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.
Event Time
- 2012-04-11 08:38:37 UTC
- 2012-04-11 14:38:37 UTC+06:00 at epicenter
- 2012-04-11 16:38:37 UTC+08:00 system time
Nearby Cities
- 369km (229mi) W from Sinabang, Indonesia
- 395km (245mi) WSW from Meulaboh, Indonesia
- 437km (271mi) SW from Banda Aceh, Indonesia
- 468km (290mi) SSW from Sabang, Indonesia
- 963km (598mi) W from Kuala Lumpur, Malaysia
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A man evacuates his family in a motorcycle in Banda Aceh after a strong earthquake struck Indonesia province April 11, 2012. |
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| People riding motorbikes and cars packed the street in Banda Aceh after a strong earthquake struck Indonesia province April 11, 2012. An 8.6 magnitude earthquake struck off Indonesia on Wednesday, sending residents around the region scurrying from buildings and raising fears of a huge tsunami as in 2004, but authorities said there were no reports suggesting a major threat. Indonesian President Susilo Bambang Yudhoyono said there were no immediate reports of casualties or damage in Aceh, the Indonesian province closest to the earthquake. |
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| Patients rest in the lawns of a government-run hospital after they were evacuated in the southern Indian city of Chennai April 11, 2012, following an earthquake which struck off Indonesia. A few thousand people were evacuated to higher ground from parts of Andaman and Nicobar islands on Wednesday following earthquakes in Indonesia, as the islands prepared for tsunami waves up to 3.9 metres high, officials said |
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| A boy cries as he is carried by his mother as they evacuate to higher ground after a strong earthquake was felt in Banda Aceh, Aceh province, Sumatra island, Indonesia, Wednesday, April 11, 2012. Two massive earthquakes triggered back-to-back tsunami warnings for Indonesia on Wednesday, sending panicked residents fleeing to high ground in cars and on the backs of motorcycles. There were no signs of deadly waves, however, or serious damage, and a watch for much of the Indian Ocean was lifted after a few hours. |
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. 
