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Dike propagation and surface faulting around Fentale Volcanic Complex, Northern Main Ethiopian Rift

Lin Way 1, Timothy Davis1, Weiyu Zheng1, Juliet Biggs1, Sam Wimpenny1, Milan Lazecky2, Tim Wright2

  • Affiliations: 1School of Earth Sciences, University of Bristol, United Kingdom; 2School of Earth and Environment, University of Leeds, United Kingdom

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 180

  • Programme No: 1.8.11

  • Theme 1 > Session 8

Abstract

Extensional stresses favour dike intrusions, posing significant hazards to local populations. However, geodetic measurements of active dike intrusions in thick continental crust are relatively rare. A dike intrusion in 2015, and more recently in 2024--2025, occurred northeast of Fentale in the Main Ethiopian Rift. Unusually, both intrusions opened over several weeks, suggesting a different rheology to the basaltic dike intrusions in Afar and Iceland. We present new, high-resolution COSMO-SkyMed and Sentinel-1 InSAR timeseries of the September-October 2024 dike intrusion. A preliminary kinematic model suggests that the InSAR displacement patterns can be explained by a ~7 km long dike with a maximum opening of ~2 m at ~5 km depth. The dike opening was accompanied by graben subsidence of at least 20 cm accommodated by multiple surface-rupturing normal faults. To investigate the mechanical relationship between dike opening and fault slip, we constructed a boundary element model featuring frictional fault surfaces within an extensional stress regime, where the faults are primed for slip. We then introduce a pressurized dike, which induces normal-sense slip along the faults. We show that fault slip occurred above the dike rather than ahead of it. Our high-resolution data provides new constraints on dike behaviour, contributing to a broader understanding of fault-dike interactions in active rift settings. Further work will investigate the role of tectonic stresses, magma overpressure and topographic load on the dike sequence, looking to forecast the location of the next dike and if it will lead to eruption. Activity is ongoing in 2025.