SN-1 and NEMO: the Italian cabled observatories

A fruitful synergy between Geophysics, Environmental Sciences, Nuclear Physics and Marine Technology has started through ongoing projects within different Italian research frameworks. The Neutrino Mediterranean Observatory (NEMO) project, funded by INFN, aims at the realization of a deep-sea experiment for the detection of cosmic neutrinos using an array of towers equipped by photosensors. To test the technological solutions proposed for the realization of the project, the Laboratiori Nazionali del Sud have set up an underwater Test Site off-shore Catania. A 25 km long submarine electro-optical cable was deployed in September 2001, in order to supply power from land and receive data from the underwater site located at a depth of 2000 m. A shore station has also been realize inside the Catania port area. In October 2001, Submarine Network-1 (SN-1), the first Italian deep-sea multidisciplinary observatory for geophysical and environmental monitoring was deployed at a depth of 2105 m, in the area of the Ibleo-maltese escarpment, in proximity of the marine tail of the NEMO cable. SN-1, funded by the Italian Gruppo Nazionale di Difesa dai Terremoti and coordinated by INGV, is presently operating in local mode storing measurements on hard disks and is powered by lithium batteries with an autonomy of approximately 200 days. In the view of mutual assistance, the coordinator institutions of NEMO and SN-1 have agreed that part of the optic fibres and power lines of the NEMO-1 underwater cable be made available to power SN-1 from land and to transfer in real time the signals acquired by the geophysical and environmental sensor packages of SN-1. On this latter's side, time series of environmental parameters useful for the analysis and interpretation of NEMO-1 detections will be available. A description of the two projects and of the 'state of the art' will be given and the benefits of the development of a submarine Italian prone site will be pointed out.