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Chile Quake Is One of the Biggest in a Century
|Last Edited||Scott³ Feb 27, 2010 12:33pm|
|Media||Newspaper - Wall Street Journal|
|News Date||Saturday, February 27, 2010 08:00:00 PM UTC0:0|
|Description||"The 8.8 magnitude earthquake that struck off coastal Chile in the early hours of the morning is one of the biggest temblors anywhere in more than a century. |
Data from the U.S. Geological Survey suggests that this morning's Chile quake tied in fifth place with an 8.8 quake that hit Ecaduor and Bolivia in 1906. Only four quakes have been bigger since 1900. The largest was a 9.5 magnitude event that struck Chile in 1960, causing 1,655 fatalities, leaving 2 million homeless, and triggering a tsunami that killed people in Hawaii, Japan and the Philippines.
Scores of countries around the Pacific Ocean are bracing for a tsunami unleashed by the latest quake, and which is now speeding across the ocean at 550 miles per hour, or the speed of a jet plane.
"A tsunami has been generated that could cause damage along coastlines of all islands in the state of Hawaii," noted the U.S. government's tsunami warning center in Hawaii.
Tsunami-causing quakes usually occur where shards of the earth's crust – tectonic plates – meet. Magma rises from deep inside the earth, causing the plates to move. They slip-slide past each other, sometimes get stuck, then jerk forward again, producing a quake.
According to the USGS, the Chile earthquake occurred at the boundary between the Nazca and South American tectonic plates. The two plates are converging at a rate of 80 mm per year, with the Nazca plate moving down and landward below the South American plate.
The huge disruption in the sea floor acted like a giant wave machine, displacing a large amount of water and triggering tsunami waves. The resulting undulations aren't usually detectable by ships since the crests often measure less than three feet in height and are hundreds of miles apart. But the force of a tsunami becomes apparent in shallower water."