Seismic Surveillance of Active Volcanoes: The Osservatorio Vesuviano Seismic Network (OVSN, Southern Italy)

Abstract

Since 1970 the Osservatorio Vesuviano (Vesuvius Observatory) of Naples, Italy has maintained local seismic networks to monitor the active volcanoes of the Neapolitan area (Vesuvio, Campi Flegrei, Ischia Island) as well as the most active seismic zone of the Campania region and Southern Apennines. During 2000–2001 the local seismic networks in the volcanic regions and the regional network were restructured and unified to form the Osservatorio Vesuviano Seismic Network (OVSN) with the purpose of improving the quality of the recorded data and the consistency of data processing. The Campania region has suffered many catastrophic volcanic events, including the A.D. 79 eruption of Vesuvio, and many damaging earthquakes, such as the 1980 magnitude 6.8 Irpinia earthquake. Moreover, seismovolcanic activity has been occurring at Campi Flegrei for tens of centuries with shallow seismicity and slow uplift or subsidence of the ground. Due to the wide class of signals that must be detected (tectonic, volcanotectonic, low-frequency events), the OVSN includes both short-period and broadband seismometers. A primary goal of this network is to recognize and analyze any seismic event that could be a precursor of volcanic unrest. The area surrounding the Vesuvio and Campi Flegrei volcanoes is among the most densely populated in Europe. Consequently, the volcanic hazard in both regions is among the highest in the world. The earthquake hazard in Campania region is very high also. The main purpose of the OVSN is to provide the most reliable and useful possible monitoring of seismic activity and to alert civil defense and other authorities of events that are potentially dangerous for people and the economy. Moreover, seismic data are analyzed together with other data such as ground deformation and chemical analysis of emitted gases, with the aim of providing useful eruption forecasts. In this paper we discuss the network improvements to give …