2012 Off the West Coast of Northern Sumatra Earthquake (11th April 2012)

2012 Off the West Coast of Northern Sumatra Earthquake (11th April 2012)

At 14:38 on April 11th, 2012 (local time/ 17:38 JST/8:38 UTC), the M 8.6 earthquake struck off the west coast of the northern Indonesian island of Sumatra. Tsunami alert was issued to the countries in Indian Ocean. According to JMA, no tsunami is expected in Japan.

Basic Information

1、Location of hypocenter: 2.311°N, 93.063°E, 22.9 km depth.

2、Magnitude: Mw 8.6.

3、Related plates: Indo-Australian plate, Eurasian plate.

4、Type of focal mechanism: Strike-slip fault.

Tectonic backgrounds

Sumatra Island is located in the plate boundary where Australian plate is subducting under Eurasian plate by 60-65mm annually, and is one of the most seismically active areas in the world. Past major earthquakes in this area are: the Sumatra Earthquake in 2004(M 9.1), with death toll of more than 200,000 people, and the M 8.7 earthquake which struck 3 month after this Sumatra Earthquake.