Magmatic Intrusion of the Fentale–Dofen Rift Valley, Ethiopia, during 2024–2025 Observed by Sentinel-1 InSAR and Multi-Source Inversion

초록

In late 2024, an unprecedented, large-scale dike intrusion occurred within the Fentale-Dofen volcanic segment in the northern Main Ethiopian Rift (MER), triggering the evacuation of approximately 75,000 residents. Differential Interferometric Synthetic Aperture Radar (DInSAR) time-series datasets using Sentinel-1 ascending and descending orbit data from 5 December 2024 to 27 February 2025 were converted into the horizontal (east-west) and vertical (up-down) components of surface deformation. The cumulative magma intrusion along the dike with a 20-degree strike and a near-vertical dip caused surface uplift up to 1,301 ± 57 mm on the western side of the dike and 1,222 ± 57 mm on the eastern side. The surface horizontally diverged by 2,956 ± 72 mm westward on the western side of the dike and 2,474 ± 72 mm eastward on the eastern side. The Fentale volcano, located on the southern edge of the Fentale-Dofen dike, seemed to experience magma withdrawal. The volcano surface subsided by 1,889 ± 57 mm and horizontally contracted by 1,429 ± 72 mm eastward on the western flank of the volcano and 1,416 ± 72 mm westward on the eastern flank. A multi-source modeling combining a uniform rectangular Okada dike model and a spherical Mogi magma chamber model was performed via Geodetic Bayesian Inversion Software (GBIS). The cumulative volume of the magma intrusion of the dike was calculated to be 1.46 km³, whereas the cumulative volume of the magma withdrawal of Fentale volcano was found to be 0.098 km³, implying both the connection of the dike and volcano and the potential existence of an independent deep magmatic supply source for the dike. This study demonstrates that the integration of ascending and descending DInSAR observations and GBIS-based Bayesian multi-source inversion provides an effective approach for the precise monitoring of subsurface magmatic processes and crustal deformation mechanisms. Copyright © 2026 Korean Society of Remote Sensing. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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