Characterization of Crustal Deformation During the May 2021 Nyiragongo Eruption Using InSAR and GNSS Data

Abstract We analyze Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS) data to characterize ground deformation and dike opening associated with the May 2021 Nyiragongo eruption. Despite documented eruptions in 1977 and 2002, Nyiragongo's magmatic system and its interaction with regional rifting remain poorly understood. Here, we use Sentinel‐1 (ESA Copernicus) and ALOS‐2 (JAXA) InSAR data and GNSS observations from the KivuGNet network, that cover the period of the eruption and dike intrusion. Deformation is dominated by a co‐eruptive dike intrusion extending over 25 km, accompanied by ground fissures of about 1.5 m opening in Goma (Democratic Republic of Congo) and Gisenyi (Rwanda). Joint inversions of four interferograms with GNSS data resolved a maximum dike opening near 10 m and a volumetric increase of about 180 Mm 3 . The inferred dike geometry aligns with observed ground deformation and seismicity, underscoring the coupling between magmatic and tectonic processes.