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On January 26, 1700 at 9:00 pm a great earthquake (M8.7–9.2) struck the Pacific Northwest shaking mountains, dropping coastal forests, and causing a tsunami that wiped away entire villages (http://walrus.wr.usgs.gov/tsunami/NAlegends.html). (This occurred before written history. Oral history of Native Americans, interviewed in 1868, told of their ancestors relating these events.) Nine hours later, in Japan, a mysterious tsunami arrived without warning flooding fields and washing away houses along the coastline from north to south. Samurai, merchants, and villagers recorded the event, but nearly three centuries would pass before scientific discoveries in North America revealed the tsunami's source. Evidence supporting the occurrence of the 1700 earthquake is detailed in the book The Orphan Tsunami of 1700 (geologist Brian Atwater and others, 2005; http://pubs.usgs.gov/pp/pp1707/).
Recent findings conclude that the Cascadia Subduction zone is more complex and volatile than previously believed. Geologists predict a 37 percent chance of a M8.2+ event in the next 50 years, and a 10 to 15 percent chance that the entire Cascadia Subduction will rupture with a M9+ event within the same time frame (http://oregonstate.edu/ua/ncs/node/13426). Sumatra, Chile, and Japan provide vivid examples of what could happen.
Quicktime (19.7 MB)
Animations and videos are made in partnership with Earthscope, USGS, and Volcano Video & Graphics.
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