Lower Crustal Earthquakes in the March 2018 Sequence Along the Western Margin of Afar

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