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Technology: Dial underwater for earthquakes

作者:卢饱芾    发布时间:2019-02-28 01:07:03    

JAPANESE geophysicists will be able to detect earthquakes using an obsolete telephone cable on the floor of the Pacific Ocean. They plan to install seismometers on the 26-year-old cable, which will supply power to the instruments and transmit data they collect. The seismometers will monitor the sea-bed across the border between the Pacific and Philippines plates, where earthquakes are common. American Telephone & Telegraph Corporation and Kokusai Denshin Denwa, the Japanese international carrier, retired the cable in August. On 1 November, the companies will donate the segment between Guam and Japan to the Earthquake Research Institute of the University of Tokyo and the Incorporated Research Institute for Seismology of the US. The cable was the first to cross the Pacific, but today its capacity of 138 simultaneous phone calls is dwarfed by a fibre-optic cable, which carries 40 000 calls. Measurement instruments require power input and a data link to the outside world; batteries and tethered buoys can meet the needs of some ocean-floor instruments, but not seismometers. The Tokyo institute plans to install three seismometers along the old cable, and put sensors of electromagnetic fields, pressure, and temperature at one of the seismometer stations. The seismic probes will be part of Japan’s planned network of seabed instruments called Poseidon. Engineers also are looking for ways to attach instruments to the cable avoiding the high cost of hauling it up from the seabed with a specialised cable ship and cutting it in two places. Charles Cox of the Scripps Institute of Oceanography in San Diego has suggested cutting the cable at one point to install an ‘acoustic modem’, which would collect data sent as sound waves by battery-powered sensors not attached to the cable. Researchers also are considering other uses for abandoned cables. Cables could regularly measure temperature and pressure at the bottom of the ocean,

 

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