GeO-TOC project-reuse of submarine cables for seismic and geoelectrical measurements

Cooperative efforts by Japanese and U.S. researchers have been initiated to reuse a former submarine telephone cable (''TPC-1,'' retired in 1991) for undersea scientific measurements. TPC-1 runs from Ninomiya, Japan to Guam, U.S.A., and has a length of ca. 2,700 km with a strike almost in the N-S direction. A prototype instrument package was successfully installed in northern Japan at depth of 100 m using a similar coaxial cable. An instrumental package has been built and will be deployed near 30 degrees N in 1996. The instrument has three component accelerometers with 24 bit A/D converters, a hydrophone using analog telemetry, and a quartz thermometer and a quartz pressure sensor with a data length of 16 bits. The data will be transmitted to the Ninomiya station in real-time. Other plans to reuse submarine telephone cables between Naoetsu, Japan and Nakhodka, Russia and between Okinawa, Japan and Guam are being considered.