Seismic activity near Sumatra portends major geological changes

BBC : Several large earthquakes that struck off the Sumatran coast on 11 April 2012 are the subject of three papers published this week in Nature. One paper discusses the fact that the quakes originated directly on the Indo-Australian tectonic plate, which comprises much of the Indian Ocean floor, rather than between tectonic plates; as a result, the tremors did not have as severe an impact as earlier quakes, such as the one that occurred in 2004. A second paper centers on the “extraordinarily complex” four-fault rupture that took place during the largest of the quakes, which at magnitude 8.7 is the largest intraplate event ever recorded. A third paper describes how the quake triggered unusually big aftershocks around the world for days afterward. The reason for the intense interest in the 11 April quakes is that the researchers believe they are indicative of major changes taking place on the ocean floor, which will eventuallyâmdash;over several million yearsâmdash;split the Indo-Australian plate in two.