During the evolution of continental rift systems, extension is thought to progressively focus in‐rift to the future breakup boundary while faults along the rift margins progressively deactivate. However, observational constraints on how strain is partitioned between rift axis and rift margins are still lacking. The Afar rift records the latest stages of rifting and incipient continental breakup. Here, we analyzed the recent M_W 5.2 earthquake on the Western Afar Margin on March 24, 2018 and the associated seismic sequence of >500 earthquakes using 24 temporary seismic stations deployed during 2017–2018. We show seismicity occurring at lower crustal depths, from ∼15 to ∼30 km, with focal mechanisms and relocated earthquakes highlighting both west‐dipping and east‐dipping normal faults. We tested earthquake depth using InSAR by processing six independent interferograms using Sentinel‐1 data acquired from both ascending and descending tracks. None of them shows evidence of surface deformation. We tested possible ranges of depth by producing forward models for a fault located at progressively increasing depths. Models show that surface deformation is not significant for fault slip at depths greater than 15 km, in agreement with the hypocentral depth of 19 km derived from seismic data for the largest earthquake. Due to the localized nature of deep earthquakes near hot springs coupled with subsurface evidence for magmatism, we favor an interpretation of seismicity induced by migrating fluids such as magma or CO₂. We suggest that deep fluid migration can occur at the rifted‐margin influencing seismicity during incipient continental rupture.

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2018年3月沿阿法尔河西缘发生的下地壳地震

在大陆裂谷系统的演化过程中，扩展被认为是将裂谷逐渐集中在未来的破裂边界上，而沿裂谷边缘的断层则逐渐失活。但是，仍然缺乏关于应变如何在裂谷轴和裂谷边缘之间分配的观测约束。阿法尔裂谷记录了裂谷和大陆初始破裂的最新阶段。在这里，我们分析了最近的M _W2018年3月24日发生在西阿法尔边缘的5.2级地震，以及使用2017-2018年期间部署的24个临时地震台站的相关地震序列，> 500次地震。我们显示出地震活动发生在地壳深度较低（从15到30 km）处，震源机制和重新定位的地震都突出了西向和东向的正断层。我们使用InSAR通过使用从上升和下降轨道获取的Sentinel-1数据处理六个独立的干涉图来测试地震深度。它们均未显示表面变形的迹象。通过为深度逐渐增加的断层生成正演模型，我们测试了可能的深度范围。模型表明，对于深度大于15 km的断层滑动，表面变形并不明显，与最大地震的地震数据得出的19 km的震中深度一致。由于温泉附近的深层地震的局部性质以及地下岩浆作用的证据，我们倾向于解释由岩浆或一氧化碳等流体迁移引起的地震活动。₂。我们认为，在初始大陆性破裂过程中，深部流体运移可能发生在裂隙边缘，影响地震活动性。