美国圣地亚哥州立大学 Hill, Ryley G.及其研究组报道了受湖泊填充事件调控的主要的南圣安地列斯地震。相关论文于2023年6月7日发表在《自然》杂志上。

研究人员使用新的地质和古地震数据，来证明南圣安地列斯断层在过去的六次大地震可能发生在Cahuilla湖的高水位期间。为了研究可能的因果关系，研究人员计算了因湖平面变化引起的随时间变化的库伦应力的变化。使用粘弹性地幔上的多孔弹性地壳的完全耦合模型，研究发现水文荷载将南圣安地列斯断层上的库伦应力增加了数百千帕，断层应力率增加了两倍以上，这可能足以引发地震。

非垂直断层倾角，断层破坏带和侧向孔隙压力扩散的存在，增强了湖泊淹没的不稳定效应。研究模型可能适用于其他地区，那些地区的水文负荷，无论是自然的还是人为的，都与大量的地震活动有关。

据介绍，水文负载可以刺激地壳的地震活动。然而，引发大地震的证据仍然难以捉摸。南加州的南圣安地列斯断层(SSAF)位于索尔顿海附近，索尔顿海是古老的Cahuilla湖的遗迹，在过去的几千年中，该湖周期性地充满和干燥。

附：英文原文

Title: Major southern San Andreas earthquakes modulated by lake-filling events

Author: Hill, Ryley G., Weingarten, Matthew, Rockwell, Thomas K., Fialko, Yuri

Issue&Volume: 2023-06-07

Abstract: Hydrologic loads can stimulate seismicity in the Earth’s crust. However, evidence for the triggering of large earthquakes remains elusive. The southern San Andreas Fault (SSAF) in Southern California lies next to the Salton Sea, a remnant of ancient Lake Cahuilla that periodically filled and desiccated over the past millennium. Here we use new geologic and palaeoseismic data to demonstrate that the past six major earthquakes on the SSAF probably occurred during highstands of Lake Cahuilla. To investigate possible causal relationships, we computed time-dependent Coulomb stress changes due to variations in the lake level. Using a fully coupled model of a poroelastic crust overlying a viscoelastic mantle, we find that hydrologic loads increased Coulomb stress on the SSAF by several hundred kilopascals and fault-stressing rates by more than a factor of 2, which is probably sufficient for earthquake triggering. The destabilizing effects of lake inundation are enhanced by a nonvertical fault dip, the presence of a fault damage zone and lateral pore-pressure diffusion. Our model may be applicable to other regions in which hydrologic loading, either natural or anthropogenic, was associated with substantial seismicity.

DOI: 10.1038/s41586-023-06058-9

Source: https://www.nature.com/articles/s41586-023-06058-9