Ground deformation and gravimetric monitoring at Somma-Vesuvius and in the Campanian volcanic area (Italy)

Abstract

This paper describes an integrated ground deformation and gravity network aimed at monitoring volcano-tectonic movements in the Campanian area (Southern Italy). It covers an area of more than 3000 km2, including the volcanic centres of Somma-Vesuvius, Campi Flegrei caldera and Ischia island. Levelling, EDM and gravity networks, as well as periodic and continuous GPS measurements are carried out. The aim of the network is twofold: monitoring ground deformations in the above mentioned volcanic areas, and studying the complex tectonics of the Campania Plain, a graben-like structure in which the Neapolitan volcanism is concentrated, in relation to the tectonics of the Southern Apennines and of the Tyrrhenian Basin. The monitoring network consists of larger-scale levelling, EDM and GPS networks covering the whole Campania Plain, connected to the relatively stable areas of Apennines, together with smaller scale networks aimed at accurately monitoring the Somma-Vesuvius volcano, one of the most dangerous over the World due to the high degree of urban development. The Somma-Vesuvius is monitored by levelling network, over 200 km long, by periodic EDM and GPS measurements and by a small network of continuously recording GPS receivers. Moreover, high precision gravimetry is also employed to deep the knowledge of the dynamic framework of the area. The main results indicate that Mt. Vesuvius and the island of Ischia are currently quiescent, while Campi Flegrei are subject to significant slow vertical ground movements, known as “bradyseism”. Recently, two large uplifts, both of about 1.8 m, affected the area respectively in 1970–72 and 1982–84.