Geodetic and Seismic Observations of the 2025 Intrusion Event at Fernandina Volcano, Galapagos Islands

The most recent eruption of Fernandina volcano in the Galapagos Islands took place in March 2024. Subsequently, during the latter part of 2024 and the first half of 2025, the volcano showed clear signs of edifice inflation, as informed by geodetic InSAR and GPS data. The InSAR analysis allowed us to identify changes in deformation patterns and localized accelerations, mainly in areas near the caldera and its interior. Finally, on November 17, 2025, IGEPN seismic stations registered a swarm of volcano-tectonic (VT) earthquakes on Fernandina’s northern flank, beginning with a 4.4 (MLv) earthquake. GPS stations showed co-seismic displacements, accompanied by significant deformation, also observed by InSAR (TerraSAR-X & Sentinel-1). Despite this sequence of signals, the seismic activity — 106 VTs located beneath the edifice —did not culminate in an eruption, as there were no lava flows nor detectable gases emitted to the surface. The inflationary pattern has diminished, but we remain attentive to further activity that could portend a future eruption, especially if there are MLv 4-5 VT events beneath the edifice. On previous occasions, these larger earthquakes have heralded an imminent eruption. Our next step is to model geodetic data to obtain a source model and its depth. While Fernandina Island is uninhabited, frequent tourist vessels pass by the shoreline to observe Galapagos wildlife and to observe lava flows entering the sea, as was the case in March 2024.