Sumatra earthquake 11 April 2012

The 8.6 magnitude earthquake that  shook the seafloor 400 kilometers off the west coast of Aceh in northern Sumatra on 11 April (see map) may not have been a killer, but its surprising power has seismologists rattled.

The quake, which lasted about 100 seconds, bears little resemblance to the catastrophic 9.1 magnitude quake that struck the same region in December 2004. Yesterday’s quake was marked predominantly by ‘strike-slip’ motion – meaning that two sections of Earth’s crust rubbed against each other horizontally rather than one piece thrusting up over or down under another. The absence of vertical motion accounts for why the quake did not generate a major tsunami. Nevertheless, this quake has generated some provocative scientific. http://blogs.nature.com

11 April 2012 Sumatra earthquake in Danau Toba