Morphological and structural analysis of the Ustica Island offshore (Southern Tyrrhenian Sea) for the definition of the marine geological hazard

This paper presents the first study of the entire surface of the Ustica Island volcanic systems. This volcanic complex is located on the boundary between the Kabilian-Calabrian chain and the Sicilian-Maghrebian domain, 58 km north-northeast off the Sicily coast. Elliptical in shape (4,5 km × 2,7 km), with a slight SW-NE orientation, the island rises to 248 m a.s.l from the adjacent sea floor, deeper more than 2000 m. In the frame of the MAGIC Project, the interpretation of detailed morphological and high resolution seismic data provides a new image of the marine morphology and structural setting of the Ustica offshore (Southern Tyrrhenian) with the aim to individuate the geological hazard elements. Different types of submarine features have been identified, including a narrow coastal shelf, debris avalanches and volcanoclastic sedimentary deposits, erosion canyons, volcanic constructions and seamounts. This study suggests that the large scale and frequency of failure events has to be taken into considerations when assessing geological hazards from landslide-generates tsunami.