Improving the Monitoring System in the Marine Sector of Campi Flegrei Volcanic Area

The marine sector of the Campi Flegrei caldera has started to be monitored over the long-term with a seafloor equipment deployed in the Gulf of Pozzuoli from 2008. The equipment includes a set of geophysical, oceanographic and environmental sensors integrated in a marine platform that was specifically designed for real-time monitoring. This platform, named CUMAS (Cabled Underwater Multidisciplinary Acquisition System), was installed in the center of the Gulf at about 2.5 km south of Pozzuoli where the sea depth is about 100 m [Iannaccone et al., 2010]. The CUMAS system consists of a seafloor module connected by cable to a buoy (elastic beacon type) equipped with autonomous power supply systems, real-time data- transmission devices and a weather station. The core of CUMAS is the seafloor module that contains geophysical and oceanographic sensors, in particular, a three-component broadband seismometer, a best in class three axis MEMS accelerometer, a low-frequency hydrophone and a high-resolution sea bottom pressure recorder. A single-point acoustic, three-component, water-current meter and a water-temperature sensor were also installed to monitor some water local physical parameters. A set of status sensors, which also included a digital compass and a two-component digital tilt-meter, were added to track the attitude of the module over the course of the experiment. The marine monitoring system transmits the data in real-time and is integrated into the Monitoring Center in Naples managed by INGV-Osservatorio Vesuviano. A continuous GPS station has been installed since the end of 2011 on the top of the buoy. The elastic beacon buoy forms a structure which is rigidly connected by a mechanical cable to the ballast on the sea bottom, a submerged float at the base of the buoy maintains tension on the cable and ensure the overall buoyancy of the system. In this way, any vertical movement of the seafloor propagates rigidly to the emerged part of the buoy itself, allowing measurement of the vertical movement of the sea ...