We investigate the dynamic interactions between the Southern San Andreas Fault (SSAF) and a proximal normal fault (NF) beneath the Salton Sea in southern California. The NF, positioned near the SSAF terminus at Bombay Beach, exhibits 11–15 displacement events across 14 stratigraphic sequences, with a range of 0.2–1.4 m of vertical offset since ∼2–3 ka. Notably, four of these events may align temporally with SSAF earthquakes, raising questions about the possible interplay between the two faults. Utilizing dynamic rupture models, we analyze the coseismic interactions between the SSAF and NF, addressing under what conditions the SSAF induces slip on the NF. Our findings reveal that a suite of SSAF ruptures, particularly those propagating from north to south, can trigger slip on the normal fault and replicate observed vertical offsets. If the SSAF extends beneath the Salton Sea, earthquakes originating south of the NF intersection are less likely to trigger normal fault slip, although we cannot exclude this possibility. Some SSAF ruptures do not trigger discernible slip on the NF, rendering such events undetectable in the stratigraphic record. Our research contributes toward discussions regarding the seismic hazard in southern California, shedding light on the interplay between the SSAF and NF.

中文翻译：

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探索南圣安德烈亚斯断层与萨尔顿海下的正常断层之间的动态相互作用


我们研究了南圣安德烈亚斯断层 （SSAF） 和南加利福尼亚萨尔顿海下方的近端正常断层 （NF） 之间的动态相互作用。NF 位于孟买海滩的 SSAF 终点附近，在 14 个地层序列中展示了 11-15 次位移事件，自 ∼2-3 ka 以来的垂直偏移范围为 0.2-1.4 m。值得注意的是，其中四个事件可能在时间上与 SSAF 地震一致，这引发了对这两个断层之间可能的相互作用的质疑。利用动态破裂模型，我们分析了 SSAF 和 NF 之间的同震相互作用，解决了 SSAF 在什么条件下诱导 NF 滑移的问题。我们的研究结果表明，一组 SSAF 破裂，尤其是那些从北向南传播的破裂，可以触发正常断层上的滑移并复制观察到的垂直偏移。如果 SSAF 延伸到萨尔顿海下方，起源于 NF 交叉点以南的地震不太可能触发正常的断层滑移，尽管我们不能排除这种可能性。一些 SSAF 破裂不会触发 NF 上明显的滑移，因此在地层记录中无法检测到此类事件。我们的研究有助于讨论南加州的地震灾害，阐明 SSAF 和 NF 之间的相互作用。