric Synthetic Aperture Radar displacements derived from both Sentinel-1 and CSK data are in good agreement with GNSS measurements. The maximum coseismic displacement occurs near the Mw 7.1 epicenter, with an estimated fault offset of ∼4.5 m on a northwest-striking rupture. Pixel tracking analysis of CSK data also reveals a sharp surface offset of ∼1 m on a second northwest-striking fault strand on which the Mw 6.4 foreshock likely nucleated, which is located ∼2–3 km east of the major rupture. The lack of clear surface displacement across this fault segment during the Mw 6.4 event suggests this fault might have ruptured twice, with more pronounced and shallow slip during the Mw 7.1 mainshock. Both Sentinel-1 and CSK data reveal clear postseismic deformation following the 2019 Ridgecrest earthquake sequence. Cumulative postseismic deformation near the Mw 7.1 epicenter ∼2 months after the mainshock reaches ∼5 cm along the satellites’ LoSs. The observed postseismic deformation near the fault is indicative of both afterslip and poroelastic rebound. We provide data derived in this study in various data formats, which will be useful for the broad community studying this earthquake sequence.