2004 Indian Ocean earthquake and tsunami

Animation of Indonesia tsunami (Credit: NOAA)

The 2004 Indian Ocean earthquake was an undersea earthquake of moment magnitude 9.0 that struck the Indian Ocean off the western coast of northern Sumatra, Indonesia on December 26, 2004 at 00:58:50 UTC (or 07:58:50 local time in Jakarta and Bangkok). It was the largest earthquake on Earth since the 9.2-magnitude Good Friday Earthquake which struck Alaska, USA, in 1964, and the fourth largest since 1900. 26,000+ were killed by the resulting tsunamis, which were as high as 10 m (33 ft) in some locations and struck within three hours of the quake.

The multiple tsunamis struck and ravaged coastal regions all over the Indian Ocean, devastating regions including the resort island of Phuket, Thailand, the Indonesian province of Aceh, the coast of Sri Lanka, coastal areas of the Indian state of Tamil Nadu, and even as far away as Somalia, 4,100 km (2,500 mi) west of the epicenter.

Quake characteristics

The quake was initially reported as magnitude 6.8 in the Richter scale. On the moment magnitude scale, which is more accurate for quakes of this size, the earthquake's magnitude was first reported as 8.1 by the United States Geological Survey, but after further analysis they increased this first to 8.5 and 8.9 and finally to 9.0.

For comparison, the largest recorded earthquake was the Great Chilean Earthquake of 1960, having a magnitude of 9.5. The only other larger quakes worldwide since 1900 were the 1964 Good Friday Earthquake (9.2) and a March 9 1957 quake [1] in the Andreanof Islands (9.1), both in Alaska, USA. The only other recorded 9.0 magnitude earthquake, in 1952 off the southeast coast of Kamchatka, U.S.S.R., spawned tsunamis that caused extensive damage in Kamchatka, the Kuril Islands and the Hawaiian Islands.

The hypocenter was at 3.298°N, 95.779°E, some 160 km (100 mi) west of Sumatra, at a depth of 10 km (6.2 mi) underwater, within the "Ring of Fire" zone of frequent earthquakes. The quake itself (apart from the tsunamis) was felt as far away as Bangladesh, India, Malaysia, Myanmar, Singapore, Thailand and the Maldives.

The earthquake was unusually large in geographical extent. 1,125 km (700 mi) of faultline slipped 15 m (50 ft) along the subduction zone where the India Plate dives under the Burma Plate. This formed a shock wave in the Indian Ocean, creating tsunamis that traveled at up to 800 km/h (500 mi/h).

The India Plate is part of the great Indo-Australian Plate, which underlies the Indian Ocean and Bay of Bengal, and is drifting northeast at an average of 5 cm/yr (2 in/yr), relative to the Burma Plate. The Burma Plate carries the Nicobar and Andaman Islands and northern Sumatra, and is pushed by the Sunda Plate to its east. Both the Burma and Sunda Plates are considered portions of the great Eurasian Plate. The tectonic activity that results as these plates scrape against each other led to the creation of the Sunda Arc.

Numerous aftershocks of between magnitude 5.7 and 6.3 were reported off the Andaman Islands in the following hours. Aftershocks off the Nicobar Islands were also reported, including ones of magnitude 7.3 [2], and 6.5 [3]. Other aftershocks between magnitude 5.6 and 6.2 occurred near the location of the original quake. See also: USGS current earthquake information.

The earthquake came just three days after a magnitude 8.1 earthquake in a completely uninhabited region west of New Zealand's sub-Antarctic Auckland Islands, and north of Australia's Macquarie Island [4]. Earthquakes above magnitude 8 are rare (about one per year on average). Coincidentally, it also struck almost exactly one year (within an hour) after a magnitude 6.6 earthquake killed 30,000 people in the city of Bam in Iran [5].

The total energy released by a magnitude 9.0 earthquake such as this one exceeds the total amount of energy consumed in the United States in one month, or the energy released by the wind of a hurricane like Hurricane Isabel over a period of 70 days ([6]). Using the famous formula E=mc², this amount of energy is equivalent to a mass of about 100 kg (220 lb) (much more than is actually converted to energy in a manmade nuclear explosion), or enough to boil 5000 litres (1,300 US gallons) of water for every man, woman and child on the planet.

Damage and casualties

Disaster Snapshot
S.No.	Country	Dead	Injured	Missing
1	Sri Lanka	13,000	3,000	Unknown
2	India	7,110	Unknown	30,000+
3	Indonesia	5,000	Unknown	30,000+
4	Thailand	1,000+	7,346	1,200
5	Somalia	100+	Unknown	Unknown
6	Myanmar	56+	Unknown	Unknown
7	Malaysia	59	200+	29
8	Maldives	52	Unknown	68
9	Bangladesh	2	Unknown	Unknown
10	Kenya	1	Unknown	Unknown
	Total	26,000+	10,546+	60,000+

The earthquake triggered massive tsunamis which struck the coasts of the Indian Ocean. The death toll from the tsunamis and the resultant floods was reported to be more than 24,000, with tens of thousands of people reported missing, and over a million left homeless. Pacific Ocean coasts were not affected. The death toll may be particularly high due to the fact that this is the first time in recorded history that a tsunami of the Indian Ocean has struck land, leaving the affected countries unprepared and the people unable to recognise the tell tale signs of an impending tsunami.

In addition to the large number of local residents, some tourists during the busy Christmas holiday travel season were among the casualties. States of emergency were declared in Sri Lanka, Indonesia and Maldives.

India

Main article: 2004 Indian Ocean earthquake in India

The entire eastern coast of India was affected, killing more than 6,500 and rendering thousands injured and/or homeless. The death toll in Tamil Nadu, which was most affected, was above 3,200. Along the eastern coast, 377 were killed in Pondichery and 89 in Andhra Pradesh. Kerala, located on the western coast of India, was also affected with 158 deaths and thousands rendered homeless. Hundreds were feared missing (1,200 in Andhra Pradesh alone). Most of the people killed were fisherfolk who lived along the coast. Many fishermen both at home and at sea were missing.

Initial reports hinted at very few casualties in the Andaman and Nicobar Islands, a Union Territory of India just north of the earthquake hypocenter, but after many subsequent aftershocks near Nicobar, fears rose. Latest reports state 3,000 dead in the region and 30,000 missing. The Indian Air Force base in Car Nicobar, near the epicenter is reported to have been completely flattened.

The worst damage was in Tamil Nadu, where the official toll was 3,000, mostly women and children. Over 1,700 were killed in the Nagapattinam district alone, over 400 in the Cuddalore district, over 525 in the Kanyakumari district and over 200 in Chennai (formerly Madras) city. It was reported that survey and rescue helicopters could not even land in Nagapattinam and Cuddalore districts due to floods and rains.

Those killed in Kanyakumari include pilgrims taking a holy dip in the sea. 650 of about 700 people trapped at the Vivekananda Memorial in an island off Kanyakumari were rescued while the search is on for others. In Chennai along the Marina Beach, people taking part in various sports activities (including children), and those who were having a morning walk along the beach, were washed away. It being a Sunday there were more people than usual on the beach. Some unconfirmed reports claim that at least 5,000 fishermen and their families may be missing just from the Marina Beach area.

Water also rushed into the nuclear reactor complex at Kalpakkam, which was then shut off. No damage or radiation leak was reported.

The Indian Army, Navy and Coast Guard were pressed into service for undertaking rescue operations and to air-drop food to the tsunami victims. The chief ministers of Tamil Nadu and Andhra Pradesh announced ex gratia relief for those affected by the tsunamis.

Indonesia

Over 5,000 were confirmed dead on the island of Sumatra. Dozens of buildings were destroyed in the initial earthquake, especially in the city of Banda Aceh on the northern tip of Sumatra, where 3,000 were reported dead. However, most deaths were the result of the tsunamis that struck the coastal regions of Aceh and North Sumatra provinces. Ten-meter tall tsunamis passed the tip of the island to race south down the Straits of Malacca and strike along the northeast coast near the town of Birun.

An accurate picture of the damage is made difficult due to the insurgency of the separatist Free Aceh Movement, which means that there are relatively few journalists, government offices, or aid workers in northern Sumatra. The west coast of Sumatra was about 100 km (60 mi) from the epicenter and would be expected to have taken heavy damage. Preliminary reports suggest more than 30,000 may be missing in western Aceh, and government officials believe the death toll in the province as a whole may reach 20,000.

On a number of small islands along the coast of Indonesia, among them the Nicobaren (although officially belonging to India) are report over 30,000 dead. At least five villages were completely destroyed. There are also unconfirmed reports that the island of Sumatra was displaced slightly by the force of the earthquake.

Malaysia

People were swept away from beaches as the tsunami hit, resulting in the deaths of 59 people as of 1 am local time: 45 in Penang, 10 in Kedah, 3 in Perak and one in Selangor. 29 people are missing. The deaths at Penang were reported to include many picnickers and children who were playing on the beach. No deaths are reported among foreign tourists. Houses in villages along coastal areas were badly damaged in Penang and numerous fishing boats were trashed on Langkawi island. The waves sent parked motorcycles crashing and cars washed with mud at stretches along Gurney Drive.

The Malaysian government announced that MYR 1,000 would be paid to the families of victims while MYR 200 would be paid to those who had sustained injuries from the tsunami. Residents who moved out of their homes immediately would also be paid MYR 200 as compensation.

Maldives

52 killed and 68 reported missing, with both figures expected to rise as communication links are restored. Two-thirds of the capital city Malé were flooded during the early hours of the day. Outlying low-level atolls were badly affected and some low lying islands were completely submerged including some of the major resorts, during the high tide.

The government has declared a state of emergency and a special task force has been set up to provide aid and supplies to the needy in the islands. Communications services have been badly affected and there was no prior rescue or relief plan whatsoever for a disaster like this.

Somalia

Villages and coastal communities in Somalia, 2,800 miles from the epicentre of the earthquake, were swept away and destroyed by the huge waves. The area is now submerged under water.

The bodies of 40 fishermen have been recovered and 60 are still missing. According to Ali Abdi Awari, Minister of Rural Development, the final toll is believed to be much higher, as the number of fishermen caught on the sea has not been established by the local authorities.

Sri Lanka

Authorities report as many as 13,000 killed, mostly children and elderly. More than 8 million people have been displaced from their ruined homes. Apart from homes, many hotels were also reported to be damaged. At Trincomalee, the tsunami reached more than 2 km (1.25 mi) inland. The government states that it has little information on the situation in the northern regions controlled by the rebel Tamil Tigers. Twenty thousand soldiers were deployed in government-controlled areas to assist in relief operations and maintain law and order after sporadic looting. Local media reported that landmines left after the two decade civil war had been washed up and spread by the surge of water.

An official Tamil Tiger website reports 1,800 dead including Tiger cadres in their rebel areas.

Thailand

Thai media report that over 2,000 are feared killed, with 866 confirmed and 7,306 injured. 100 tourists, mainly scuba divers, are reported missing. The popular tourist resort of Phuket was badly hit. The bodies of 44 foreign tourists are reported to have been recovered at Phuket. Hundreds of holiday bungalows on the Phi Phi Islands were washed out to sea. Lorry drivers were quick to offer assistance, driving victims to higher ground and away from the surging waters. Local reports say many scuba divers were found dead, with their bodies torn apart by the tsunami. Among the dead was Bhumi Jensen, a grandson of King Rama IX, whose body was found at Phang Nga on Monday afternoon.

Other countries and territories directly affected by the earthquake and tsunamis

Australia: Tremors felt along the north-western coast, no direct casualties reported.
Bangladesh: Two children killed after a tourist boat capsized in surging waves.
Cocos (Keeling) Islands (Australia): After earlier scares, no casualties were reported.
Kenya: Waves struck Kenya causing some minor damage. One person drowned near Mombasa, another one injured.
Mauritius: Struck by wave, no reports on casualties, a village in the north of the island completely submerged.
Myanmar (formerly Burma): Ten people killed and a bridge destroyed. South-eastern coast hit by tremors, property damage, unknown casualties (the ruling military government rarely release details about any disaster). International humanitarian organisations in Rangoon report 56 deaths, but expect the final toll to be significantly higher.
Oman: Waves hit coastline but no casualties.
Réunion (France): Over 200 boats sunk, the damage to the port infrastructures costing over €500,000, according to the Chamber of Commerce.
Seychelles: Three killed (unconfirmed), seven people missing. Major bridge in Victoria destroyed
Singapore: Strong tremors felt by residents in high-rise apartment blocks in the south of the city.

Damage in historical and global context

File:2004 indian ocean earthquake tectonic.jpg

The tectonic map

Although the earthquake was among the most powerful ever recorded, the likely death-toll is lower than would have been the case if it had struck at a densely populated area. The worst earthquakes recorded in recent times in terms of casualties were the Tangshan, China, earthquake of 1976, in which 240,000 were killed, a quake in Iran in 1978 (250,000), and the Tokyo earthquake of 1923 (140,000). If the death-toll from this quake reaches 100,000, as now appears quite possible, it will be the fifth worst quake in the past century.

The nations of the Indian Ocean do not participate in an international tsunami early warning system like that in the Pacific Ocean, mostly as a result of the historical rarity of tsunamis in the Indian Ocean. In the Pacific, a system of sensors is linked to monitoring stations so that local media can warn the populace to seek higher ground well before a tsunami arrives. Thailand is a member of the Pacific tsunami warning system, but all of its ocean buoys, upon which wave sensors are mounted, are on the east coast of the country. A single wave station south of the epicenter measured a two foot tall tsunami moving towards Australia. The US Geological Survey has stated that if a monitoring and warning system had been in place, the loss of life could have been reduced, especially in areas that were struck by tsunamis more than three hours after the initial tremor, such as Sri Lanka and India. Furthermore, in Pacific regions where tsunamis are more well-known, the receding of the sea from the coast would have warned many people of an impending freak wave. In the Indian Ocean region this rare sight may have induced people to visit the coast to investigate. Also, the intensity of the tremors in India and Sri Lanka was too low to raise an alarm.

After the earthquake, the Indian government has decided to install equipment to warn about impending tsunamis and join a group of countries that would share information on tsunamis.

External links

Wikinews: Strongest earthquake in 40 years hits Southeast Asia.
Magnitude 9.0 – OFF THE WEST COAST OF NORTHERN SUMATRA USGS, December 26, 2004 at 00:58:50 UTC.
USGS: Largest earthquakes in the world since 1900

Sites with links to relevant pages