Simple shear origin of the cross-faults ruptured in the 2019 Ridgecrest earthquake sequence
Simple shear origin of the cross-faults ruptured in the 2019 Ridgecrest earthquake sequence
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DOI：
10.1038/s41561-021-00758-5
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发表时间：
2021-06-03
影响因子：
18.3
通讯作者：
Jin, Zeyu
中科院分区：
文献类型：
--
作者：
Fialko, Yuri;Jin, Zeyu
构造活动区域中越来越多的观察结果揭示了一组高角度的共轭断层（“交叉构造”），这些断层显然与基于实验数据的故障理论相矛盾。可能的解释包括原位摩擦的原位系数，下地壳中延性剪切带的主要控制以及构造旋转。在地震深度的压力，变形历史和断层几何形状的状态下，这些机制之间的歧视受到了阻碍。在这里，我们结合了地震，地球和地质数据，以证明Ridgecrest（加利福尼亚州）区域中无处不在的横断型，包括2019年强烈地震序列破裂的区域，这是由于最初与实验数据一致的最佳优化方向而旋转的。可以通过大地测量的速度场来解释推断的旋转模式。我们的模型表明，在加利福尼亚东部剪切带中观察到的断层不对称旋转可能是由简单的剪切而产生的。相同的机制可以负责在其他构造环境中观察到的高角度共轭断层。根据2019年RIDGECREST序列与区域地质数据结合的2019 RIDGECREST序列的变形分析，加州东部剪切区的断层旋转可能是由简单剪切造成的。
Observations in tectonically active areas increasingly reveal sets of high-angle conjugate faults ('cross-faults') that apparently contradict theories of faulting based on experimental data. Possible explanations include a low in situ coefficient of friction, dominant control of ductile shear zones in the lower crust, and tectonic rotation. Discrimination between these mechanisms has been hindered by uncertainties in the state of stress, deformation history and fault geometry at seismogenic depths. Here we use a combination of seismic, geodetic and geologic data to demonstrate that ubiquitous cross-faults in the Ridgecrest (California) area, including those ruptured in the sequence of strong earthquakes in 2019, result from rotation from an initially optimal orientation consistent with experimental data. The inferred rotation pattern can be explained by the geodetically measured velocity field. Our model suggests that the observed asymmetric rotation of faults in the Eastern California Shear Zone can result from simple shear. The same mechanism can be responsible for high-angle conjugate faults observed in other tectonic settings.Asymmetric rotation of faults in the Eastern California Shear Zone may result from simple shear, according to an analysis of deformation in the area of the 2019 Ridgecrest earthquake sequence in combination with regional geological data.