13 July 2015

Big Earthquake in Pacific Northwest now OVERDUE

Interesting piece on New Yorker website about the fact that the threat of a REALLY big Earthquake, comparable to Fukushima (roughly 9 on Richter) is actually greater in "Cascadia," i.e. Far Northern Calif., Oregon, Washington, British Columbia, than in the part of California South of Cape Mendocino (the Pacific Plate part, dominated by the strike/slip San Andreas Fault. Why? BECAUSE it's strike/slip, even the "Big One" down here is likely to be no greater than 8.2 or 8.3. But core samples and other measures of the subduction zone fault in the Cascadia region shows that roughly every 243 years, with the last one occurring in January, 1700... 315 years ago.... the region is hit by a HUGE Earthquake, that causes land to shift by tens of feet Westward and many feet vertically, resulting in an enormous and devastating Pacific tsunami. (The one in 1700 was an "orphan" tsunami; even then the Japanese knew that tsunamis were associated with Earthquakes, but the 1700 tsunami affected the entire archipelago of Japan, but was not associated with any earthquake... because the Earthquake was in Oregon and Washington!)

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