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Thursday, August 25, 2011

Cascadia Subduction Zone: Scientists seek to hear sounds from treacherous, mysterious Cascadia fault - 18th Aug 2011

The devastating might of Earth's mysterious movements was put on tragic display this year when the Tohoku earthquake struck off the coast of Japan.

The magnitude 9.0 quake was produced by a sudden lurch along a subduction zone, a place where one tectonic plate dives beneath another in an epic, slow-motion collision.

Unbeknown to many on the other side of the Pacific Ocean, a similar subduction zone lurks along the North American coastline.

The Cascadia subduction zone — a tectonic border region where the oceanic Juan de Fuca plate is grinding slowly beneath the North American plate — stretches from Northern California up to Vancouver Island. And although scientists are busily studying the fault, which has produced massive earthquakes in the past, some aspects of Cascadia's character and structure remain largely mysterious.

"We don't really know very much about what's going on," said Andrew Barclay, a research scientist at Columbia University's Lamont-Doherty Earth Observatory.

Seafloor sensing
Barclay and a group of colleagues recently returned from an expedition to install 15 newly developed sensors off the coast of northern Washington state, in the first U.S. attempt to gather data on the portion of the fault trickiest to study — the part that lies under the ocean.

In late July, researchers spent more than a week aboard a research vessel, hoisting the 1,500-pound instruments overboard and, with the help of very long cables and a sturdy crane, settling each massive sensor on the seafloor. Read More