Sumatra 8.6 Magnitude Earthquake Was Largest Within-Plate Quake In Observed History
An 8.6 magnitude earthquake occurred 62 miles off the coast of Sumatra on April 11th, 2012.
Along with being severe by any measure, in one way it was the largest earthquake in observed human history; it originated within the plate rather than at a plate boundary.
The quake originated under the Wharton Basin in the Indian Ocean, where hundreds of miles of rock were under crushing tension, causing the plate to deform at its base. This 'deforming zone' was also absorbing tension as two plates, the Indian and Australian plates, rotated toward each other.
One month after the earthquake, researchers visited the Wharton Basin to reconstruct the rupture history of the events of April 11th in order to gain a better understanding of the general nature of these rare large within-plate earthquakes. They used back projection analysis, which tracks radiation that emanates as new locations along a rupture path become active.
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http://www.science20.com/news_articles/sumatra_86_magnitude_earthquake_was_largest_withinplate_quake_observed_history-93556
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