On February 20, 2008, an
earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
with a
moment magnitude of 7.4 struck off the coast of
Sumatra at a hypocentre depth of 26 km. The earthquake had an epicenter located on the island of
Simeulue
Simeulue is an island of Indonesia, off the west coast of Sumatra. It covers an area of 1754 square kilometres (677 square miles), including minor offshore islands. It had a population of 80,674 at the 2010 census and 92,865 at the 2020 censu ...
, northwest from
Sinabang, a small town on the island. Three people were killed and an additional 25 seriously injured as a result of the earthquake.
Tectonic setting
The west coast of Sumatra is dominated by the Sunda megathrust; a 5,000 km long convergent boundary where the Australian Plate subducts beneath the
Burma Plate and
Sunda Plate
The Sunda Plate is a minor tectonic plate straddling the Equator in the Eastern Hemisphere on which the majority of Southeast Asia is located.
The Sunda Plate was formerly considered a part of the Eurasian Plate, but the GPS measurements have ...
at a rate of 60 mm/yr. The subduction zone offshore Sumatra has been responsible for several large earthquakes in 2004 and 2005.
Earthquake
The Simeulue earthquake occurred as a result of thrust faulting along the subduction zone where the Australian and Burma Plates meet. It earthquake had an epicenter close to another magnitude 7.4 earthquake in 2002. That was considered a foreshock of the 2004 event. The rupture patch for the 2008 event is located between the southern rupture area of the 2004 quake, and the northern rupture for another 2005 quake. Prior to this quake, that section of the megathrust was considered a
seismic gap A seismic gap is a segment of an active fault known to produce significant earthquakes that has not slipped in an unusually long time, compared with other segments along the same structure. There is a hypothesis or theory that states that over long ...
that last ruptured in 1797. It was not considered an aftershock of neither the 2004 or 2005 earthquakes. During the earthquake in 2008, a circular rupture area with a diameter of 60 km broke and slipped for 2.2 meters at its maximum.
Damage and casualties
Four people were reported killed and 25 suffered serious injuries from the quake. The earthquake damaged many buildings in Simeulue due to the strong ground shaking. It was felt in northern Sumatra, the Malay Peninsula, Singapore, and even Thailand. This caused many residents along the Sumatran coast to evacuate for fear of a tsunami.
See also
*
List of earthquakes in 2008
*
List of earthquakes in Indonesia
References
2008 earthquakes
Earthquakes in Indonesia
2008 disasters in Indonesia
February 2008 events in Asia
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