Multidisciplinary geophysical measurements on the ocean floor using decommissioned submarine cables: VENUS project

To perform geophysical and multidisciplinary real-time measurements on the ocean floor, it has been attempted to reuse decommissioned submarine cables . The VENUS project reuses the TPC-2, which is one of these systems and run s across the entire Philippine Sea Plate between Guam Island and Okinawa Is land. The VENUS system comprises an ocean floor observatory, a submarine ca ble, and a land system. The major components of the ocean floor observatory are geophysical instruments and a telemetry system. There are seven scient ific instrument units including broad-band seismometers (OBBS) and a hydrop hone array. Digital telemetry using the old analog telephone cable obtains high data accuracy and real-time accessibility to data from a laboratory on Land. The bottom-telemetry system and a part of sensor units were installed at a depth of 2157 m on the landward slope of the Ryukyu (Nansei-Syoto) Trench o n August 29, 1999, The data from the hydrophone array and tsunami gauge hav e been correctly transmitted to the data center. The rest of the scientific instruments will be deployed by deep-tow equipment and a remotely operated vehicle. Using a decommissioned submarine cable will greatly reduce constr uction costs compared to using a new cable system.