Indonesia Earthquake Today at 8.6 Magnitude

An 8.6 magnitude earthquake hit Indonesia today creating fear in people around the coastal areas, especially those in Aceh. In 2004, a tsunami killed 170,000 people in the province alone. The U.S. Geological Survey was centered 20 miles beneath the ocean floor around 269 miles from Aceh province.

The Pacific Tsunami Warning Center in Hawaii issued a tsunami watch for Indonesia, India, Sri Lanka, Australia, Myanmar, Thailand, the Maldives and other Indian Ocean islands, Malaysia, Pakistan, Somalia, Oman, Iran, Bangladesh, Kenya, South Africa and Singapore.

USGS Tectonic Summary

The M8.6 April 11, 2012 earthquake off the west coast of northern Sumatra, Indonesia, occurred as a result of strike-slip faulting within the oceanic lithosphere of the Indo-Australia plate. The quake was located approximately 100 km to the southwest of the major subduction zone that defines the plate boundary between the Indo-Australia and Sunda plates offshore Sumatra. At this location, the Indo-Australia plate moves north-northeast with respect to the Sunda plate at a velocity of approximately 52 mm/yr.

Large strike-slip earthquakes, while rare, are not unprecedented in this region of the Indo-Australian plate. Since the massive M 9.1 earthquake that ruptured a 1300 km long segment of the Sumatran megathrust plate boundary in December of 2004, three large strike-slip events have occurred within 50 km of the April 11, 2012 even. These earthquakes occurred on April 19 2006 (Mw6.2), October 4 2007 (Mw6.2) and January 10, 2012 (Mw7.2). In all three cases, the style of faulting was similar. These events align approximately with fabric of the sea floor in the diffuse boundary zone between the Indian and Australian plates.