Localized fault-zone dilatancy and surface inelasticity of the 2019 Ridgecrest earthquakes
Localized fault-zone dilatancy and surface inelasticity of the 2019 Ridgecrest earthquakes
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DOI：
10.1038/s41561-020-0628-8
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发表时间：
2020-09-07
影响因子：
18.3
通讯作者：
Hollingsworth, James
中科院分区：
文献类型：
--
作者：
Barnhart, William D.;Gold, Ryan D.;Hollingsworth, James
地震产生一系列弹性和非弹性变形过程，这些过程在不同的长度和时间尺度上得到反映。虽然弹性长期以来一直主导着活动构造的研究假设，但人们越来越关注地震的非弹性特征，特别是地表断层破裂带本身的非弹性特征，以及它们与地面破裂危险和破坏带力学的关系。在这里，我们提供了2019年加州里奇克雷斯特地震的详细同震地表应变分析。我们从卫星光学图像中获得三维高分辨率的地表位移，然后反演同震地表应变张量。我们发现，在这些地震中，断层带扩张是普遍存在的，非弹性破坏是存在的，但相对局部化（中值宽度为31米）。非弹性破坏带的宽度与断层外变形、地表地质或位移大小无关。相反，非弹性破坏的程度和运动学反映了断裂破坏带的活动糜棱岩变形，这种变形受断裂速度和断裂成熟度的影响。这些结果强调了单次地震如何对断层的长期永久地质记录做出贡献。根据对卫星图像得出的地表位移的分析，2019年里奇克雷斯特地震的非弹性破坏是局部的，并受到断层破坏带的糜棱岩变形的影响。
Earthquakes produce a spectrum of elastic and inelastic deformation processes that are reflected across various length and time scales. While elasticity has long dominated research assumptions in active tectonics, increasing interest has focused on the inelastic characteristics of earthquakes, particularly those of the surface fault rupture zone itself, and how they relate to ground rupture hazard and the mechanics of damage zones. Here we present detailed co-seismic surface-strain analysis of the 2019 Ridgecrest, California, earthquakes. We derive three-dimensional high-resolution surface displacements from satellite optical imagery, which we then invert for the co-seismic surface-strain tensors. We show that fault-zone dilation is pervasive throughout these earthquakes and that inelastic failure is present but relatively localized (median width of 31 m). The width of the inelastic failure zone is not correlated to off-fault deformation, surface geology or displacement magnitude. Instead, the extent and kinematics of inelastic failure reflect active, mylonitic deformation of the fault damage zone that is influenced by rupture velocity and fault maturity. These results highlight how a single earthquake contributes to the long-term, permanent geologic record of faulting.Inelastic failure in the 2019 Ridgecrest earthquakes was localized and influenced by mylonitic deformation of the fault damage zone, according to an analysis of surface displacements derived from satellite images.