~~~~YahooNews1

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The earthquakes that rocked Tohoku, Japan in 2011, Sumatra in 2004 and Chile in 1960 — all of magnitude 9.0 or greater — should not have happened, according to seismologist’s theories of earthquake cycles. And that might mean earthquake prediction needs an overhaul, some researchers say.

All three earthquakes struck along subduction zones, where two of Earth’s tectonic plates collide and one dives beneath the other. Earlier earthquakes had released the pent-up strain along Chile’s master fault, meaning no big quakes were coming, scientists had thought. Japan and Sumatra both sat above on old oceanic crust, thought to be too stiff for superquakes.

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~~~~Superquakes1

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http://news.yahoo.com/potential-superquakes-underestimated-recent-earthquakes-show-153606464.html

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