Misure di deformazione verticale sul fondo marino in acque costiere con sensore di pressione: applicazione all’area dei Campi Flegreii

Abstract

The following work represents the first vertical deformation measurement of the ground in coastal waters obtained through the use of a BPR sensor (Bottom Pressure Recorder) installed in shallow water, with an accuracy comparable with that of the measures carried out by a GPS network placed on the mainland. The described measurement method allows the use of pressure sensors - based on quartz technology - as a possible and low cost integration, which allows the extension in the coastal waters of the geodetic monitoring networks located on the mainland. The area under investigation is the caldera of Campi Flegrei (Pozzuoli) in which even the bradyseism is continually monitored by the Vesuvius Observatory surveillance system in Naples. In the Gulf of Pozzuoli, which is the submerged part of the caldera, on-going studies are performing innovative methods for geophysical monitoring at sea bottom, and – in particular – vertical measures of the soil through the use of BPR sensors. Even in the shallow water condition, such as that of the Gulf of Pozzuoli, it is noted that the BPR can provide reliable estimates of vertical movements of the soil at sea bottom, through the correction of the pressure data with environmental data and it comparison with the sea level obtained from the tide gauge network. In the pages that follow, it provides guidance as to the real possibility to use BPR for the vertical movements measure of the ground, at speeds of a few centimetres per year, in the submerged part of an active volcanic area, where the sea depth does not exceed one hundred meters.