The recent 2019 Ridgecrest earthquake sequence in southern California jostled the seismological community by revealing a complex and cascading foreshock series that culminated in a Mw 7.1 mainshock. But the central Garlock fault, despite being located immediately south of this sequence, did not coseismically fail. Instead, the Garlock fault underwent postseismic creep and exhibited a sizeable earthquake swarm. The dynamic details of the rupture process during the mainshock are largely unknown, as is the amount of stress needed to bring the Garlock fault to failure. We present an integrated view of how stresses changed on the Garlock fault during and after the mainshock using a combination of tools including kinematic slip inversion, Coulomb stress change (⁠ΔCFS⁠), and dynamic rupture modeling. We show that positive ΔCFSs cannot easily explain observed aftershock patterns on the Garlock fault but are consistent with where creep was documented on the central Garlock fault section. Our dynamic model is able to reproduce the main slip asperities and kinematically estimated rupture speeds (⁠≤2 km/s⁠) during the mainshock, and suggests the temporal changes in normal and shear stress on the Garlock fault were the greatest near the end of rupture. The largest static and dynamic stress changes on the Garlock fault we observe from our models coincide with the creeping region, suggesting that positive stress perturbations could have caused this during or after the mainshock rupture. This analysis of near‐field stress‐change evolution gives insight into how the Ridgecrest sequence influenced the local stress field of the northernmost eastern California shear zone.

中文翻译：

---

2019年Ridgecrest地震序列期间和之后Garlock断层的应力变化

最近的2019年南加州里奇克莱斯特（Ridgecrest）地震序列揭示了一个复杂且级联的前震系列，最终导致Mw 7.1主震，震撼了地震学界。但是，尽管加洛克中央断裂位于该层序的正南，但并未因地震而失败。取而代之的是，加洛克断裂经历了地震后的蠕变，并表现出相当大的地震群。主震期间破裂过程的动态细节以及将Garlock断层破坏所需的应力量尚不清楚。我们使用运动滑动反演，库仑应力变化（ΔCFS⁠）和动态破裂建模等工具的组合，对主震期间和之后Garlock断层的应力变化进行了综合介绍。我们表明，正ΔCFS不能轻易解释Garlock断层上观察到的余震模式，但与记录在Garlock中央断层上的蠕变位置一致。我们的动力学模型能够重现主震过程中的主要滑动不平度和运动学估计的破裂速度（⁠≤2km /s⁠），并表明Garlock断层的法向应力和剪应力的时间变化最大。破裂。我们从模型中观察到的Garlock断层上最大的静态和动态应力变化与蠕变区域相吻合，表明正应力扰动可能是在主冲击破裂期间或之后引起的。