On 23 June 2020, an Mw 7.4 earthquake struck offshore Oaxaca, Mexico, providing a unique opportunity to understand the seismogenic tectonics of the Mexican subduction zone. In this study, near‐field coseismic deformation caused by the event was retrieved from Global Positioning System (GPS) observations and Interferometric Synthetic Aperture Radar (InSAR) measurements. Given static geodetic measurements, high‐rate GPS waveforms, and teleseismic waveforms, the fault geometry and rupture process for the 2020 Oaxaca earthquake were robustly determined by nonlinear joint inversions. The main slip was located at a depth of 20–30 km with a peak slip of 3.4 m near the epicenter. The total released moment was 1.70×1020 N·m⁠, corresponding to Mw 7.4. The whole rupture process lasted 14 s, with the dominant rupture slip occurring 5–8 s after initial rupture. The mainshock rupture mostly occurred along the fault strike, covering a size of ∼55 km(along strike)×∼35 km(along dip) and totally overlapping with the 1965 Mw 7.5 rupture zone. We speculate that this 2020 earthquake is a repeat event following that in 1965. Fluid percolation under the slab may be one of the key factors affecting the seismogenic depth in the Oaxaca region.

中文翻译：

---

2020年墨西哥瓦哈卡7.4兆瓦的震源特征，根据GPS，InSAR和远震波形估算的地震

2020年6月23日，墨西哥瓦哈卡近海发生了7.4兆瓦地震，为了解墨西哥俯冲带的地震构造提供了独特的机会。在这项研究中，从全球定位系统（GPS）观测和干涉式合成孔径雷达（InSAR）测量中获取了由该事件引起的近场同震形变。在给出静态大地测量值，高速率GPS波形和远震波形的情况下，通过非线性联合反演可以可靠地确定2020年瓦哈卡地震的断层几何形状和破裂过程。主滑动位于震中中心附近，深度为20 m至30 km，峰值滑动为3.4 m。总释放力矩为1.70×1020 N·m⁠，相当于Mw 7.4。整个破裂过程持续14 s，主要破裂滑移发生在初次破裂后5-8 s。主震破裂多发生在断层走向上，覆盖范围为〜55 km（沿走向）×〜35 km（沿倾角），与1965 Mw 7.5破裂带完全重叠。我们推测这次2020年地震是继1965年之后的又一次事件。平板下的渗流可能是影响瓦哈卡州地震发生深度的关键因素之一。