Saturday, May 3, 2008

Inside The Tsunami Factory

What causes a monster wave? Scientists are drilling seismic hot zones to find out.

Over the past 1,300 years, the Nankai Trough, the 500-mile-long boundary between two tectonic plates off the southwestern coast of Japan, has been one of the world’s most active tsunami hotspots. Now an international team of scientists has embarked on a multiyear project to drill four miles down into the heart of this subterranean wave machine. The Nankai Trough Seismogenic Zone
Experiment, called Nantroseize, will be the first attempt to penetrate a tsunami generating hotspot and could help scientists understand the source of the huge swells. “We can monitor the ocean all we want, but we’ll never understand why some earthquakes produce tsunamis and why others do not until we understand how faults work,” says geophysicist Nathan Bangs of the University of Texas.

Last year, prior to drilling, researchers aboard captured 3-D seismic images of the fault zone where one plate slips beneath the other. The images helped the scientists pick the best spots to drill, but they also revealed new, steeper faults in the rock. Bangs says these near-vertical faults could explain why the Nankai Trough produces roughly one monster earthquake (8+ on the Richter scale) every 150 years.

More answers should come in the next four years, as researchers drop a drill down to the ocean floor and send it churning into as much as 20,000 feet of rock. By dropping seismometers and other instruments into the holes, they will be able to monitor the fault zone in real time. Although most scientists doubt that they will ever truly be able to predict tsunamis, the information could help identify other potential tsunami hotspots around the globe.

*.* Source of Information : May 2008 Popular Science

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