2004 Indian Ocean earthquake
Overview
 
The 2004 Indian Ocean earthquake was an undersea
Submarine earthquake
A submarine, undersea, or underwater earthquake is an earthquake that occurs underwater at the bottom of a body of water, especially an ocean. They are the leading cause of tsunamis...

 megathrust earthquake
Megathrust earthquake
Megathrust earthquakes occur at subduction zones at destructive plate boundaries , where one tectonic plate is forced under another. Due to the shallow dip of the plate boundary, which causes large sections to get stuck, these earthquakes are among the world's largest, with moment magnitudes ...

 that occurred at 00:58:53 UTC
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 Sunday, December 26, 2004, with an epicentre off the west coast 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...

, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

. The quake itself is known by the scientific community
Scientific community
The scientific community consists of the total body of scientists, its relationships and interactions. It is normally divided into "sub-communities" each working on a particular field within science. Objectivity is expected to be achieved by the scientific method...

 as the Sumatra-Andaman earthquake. The resulting tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

 is given various names, including the 2004 Indian Ocean tsunami, South Asian Tsunami, Indonesian Tsunami, and Boxing Day
Boxing Day
Boxing Day is a bank or public holiday that occurs on 26 December, or the first or second weekday after Christmas Day, depending on national or regional laws. It is observed in Australia, Canada, New Zealand, the United Kingdom and some other Commonwealth nations. In Ireland, it is recognized as...

 Tsunami
.

The earthquake was caused by subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

 and triggered a series of devastating tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

s along the coasts of most landmasses bordering the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

, killing over 230,000 people in fourteen countries, and inundating coastal communities with waves up to 30 metres (98.4 ft) high.
Encyclopedia
The 2004 Indian Ocean earthquake was an undersea
Submarine earthquake
A submarine, undersea, or underwater earthquake is an earthquake that occurs underwater at the bottom of a body of water, especially an ocean. They are the leading cause of tsunamis...

 megathrust earthquake
Megathrust earthquake
Megathrust earthquakes occur at subduction zones at destructive plate boundaries , where one tectonic plate is forced under another. Due to the shallow dip of the plate boundary, which causes large sections to get stuck, these earthquakes are among the world's largest, with moment magnitudes ...

 that occurred at 00:58:53 UTC
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 Sunday, December 26, 2004, with an epicentre off the west coast 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...

, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

. The quake itself is known by the scientific community
Scientific community
The scientific community consists of the total body of scientists, its relationships and interactions. It is normally divided into "sub-communities" each working on a particular field within science. Objectivity is expected to be achieved by the scientific method...

 as the Sumatra-Andaman earthquake. The resulting tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

 is given various names, including the 2004 Indian Ocean tsunami, South Asian Tsunami, Indonesian Tsunami, and Boxing Day
Boxing Day
Boxing Day is a bank or public holiday that occurs on 26 December, or the first or second weekday after Christmas Day, depending on national or regional laws. It is observed in Australia, Canada, New Zealand, the United Kingdom and some other Commonwealth nations. In Ireland, it is recognized as...

 Tsunami
.

The earthquake was caused by subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

 and triggered a series of devastating tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

s along the coasts of most landmasses bordering the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

, killing over 230,000 people in fourteen countries, and inundating coastal communities with waves up to 30 metres (98.4 ft) high. It was one of the deadliest natural disasters in recorded history. Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

 was the hardest hit, followed by Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, and Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

.

With a magnitude
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...

 of Mw 9.1–9.3, it is the third largest earthquake ever recorded on a seismograph. This earthquake had the longest duration of faulting ever observed, between 8.3 and 10 minutes. It caused the entire planet to vibrate as much as 1 centimetre (0.393700787401575 in) and triggered other earthquakes as far away as Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

. Its epicentre was between Simeulue
Simeulue
Simeulue Regency is a regency in the Aceh province of Indonesia. It occupies the whole island of Simeulue , 150 km off the west coast of Sumatra, with a population of 80,279 ....

 and mainland Indonesia.

The plight of the affected people and countries
Countries affected by the 2004 Indian Ocean earthquake
This article lists the countries affected by the 2004 Indian Ocean earthquake and the resulting tsunami in alphabetical order – for detailed information about each country see their individual articles...

 prompted a worldwide humanitarian response
Humanitarian response to the 2004 Indian Ocean earthquake
The humanitarian response to the 2004 Indian Ocean earthquake was prompted by one of the worst natural disasters of modern times. On 26 December 2004, the earthquake, which struck off the northwest coast of the Indonesian island of Sumatra, generated a tsunami that wreaked havoc along much of the...

. In all, the worldwide community donated more than $14 billion (2004 U.S. dollars
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....

) in humanitarian aid.

Earthquake characteristics

The 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...

 was initially documented as moment magnitude
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...

 8.8. In February 2005 scientists revised the estimate of the magnitude to 9.0. Although the Pacific Tsunami Warning Center
Pacific Tsunami Warning Center
The Pacific Tsunami Warning Center is one of two tsunami warning centers that are operated by NOAA in the United States. Headquartered in Ewa Beach, Hawaii, the PTWC is part of an international tsunami warning system program and serves as the operational center for TWS of the Pacific issuing...

 has accepted these new numbers, the United States Geological Survey
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...

 has so far not changed its estimate of 9.1. The most recent studies in 2006 have obtained a magnitude of Mw 9.1–9.3. Dr. Hiroo Kanamori
Hiroo Kanamori
is a Japanese American seismologist who has made fundamental contributions to understanding the physics of earthquakes and the tectonic processes that cause them....

 of the California Institute of Technology
California Institute of Technology
The California Institute of Technology is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering...

 believes that Mw 9.2 is a good representative value for the size of this great earthquake.

The hypocentre of the main earthquake was approximately 160 km (99.4 mi), in the Indian Ocean just north of Simeulue
Simeulue
Simeulue Regency is a regency in the Aceh province of Indonesia. It occupies the whole island of Simeulue , 150 km off the west coast of Sumatra, with a population of 80,279 ....

 island, off the western coast of northern Sumatra, at a depth of 30 km (18.6 mi) below mean sea level (initially reported as 10 km (6.2 mi)). The northern section of 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...

, which had been assumed dormant, ruptured; the rupture having a length of 1300 km (807.8 mi). The earthquake (followed by the tsunami) was felt simultaneously as far away as Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...

, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, Malaysia, Myanmar
Myanmar
Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....

, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

, Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...

 and the Maldives
Maldives
The Maldives , , officially Republic of Maldives , also referred to as the Maldive Islands, is an island nation in the Indian Ocean formed by a double chain of twenty-six atolls oriented north-south off India's Lakshadweep islands, between Minicoy Island and...

. Splay faults, or secondary "pop up faults", caused long, narrow parts of the sea floor to pop up in seconds. This quickly elevated the height and increased the speed of waves, causing the complete destruction of the nearby Indonesian town of Lhoknga
Lhoknga
Lhoknga, , is a town in the subdistrict of Aceh Besar, Aceh, Indonesia, located on the western side of the island of Sumatra, 13 km southwest of Banda Aceh. It was completely flattened and destroyed by the 2004 Boxing Day Tsunami, where its population dwindled from 7500 to 400...

.
Indonesia lies between the Pacific Ring of Fire
Pacific Ring of Fire
The Pacific Ring of Fire is an area where large numbers of earthquakes and volcanic eruptions occur in the basin of the Pacific Ocean. In a horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and/or plate movements...

 along the north-eastern islands adjacent to and including New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...

 and the Alpide belt
Alpide belt
The Alpide belt is a mountain range which extends along the southern margin of Eurasia. Stretching from Java to Sumatra through the Himalayas, the Mediterranean, and out into the Atlantic, it includes the Alps, the Carpathians, the mountains of Asia Minor and Iran, the Hindu Kush, the Himalayas,...

 along the south and west from 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...

, Java, Bali
Bali
Bali is an Indonesian island located in the westernmost end of the Lesser Sunda Islands, lying between Java to the west and Lombok to the east...

, Flores
Flores
Flores is one of the Lesser Sunda Islands, an island arc with an estimated area of 14,300 km² extending east from the Java island of Indonesia. The population was 1.831.000 in the 2010 census and the largest town is Maumere. Flores is Portuguese for "flowers".Flores is located east of Sumbawa...

, and Timor
Timor
Timor is an island at the southern end of Maritime Southeast Asia, north of the Timor Sea. It is divided between the independent state of East Timor, and West Timor, belonging to the Indonesian province of East Nusa Tenggara. The island's surface is 30,777 square kilometres...

.

Great earthquakes such as the Sumatra-Andaman event, which are invariably associated with megathrust events in subduction zones, have seismic moment
Seismic moment
Seismic moment is a quantity used by earthquake seismologists to measure the size of an earthquake. The scalar seismic moment M_0 is defined by the equationM_0=\mu AD, where*\mu is the shear modulus of the rocks involved in the earthquake...

s that can account for a significant fraction of the global earthquake moment across century-scale time periods. The Sumatra-Andaman earthquake was the largest earthquake since 1964, and the second largest since the Kamchatka earthquake
Kamchatka earthquakes
3 earthquakes, which occurred off the coast of Kamchatka Peninsula in far eastern Russia in 1737, 1923 and 1952, were megathrust earthquakes and caused tsunamis. They occurred where the Pacific Plate subducts under the Okhotsk Plate at the Kuril-Kamchatka Trench. The depth of the trench at the...

 of October 16, 1737.

Of all the seismic moment
Seismic moment
Seismic moment is a quantity used by earthquake seismologists to measure the size of an earthquake. The scalar seismic moment M_0 is defined by the equationM_0=\mu AD, where*\mu is the shear modulus of the rocks involved in the earthquake...

 released by earthquakes in the 100 years from 1906 through 2005, roughly one-eighth was due to the Sumatra-Andaman event. This quake, together with the Good Friday Earthquake
Good Friday Earthquake
The 1964 Alaska earthquake, also known as the Great Alaskan Earthquake, the Portage Earthquake and the Good Friday Earthquake, was a megathrust earthquake that began at 5:36 P.M. AST on Good Friday, March 27, 1964...

 (Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

, 1964) and the Great Chilean Earthquake
Great Chilean Earthquake
The 1960 Valdivia earthquake or Great Chilean Earthquake of Sunday, 22 May 1960 is to date the most powerful earthquake ever recorded on Earth, rating 9.5 on the moment magnitude scale...

 (1960), account for almost half of the total moment. The much smaller but still catastrophic 1906 San Francisco earthquake
1906 San Francisco earthquake
The San Francisco earthquake of 1906 was a major earthquake that struck San Francisco, California, and the coast of Northern California at 5:12 a.m. on Wednesday, April 18, 1906. The most widely accepted estimate for the magnitude of the earthquake is a moment magnitude of 7.9; however, other...

 is included in the diagram below for perspective. Mw denotes the magnitude of an earthquake 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...

.

Since 1900 the only earthquakes recorded with a greater magnitude were the 1960 Great Chilean Earthquake
Great Chilean Earthquake
The 1960 Valdivia earthquake or Great Chilean Earthquake of Sunday, 22 May 1960 is to date the most powerful earthquake ever recorded on Earth, rating 9.5 on the moment magnitude scale...

 (magnitude 9.5) and the 1964 Good Friday Earthquake
Good Friday Earthquake
The 1964 Alaska earthquake, also known as the Great Alaskan Earthquake, the Portage Earthquake and the Good Friday Earthquake, was a megathrust earthquake that began at 5:36 P.M. AST on Good Friday, March 27, 1964...

 in Prince William Sound
Prince William Sound
Prince William Sound is a sound off the Gulf of Alaska on the south coast of the U.S. state of Alaska. It is located on the east side of the Kenai Peninsula. Its largest port is Valdez, at the southern terminus of the Trans-Alaska Pipeline System...

 (9.2). The only other recorded earthquakes of magnitude 9.0 or greater were off Kamchatka
Kamchatka Peninsula
The Kamchatka Peninsula is a peninsula in the Russian Far East, with an area of . It lies between the Pacific Ocean to the east and the Sea of Okhotsk to the west...

, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, on November 4, 1952 (magnitude 9.0) and Tōhoku, Japan
2011 Tōhoku earthquake and tsunami
The 2011 earthquake off the Pacific coast of Tohoku, also known as the 2011 Tohoku earthquake, or the Great East Japan Earthquake, was a magnitude 9.0 undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST on Friday, 11 March 2011, with the epicenter approximately east...

 (magnitude 9.0) on March 11, 2011. Each of these megathrust earthquake
Megathrust earthquake
Megathrust earthquakes occur at subduction zones at destructive plate boundaries , where one tectonic plate is forced under another. Due to the shallow dip of the plate boundary, which causes large sections to get stuck, these earthquakes are among the world's largest, with moment magnitudes ...

s also spawned tsunamis in the Pacific Ocean. However, the death toll from these was significantly lower, primarily because of the lower population density
Population density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...

 along the coasts near affected areas and the much greater distances to more populated coasts and also due to the superior infrastructure and warning systems in MEDCs (More Economically Developed Countries) such as Japan.

Other very large megathrust earthquakes occurred in 1868 (Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

, Nazca Plate
Nazca Plate
]The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction along the Peru-Chile Trench of the Nazca Plate under the South American Plate is largely responsible for the...

 and South American Plate
South American Plate
The South American Plate is a continental tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the Mid-Atlantic Ridge....

); 1827 (Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

, Nazca Plate and South American Plate); 1812 (Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...

, Caribbean Plate
Caribbean Plate
The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the north coast of South America....

 and South American Plate) and 1700 (western North America, Juan de Fuca Plate
Juan de Fuca Plate
The Juan de Fuca Plate, named after the explorer of the same name, is a tectonic plate, generated from the Juan de Fuca Ridge, and subducting under the northerly portion of the western side of the North American Plate at the Cascadia subduction zone...

 and North American Plate
North American Plate
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...

). All of them are believed to be greater than magnitude 9, but no accurate measurements were available at the time.

Tectonic plates

The megathrust earthquake
Megathrust earthquake
Megathrust earthquakes occur at subduction zones at destructive plate boundaries , where one tectonic plate is forced under another. Due to the shallow dip of the plate boundary, which causes large sections to get stuck, these earthquakes are among the world's largest, with moment magnitudes ...

 was unusually large in geographical and geological extent. An estimated 1600 kilometres (994.2 mi) of fault surface slipped (or ruptured) about 15 metres (49.2 ft) along the subduction zone where the India Plate
India Plate
The India Plate or Indian Plate is a tectonic plate that was originally a part of the ancient continent of Gondwanaland from which it split off, eventually becoming a major plate. About 50 to 55 million years ago , it fused with the adjacent Australian Plate...

 slides (or subducts) under the overriding Burma Plate
Burma Plate
The Burma Plate is a small tectonic plate or microplate located in Southeast Asia, often considered a part of the larger Eurasian Plate. The Andaman Islands, Nicobar Islands, and northwestern Sumatra are located on the plate...

. The slip did not happen instantaneously but took place in two phases over a period of several minutes:
  • Seismographic and acoustic data indicate that the first phase involved a rupture about 400 kilometres (248.5 mi) long and 100 kilometres (62.1 mi) wide, located 30 kilometres (18.6 mi) beneath the sea bed—the largest rupture ever known to have been caused by an earthquake. The rupture proceeded at a speed of about 2.8 km/s (10000 kilometre per hour), beginning off the coast of 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...

     and proceeding north-westerly over a period of about 100 seconds.
  • A pause of about another 100 seconds took place before the rupture continued northwards towards the Andaman
    Andaman Islands
    The Andaman Islands are a group of Indian Ocean archipelagic islands in the Bay of Bengal between India to the west, and Burma , to the north and east...

     and Nicobar Islands
    Nicobar Islands
    The Nicobar Islands are an archipelagic island chain in the eastern Indian Ocean...

    . However, the northern rupture occurred more slowly than in the south, at about 2.1 km/s (7500 km/h or 4,660.3 mph), continuing north for another five minutes to a plate boundary where the fault type changes from subduction to strike-slip (the two plates slide past one another in opposite directions).


The India Plate
India Plate
The India Plate or Indian Plate is a tectonic plate that was originally a part of the ancient continent of Gondwanaland from which it split off, eventually becoming a major plate. About 50 to 55 million years ago , it fused with the adjacent Australian Plate...

 is part of the great 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...

, which underlies the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and Bay of Bengal
Bay of Bengal
The Bay of Bengal , the largest bay in the world, forms the northeastern part of the Indian Ocean. It resembles a triangle in shape, and is bordered mostly by the Eastern Coast of India, southern coast of Bangladesh and Sri Lanka to the west and Burma and the Andaman and Nicobar Islands to the...

, and is drifting north-east at an average of 6 centimetres per year (6 centimetres (2.4 in) inches per year). The India Plate meets the Burma Plate
Burma Plate
The Burma Plate is a small tectonic plate or microplate located in Southeast Asia, often considered a part of the larger Eurasian Plate. The Andaman Islands, Nicobar Islands, and northwestern Sumatra are located on the plate...

 (which is considered a portion of the great 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...

) at the Sunda Trench. At this point the India Plate subducts beneath the Burma Plate, which carries the Nicobar Islands
Nicobar Islands
The Nicobar Islands are an archipelagic island chain in the eastern Indian Ocean...

, the Andaman Islands
Andaman Islands
The Andaman Islands are a group of Indian Ocean archipelagic islands in the Bay of Bengal between India to the west, and Burma , to the north and east...

, and northern 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...

. The India Plate sinks deeper and deeper beneath the Burma Plate until the increasing temperature and pressure drive volatiles
Volatiles
In planetary science, volatiles are that group of chemical elements and chemical compounds with low boiling points that are associated with a planet's or moon's crust and/or atmosphere. Examples include nitrogen, water, carbon dioxide, ammonia, hydrogen, and methane, all compounds of C, H, O...

 out of the subducting plate. These volatiles rise into the overlying plate causing partial melting
Partial melting
Partial melting occurs when only a portion of a solid is melted. For mixed substances, such as a rock containing several different minerals or a mineral that displays solid solution, this melt can be different from the bulk composition of the solid....

 and the formation of magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...

. The rising magma intrudes into the crust above and exits the Earth's crust through volcanoes in the form of a volcanic arc
Volcanic arc
A volcanic arc is a chain of volcanoes positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in a volcanic island arc. Generally they result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench...

. The volcanic activity that results as the Indo-Australian Plate subducts 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...

 has created the Sunda Arc
Sunda Arc
The Sunda Arc is a volcanic arc that has produced the islands of Sumatra and Java, the Sunda Strait and the Lesser Sunda Islands. A chain of volcanoes forms the topographic spine of these islands...

.

As well as the sideways movement between the plates, the sea floor is estimated to have risen by several metres, displacing an estimated 30 cubic kilometres (7.2 cu mi) of water and triggering devastating tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

 waves. The waves did not originate from a point source
Point source
A point source is a localised, relatively small source of something.Point source may also refer to:*Point source , a localised source of pollution**Point source water pollution, water pollution with a localized source...

, as was inaccurately depicted in some illustrations of their paths of travel, but rather radiated outwards along the entire 1600 kilometres (994.2 mi) length of the rupture (acting as a line source
Line source
A line source is a source of air, noise, water contamination or electromagnetic radiation that emanates from a linear geometry...

). This greatly increased the geographical area over which the waves were observed, reaching as far as Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, and the Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...

. The raising of the sea floor significantly reduced the capacity of the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

, producing a permanent rise in the global sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...

 by an estimated 0.1 millimetre (0.00393700787401575 in).

Aftershocks and other earthquakes

Numerous aftershock
Aftershock
An aftershock is a smaller earthquake that occurs after a previous large earthquake, in the same area of the main shock. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock...

s were reported off the Andaman Islands
Andaman Islands
The Andaman Islands are a group of Indian Ocean archipelagic islands in the Bay of Bengal between India to the west, and Burma , to the north and east...

, the Nicobar Islands
Nicobar Islands
The Nicobar Islands are an archipelagic island chain in the eastern Indian Ocean...

 and the region of the original epicentre in the hours and days that followed. The magnitude 8.7 2005 Sumatra earthquake
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...

, which originated off the coast of the Sumatran island of Nias
Nias
Nīas is an island off the western coast of Sumatra, Indonesia. Nias is also the name of the archipelago, containing the Hinako archipelago....

, is not considered an aftershock, despite its proximity to the epicenter, and was most likely triggered by stress changes associated with the 2004 event. This earthquake was so large that it produced its own aftershocks (some registering a magnitude of as great as 6.1) and presently ranks as the 7th largest earthquake on record since 1900. Other aftershocks of up to magnitude 6.6 continued to shake the region daily for up to three or four months. As well as continuing aftershocks, the energy released by the original earthquake continued to make its presence felt well after the event. A week after the earthquake, its reverberations could still be measured, providing valuable scientific data about the Earth's interior.

The 2004 Indian Ocean earthquake came just three days after a magnitude 8.1 earthquake in an uninhabited region west of New Zealand's sub-Antarctic Auckland Islands
Auckland Islands
The Auckland Islands are an archipelago of the New Zealand Sub-Antarctic Islands and include Auckland Island, Adams Island, Enderby Island, Disappointment Island, Ewing Island, Rose Island, Dundas Island and Green Island, with a combined area of...

, and north of Australia's Macquarie Island
Macquarie Island
Macquarie Island lies in the southwest corner of the Pacific Ocean, about half-way between New Zealand and Antarctica, at 54°30S, 158°57E. Politically, it has formed part of the Australian state of Tasmania since 1900 and became a Tasmanian State Reserve in 1978. In 1997 it became a world heritage...

. This is unusual, since earthquakes of magnitude 8 or more occur only about once per year on average. Some seismologists have speculated about a connection between these two earthquakes, saying that the former one might have been a catalyst to the Indian Ocean earthquake, as the two earthquakes happened on opposite sides of 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...

. However, the U.S. Geological Survey
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...

 sees no evidence of a causal relationship in this incident. Coincidentally, the earthquake struck almost exactly one year (to the hour) after a 6.6 magnitude earthquake killed an estimated 30,000 people in the city of Bam
Bam, Iran
Bam is a city in and the capital of Bam County, Kerman Province, Iran. At the 2006 census, its population was 73,823, in 19,572 families.The modern Iranian city of Bam surrounds the Bam citadel. Before the 2003 earthquake the official population count of the city was roughly 43,000. There are...

 in Iran
Iran
Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...

 on December 26, 2003.

Some scientists confirm that the December earthquake had activated Leuser Mountain
Mount Leuser
Mount Leuser is the tallest mountain in the Indonesian province of Aceh, with an elevation of .The Gunung Leuser National Park protects the mountain and its surrounding ecosystems. It has been confirmed by some scientists that 2004 Indian Ocean earthquake has activated the volcano...

, a volcano in Aceh province along the same range of peaks as Mount Talang
Mount Talang
Mount Talang is an active stratovolcano in West Sumatra, Indonesia. Talang has two crater lakes on its flanks, the largest of which is 1 x 2 km wide and is called Lake Talang....

, while the 2005 Sumatra earthquake
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...

 had sparked activity in Lake Toba
Lake Toba
Lake Toba is a lake and supervolcano. The lake is 100 kilometres long and 30 kilometres wide, and 505 metres at its deepest point. Located in the middle of the northern part of the Indonesian island of Sumatra with a surface elevation of about , the lake stretches from to...

, an ancient crater in Sumatra. Geologists say that the eruption of Mount Talang
Mount Talang
Mount Talang is an active stratovolcano in West Sumatra, Indonesia. Talang has two crater lakes on its flanks, the largest of which is 1 x 2 km wide and is called Lake Talang....

 in April 2005 is connected to the December earthquake.

Energy released

The energy released on the Earth's surface only (ME, which is the seismic potential for damage) by the 2004 Indian Ocean earthquake and tsunami was estimated at 1.1×1017 joule
Joule
The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...

s, or 26.3 megatons of TNT. This energy is equivalent to over 1502 times that of the Hiroshima atomic bomb, but less than that of Tsar Bomba
Tsar Bomba
Tsar Bomba is the nickname for the AN602 hydrogen bomb, the most powerful nuclear weapon ever detonated. It was also referred to as Kuz'kina Mat , in this usage meaning "something that has not been seen before"....

, the largest nuclear weapon ever detonated. However, this is but a tiny fraction of the total work
Mechanical work
In physics, work is a scalar quantity that can be described as the product of a force times the distance through which it acts, and it is called the work of the force. Only the component of a force in the direction of the movement of its point of application does work...

 done MW (and thus energy) by this quake, 4.0×1022 joule
Joule
The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...

s (4.0×1029 erg
Erg
An erg is the unit of energy and mechanical work in the centimetre-gram-second system of units, symbol "erg". Its name is derived from the Greek ergon, meaning "work"....

s), the vast majority underground. This equates to 4.0×1022 J, over 363,000 times more than its ME. This is a truly enormous figure, equivalent to 9,560 gigatons of TNT equivalent
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...

 (550 million times that of Hiroshima), or about 370 years of energy use in the United States
Energy use in the United States
The United States is the 2nd largest energy consumer in terms of total use in 2010 . The U.S. ranks seventh in energy consumption per-capita after Canada and a number of small countries....

 at 2005 levels of 1.08×1020 J.

The only recorded earthquakes with a larger MW were the 1960 Chilean and 1964 Alaskan quakes, with 2.5×1023 joules (250 ZJ) and 7.5×1022 joules (75 ZJ) respectively.

The earthquake generated a seismic oscillation of the Earth's surface of up to 20–30 cm (7.9–11.8 in), equivalent to the effect of the tidal forces caused by the Sun and Moon. The shock waves of the earthquake were felt across the planet; as far away as the U.S. state of Oklahoma
Oklahoma
Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...

, where vertical movements of 3 mm (0.118110236220472 in) were recorded. By February 2005, the earthquake's effects were still detectable as a 20 um complex harmonic oscillation of the Earth's surface, which gradually diminished and merged with the incessant free oscillation of the Earth more than 4 months after the earthquake.

Because of its enormous energy release and shallow rupture depth, the earthquake generated remarkable seismic ground motions around the globe, particularly due to huge Rayleigh (surface) elastic waves
Rayleigh wave
Rayleigh waves are a type of surface acoustic wave that travels on solids. They are produced on the Earth by earthquakes, in which case they are also known as "ground roll", or by other sources of seismic energy such as ocean waves an explosion or even a sledgehammer impact...

 that exceeded 1 cm (0.393700787401575 in) in vertical amplitude everywhere on Earth. The record section plot below displays vertical displacements of the Earth's surface recorded by seismometers from the IRIS/USGS Global Seismographic Network plotted with respect to time (since the earthquake initiation) on the horizontal axis, and vertical displacements of the Earth on the vertical axis (note the 1 cm scale bar at the bottom for scale). The seismograms are arranged vertically by distance from the epicenter in degrees. The earliest, lower amplitude, signal is that of the compressional (P) wave, which takes about 22 minutes to reach the other side of the planet (the antipode
Antipodes
In geography, the antipodes of any place on Earth is the point on the Earth's surface which is diametrically opposite to it. Two points that are antipodal to one another are connected by a straight line running through the centre of the Earth....

; in this case near Ecuador). The largest amplitude signals are seismic surface waves that reach the antipode after about 100 minutes. The surface waves can be clearly seen to reinforce near the antipode (with the closest seismic stations in Ecuador), and to subsequently encircle the planet to return to the epicentral region after about 200 minutes. A major aftershock (magnitude 7.1) can be seen at the closest stations starting just after the 200 minute mark. This aftershock would be considered a major earthquake under ordinary circumstances, but is dwarfed by the mainshock.

The shift of mass and the massive release of energy very slightly altered the Earth's rotation. The exact amount is not yet known, but theoretical models suggest the earthquake shortened the length of a day by 2.68 microsecond
Microsecond
A microsecond is an SI unit of time equal to one millionth of a second. Its symbol is µs.A microsecond is equal to 1000 nanoseconds or 1/1000 millisecond...

s, due to a decrease in the oblateness of the Earth. It also caused the Earth to minutely "wobble" on its axis by up to 2.5 cm (0.984251968503937 in) in the direction of 145° east longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

, or perhaps by up to 5 or. However, because of tidal effects of the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

, the length of a day increases at an average of 15 µs
Microsecond
A microsecond is an SI unit of time equal to one millionth of a second. Its symbol is µs.A microsecond is equal to 1000 nanoseconds or 1/1000 millisecond...

 per year, so any rotational change due to the earthquake will be lost quickly. Similarly, the natural Chandler wobble
Chandler wobble
The Chandler wobble is a small motion in the Earth's axis of rotation relative to the Earth's surface, which was discovered by American astronomer Seth Carlo Chandler in 1891. It amounts to on the Earth's surface and has a period of 433 days...

 of the Earth, which in some cases can be up to 15 m (49.2 ft), will eventually offset the minor wobble produced by the earthquake.

More spectacularly, there was 10 m (32.8 ft) movement laterally and 4 metre vertically along the fault line. Early speculation was that some of the smaller islands south-west of Sumatra, which is on the Burma Plate
Burma Plate
The Burma Plate is a small tectonic plate or microplate located in Southeast Asia, often considered a part of the larger Eurasian Plate. The Andaman Islands, Nicobar Islands, and northwestern Sumatra are located on the plate...

 (the southern regions are on the Sunda Plate
Sunda Plate
The Sunda Plate is the tectonic plate on which the majority of Southeast Asia is located. It was formerly considered a part of the Eurasian Plate, but GPS measurements have confirmed its independent movement at 10 mm/yr eastward relative to Eurasia...

), might have moved south-west by up to 36 m (118.1 ft), but more accurate data released more than a month after the earthquake found the movement to be about 20 cm (8 in). Since movement was vertical as well as lateral, some coastal areas may have been moved to below sea level. The Andaman and Nicobar Islands appear to have shifted south-west by around 1.25 metre and to have sunk by 1 metre.

In February 2005, the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 vessel HMS Scott
HMS Scott (H131)
HMS Scott is an ocean survey vessel of the Royal Navy, and the only vessel of her class. She is the third Royal Navy ship to carry the name, and the second to be named after the Antarctic explorer, Robert Falcon Scott. She was ordered to replace the survey ship HMS Hecla.-Construction:She was...

 surveyed the seabed around the earthquake zone, which varies in depth between 1000 m (546.8 fathom; 3,280.8 ft). The survey, conducted using a high-resolution, multi-beam sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

 system, revealed that the earthquake had made a huge impact on the topography of the seabed. 1500 metres (4,921.3 ft) thrust ridges created by previous geologic activity along the fault had collapsed, generating landslides several kilometers wide. One such landslide consisted of a single block of rock some 100 m high and 2 km long (300 ft by 1.25 mi). The momentum of the water displaced by tectonic uplift had also dragged massive slabs of rock, each weighing millions of tons, as far as 10 km (6 mi) across the seabed. An oceanic trench
Oceanic trench
The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. They are also the deepest parts of the ocean floor....

 several kilometres wide was exposed in the earthquake zone.

The TOPEX/Poseidon
TOPEX/Poseidon
Launched in 1992, TOPEX/Poseidon was a joint satellite mission between NASA, the U.S. space agency, and CNES, the French space agency, to map ocean surface topography. The first major oceanographic research vessel to sail into space, TOPEX/Poseidon helped revolutionize oceanography by proving the...

 and Jason 1
Jason 1
Jason-1 is a satellite oceanography mission to monitor global ocean circulation, study the ties between the ocean and the atmosphere, improve global climate forecasts and predictions, and monitor events such as El Niño and ocean eddies....

 satellites happened to pass over the tsunami as it was crossing the ocean. These satellites carry radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

s that measure precisely the height of the water surface; anomalies of the order of 50 cm (19.7 in) were measured. Measurements from these satellites may prove invaluable for the understanding of the earthquake and tsunami. Unlike data from tide gauge
Tide gauge
A tide gauge is a device for measuring sea level and detecting tsunamis.Sensors continuously record the height of the water level with respect to a height reference surface close to the geoid...

s installed on shores, measurements obtained in the middle of the ocean can be used for computing the parameters of the source earthquake without having to compensate for the complex ways in which close proximity to the coast changes the size and shape of a wave.

Tsunami characteristics

The sudden vertical rise of the seabed
Seabed
The seabed is the bottom of the ocean.- Ocean structure :Most of the oceans have a common structure, created by common physical phenomena, mainly from tectonic movement, and sediment from various sources...

 by several metres during the earthquake displaced massive volumes of water, resulting in a tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

 that struck the coasts of the Indian Ocean. A tsunami which causes damage far away from its source is sometimes called a teletsunami
Teletsunami
A teletsunami is a tsunami that originates from a distant source, which is more than 1,000 km away from the area of interest . A teletsunami can travel across an entire ocean...

 and is much more likely to be produced by vertical motion of the seabed than by horizontal motion.

The tsunami, like all others, behaved very differently in deep water than in shallow water. In deep ocean water, tsunami waves form only a small hump, barely noticeable and harmless, which generally travels at a very high speed of 500 to 1000 km/h (310.7 to 621.4 mph); in shallow water near coastlines, a tsunami slows down to only tens of kilometres per hour, but in doing so forms large destructive waves. Scientists investigating the damage in Aceh found evidence that the wave reached a height of 24 metres (78.7 ft) when coming ashore along large stretches of the coastline, rising to 30 metres (98.4 ft) in some areas when travelling inland.

Radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 satellites recorded the heights of tsunami waves in deep water: at two hours after the earthquake, the maximum height was 60 centimetres (2 ft). These are the first such observations ever made. Unfortunately these observations could not be used to provide a warning, since the satellites were not built for that purpose and the data took hours to analyze.

According to Tad Murty
Tad Murty
Tad S. Murty is an Indian-Canadian oceanographer and expert on tsunamis. He is the former president of the Tsunami Society. He is an adjunct professor in the departments of Civil Engineering and Earth Sciences at the University of Ottawa...

, vice-president of the Tsunami Society
Tsunami Society
The Tsunami Society, also known as the International Tsunami Society, is a professional society for the research of and dissemination of knowledge about tsunamis. The society was founded in Honolulu, Hawaii in 1982...

, the total energy of the tsunami waves was equivalent to about five megatons
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...

 of TNT (20 petajoules). This is more than twice the total explosive energy used during all of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 (including the two atomic bombs), but still a couple of orders of magnitude
Order of magnitude
An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. In its most common usage, the amount being scaled is 10 and the scale is the exponent being applied to this amount...

 less than the energy released in the earthquake itself. In many places the waves reached as far as 2 km (1.2 mi) inland.
Because the 1600 km (994.2 mi) fault affected by the earthquake was in a nearly north-south orientation, the greatest strength of the tsunami waves was in an east-west direction. Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...

, which lies at the northern end of the Bay of Bengal
Bay of Bengal
The Bay of Bengal , the largest bay in the world, forms the northeastern part of the Indian Ocean. It resembles a triangle in shape, and is bordered mostly by the Eastern Coast of India, southern coast of Bangladesh and Sri Lanka to the west and Burma and the Andaman and Nicobar Islands to the...

, had very few casualties despite being a low-lying country relatively near the epicenter. It also benefited from the fact that the earthquake proceeded more slowly in the northern rupture zone, greatly reducing the energy of the water displacements in that region.

Coasts that have a landmass between them and the tsunami's location of origin are usually safe; however, tsunami waves can sometimes diffract
Diffraction
Diffraction refers to various phenomena which occur when a wave encounters an obstacle. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1665...

 around such landmasses. Thus, the Indian state of Kerala
Kerala
or Keralam is an Indian state located on the Malabar coast of south-west India. It was created on 1 November 1956 by the States Reorganisation Act by combining various Malayalam speaking regions....

 was hit by the tsunami despite being on the western coast of India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, and the western coast of Sri Lanka also suffered substantial impacts. Also distance alone was no guarantee of safety; Somalia
Somalia
Somalia , officially the Somali Republic and formerly known as the Somali Democratic Republic under Socialist rule, is a country located in the Horn of Africa. Since the outbreak of the Somali Civil War in 1991 there has been no central government control over most of the country's territory...

 was hit harder than Bangladesh despite being much farther away.

Because of the distances involved, the tsunami took anywhere from fifteen minutes to seven hours (for Somalia
Somalia
Somalia , officially the Somali Republic and formerly known as the Somali Democratic Republic under Socialist rule, is a country located in the Horn of Africa. Since the outbreak of the Somali Civil War in 1991 there has been no central government control over most of the country's territory...

) to reach the various coastlines. The northern regions of the Indonesian island of Sumatra were hit very quickly, while Sri Lanka and the east coast of India were hit roughly 90 minutes to two hours later. Thailand was also struck about two hours later despite being closer to the epicentre, because the tsunami travelled more slowly in the shallow Andaman Sea
Andaman Sea
The Andaman Sea or Burma Sea is a body of water to the southeast of the Bay of Bengal, south of Burma, west of Thailand and east of the Andaman Islands, India; it is part of the Indian Ocean....

 off its western coast.

The tsunami was noticed as far as Struisbaai
Struisbaai
Struisbaai is a coastal settlement in the Overberg region of South Africa's Western Cape province. The town is two hours South from Cape Town in the Cape Agulhas Local Municipality within the Overberg District, and four kilometers from the southernmost point of the African continent at Cape...

 in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, some 8500 km (5,281.7 mi) away, where a 1.5 m (5 ft) high tide surged on shore about 16 hours after the earthquake. It took a relatively long time to reach this spot at the southernmost point of Africa, probably because of the broad continental shelf off South Africa and because the tsunami would have followed the South African coast from east to west. The tsunami also reached Antarctica, where tidal gauges at Japan's Showa Base recorded oscillations of up to a metre (1 metre), with disturbances lasting a couple of days.

Some of the tsunami's energy escaped into the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, where it produced small but measurable tsunamis along the western coasts of North and South America, typically around 20 centimetre. At Manzanillo
Manzanillo, Colima
The name Manzanillo refers to the city as well as its surrounding municipality in the Mexican state of Colima. The city, located on the Pacific Ocean, contains Mexico's busiest port. Manzanillo was the third port created by the Spanish in the Pacific during the New Spain period...

, Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, a 2.6 m (8.5 ft) crest-to-trough tsunami was measured. As well, the tsunami was large enough to be detected in Vancouver
Vancouver
Vancouver is a coastal seaport city on the mainland of British Columbia, Canada. It is the hub of Greater Vancouver, which, with over 2.3 million residents, is the third most populous metropolitan area in the country,...

, British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

. This puzzled many scientists, as the tsunamis measured in some parts of South America were larger than those measured in some parts of the Indian Ocean. It has been theorized that the tsunamis were focused and directed at long ranges by the mid-ocean ridge
Mid-ocean ridge
A mid-ocean ridge is a general term for an underwater mountain system that consists of various mountain ranges , typically having a valley known as a rift running along its spine, formed by plate tectonics. This type of oceanic ridge is characteristic of what is known as an oceanic spreading...

s which run along the margins of the continental plates.

Signs and warnings

Despite a lag of up to several hours between the earthquake and the impact of the tsunami, nearly all of the victims were taken completely by surprise. There were no tsunami warning system
Tsunami warning system
A Tsunami warning system is used to detect tsunamis in advance and issue warnings to prevent loss of life and damage. It consists of two equally important components: a network of sensors to detect tsunamis and a communications infrastructure to issue timely alarms to permit evacuation of coastal...

s in the Indian Ocean to detect tsunamis or to warn the general populace living around the ocean. Tsunami detection is not easy because while a tsunami is in deep water it has little height and a network of sensors is needed to detect it. Setting up the communications infrastructure to issue timely warnings is an even bigger problem, particularly in a relatively poor part of the world.

Tsunamis are much more frequent in the Pacific Ocean because of earthquakes in the "Ring of Fire
Pacific Ring of Fire
The Pacific Ring of Fire is an area where large numbers of earthquakes and volcanic eruptions occur in the basin of the Pacific Ocean. In a horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and/or plate movements...

", and an effective tsunami warning system has long been in place there. Although the extreme western edge of the Ring of Fire extends into the Indian Ocean (the point where this earthquake struck), no warning system exists in that ocean. Tsunamis there are relatively rare despite earthquakes being relatively frequent in Indonesia. The last major tsunami was caused by the Krakatoa
Krakatoa
Krakatoa is a volcanic island made of a'a lava in the Sunda Strait between the islands of Java and Sumatra in Indonesia. The name is used for the island group, the main island , and the volcano as a whole. The island exploded in 1883, killing approximately 40,000 people, although some estimates...

 eruption of 1883. It should be noted that not every earthquake produces large tsunamis; on March 28, 2005, a magnitude 8.7 earthquake hit roughly the same area of the Indian Ocean but did not result in a major tsunami.

In the aftermath of the disaster, there is now an awareness of the need for a tsunami warning system for the Indian Ocean. The United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...

 started working on an Indian Ocean Tsunami Warning System
Indian Ocean Tsunami Warning System
The Indian Ocean Tsunami Warning System is a tsunami warning system set up to provide warning to inhabitants of nations bordering the Indian Ocean of approaching tsunamis. It was agreed to in a United Nations conference held in January 2005 in Kobe, Japan as an initial step towards an International...

 and by 2005 had the initial steps in place. Some have even proposed creating a unified global tsunami warning system, to include the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 and Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

.

The first warning sign of a possible tsunami is the earthquake itself. However, tsunami can strike thousands of kilometres away where the earthquake is only felt weakly or not at all. Also, in the minutes preceding a tsunami strike, the sea often recedes temporarily from the coast. Around the Indian Ocean, this rare sight reportedly induced people, especially children, to visit the coast to investigate and collect stranded fish on as much as 2.5 km (1.6 mi) of exposed beach, with fatal results. However, not all tsunami causes this "disappearing sea" effect. In some cases, there are no warning signs at all: the sea will suddenly swell without retreating, surprising many people and giving them little time to flee.

One of the few coastal areas to evacuate ahead of the tsunami was on the Indonesian island of Simeulue
Simeulue
Simeulue Regency is a regency in the Aceh province of Indonesia. It occupies the whole island of Simeulue , 150 km off the west coast of Sumatra, with a population of 80,279 ....

, very close to the epicentre. Island folklore recounted an earthquake and tsunami in 1907, and the islanders fled to inland hills after the initial shaking yet before the tsunami struck. On Maikhao beach in northern Phuket
Phuket City
Phuket is a city located in the southeast of Phuket Island, Thailand. It is the capital of the Phuket Province, covering all of the island. As of 2007 the city has a population of 75,573 people...

, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

, a 10-year-old British
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 tourist named Tilly Smith
Tilly Smith
Tilly Smith is a British girl who, at the age of 10, was credited with saving nearly a hundred foreign tourists at Maikhao Beach in Thailand by warning beachgoers minutes before the arrival of the tsunami caused by the 2004 Indian Ocean earthquake....

 had studied tsunami in geography at school and recognised the warning signs of the receding ocean and frothing bubbles. She and her parents warned others on the beach, which was evacuated safely. John Chroston
John Chroston
John Chroston, a biology teacher at Falkirk High School, Scotland, was one of the few tourists present during the Indian Ocean earthquake able to recognise tsunami warning signs and prompt a beach evacuation. John Chroston, a biology teacher at Falkirk High School, Scotland, was one of the few...

, a biology teacher from Scotland, also recognised the signs at Kamala Bay north of Phuket, taking a busload of vacationers and locals to safety on higher ground.

Anthropologists had initially expected the aboriginal population
Andamanese
The Andamanese people are the various aboriginal inhabitants of the Andaman Islands, which is the northern district of the Andaman and Nicobar Islands union territory of India, located in the southeastern part of the Bay of Bengal. They include the Great Andamanese, Jarawa, Onge, Sentinelese, and...

 of the Andaman Islands
Andaman Islands
The Andaman Islands are a group of Indian Ocean archipelagic islands in the Bay of Bengal between India to the west, and Burma , to the north and east...

 to be badly affected by the tsunami and even feared the already depopulated Onge tribe could have been wiped out. Of the six native tribes only the Nicobarese, who had converted to Christianity and taken up agriculture in place of their previous hunter-gatherer
Hunter-gatherer
A hunter-gatherer or forage society is one in which most or all food is obtained from wild plants and animals, in contrast to agricultural societies which rely mainly on domesticated species. Hunting and gathering was the ancestral subsistence mode of Homo, and all modern humans were...

 lifestyle, and mainland settlers suffered significant losses. Many of the aboriginal
Indigenous peoples
Indigenous peoples are ethnic groups that are defined as indigenous according to one of the various definitions of the term, there is no universally accepted definition but most of which carry connotations of being the "original inhabitants" of a territory....

 tribes evacuated and suffered fewer casualties.

Phases and wave form

A tsunami can arrive at a coastline in one of two ways. In the first form, a negative wave, a trough precedes the actual arrival of the crest or "wave" itself. Here, the more common and better recognized warning sign of an impending tsunami strike is a rapidly receding sea followed by a sudden onrushing body of water traveling inland at high speed.

The second form in which a tsunami arrives is the positive wave or crest first. In this case, the warning signs are much more vague if any. The sea will usually start rising immediately, slowly at first without the receding phase, like an on-coming high tide. However, instead of stopping at tidal level, the sea will keep rising faster and faster until the crest of the tsunami passes and continues moving inland. The second form of tsunami waves are usually more dangerous, since they can arrive without easily identifiable warning, giving residents less time to prepare and outrun the tsunami. These two types of tsunamis are usually generated simultaneously (in opposing direction of travel) by a megathrust earthquake
Megathrust earthquake
Megathrust earthquakes occur at subduction zones at destructive plate boundaries , where one tectonic plate is forced under another. Due to the shallow dip of the plate boundary, which causes large sections to get stuck, these earthquakes are among the world's largest, with moment magnitudes ...

 similar to the 2004 Indian Ocean earthquake.

Retreat-rise cycle (negative wave)

The tsunami was a succession of several waves, occurring in retreat and rise cycles with a period of over 30 minutes between each peak. The third wave was the most powerful and reached highest, occurring about an hour and a half after the first wave.

Rise-retreat-rise cycle (positive wave)

If the crest of a tsunami arrives first, there won't be any recession. The sea level will increase rapidly to inundate everything in the path of the tsunami. This appears to be the case in countries such as Sri Lanka and India that lies to the west of the Andaman-Sumatra fault where the tsunami originates.

Death toll and casualties

According to the U.S. Geological Survey a total of 227,898 people died (see table below for details). Measured in lives lost, this is one of the ten worst earthquakes in recorded history, as well as the single worst tsunami in history. Indonesia was the worst affected area, with most death toll estimates at around 170,000. However, another report by health minister Fadilah Supari has estimated the death total to be as high as 220,000 in Indonesia alone, giving a total of 280,000 casualties.

The tsunami caused serious damage and deaths as far as the east coast of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

, with the farthest recorded death due to the tsunami occurring at Rooi Els in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, 8000 km (4,971 mi) away from the epicentre. In total, eight people in South Africa died due to abnormally high sea levels and waves.

Relief agencies report that one-third of the dead appear to be children. This is a result of the high proportion of children in the populations of many of the affected regions and because children were the least able to resist being overcome by the surging waters. Oxfam
Oxfam
Oxfam is an international confederation of 15 organizations working in 98 countries worldwide to find lasting solutions to poverty and related injustice around the world. In all Oxfam’s actions, the ultimate goal is to enable people to exercise their rights and manage their own lives...

 went on to report that as many as four times more women than men were killed in some regions because they were waiting on the beach for the fishermen to return and looking after their children in the houses.

In an addition to the large number of local residents, up to 9,000 foreign tourists (mostly Europeans) enjoying the peak holiday travel season were among the dead or missing, especially people from the Nordic countries
Nordic countries
The Nordic countries make up a region in Northern Europe and the North Atlantic which consists of Denmark, Finland, Iceland, Norway and Sweden and their associated territories, the Faroe Islands, Greenland and Åland...

. The European nation hardest hit may have been Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

, whose death toll was 543.

States of emergency
State of emergency
A state of emergency is a governmental declaration that may suspend some normal functions of the executive, legislative and judicial powers, alert citizens to change their normal behaviours, or order government agencies to implement emergency preparedness plans. It can also be used as a rationale...

 were declared in Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

, and the Maldives
Maldives
The Maldives , , officially Republic of Maldives , also referred to as the Maldive Islands, is an island nation in the Indian Ocean formed by a double chain of twenty-six atolls oriented north-south off India's Lakshadweep islands, between Minicoy Island and...

. The United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...

 estimated at the outset that the relief operation would be the costliest in human history. Then UN Secretary-General Kofi Annan
Kofi Annan
Kofi Atta Annan is a Ghanaian diplomat who served as the seventh Secretary-General of the UN from 1 January 1997 to 31 December 2006...

 stated that reconstruction would probably take between five and ten years. Governments and non-governmental organisations feared that the final death toll
Death Toll
Death Toll is a 2008 action film starring DMX, Lou Diamond Phillips, Leila Arcieri and Keshia Knight Pulliam, written and produced by Daniel Garcia of the rap group Kane & Abel and directed by Phenomenon...

 might double as a result of diseases, prompting a massive humanitarian response
Humanitarian response to the 2004 Indian Ocean earthquake
The humanitarian response to the 2004 Indian Ocean earthquake was prompted by one of the worst natural disasters of modern times. On 26 December 2004, the earthquake, which struck off the northwest coast of the Indonesian island of Sumatra, generated a tsunami that wreaked havoc along much of the...

. In the end, this fear did not materialise.

For purposes of establishing timelines of local events, the time zone
Time zone
A time zone is a region on Earth that has a uniform standard time for legal, commercial, and social purposes. In order for the same clock time to always correspond to the same portion of the day as the Earth rotates , different places on the Earth need to have different clock times...

s of affected areas are: UTC+3: (Kenya, Madagascar, Somalia, Tanzania); UTC+4: (Mauritius, Réunion, Seychelles); UTC+5: (Maldives); UTC+5:30: (India, Sri Lanka); UTC+6: (Bangladesh); UTC+6:30: (Cocos Islands, Myanmar); UTC+7: (Indonesia (western), Thailand); UTC+8: (Malaysia, Singapore). Since the earthquake occurred at 00:58:53 UTC, add the above offsets to find the local time of the earthquake.
Country where
deaths occurred
Confirmed Estimated1 Injured Missing Displaced
Indonesia
Effect of the 2004 Indian Ocean earthquake on Indonesia
Indonesia was seriously affected by the earthquake and tsunami created by the 2004 Indian Ocean earthquake on 26 December 2004, swamping the northern and western coastal areas of Sumatra, and the smaller outlying islands off Sumatra...

130,736 167,799 n/a 37,063 500,000+
Sri Lanka
Effect of the 2004 Indian Ocean earthquake on Sri Lanka
As of 16:35 GST 3 January 2005, Sri Lankan authorities report 30,196 confirmed deaths after the island was hit by the tsunami resulting from the 2004 Indian Ocean earthquake on December 26, 2004. Many of the dead were adults and the elderly. The south and east coasts were worst hit. One and a half...

2
35,322 35,322 21,411 n/a 516,150
India
Effect of the 2004 Indian Ocean earthquake on India
In India, 10,136 people, according to official estimates, were killed and hundreds of thousands were rendered homeless when a tsunami triggered by the 2004 Indian Ocean earthquake near the Indonesian island of Sumatra hit the southern peninsular coast on 26 December 2004. The earthquake registered...

12,405 18,045 n/a 5,640 647,599
Thailand
Effect of the 2004 Indian Ocean earthquake on Thailand
frame|Map showing the provinces of Thailand affectedThe Thai government reported 4,812 confirmed deaths, 8,457 injuries, and 4,499 missing after the country was hit by a tsunami caused by the Indian Ocean earthquake on 26 December 2004. The Thai authorities estimate that at least 8,150 are likely...

5,3953 8,212 8,457 2,817 7,000
Somalia
Effect of the 2004 Indian Ocean earthquake on Somalia
The effect of the 2004 Indian Ocean earthquake on Somalia was devastating. Villages and coastal communities in Somalia, as far as from the epicentre of the 2004 Indian Ocean earthquake, were swept away and destroyed by the resulting tsunami on 26 December 2004. The confirmed death toll stood at...

78 289 n/a n/a 5,000
Myanmar (Burma)
Effect of the 2004 Indian Ocean earthquake on Myanmar
Official reports from the government of Myanmar cite a death toll of 90 due to the tsunami caused by the 2004 Indian Ocean earthquake on 26 December 2004. However, some estimates put the toll at between 400 to 600...

61 400–600 45 200 3,200
Maldives
Effect of the 2004 Indian Ocean earthquake on the Maldives
In the Maldives, 82 people were killed and 26 reported missing and presumed dead after it was hit by a tsunami caused by the 2004 Indian Ocean earthquake on 26 December 2004. Two-thirds of the capital city Malé was flooded during the early hours of the day...

82 108 n/a 26 15,000+
Malaysia
Effect of the 2004 Indian Ocean earthquake on Malaysia
Malaysia was affected by the Indian Ocean earthquake on 26 December 2004. Despite its proximity to the epicentre of the earthquake, Malaysia escaped the kind of damage that struck countries thousands of miles further away. Since the epicentre was on the western coast of Sumatra, the island largely...

68 75 299 6 n/a
Tanzania 10 13 n/a n/a n/a
Seychelles 3 3 57 n/a 200
Bangladesh 2 2 n/a n/a n/a
South Africa 24 2 n/a n/a n/a
Yemen 2 2 n/a n/a n/a
Kenya 1 1 2 n/a n/a
Madagascar n/a n/a n/a n/a 1,000+
Total ~184,167 ~230,273 ~125,000 ~45,752 ~1.69 million


1 Includes those reported under 'Confirmed'. If no separate estimates are available, the number in this column is the same as reported under 'Confirmed'.

2 Does not include approximately 19,000 missing people initially declared by Tamil Tiger authorities from regions under their control.

3 Data includes at least 2,464 foreigners.

4 Does not include South African citizens who died outside of South Africa (e.g., tourists in Thailand). For more information on those deaths, see this

Countries affected

The earthquake and resulting tsunami affected many countries in Southeast Asia and beyond, including Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

, Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

, the Maldives
Maldives
The Maldives , , officially Republic of Maldives , also referred to as the Maldive Islands, is an island nation in the Indian Ocean formed by a double chain of twenty-six atolls oriented north-south off India's Lakshadweep islands, between Minicoy Island and...

, Somalia
Somalia
Somalia , officially the Somali Republic and formerly known as the Somali Democratic Republic under Socialist rule, is a country located in the Horn of Africa. Since the outbreak of the Somali Civil War in 1991 there has been no central government control over most of the country's territory...

, Myanmar
Myanmar
Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....

, Malaysia, Seychelles
Seychelles
Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....

 and others. Many other countries, especially Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 and those in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, had large numbers of citizens traveling in the region on holiday. Both Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 and Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 lost over 500 citizens each in the disaster.

Event in historical context

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...

 was the biggest in the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 in some 700 years, or since around A.D. 1400. In 2008, a team of scientists working on Phra Thong, a barrier island along the hard-hit west coast of Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

, reported evidence of at least three previous major tsunamis in the preceding 2,800 years, the most recent from about 550 to 700 years ago. A second team found similar evidence of previous tsunamis during the last 1,200 years in 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...

, a province at the northern tip 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...

. Radiocarbon dating of bark fragments in soil below the second sand layer led the scientists to estimate that the most recent predecessor to the 2004 tsunami probably occurred between A.D. 1300 and 1450.

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...

 was the third most powerful earthquake recorded since 1900, and the confirmed death toll
Death Toll
Death Toll is a 2008 action film starring DMX, Lou Diamond Phillips, Leila Arcieri and Keshia Knight Pulliam, written and produced by Daniel Garcia of the rap group Kane & Abel and directed by Phenomenon...

 is just under 200,000 due to the ensuing tsunami. The deadliest earthquakes since 1900 were the Tangshan, China earthquake of 1976, in which at least 255,000 were killed; the earthquake of 1927 in Xining
Xining
Xining is the capital of Qinghai province, People's Republic of China, and the largest city on the Tibetan Plateau. It has 2,208,708 inhabitants at the 2010 census whom 1,198,304 live in the built up area made of 4 urban districts.-History:...

, Qinghai
Qinghai
Qinghai ; Oirat Mongolian: ; ; Salar:) is a province of the People's Republic of China, named after Qinghai Lake...

, China (200,000); the Great Kanto earthquake which struck Tokyo
Tokyo
, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...

 in 1923 (143,000); and the Gansu
Gansu
' is a province located in the northwest of the People's Republic of China.It lies between the Tibetan and Huangtu plateaus, and borders Mongolia, Inner Mongolia, and Ningxia to the north, Xinjiang and Qinghai to the west, Sichuan to the south, and Shaanxi to the east...

, China, earthquake of 1920 (200,000). The deadliest known earthquake in history occurred in 1556 in Shaanxi, China, with an estimated death toll of 830,000, though figures from this time period may not be reliable.

The 2004 tsunami is the deadliest in recorded history. Prior to 2004, the deadliest recorded tsunami in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 was in 1782, when 40,000 people were killed by a tsunami in the South China Sea
South China Sea
The South China Sea is a marginal sea that is part of the Pacific Ocean, encompassing an area from the Singapore and Malacca Straits to the Strait of Taiwan of around...

. The tsunami created by the 1883 eruption of Krakatoa
Krakatoa
Krakatoa is a volcanic island made of a'a lava in the Sunda Strait between the islands of Java and Sumatra in Indonesia. The name is used for the island group, the main island , and the volcano as a whole. The island exploded in 1883, killing approximately 40,000 people, although some estimates...

 is thought to have resulted in 36,000 deaths. The most deadly tsunami between 1900 and 2004 occurred in 1908 in Messina, Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, on the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...

, where the earthquake and tsunami killed 70,000. The most deadly tsunami in the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 resulted from the 1755 Lisbon earthquake
1755 Lisbon earthquake
The 1755 Lisbon earthquake, also known as the Great Lisbon Earthquake, was a megathrust earthquake that took place on Saturday 1 November 1755, at around 9:40 in the morning. The earthquake was followed by fires and a tsunami, which almost totally destroyed Lisbon in the Kingdom of Portugal, and...

, which, combined with the toll from the actual earthquake and resulting fires, killed over 100,000.

The 2004 earthquake and tsunami combined have been described as the deadliest natural disaster
Natural disaster
A natural disaster is the effect of a natural hazard . It leads to financial, environmental or human losses...

 since either the 1976 Tangshan earthquake or the 1970 Bhola cyclone
1970 Bhola cyclone
The 1970 Bhola cyclone was a devastating tropical cyclone that struck East Pakistan and India's West Bengal on November 12, 1970. It was the deadliest tropical cyclone ever recorded, and one of the deadliest natural disasters in modern times...

, or could conceivably exceed both of these. Because of uncertainty over death tolls, it might never be known for sure which of these natural disasters was the deadliest.

Possible human component in magnitude of damage

In an opinion piece in the Wall Street Journal, published five days after the tsunami, a journalist, Andrew Browne, argued that the human destruction of coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

s may have played a role in exacerbating the destruction caused by the tsunami. Many countries across Asia, including Indonesia, Sri Lanka and Bangladesh, have put forth efforts to destroy the coral surrounding their beaches, and instead make way for shrimp farms and other economic choices. On the Surin Island
Surin Island
The Surin Islands is an archipelago of five islands of the Andaman Sea, located 55 km from the Thai mainland. Administratively, the islands are part of Tambon Ko Phra Thong, Amphoe Khura Buri, in the Phang Nga Province of Thailand....

 chain of Thailand's coast, Browne argued, people may have been saved as the tsunami rushed against the coral reefs, lessening its impact. However, there were many fewer people on these islands, which helps explain the lower death toll. Many reefs areas around the Indian Ocean have been destroyed using dynamite because they are considered impediments to shipping, an important part of the South Asian economy. Similarly, Browne argued that the removal of coastal mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

 trees may have intensified the effect of the tsunami in some locations. He argued that these trees, which lined the coast but were removed to make way for coastal residences, might have lessened the force of the tsunami, in certain areas. Another factor, Browne argued, is the removal of coastal sand dune
Dune
In physical geography, a dune is a hill of sand built by wind. Dunes occur in different forms and sizes, formed by interaction with the wind. Most kinds of dunes are longer on the windward side where the sand is pushed up the dune and have a shorter "slip face" in the lee of the wind...

s.

Humanitarian, economic and environmental impact

A great deal of humanitarian aid
Humanitarian aid
Humanitarian aid is material or logistical assistance provided for humanitarian purposes, typically in response to humanitarian crises including natural disaster and man-made disaster. The primary objective of humanitarian aid is to save lives, alleviate suffering, and maintain human dignity...

 was needed because of widespread damage of the infrastructure
Infrastructure
Infrastructure is basic physical and organizational structures needed for the operation of a society or enterprise, or the services and facilities necessary for an economy to function...

, shortages of food and water, and economic damage. Epidemic
Epidemic
In epidemiology, an epidemic , occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience...

s were of special concern due to the high population density
Population density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...

 and tropical climate
Tropical climate
A tropical climate is a climate of the tropics. In the Köppen climate classification it is a non-arid climate in which all twelve months have mean temperatures above...

 of the affected areas. The main concern of humanitarian and government agencies was to provide sanitation facilities and fresh drinking water to contain the spread of diseases such as cholera
Cholera
Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...

, diphtheria
Diphtheria
Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...

, dysentery
Dysentery
Dysentery is an inflammatory disorder of the intestine, especially of the colon, that results in severe diarrhea containing mucus and/or blood in the faeces with fever and abdominal pain. If left untreated, dysentery can be fatal.There are differences between dysentery and normal bloody diarrhoea...

, typhoid and hepatitis A
Hepatitis A
Hepatitis A is an acute infectious disease of the liver caused by the hepatitis A virus , an RNA virus, usually spread the fecal-oral route; transmitted person-to-person by ingestion of contaminated food or water or through direct contact with an infectious person...

 and B.

There was also a great concern that the death toll could increase as disease and hunger spread. However, because of the initial quick response, this was minimized.

In the days following the tsunami, significant effort was spent in burying
Burial
Burial is the act of placing a person or object into the ground. This is accomplished by excavating a pit or trench, placing an object in it, and covering it over.-History:...

 bodies hurriedly for fear of disease. However, the public health
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...

 risks may have been exaggerated, and therefore this may not have been the best way to allocate resources. The World Food Programme
World Food Programme
The World Food Programme is the food aid branch of the United Nations, and the world's largest humanitarian organization addressing hunger worldwide. WFP provides food, on average, to 90 million people per year, 58 million of whom are children...

 provided food aid to more than 1.3 million people affected by the tsunami.
Nations all over the world provided over US$14 billion in aid for damaged regions, with the governments of Australia
Government of Australia
The Commonwealth of Australia is a federal constitutional monarchy under a parliamentary democracy. The Commonwealth of Australia was formed in 1901 as a result of an agreement among six self-governing British colonies, which became the six states...

 pledging US$819.9 million (including a US$760.6-million aid package for Indonesia), Germany offering US$660 million, Japan offering US$500 million, Canada
Government of Canada
The Government of Canada, formally Her Majesty's Government, is the system whereby the federation of Canada is administered by a common authority; in Canadian English, the term can mean either the collective set of institutions or specifically the Queen-in-Council...

 offering US$343 million, Norway and the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 offering both US$183 million, the United States offering US$35 million initially (increased to US$350 million), and the World Bank
World Bank
The World Bank is an international financial institution that provides loans to developing countries for capital programmes.The World Bank's official goal is the reduction of poverty...

 offering US$250 million. Also Italy offered US$95 million, increased later to US$113 million of which US$42 million was donated by the population using the SMS system According to USAID, the US has pledged additional funds in long-term U.S. support to help the tsunami victims rebuild their lives. On February 9, 2005, President Bush asked Congress to increase the U.S. commitment to a total of $
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....

950 million. Officials estimated that billions of dollars would be needed. Bush also asked his father, former President George H. W. Bush, and former President Bill Clinton to lead a U.S. effort to provide private aid to the tsunami victims.

In mid-March the Asian Development Bank
Asian Development Bank
The Asian Development Bank is a regional development bank established on 22 August 1966 to facilitate economic development of countries in Asia...

 reported that over US$4 billion in aid promised by governments was behind schedule. Sri Lanka reported that it had received no foreign government aid, while foreign individuals had been generous. Many charities were given considerable donations from the public. For example, in the UK the public donated roughly £330,000,000 sterling (nearly US$600,000,000). This considerably outweighed the donation by the government and came to an average of about £5.50 (US$10) donated by every citizen.

In August 2006, fifteen local aid staff working on post-tsunami rebuilding were found executed in northeast Sri Lanka after heavy fighting, the main umbrella body for aid agencies in the country said. There had been reports and rumors that the local aid workers had been killed.

Economic impact

The impact on coastal fishing communities and the people living there, some of the poorest in the region, has been devastating with high losses of income earner
Income earner
Income earner refers to an individual who through work, investments or a combination of both derives income, which has a fixed and very fixed value of his/her income...

s as well as boats and fishing gear. In Sri Lanka artisanal fishery, where the use of fish baskets, fishing traps, and spears are commonly used, is an important source of fish for local markets; industrial fishery is the major economic activity, providing direct employment to about 250,000 people. In recent years the fishery industry has emerged as a dynamic export-oriented sector, generating substantial foreign exchange earnings. Preliminary estimates indicate that 66% of the fishing fleet and industrial infrastructure in coastal regions have been destroyed by the wave surges, which will have adverse economic effects both at local and national levels.

The tsunami created demand for fiberglass reinforced plastic catamarans in boatyards of Tamil Nadu.

But some economists believe that damage to the affected national economies will be minor because losses in the tourism and fishing industries are a relatively small percentage of the GDP
Gross domestic product
Gross domestic product refers to the market value of all final goods and services produced within a country in a given period. GDP per capita is often considered an indicator of a country's standard of living....

. However, others caution that damage to infrastructure is an overriding factor. In some areas drinking water supplies and farm fields may have been contaminated for years by salt water from the ocean.

Both the earthquake and the tsunami may have affected shipping in the Malacca Straits by changing the depth of the seabed and by disturbing navigational buoys and old shipwrecks. Compiling new navigational charts may take months or years.

Countries in the region appealed to tourists to return, pointing out that most tourist infrastructure is undamaged. However, tourists were reluctant to do so for psychological reasons. Even beach resorts in parts of Thailand which were completely untouched by the tsunami were hit by cancellations.

Environmental impact

Beyond the heavy toll on human lives, the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 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...

 has caused an enormous environmental impact that will affect the region for many years to come. It has been reported that severe damage has been inflicted on ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

s such as mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

s, coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

s, forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

s, coastal wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....

s, vegetation
Vegetation
Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...

, sand dunes and rock
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...

 formations, animal and plant biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

 and groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...

. In addition, the spread of solid and liquid waste and industrial chemicals, water pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....

 and the destruction of sewage
Sewage
Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...

 collectors and treatment plants threaten the environment even further, in untold ways. The environmental impact will take a long time and significant resources to assess.

According to specialists, the main effect is being caused by poisoning of the freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 supplies and the soil by saltwater
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

 infiltration and deposit of a salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

 layer over arable land. It has been reported that in the Maldives, 16 to 17 coral reef atolls that were overcome by sea waves are completely without fresh water and could be rendered uninhabitable for decades. Uncountable wells that served communities were invaded by sea, sand and earth; and aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...

s were invaded through porous rock. Salted-over soil becomes sterile, and it is difficult and costly to restore for agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

. It also causes the death of plants and important soil micro-organisms. Thousands of rice, mango and banana plantations in Sri Lanka were destroyed almost entirely and will take years to recover. On the island's east coast, the tsunami contaminated wells on which many villagers relied for drinking water. The Colombo-based International Water Management Institute
International Water Management Institute
The International Water Management Institute is a non-profit research organisation with headquarters in Colombo, Sri Lanka, and offices across Africa and Asia...

 monitored the effects of saltwater and concluded that the wells recovered to pre-tsunami drinking water quality one and a half years after the event. IWMI developed protocols for cleaning wells contaminated by saltwater; these were subsequently officially endorsed by the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...

 as part of its series of Emergency Guidelines.

The United Nations Environment Programme
United Nations Environment Programme
The United Nations Environment Programme coordinates United Nations environmental activities, assisting developing countries in implementing environmentally sound policies and practices. It was founded as a result of the United Nations Conference on the Human Environment in June 1972 and has its...

 (UNEP) is working with governments of the region in order to determine the severity of the ecological impact and how to address it. UNEP has decided to earmark a US$1,000,000 emergency fund and to establish a Task Force to respond to requests for technical assistance from countries affected by the tsunami. In response to a request from the Maldivian Government
Politics of the Maldives
The politics of the Maldives take place in the framework of a presidential republic, whereby the President is the Head of Government. Executive power is exercised by the government. The President heads the executive branch and appoints the Cabinet; Like many presidential democracies, each member of...

, the Australian Government sent ecological experts to help restore marine environments and coral reefs—the lifeblood of Maldivian tourism. Much of the ecological expertise has been rendered from work with the Great Barrier Reef
Great Barrier Reef
The Great Barrier Reef is the world'slargest reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,600 kilometres over an area of approximately...

, in Australia's northeastern waters.

Other effects

Many health professionals and aid workers have reported widespread psychological trauma associated with the tsunami. Traditional beliefs in many of the affected regions state that a relative of the family must bury the body of the dead, and in many cases, no body remained to be buried.

The hardest hit area, 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...

, is considered to be a religiously conservative Islam
Islam
Islam . The most common are and .   : Arabic pronunciation varies regionally. The first vowel ranges from ~~. The second vowel ranges from ~~~...

ic society and has had no tourism nor any Western presence in recent years due to armed conflict between the Indonesian military and Acehnese separatists
Free Aceh Movement
The Free Aceh Movement , also known as the Aceh Sumatra National Liberation Front , was a separatist group seeking independence for the Aceh region of Sumatra from Indonesia. GAM fought against Indonesian government forces in the Aceh Insurgency from 1976 to 2005, costing over 15,000 lives...

. Some believe that the tsunami was divine punishment for lay Muslim
Muslim
A Muslim, also spelled Moslem, is an adherent of Islam, a monotheistic, Abrahamic religion based on the Quran, which Muslims consider the verbatim word of God as revealed to prophet Muhammad. "Muslim" is the Arabic term for "submitter" .Muslims believe that God is one and incomparable...

s shirking their daily prayers and/or following a materialistic lifestyle. Others have said that Allah
Allah
Allah is a word for God used in the context of Islam. In Arabic, the word means simply "God". It is used primarily by Muslims and Bahá'ís, and often, albeit not exclusively, used by Arabic-speaking Eastern Catholic Christians, Maltese Roman Catholics, Eastern Orthodox Christians, Mizrahi Jews and...

 was angry that there were Muslims killing other Muslims in an ongoing conflict. Women in Aceh required a special approach from foreign aid agencies, and continue to have unique needs.

The widespread devastation caused by the tsunami led the main rebel group GAM
Free Aceh Movement
The Free Aceh Movement , also known as the Aceh Sumatra National Liberation Front , was a separatist group seeking independence for the Aceh region of Sumatra from Indonesia. GAM fought against Indonesian government forces in the Aceh Insurgency from 1976 to 2005, costing over 15,000 lives...

 to declare a cease-fire on December 28, 2004 followed by the Indonesian government, and the two groups resumed long-stalled peace talks, which resulted in a peace agreement signed August 15, 2005. The agreement explicitly cites the tsunami as a justification.

The extensive international media coverage of the tsunami, and the role of mass media and journalists in reconstruction, were discussed by editors of newspapers and broadcast media in tsunami-affected areas, in special video-conferences set up by the Asia Pacific Journalism Centre.

The December 26, 2004 Asian Tsunami left both the people and government of India in a state of heightened alert. On December 30, 2004, four days after the tsunami, the Portland, Oregon
Portland, Oregon
Portland is a city located in the Pacific Northwest, near the confluence of the Willamette and Columbia rivers in the U.S. state of Oregon. As of the 2010 Census, it had a population of 583,776, making it the 29th most populous city in the United States...

-based company Terra Research notified the India government that its sensors indicated there was a possibility of 7.9 to 8.1 magnitude tectonic shift in the next 12 hours between 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...

 and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. In response, the India Home Affairs
Minister for Home Affairs (India)
The Home Minister, or more properly the Minister for Home Affairs, is a position in the Indian Cabinet, at both State and Union levels. The Home Ministry is one of the most important, powerful and high profile ministry after the Prime Minister...

 minister announced that a fresh onslaught of deadly tidal waves were likely along the India southern coast and Andaman
Andaman Islands
The Andaman Islands are a group of Indian Ocean archipelagic islands in the Bay of Bengal between India to the west, and Burma , to the north and east...

 and Nicobar Islands
Nicobar Islands
The Nicobar Islands are an archipelagic island chain in the eastern Indian Ocean...

, even as there was no sign of turbulences in the region. The announcement generated panic in the Indian Ocean region and caused thousands to flee their homes, which resulted in jammed roads. The announcement was a false alarm and the Home Affairs minister withdrew their announcement. On further investigation, the India government learned that the consulting company Terra Research was run from the home of a self-described earthquake forecaster
Earthquake prediction
An earthquake prediction is a prediction that an earthquake of a specific magnitude will occur in a particular place at a particular time . Despite considerable research efforts by seismologists, scientifically reproducible predictions cannot yet be made to a specific day or month...

 who had no telephone listing and maintained a website where he sold copies of his detection system. Three days after the announcement, Indian National Congress
Indian National Congress
The Indian National Congress is one of the two major political parties in India, the other being the Bharatiya Janata Party. It is the largest and one of the oldest democratic political parties in the world. The party's modern liberal platform is largely considered center-left in the Indian...

 president Sonia Gandhi
Sonia Gandhi
Sonia Gandhi is an Italian-born Indian politician and the President of the Indian National Congress, one of the major political parties of India. She is the widow of former Prime Minister of India, Rajiv Gandhi...

 called Science & Technology minister Kapil Sibal
Kapil Sibal
Kapil Sibal is an Indian politician and lawyer. He is currently the Minister of Communications and Information Technology. He also held the two ministries Ministry of Science and Technology and Ministry of Earth Sciences in the First Manmohan Singh Cabinet...

 to express her concern about Sibal's December 30 public warning being "hogwash".

Another result of the tsunami, respective toward Indian culture, was the water that washed away centuries of sand from some of the ruins of a 1,200-year-old lost city at Mahabalipuram on the south coast of India. The site, containing such notable structures as a half-buried granite lion near a 7th century Mahablipuram temple and a relic depicting an elephant, is part of what archaeologists believe to be an ancient port city that was swallowed by the sea hundreds of years ago.

The tsunami had a severe humanitarian and political impact in Sweden. The hardest hit country outside Asia, 543 Swedish tourists, mainly in Thailand, died. With no single incident having killed more Swedish people since the battle of Poltava
Battle of Poltava
The Battle of Poltava on 27 June 1709 was the decisive victory of Peter I of Russia over the Swedish forces under Field Marshal Carl Gustav Rehnskiöld in one of the battles of the Great Northern War. It is widely believed to have been the beginning of Sweden's decline as a Great Power; the...

 in 1709, the cabinet of Göran Persson
Cabinet of Göran Persson
Göran Persson served as Prime Minister of Sweden between March 22, 1996 and October 6, 2006. Persson took over after Ingvar Carlsson, who retired as party leader and Prime Minister...

 was heavily criticized for lack of action.

Apung 1
Apung 1
PLTD Apung 1 is an electric generator ship in Banda Aceh, Sumatra, Indonesia that has become a tourist attraction. The 2,600 ton vessel had been in the sea and was flung 2 to 3 km inland by the 2004 Indian Ocean earthquake and tsunami. It was owned by PLN, the local power generating company, and...

, a 2600 ton ship, was flung some 2-3 km inland by the tsunami, and has become a popular tourist attraction in Banda Aceh
Banda Aceh
Banda Aceh is the provincial capital and largest city in the province of Aceh, Indonesia, located on the island of Sumatra, with an elevation of 35 meters. The city regency covers an area of 64 square kilometres and according to the 2000 census had a population of 219,070 people...

.

See also

  • Aceh Tsunami Museum
    Aceh Tsunami Museum
    The Aceh Tsunami Museum, located in Banda Aceh, Indonesia, is a museum designed as a symbolic reminder of the 2004 Indian Ocean earthquake and tsunami disaster, as well as an educational center and an emergency disaster shelter in case the area is ever hit by a tsunami again.- Design :The Aceh...

  • Aid Still Required
    Aid Still Required
    Aid Still Required is a not for profit 501c3 organization committed to bringing attention and humanitarian aid to areas suffering from natural disasters or human crises. Incorporated in Santa Monica, California in 2008 as a result of founders Hunter and Andrea Herz Payne’s three-year journey...

  • Children of the Tsunami: No More Tears
    Children of the Tsunami: No More Tears
    Children of Tsunami: No More Tears is a 24-minute documentary film that was produced at the end of 2005. The program depicts the lives of eight children in four Asian countries during the year following the Indian Ocean tsunami that struck South and Southeast Asia on 26 December 2004...

    (documentary film)
  • July 2006 Java earthquake
    July 2006 Java earthquake
    The July 2006 Java earthquake was a magnitude 7.7 earthquake off the southwestern coast of Java, Indonesia. It occurred on July 17, 2006, at 08:24 UTC ....

  • List of earthquakes
  • List of Indonesian earthquakes
  • May 2006 Java earthquake
    May 2006 Java earthquake
    The May 2006 Java earthquake occurred at 05:54 local time on 27 May 2006 , in the Indian Ocean around south-southwest of the Indonesian city of Yogyakarta, near Galur, on the southern side of the island of Java , 10 km below the seabed, with a magnitude of 6.2, according to the U.S....

  • Megathrust earthquake
    Megathrust earthquake
    Megathrust earthquakes occur at subduction zones at destructive plate boundaries , where one tectonic plate is forced under another. Due to the shallow dip of the plate boundary, which causes large sections to get stuck, these earthquakes are among the world's largest, with moment magnitudes ...

  • Megatsunami
    Megatsunami
    Megatsunami is an informal term to describe a tsunami that has initial wave heights that are much larger than normal tsunamis...

  • Plate tectonics
    Plate tectonics
    Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

  • Pornthip Rojanasunand
    Pornthip Rojanasunand
    Khunying Pornthip Rojanasunand, also spelled Porntip Rojanasunan, M.D. is a Thai forensic pathologist, author, human rights activist, and cancer survivor....

    , a prominent Thai
    Thai people
    The Thai people, or Siamese, are the main ethnic group of Thailand and are part of the larger Tai ethnolinguistic peoples found in Thailand and adjacent countries in Southeast Asia as well as southern China. Their language is the Thai language, which is classified as part of the Kradai family of...

     doctor who took charge of ID of bodies
  • Queen of the Sea rail disaster, caused by the tsunami was the deadliest rail disaster in history
  • Seismology
    Seismology
    Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic,...

  • Seismotectonics
    Seismotectonics
    Seismotectonics is the study of the relationship between the earthquakes, active tectonics and individual faults of a region. It seeks to understand which faults are responsible for seismic activity in an area by analysing a combination of regional tectonics, recent instrumentally recorded events,...

  • 2011 Tōhoku earthquake and tsunami
    2011 Tōhoku earthquake and tsunami
    The 2011 earthquake off the Pacific coast of Tohoku, also known as the 2011 Tohoku earthquake, or the Great East Japan Earthquake, was a magnitude 9.0 undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST on Friday, 11 March 2011, with the epicenter approximately east...

  • Tectonics
    Tectonics
    Tectonics is a field of study within geology concerned generally with the structures within the lithosphere of the Earth and particularly with the forces and movements that have operated in a region to create these structures.Tectonics is concerned with the orogenies and tectonic development of...

  • Tsunami
    Tsunami
    A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

  • Tsunami: The Aftermath, a television miniseries about its after-effects
  • Tsunami Evaluation Coalition
    Tsunami Evaluation Coalition
    The Tsunami Evaluation Coalition was a unique learning and accountability initiative in the relief and development sector. It was first established in February 2005 to carry out joint evaluations of the response to the Asian earthquake and tsunamis of 26 December 2004.The TEC had over 50 member...



External links

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