Originally published on Thu September 27, 2012 8:31 am
On April 11 of this year, an extraordinary cluster of earthquakes struck off Sumatra. The largest shock, magnitude 8.7, produced stronger ground-shaking than any earthquake ever recorded. And it surprised seismologists by triggering more than a dozen moderate earthquakes around the world.
The quakes are also a sign of big changes to come in the Earth's crust.
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