Source modelling of the 2015 Wolf volcano (Galápagos) eruption inferred from Sentinel 1-A DInSAR deformation maps and pre-eruptive ENVISAT time series

We investigate the surface deformation of the May-July 2015 Wolf volcano (Galápagos) eruption, retrieved through space-borne differential synthetic aperture radar interferometry (DInSAR) measurements. To do this, we first examine the ENVISAT SAR acquisitions which imaged the volcano during the 2004-2010 time period, in order to retrieve the pre-eruptive deformations through the Small BAseline Subset (SBAS) DInSAR approach. These measurements allow us to focus on the recent volcano dynamics and to constrain the geometry and characteristics of the main deformation source. In particular, our analytic modelling results suggest that a sill-like source, 2.5 km long, 2.0 km wide and located at depth of about 1.5 km from the caldera floor, fits the observed uplift and E-W pattern, in good agreement with other studies that highlight the existence of a flat-topped shallow source. Subsequently, by considering that the main source maintains similar geometrical and kinematical characteristics over time, we analyse the deformation patterns related to the 2015 eruption. In this case, we invert two Sentinel 1-A DInSAR maps encompassing the May-July 2015 eruption. The observed deformation can be attributed to a magmatic system with pressure change in a single shallow magma body (sill-like source), and the formation of a circumferential dike feeding the eruptive fissure on the SE rim of the summit caldera. This work provides new insights on the caldera dynamics of Wolf volcano and confirms the importance of remote sensing data to improve our knowledge of remote volcanic areas.