August 5, 2009

Underground water can affect earthquakes

Water deep underground helps subduction zones of tectonic plates mature, making the zone capable of generating powerful earthquakes, U.S. researchers said.

The study expands geophysicists' understanding about earthquakes, the University of Utah said Wednesday in a news release.

It hasn't been on people's minds that fluid-generating processes way out of sight reach up and cause damage right under our feet, said Phil Wannamaker, the study's chief author and a geophysicist at the university's Energy and Geoscience Institute.

Understanding how one of Earth's tectonic plates can dive, or subduct, beneath another to create earthquake-generating faults is critical because subduction and faulting are major processes all over the world, especially in the Ring of Fire around the Pacific Ocean, Wannamaker said.

Wannamaker and scientists from the United States, New Zealand and Japan studied an area off New Zealand, location of one of the world's youngest subduction zones where the Pacific plate dives beneath the Australian plate. They used magnetotelluric sounding, similar to using X-rays to scan patients and seismic waves to search for oil and gas. A subsequent computer graphic revealed large amounts of water in different areas and depths that could affect the plates, paving the way for earthquakes.

These fluids certainly could burst upward ... and trigger major earthquakes, Wannamaker said.

The scientists' findings were reported in the latest edition of Nature.