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 Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...

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 Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

off the west coast of the island, Sumatra also has a large

strike-slip fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

, 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 all of this entry re immigration is a complete fabrication Indian Australians or Indo-Australians are Australians of Indian ancestry. This includes both those who are Australian by birth, and those born in India or elsewhere in the Indian d ...

and

Eurasian Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

plates. The fault ends in the north just below the city of

Banda Aceh Banda Aceh ( Acehnese: ''Banda Acèh'', Jawoë: كوتا بند اچيه) is the capital and largest city in the province of Aceh, Indonesia. It is located on the island of Sumatra and has an elevation of . The city covers an area of and had ...

, which was devastated in the

2004 Indian Ocean earthquake An earthquake and a tsunami, known as the Boxing Day Tsunami and, by the scientific community, the Sumatra–Andaman earthquake, occurred at 07:58:53 local time (UTC+7) on 26 December 2004, with an epicentre off the west coast of northern Suma ...

. 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 Strain partitioning is commonly referred to as a deformation process in which the total strain experienced on a rock, area, or region, is heterogeneously distributed in terms of the strain intensity and strain type (i.e. pure shear, simple shear, ...

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 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 ...

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 l ...

. 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 Sunda Arc is a volcanic arc that produced the volcanoes that form the topographic spine of the islands of Sumatra, Nusa Tenggara, and Java, the Sunda Strait and the Lesser Sunda Islands. The Sunda Arc begins at Sumatra and ends at Flores, ...

. 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: M_w 7.0 event near the northern tip of Sumatra and the city Banda Aceh. * September 19, 1936: M_w 7.2 event (3.685°N 97.535°E) *

March 2007 Sumatra earthquakes The March 2007 Sumatra earthquakes occurred near the northern end of Lake Singkarak in Sumatra, Indonesia, on March 6. The first shock in this earthquake doublet struck with a maximum Mercalli intensity of VIII (''Severe'') and the second shock ...

: 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 natural ...

. *

2022 Sumatra earthquake On 25 February 2022, a moment magnitude 6.2 earthquake struck West Sumatra, Indonesia at a depth of . Preceded by one foreshock and followed by over 200 aftershocks, the mainshock had an epicenter at the foot of Mount Talakmau in Pasaman R ...

: 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 West Sumatra, Dutch East Indies (today Indonesia) was struck by an earthquake doublet on June 28, 1926. The first earthquake occurred at 10:23 local time, with an estimated magnitude of 6.7 on the surface wave magnitude scale with an intensity ...

: Doublet earthquake measuring 6.7 and 6.4. At least 411 people killed. *

1943 Alahan Panjang earthquakes The 1943 Alahan Panjang earthquakes occurred on June 8 and June 9 UTC (June 9, 1943, local time) in Sumatra, then under Japanese occupation. This was an earthquake doublet (the shocks occurred at the same location on consecutive days). The firs ...

: Doublet earthquakes of moment magnitude 7.2 and 7.5 occurred within 7 hours of each other on June 8 and 9 southeast of

. *

1995 Kerinci earthquake The 1995 Kerinci earthquake struck near Sungai Penuh in Jambi Province on the island of Sumatra, Indonesia. It earthquake occurred at 01:18 WIB (UTC +7) local time on October 7. The earthquake measured 6.7 on the moment magnitude scale, and 6. ...

: Moment magnitude 6.8 earthquake, killed at least 84 people and caused 1,868 injuries. *

1994 Liwa earthquake The 1994 Liwa earthquake occurred on . It was located in southern Sumatra, Indonesia. The magnitude of the earthquake was put at 6.9, 7.0, or 7.2, according to different sources."The Sumatran Fault Zone – From Source to Hazard" by D. H. Nat ...

: 7.0 M_w event caused 207 deaths near the southern tip of Sumatra. *

1933 Sumatra earthquake The 1933 Sumatra earthquake or Liwa earthquake occurred in West Lampung Regency, Lampung Province, Indonesia on June 25. The earthquake had an estimated surface-wave magnitude () of 7.7 occurring at a shallow depth of 20 km. It had an epic ...

: M_w 7.6 event (5.226°S 104.596°E) southern of Sumatra. More than 76 people killed and extensive damage. Two towns destroyed.

References

External links

Great Sumatran Fault
Seismic faults of Southeast Asia Geology of Indonesia Strike-slip faults Seismic faults of Indonesia {{tectonics-stub

Geologic significance

Earthquakes

See also

References

External links