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Permanent Multidisciplinary Seafloor Observatoty deployed in the Catania Gulf (Italy)

SN1 observatory is a four-leg marine aluminium frame (overall dimension 2.90m x 2.90m x 2.90m, Weight: 14 kN in air, 8.2 kN in water) supporting all equipment and vessels constituting the scientific and operative payload based on the GEOSTAR technology and mainly addressed to seismology and oceanography.

It was designed in the framework of the SN1 project as a reduced-size version of GEOSTAR observatory, using the same features in regard to deployment/recovery procedures using the MODUS vehicle (Mobile Docker for Underwater Science), the data acquisition system and the special device for seismometer installation developed in GEOSTAR project.

Figure 1
On the left: SN-1 observatory during recovery operation on Urania R/V.
The seismometer is unlatched from the station.
On the Right: SN-1 design, lateral view. Seismometer is in its originary position, latched to the station 

From October 2002 to May 2003 SN1 successfully completed its first long-term experiment about 25 km East of Catania (Southern Italy, Eastern Sicily) at 2105-m depth in autonomous mode without any permanent acoustic or physical connection with the sea surface. SN1 was equipped with a vertical acoustic link to allow the remote request of the observatory data from a ship of opportunity and the retrieval of segments of acquired time series.

After this experiment SN1 was fitted with a fibre-optic telemetry interface, so as to be compatible with the electro-optical cable owned and deployed off-shore from Catania by INFN and related with particle physics experiments.
In January 2005, the observatory was deployed by MODUS in the same site of the first mission at 2060 m w.d., and connected to the submarine cable, thus becoming part of the underwater infrastructure NEMO-SN1. These activities were performed under an agreement between two major Italian scientific institutions, INGV and INFN.

Figure 2 Layout of the NEMO-SN1 underwater structure in Sicily

In this new configuration SN1 receives power from the shore, can communicate in real-time with the shore station inside Catania harbour, and is integrated in the INGV land based networks. SN1 is the first real-time seafloor observatory in Europe and one of the few in the world. It is also the first operative seafloor observatory in one of the «key-sites» planned in ESONET and EMSO projects.

Figure 3 SN-1 and MODUS vehicle before deployment and connection to submarine cable interface


Figure 4 The cable route from Catania harbour to 25-km east in the Ionian Sea


Figure 5 The ROV connecting SN-1 observatory to the cable interface (top)
SN-1 on the seafloor during the cable connecting operations (bottom)


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