Free Republic

The Cascadia fault, a 600-mile-long collision between two chunks of the earth's crust off the Pacific Northwest coast, has been quiet for a long time, and that is not a comforting fact. Major earthquakes occur somewhere in the world every year or two. Catastrophic tsunamis - giant waves generated by undersea earthquakes or landslides - strike less often, and some of the largest of tsunamis originate in places that do not, at first glance, appear particularly treacherous. The devastating tsunamis created Dec. 26 by a magnitude 9.0 earthquake that killed as many as 150,000 people on the shores of the...

At 9PM on January 26, 1700 one of the world's largest earthquakes occurred along the west coast of North America. The undersea Cascadia thrust fault ruptured along a 680 mile length, from mid Vancouver Island to northern California in a great earthquake, producing tremendous shaking and a huge tsunami that swept across the Pacific. The Cascadia fault is the boundary between two of the Earth's tectonic plates: the smaller offshore Juan de Fuca plate that is sliding under the much larger North American plate. The earthquake also left unmistakable signatures in the geological record as the outer coastal regions subsided...

Once overlooked because of its relative inactivity compared to other subduction zones around the world, the Cascadia Subduction Zone (CSZ) — and the potentially devastating megathrust earthquakes and tsunamis it could unleash — are today well known to both geoscientists and the public. Beginning with the efforts of John Adams of the Geological Survey of Canada and Brian Atwater of the U.S. Geological Survey in the late 1980s, a series of oceanic research cruises and datasets has steadily advanced our understanding of Cascadia. It seems like there is “a paradigm change every few years,” says Chris Goldfinger, a geologist at...