The Contribution of Underwater Systems for the Study of the Emerged Volcanoes and Seamounts of Southern Italy

This chapter examines the signals collected by multidisciplinary seafloor observatories and subsea instruments in Southern Tyrrhenian region. It provides an overview of the systems, emphasizing the key characteristics of the sensors. Various types of signals (such as seismological, magnetic, deformation, and oceanographic data), detected underwater and related to onshore and offshore volcanic structures, are analysed and compared, where possible, with data from land-based stations. The focus is on several case studies from Southern Italy, a region of high geological activity, and tectonic and volcanic features. This area includes two of the world's most active volcanoes, Mt. Etna and Stromboli, as well as the Marsili Seamount, the largest volcanic seamount in the Tyrrhenian Sea bathyal plain. Although extensive research has been conducted on Mt. Etna and Stromboli, the functioning of their deepest and submerged parts, as well as the nature and evolution of their activity, remains incomplete. This is also particularly true for volcanic seamounts like Marsili. Seafloor instrumentation, including Ocean Bottom Seismometers and Hydrophones (OBSHs), and multiparametric seafloor observatories play a crucial role in monitoring volcanic activity contributing significantly to understanding of volcanic behaviour and its temporal evolution. Additionally, swath bathymetry data aid in visualizing tectonic and volcanic structures.