Surface deformation associated with fractures near the 2019 Ridgecrest earthquake sequence
Surface deformation associated with fractures near the 2019 Ridgecrest earthquake sequence
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DOI：
10.1126/science.abd1690
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发表时间：
2020-10
期刊：
影响因子：
56.9
通讯作者：
Xiaohua Xu;D. Sandwell;L. Ward;C. Milliner;B. Smith‐Konter;P. Fang;Y. Bock
中科院分区：
文献类型：
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作者：
Xiaohua Xu;D. Sandwell;L. Ward;C. Milliner;B. Smith‐Konter;P. Fang;Y. Bock
绘制反向运动 毫不奇怪，与地震相关的大多数变形都与断层破裂方向相同。徐等人利用卫星成像发现了与2019年里奇克莱斯特地震序列相关的、向相反方向移动的变形区域。这些区域因非弹性变形而朝此方向移动，这有助于适应该序列的整体断层破裂。由于雷达成像技术的改进，这些观测成为可能，而且可能比之前认为的更为常见。《科学》，本期第605页 里奇克莱斯特地震序列存在一些与断层破裂方向相反的变形区域。当代地震灾害模型取决于对地壳中应变如何分布的理解，以及在活动断层的广大区域精确探测毫米级变形的能力。卫星雷达观测揭示了2019年里奇克莱斯特地震序列周围数百个此前未绘制的线性应变集中区（或裂缝）。我们记录并分析了其中169条裂缝的位移和宽度。尽管大多数裂缝是沿主构造应力方向（正向）位移的，但其中大量裂缝是沿相反（反向）方向位移的。我们建立了一个模型来解释这些位移的存在和行为。一个重要的启示是，许多正向构造应变是由许多先前存在的断层上的摩擦滑动所调节的。
Mapping out backward motion Most deformation associated with an earthquake is, not surprisingly, in the same direction as the fault rupture. Xu et al. used satellite imaging to find areas of deformation associated with the 2019 Ridgecrest earthquake sequence that moved in the opposite direction. These regions moved in this direction because of inelastic deformation, which helped to accommodate the overall fault rupture for the sequence. The observations were possible because of improved radar imaging and are likely more common than previously believed. Science, this issue p. 605 The Ridgecrest earthquake sequence had regions that deformed in the opposite direction of fault rupture. Contemporary earthquake hazard models hinge on an understanding of how strain is distributed in the crust and the ability to precisely detect millimeter-scale deformation over broad regions of active faulting. Satellite radar observations revealed hundreds of previously unmapped linear strain concentrations (or fractures) surrounding the 2019 Ridgecrest earthquake sequence. We documented and analyzed displacements and widths of 169 of these fractures. Although most fractures are displaced in the direction of the prevailing tectonic stress (prograde), a large number of them are displaced in the opposite (retrograde) direction. We developed a model to explain the existence and behavior of these displacements. A major implication is that much of the prograde tectonic strain is accommodated by frictional slip on many preexisting faults.