2002 Sumatra earthquake
Encyclopedia
The 2002 Sumatra earthquake occurred at 01:26 UTC
on 2 November. It had a magnitude of 7.3 on the moment magnitude scale
with an epicenter
just north of Simeulue island and caused three deaths. This earthquake
is regarded as a foreshock
of the 2004 Indian Ocean earthquake
, which had an epicenter about 60 km to the northwest.
between the Indo-Australian Plate
and the Eurasian Plate
. The convergence between these plates is highly oblique near Sumatra, with the displacement being accommodated by near pure dip-slip faulting along the subduction zone, known as the Sunda megathrust
, and near pure strike-slip faulting along the Great Sumatran fault
. The major slip events on the subduction zone interface are typically of megathrust type. Historically, great or giant megathrust earthquakes have been recorded in 1797
, 1833
, 1861
, 2004
, 2005
and 2007, most of them being associated with devastating tsunamis. Smaller (but still large) megathrust events have also occurred in the small gaps between the areas that slip during the larger events, in 1935
, 1984
, 2000
and 2002.
(VI
'Strong'), Meulaboh
and Singkil
(V 'Rather strong') in the Aceh
province of Sumatra
.
s. From its proximity to the epicenter of the 2004 earthquake, it is regarded as a foreshock of that event. Microatolls around Simeulue show evidence of uplift as a result of the 2002 event, distinct from the uplift caused by the 2004 event.
Waveforms from this earthquake have been used to model the propagation of Rayleigh waves during the 2004 earthquake using an empirical Green's function
analysis.
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
on 2 November. It had a magnitude of 7.3 on the moment magnitude scale
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
with an epicenter
Epicenter
The epicenter or epicentre is the point on the Earth's surface that is directly above the hypocenter or focus, the point where an earthquake or underground explosion originates...
just north of Simeulue island and caused three deaths. This earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
is regarded as a foreshock
Foreshock
A foreshock is an earthquake that occurs before a larger seismic event and is related to it in both time and space. The designation of an earthquake as foreshock, mainshock or aftershock is only possible after the event....
of the 2004 Indian Ocean earthquake
2004 Indian Ocean earthquake
The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, December 26, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra-Andaman earthquake...
, which had an epicenter about 60 km to the northwest.
Tectonic setting
The island of Sumatra lies on the convergent plate boundaryConvergent boundary
In plate tectonics, a convergent boundary, also known as a destructive plate boundary , is an actively deforming region where two tectonic plates or fragments of lithosphere move toward one another and collide...
between the Indo-Australian Plate
Indo-Australian Plate
The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinent and adjacent waters...
and the Eurasian Plate
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...
. The convergence between these plates is highly oblique near Sumatra, with the displacement being accommodated by near pure dip-slip faulting along the subduction zone, known as the Sunda megathrust
Sunda megathrust
The Sunda megathrust is a fault that extends approximately 5,500 km from Myanmar in the north, running along the southwestern side of Sumatra, to the south of Java and Bali before terminating near Australia...
, and near pure strike-slip faulting along the Great Sumatran fault
Great Sumatran fault
The Indonesian island of Sumatra is located in a highly seismic area of the world. In addition to the subduction zone and the associated Sunda Arc off the west coast of the island, Sumatra also has a large strike-slip fault, the so-called Great Sumatran Fault, running the entire length of the island...
. The major slip events on the subduction zone interface are typically of megathrust type. Historically, great or giant megathrust earthquakes have been recorded in 1797
1797 Sumatra earthquake
The 1797 Sumatra earthquake was the first in a series of great earthquakes that ruptured part of the Sumatran segment of the Sunda megathrust. It caused a damaging tsunami that was particularly severe near Padang, where a 150-200 ton English ship was driven 1 km inland up the Arau...
, 1833
1833 Sumatra earthquake
The 1833 Sumatra earthquake occurred on November 25, 1833, about 22:00 local time, with an estimated magnitude in the range Mw= 8.8–9.2. It caused a large tsunami that flooded the southwestern coast of the island. There are no reliable records of the loss of life, with the casualties being...
, 1861
1861 Sumatra earthquake
The 1861 Sumatra earthquake occurred on February 16, 1861. It was the last in a sequences of earthquakes that ruptured adjacent parts of the Sumatran segment of the Sunda megathrust. It caused a devastating tsunami which led to several thousand fatalities. The earthquake was felt as far away as the...
, 2004
2004 Indian Ocean earthquake
The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, December 26, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra-Andaman earthquake...
, 2005
2005 Sumatra earthquake
The 2005 Sumatra earthquake, referred to as the Nias Earthquake by the scientific community, was a major earthquake on 28 March 2005, located off the west coast of northern Sumatra, Indonesia. Approximately 1300 people were killed by the earthquake, mostly on the island of Nias...
and 2007, most of them being associated with devastating tsunamis. Smaller (but still large) megathrust events have also occurred in the small gaps between the areas that slip during the larger events, in 1935
1935 Sumatra earthquake
The 1935 Sumatra earthquake occurred at 02:35 UTC on 28 December 1935. It had a magnitude of Mw = 7.7 and a maximum felt intensity of VIII on the mercalli intensity scale. It triggered a minor tsunami.-Tectonic setting:...
, 1984
1984 Northern Sumatra earthquake
The 1984 Northern Sumatra earthquake occurred on November 17, 1984 at 06:49 UTC. The epicenter was located off the coast of Sumatra, near the island of Nias. It was an Mw 7.2 earthquake. Building damage was reported in Nias island. This earthquake could be strongly felt in parts of Northern...
, 2000
2000 Sumatra earthquake
The 2000 Sumatra earthquake struck at 23:30 local time on June 4, 2000 off the coast of southern Sumatra, Indonesia with a magnitude of 7.9 Mw. The United States Geological Survey reported 103 fatalities, in addition to 2,174 injured people...
and 2002.
Damage
The greatest effects were felt on the island of Simeulue, where 994 buildings were damaged, three people died and 65 were injured. The earthquake was also felt at TapaktuanTapaktuan
Tapaktuan is a town in the southwest of Aceh province. The city is the capital of South Aceh Regency.-Further reading:...
(VI
Mercalli intensity scale
The Mercalli intensity scale is a seismic scale used for measuring the intensity of an earthquake. It measures the effects of an earthquake, and is distinct from the moment magnitude M_w usually reported for an earthquake , which is a measure of the energy released...
'Strong'), Meulaboh
Meulaboh
Meulaboh is the capital of West Aceh Regency, Indonesia. Meulaboh is among the hardest hit areas by the 2004 Indian Ocean earthquake. Being just 150 km from the epicenter of the earthquake, Meulaboh was hit by tsunami, leaving the estimated deaths of 40,000 people out of 120,000...
and Singkil
Singkil, Indonesia
Singkil is a town in Aceh province of Indonesia and it is the seat of Aceh Singkil Regency....
(V 'Rather strong') in the Aceh
Aceh
Aceh is a special region of Indonesia, located on the northern tip of the island of Sumatra. Its full name is Daerah Istimewa Aceh , Nanggroë Aceh Darussalam and Aceh . Past spellings of its name include Acheh, Atjeh and Achin...
province of Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
.
Characteristics
The rupture area of the 2002 earthquake lies at the boundary between the rupture areas of the 2004 and 2005 earthquakes as determined by the uplift patterns or coral microatollMicroatoll
A microatoll is a discoid colony of coral, dead on the top but living around the perimeter. Growth is mainly lateral, as upward growth is limited by exposure to air. Microatolls may be up to in diameter. They are named for their resemblance to island atolls formed during the subsidence of...
s. From its proximity to the epicenter of the 2004 earthquake, it is regarded as a foreshock of that event. Microatolls around Simeulue show evidence of uplift as a result of the 2002 event, distinct from the uplift caused by the 2004 event.
Waveforms from this earthquake have been used to model the propagation of Rayleigh waves during the 2004 earthquake using an empirical Green's function
Green's function
In mathematics, a Green's function is a type of function used to solve inhomogeneous differential equations subject to specific initial conditions or boundary conditions...
analysis.