InSAR measurements of ground deformations at Ischia island (Naples, Italy) along two decades dataset

Ground deformation at volcanic areas is mainly driven by the interaction between lithology, morphology, seismology and volcanism. In the latest decades, radar interferometry has contributed to understand the volcanic dynamics through the measurement of ground deformations. This work focuses on the displacement analysis at Ischia, an active volcanic island located at the north-western end of the Gulf of Naples and characterized by a long eruptive and seismic history. The central portion of the island is dominated by Mt. Epomeo, a volcano-tectonic horst formed by caldera resurgence, tilted southward and bordered by a system of faults and fractures which represent the preferred degassing pathway of the hydrothermal system beneath the island. Seismicity is mainly concentrated in the northern area and the most recent and severe seismic sequence started with the Mw 3.9 earthquake on August 21^st 2017 producing several damages and also victims. In this study, the investigation of surface displacement was carried out over a continuous time interval of about 17 years by using Synthetic Aperture Radar (SAR) dataset with different temporal and spatial resolutions. The Small Baseline Subset interferometric technique was applied to the dataset allowing the identification of the areas more potentially prone to trigger slope instability phenomena. The resulting ground displacement maps identified the highest deformations along the north-western, western and southern slopes of Mt. Epomeo and were validated by using GPS data acquired by local geodetic network. Mean velocity maps obtained from C-band Envisat and Sentinel-1 and X-band COSMO-SkyMed SAR data will be presented together with the ground deformation effects caused by the 2017 seismic swarm.