Earthquake ruptures produce fault slip and kilometer-wide diffuse deformation of the host rocks. However, the origin of the diffuse deformation and its role in the rupture process are debated. We produce a refined slip model for the 2019 Ridgecrest, California, earthquakes, and analyze the relations between down-dip rupture process, and surface diffuse deformation. We show that the decrease in coseismic slip toward the ground surface, also known as shallow slip deficit (SSD), correlates with the occurrence of diffuse deformation at the surface, which is not accounted for by models assuming elastic host rocks. Hence, we suggest that a significant part of the SSD in earthquake source models could be interpreted as a proxy for shallow diffuse inelastic deformation around faults. Revisiting earthquake source models for 28 continental earthquakes, we discuss the controlling parameters of the SSD and diffuse deformation, and propose a conceptual model of the near-field coseismic surface deformation.

中文翻译：

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由弥漫性断层外变形引起的同震浅滑差


地震破裂产生断层滑移和主岩千米宽的弥散变形。然而，弥漫变形的起源及其在破裂过程中的作用存在争议。我们为 2019 年加利福尼亚州 Ridgecrest 地震制作了一个改进的滑移模型，并分析了下倾破裂过程与表面弥散变形之间的关系。我们表明，朝向地表的同震滑移减少，也称为浅滑移亏缺 （SSD），与表面弥散变形的发生相关，而假设弹性主岩的模型没有考虑到这一点。因此，我们建议地震源模型中 SSD 的很大一部分可以解释为断层周围浅层弥散非弹性变形的代理。重新审视 28 次大陆地震的震源模型，讨论了 SSD 和扩散变形的控制参数，并提出了近场同震表面变形的概念模型。