A shallow‐dipping dike fed the 1995 flank eruption at Fernandina Volcano, Galápagos, observed by satellite radar interferometry

Satellite radar interferometry data reveal strong localized uplift in a semi‐ circular pattern on the southwest flank of Fernandina volcano, Galápagos, where an eruption took place in January to April, 1995. The observations show a maximum decrease in radar range of 0.75 m, and they are consistent with a model of a shallow‐dipping dike intrusion feeding this fissure eruption. We solve for the best‐fit single rectangular dislocation dike source using non‐linear inversion techniques where simulated annealing searching algorithm is used to avoid local minima. The best‐fit dike is 3.8 km long, 2.3 km high, 0.86 m thick and with a 34° dip. The total dike volume (7.5 × 10 −3 km³) is ∼40% of the volume of extrusive materials estimated to have been produced during the eruption. The data do not permit a sub‐vertical dike, implying that the least principal stress direction is not horizontal as is usually assumed.