Friday's earthquake in Bam, Iran, that killed more than 50,000 reminds us that earthquakes are still a major cause of death and destruction throughout the world, and the United States may not be spared. The Bam quake measured 6.8 on the Richter scale, but scientists say a monster quake as high as 9.0 is likely to occur in the Pacific Northwest. California's San Andreas Fault, the most popular locale for the feared "Big One," is also causing renewed concern.
A recent article in the Tri-Valley Herald
says "the Pacific Northwest could be struck by a magnitude 9 quake, shaking the region 10 times more violently than San Francisco's famous 1906 quake and for 12 times longer. Scientists call it a 'mega-thruster' and say the Seattle area is especially vulnerable."
That is because Seattle rests on loose, liquefiable dirt and the downtown straddles the Puget Sound area's largest fault. "Researchers foresee instantaneous damage deep into Southwest Canada and Northern California. Seattle, Vancouver and Portland are loaded with buildings not outfitted for earthquakes.
"It will extend from Cape Mendocino to Vancouver. And all of those folks will experience two to three minutes of strong shaking. The (1989) Loma Prieta earthquake lasted 15 seconds and that felt like an eternity."
Within minutes of the quake, tsunamis up to 60 feet high could slam the coast. In the century's three largest quakes -- 1964 in Alaska, 1960 in Chile and 1952 quake in Kamchatka -- tsunamis and landslides killed more people than ground shaking.
Oregon State University geophysicist Chris Goldfinger said the Puget Sound cores revealed two monster quakes roughly every 300 to 400 years, then a longer interval, then a single big quake. The last one was in January 1700. Japanese records at that time say rice farmers saw waves up to 15 feet high charge out of the east without warning, wrecking homes and swamping fields.
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