Sunday, July 27, 2008

Cascadia fault (near Seattle) could generate major earthquake and tsunami


Today, while thunderstorms moved through northern Virginia, the Weather Channel aired a particularly scary half-hour segment of The Weather Channel's “It Could Happen Tomorrow” from Atlas Media, about the effect that an offshore earthquake could have on the Seattle area. The topic would work well for the History Channel's "mega disasters" series.

In March 1964 southern Alaska suffered a 9.2 magnitude earthquake when an offshore subduction fault slipped. There is a similar zone off the coast in the Pacific Northwest, running from Oregon to British Columbia. The mechanics of the Indonesian earthquaked on Dec. 26, 2004 and resulting tsunami are similar.

A 9.2 magnitude quake along the Cascadia Subduction Zone could devastate Seattle, knocking down many older buildings. A tsunami of forty feet might engulf the nearby coast (although Seattle itself is protected by outer islands like Bainbridge and Vashon, and the Olympic Peninsula), completely destroying the town of Westport (20000 residents), which has few escape routes.

There is a 10% chance of a large underwater quake along the Cascadia fault within the next 50 years, according to the program.

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