PerspectiveGeophysics

A Rogue Earthquake Off Sumatra

Science  01 Jun 2012:
Vol. 336, Issue 6085, pp. 1118-1119
DOI: 10.1126/science.1223983

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Summary

The magnitude (Mw) 8.6 earthquake of 11 April 2012 off the coast of Sumatra is one for the record books. It is far and away the largest strike-slip earthquake in the instrumental record. The Mw 8.2 aftershock that occurred just over 2 hours later is also among the largest such earthquakes. Furthermore, the 11 April mainshock may be the largest intraplate earthquake ever recorded, although the location (see the figure) is consistent with the notion of a wide, diffuse plate boundary that bisects the Indo-Australian Plate near the Ninetyeast Ridge (1). The earthquakes are the latest in a series of large (Mw 8) intraplate strike-slip earthquakes in oceanic lithosphere (2). What do these earthquakes reveal about earthquake physics, and how might they change earthquake hazard assessment?