Interferometric Analysis of Ground Deformation and Seismic Activity Associated with 2017 Ischia Earthquake

Volcanic islands, such as Ischia (Naples, Italy), are prone to ground displacement and slope instability due to their unique morphology. Dominated by Mt. Epomeo (787 m a.s.l.), the island’s deformation was analyzed using 143 Sentinel-1A acquisitions processed with PyGMTSAR. From January 2015 to December 2019, the Small Baseline Subset (SBAS) technique produced a 1D LOS velocity map, ranging from 30.79 to -24.75 mm/year, and corresponding displacement time series. The northwestern and eastern slopes of Mt. Epomeo exhibited maximum displacements of -128 mm and -134 mm, respectively. The highest deformation was observed in northern Ischia. Additionally, the seismic swarm linked to the M<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">w</inf> 3.9 earthquake on August 21, 2017, correlated with a sudden subsidence near the epicenter, followed by a gradual return to pre-earthquake levels, indicating an acceleration in ground displacement after the mainshock.