We develop finite element models of the coseismic displacement field accounting for the 3D elastic structures surrounding the epicentral area of the 2019 Ridgecrest earthquake sequence containing two major events of M_w7.1 and M_w6.4. The coseismic slip distribution is inferred from the surface displacement field recorded by interferometric synthetic aperture radar. The rupture dip geometry is further optimized using a novel nonlinear-crossover-linear inversion approach. It is found that accounting for elastic heterogeneity and fault along-strike curvilinearity improves the fit to the observed displacement field and yields a more accurate estimate of geodetic moment and Coulomb stress changes. We observe spatial correlations among the locations of aftershocks and patches of high slip, and rock anomalous elastic properties, suggesting that the shallow crust's elastic structures possibly controlled the Ridgecrest earthquake sequence. Most of the coseismic slip with a peak slip of 7.4 m at 3.6 km depth occurred above a zone of reduced S-wave velocity and significant post-M_w7.1 afterslip. This implies that viscous materials or fluid presence might have contributed to the low rupture velocity of the mainshock. Moreover, the zone of high slip on the northwest-trending fault segment is laterally bounded by two aftershock clusters, whose location is characterized by intermediate rock rigidity. Notably, some minor orthogonal faults consistently end above a subsurface rigid body. Overall, these observations of structural controls improve our understandings of the seismogenesis within incipient fault systems.

中文翻译：

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通过 3D 速度结构的高保真弹性模型研究 2019 年 Ridgecrest 地震序列的结构控制

我们开发了同震位移场的有限元模型，用于解释 2019 年 Ridgecrest 地震序列震中区周围的 3D 弹性结构，其中包含 M _w 7.1 和 M _w两个主要事件6.4. 从干涉合成孔径雷达记录的地表位移场推断同震滑动分布。使用新的非线性交叉线性反演方法进一步优化破裂倾角几何形状。结果表明，考虑到弹性非均质性和断层沿走向曲线，可以改进对观测位移场的拟合，并可以更准确地估计大地力矩和库仑应力变化。我们观察到余震位置和高滑动斑块与岩石异常弹性特性之间的空间相关性，表明浅地壳的弹性结构可能控制了里奇克莱斯特地震序列。大多数在 3.6 km 深度具有 7.4 m 峰值滑移的同震滑移发生在S减少的区域之上- 波速和显着的后 M _w 7.1 后滑。这意味着粘性物质或流体的存在可能导致主震的低破裂速度。此外，西北向断层段上的高滑移带横向以两个余震群为界，其位置具有中等岩石刚度的特点。值得注意的是，一些小的正交断层始终在地下刚体上方结束。总体而言，这些对结构控制的观察提高了我们对初始断层系统内地震发生的理解。