The researchers aren't sure exactly what causes the dilation, but it has multiple implications. First, it changes how scientists view seafloor spreading since there isn't an automatic outpouring of lava, or hot liquid via hydrothermal vents previously associated with tectonic plate theory.
The size of these potential "voids" also intrigues scientists, who wonder how much seawater can be subsumed. If large, or frequent, they could affect surrounding water temperatures and chemical composition, Dziak said.
Finally, water migrating downward through the Earth may be enough to trigger the growth of bacteria at startling depths. Last year, in an unrelated study, OSU oceanographer Martin Fisk and a team of researchers found bacteria in a hole drilled 4,000 feet through volcanic rock. Basalt rocks have all of the elements required for life, Fisk pointed out, including carbon, phosphorous and nitrogen. Only water is needed to complete the formula.
Dziak is able to monitor offshore activities from his laboratory at OSU's Hatfield Marine Science Center in Newport, where he uses an array of undersea hydrophones through a unique arrangement with the U.S. Navy. During the past dozen years, Dziak and his research team have recorded more than 30,000 earthquakes in the Pacific Ocean off the Northwest coast few of which have ever shown up on land-based seismic equipment.
The earthquakes, most having a magnitude of 2.0 to 4.0, originate along the Juan de Fuca Ridge, a submarine mountain range 300 miles west of the Oregon coast that was formed by seafloor spreading or the movement of oceanic plates away from one another.
"It is the only real-time hydrophone system in the world available for civilian research," Dziak said. "It allows us to listen to the earthquakes as they occur and when something unusual happens, we can send out a group of scientists to study the events as they unfold.
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Contact: Robert Dziak
robert.dziak@oregonstate.edu
541-867-0175
Oregon State University
14-Jul-2004