A new mooring system has been developed by U.S. researchers to install a seismic monitoring station on the top of an active underwater volcano in the southeastern Caribbean Sea. According to the researchers who installed the underwater earthquake monitoring system on top of Kick'em Jenny volcano, their Real Time Offshore Seismic Station (RTOSS) will significantly improve the ability of natural hazard managers to notify and protect the island of Granada's residents from volcanic eruptions and tsunamis.
The left image above describes the three main elements of the Real-Time Offshore Seismic Station: an ocean-bottom seismometer; a stretchy, electrically wired mooring cable; and a buoy with radio transmitters that send observations to shore. (Credits: E. Paul Oberlander, Woods Hole Oceanographic Institution; link to a larger version) On the right is a map showing the location of the the Kick'em Jenny submarine volcano in the southeastern Caribbean Sea. (Credits: Uri ten Brink, U.S. Geological Survey; link to a larger version)
Part of a project to develop new technology for earthquake monitoring in coastal areas, the Real Time Offshore Seismic Station (RTOSS) uses an ocean-bottom seismometer (OBS) deployed directly on top of the volcano -- 250 meters beneath the sea surface -- to collect real-time data from Kick'em Jenny. RTOSS employs a special mooring design that allows seismic data to be transmitted by high-frequency radio to a land-based observatory in the village of Sauteurs. The data will reach the shore within milliseconds of being collected, which will significantly improve the ability of researchers to monitor seismic activity as it happens, a basic requirement for reducing hazards from volcanic gas and rock bursts and from tsunami-generating seafloor avalanches.
The most important element of the RTOSS is the electrically wired mooring cable connecting the seafloor and the buoy on the sea surface.
This hose is designed to compensate for the movement of waves, tides, and currents (which are notoriously rough around Kick'em Jenny), and stretches to more than two times its original length without snapping. Electrical conductors are spiraled through the wall of the hose so that the wires straighten out, rather than break, when the hose stretches. A surface buoy on the end of the mooring uses solar panels to power the radio transmitters that send the data approximately seven kilometers (four miles) to a shore station near the coast.
And for more details about the activities of an underwater volcano, you can read the Kick'em Jenny page at the University of the West Indies's Seismic Research Unit.
Sources: Woods Hole Oceanographic Institution news release, via EurekAlert!, May 10, 2007; and various websites
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