On 23 June 2020, a large (⁠Mw 7.4) interplate thrust earthquake struck near the town of La Crucecita in the state of Oaxaca in southern Mexico, following a 55‐yr interseismic period. A seismic source model is well constrained by teleseismic waveforms, static Global Positioning System offsets, and tsunami data, suggesting that the earthquake occurred on the slab interface at a dip of ∼23°⁠, with a narrow elliptical asperity concentrating around a shallow depth of ∼20 km⁠. The rupture propagates bilaterally from the hypocenter, and the down‐dip rupture is restricted to ∼25 km by slow slip events (SSEs). The down‐dip shear stress is released by SSEs during the interseismic period, limiting the earthquake magnitude and possibly resulting in the characteristic earthquake. The 2020 La Crucecita event, thus, is a good reminder to assess the seismic and tsunami potential in this region. The stress changes caused by the coseismic slip of the 2017 Mw 8.2 Chiapas earthquake are too small to trigger the 2020 La Crucecita earthquake. However, combined with the postseismic afterslip effects that play a leading role, it greatly promotes the eventual occurrence of the La Crucecita event. The results demonstrate the importance of considering postseismic afterslip, when evaluating seismic hazard and its migratory pattern.

中文翻译：

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2020 Mw 7.4拉克鲁塞奇塔的狭窄破裂，墨西哥，地震

2020年6月23日，在经历了55年的间震时期之后，墨西哥南部瓦哈卡州的La Crucecita镇附近发生了一次大的板间推力地震（Mw 7.4）。地震震源模型受到远震波形，静态全球定位系统偏移和海啸数据的很好约束，这表明地震发生在平板界面上，倾角约为23°⁠，窄椭圆形凹凸集中在浅水深处。约20公里。破裂从震源向两侧传播，而下倾破裂被慢滑事件（SSE）限制在约25 km。地震期间，SSE释放下倾切应力，从而限制了地震幅度，并可能导致特征地震。因此，2020年La Crucecita活动 很好地提醒您评估该地区的地震和海啸潜力。由2017年Mw 8.2恰帕斯州地震引起的同震滑动引起的应力变化太小，无法触发2020年La Crucecita地震。但是，结合起主导作用的后地震后滑效应，它极大地促进了La Crucecita事件的最终发生。结果表明，在评估地震危险及其迁移模式时，考虑地震后滑移的重要性。