Installazione di dispositivi DAS per il potenziamento del monitoraggio dei Campi Flegrei

Distributed dynamic strain sensing has been demonstrated to be useful to record and locate earthquakes, in particular using existing Telecom fibre optic networks. In urban areas, as the deployment of conventional seismometers is particularly challenging, mainly because of high noise conditions and difficulties in finding adequate locations, the existence of fibre optic telecom network to be repurposed as array of seismic sensors makes DFOS (Distributed Fiber Optic Sensing) attractive. Here we report observations in the Napolitean volcanic area of Napoli and Campi Flegrei, Italy. In order to enhance the monitoring of the current unrest (increased seismic activity and deformation) observed since 2005, we interrogated two telecom fibre optic cables crossing the Campi Flegrei active seismic area using two DAS (Distributed Acoustic Sensing) interrogators for 4 months (October 2023 - February 2024). We connected an A1 (Febus) interrogator in Bagnoli Centrale Telecom to a ~20 km telecom cable crossing Campi Flegrei caldera and an iDAS (Silixa) interrogator in Napoli Centrale to a ~430 km long cable partly on-land from Napoli until the coastal area (~23 km) and in submarine environment toward Salerno and Southern Italy. We designed a protocol to automatically download files corresponding to the earthquake times provided by the INGV-OV catalog for further analysis in Catania. Thanks to the dense spatial coverage of the records, we show that the cables are suitable to detect earthquakes (537 events) over those reported in the INGV catalog (567 events). We find that swarms of events occur, where single events are better detected on the DAS data with respect to conventional seismic records. Our protocol is the first step demonstrating that fibre optic sensing can be used in real time to help monitoring of increased seismic activity.