The
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
n island of
Sumatra is located in a highly
seismic
Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other ...
area of the world. In addition to the
subduction zone off the west coast of the island, Sumatra also has a large
strike-slip fault, the Great Sumatran Fault also known as Semangko Fault, running the entire length of the island. This fault zone accommodates most of the strike-slip motion associated with the oblique convergence between the
Indo-Australian and
Eurasian
Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern Hemisphere, Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Ja ...
plates. The fault ends in the north just below the city of
Banda Aceh, which was devastated in the
2004 Indian Ocean earthquake. After the December 2004 earthquake, pressure on the Great Sumatran Fault has increased tremendously, especially in the north.
Geologic significance
The Great Sumatran Fault is part of the system where
strain partitioning was first described in
plate tectonics
Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...
. The convergence between the
Indo-Australian Plate
The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and the surrounding ocean and extends northwest to include the Indian subcontinent and the adjacent waters. It was formed by the fusion of the Indian an ...
and the
Sunda Plate is not perpendicular to the plate boundary in this region. Instead, the two plates move at an oblique angle. Most of the convergent strain is accommodated by thrust motion at the plate boundary "megathrust" fault that defines the
Sunda Trench
The Sunda Trench, earlier known as and sometimes still indicated as the Java Trench, is an oceanic trench located in the Indian Ocean near Sumatra, formed where the Australian- Capricorn plates subduct under a part of the Eurasian Plate. It is ...
. But the oblique motion (the part of the plate motion parallel to the plate boundary) is accommodated by the Great Sumatran Fault, which runs along the volcanic
Sunda Arc.
The area between the main plate boundary thrust fault and the Great Sumatran fault forms a "sliver plate" that includes the entire offshore forearc, forearc islands, and the portion of Sumatra west of the Great Sumatran Fault. This sliver plate is not a single rigid bloc, and the details of its internal deformation are under active investigation.
Earthquakes
Listed from northwest to southeast:
* April 2, 1964:
Mw 7.0 event near the northern tip of Sumatra and the city Banda Aceh.
* September 19, 1936:
Mw 7.2 event (3.685°N 97.535°E)
*
March 2007 Sumatra earthquakes: Doublet earthquakes of moment magnitude 6.4 and 6.3 two hours apart northeast of
Lake Singkarak
Lake Singkarak ( id, Danau Singkarak) is a lake in West Sumatra, Indonesia. It is located between the regencies of Tanah Datar and Solok Regency. It has an area of 107.8 km2, being approximately 21 km long and 7 km wide. The natura ...
.
*
2022 Sumatra earthquake: A magnitude 6.2 earthquake damaged dozens of homes, offices and a school.
Six killed and 32 injured. Felt in Malaysia and Singapore.
*
1926 Padang Panjang earthquakes: Doublet earthquake measuring 6.7 and 6.4. At least 411 people killed.
*
1943 Alahan Panjang earthquakes: Doublet earthquakes of moment magnitude 7.2 and 7.5 occurred within 7 hours of each other on June 8 and 9 southeast of
Lake Singkarak
Lake Singkarak ( id, Danau Singkarak) is a lake in West Sumatra, Indonesia. It is located between the regencies of Tanah Datar and Solok Regency. It has an area of 107.8 km2, being approximately 21 km long and 7 km wide. The natura ...
.
*
1995 Kerinci earthquake: Moment magnitude 6.8 earthquake, killed at least 84 people and caused 1,868 injuries.
*
1994 Liwa earthquake: 7.0
Mw event caused 207 deaths near the southern tip of Sumatra.
*
1933 Sumatra earthquake:
Mw 7.6 event (5.226°S 104.596°E) southern of Sumatra.
More than 76 people killed and extensive damage. Two towns destroyed.
See also
*
Pacific Ring of Fire
The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. The Ring o ...
References
External links
Great Sumatran Fault
Seismic faults of Southeast Asia
Geology of Indonesia
Strike-slip faults
Seismic faults of Indonesia
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