The 2004 Indian Ocean Earthquake and Tsunami

2004 Indian Ocean earthquake and tsunami

• On December 26, 2004, a magnitude 9.1-9.3 earthquake struck off the west coast of northern Sumatra, Indonesia, causing a massive tsunami with waves up to 30m high.

• The tsunami killed an estimated 227,898 people in 14 countries, making it one of the deadliest natural disasters in recorded history.

• The earthquake was the third-largest ever recorded based on seismographic measurements and had the longest duration of faulting ever observed, between eight and ten minutes.

• The earthquake's epicentre was between Simeulue and mainland Sumatra and remotely triggered earthquakes as far away as Alaska.

• The 2004 Indian Ocean earthquake accounted for roughly one-eighth of all the moment released by earthquakes in the 100 years from 1906 through 2005.

• The earthquake's energy release was equivalent to over 1,500 times that of the Hiroshima atomic bomb, but less than that of the Tsar Bomba, the largest nuclear weapon ever detonated.

• The earthquake generated a seismic oscillation of the Earth's surface of up to 200-300mm and was felt across the planet, as far away as Oklahoma.

• The earthquake's energy release slightly altered the Earth's rotation, shortening the length of a day by 2.68 microseconds and causing the Earth to minutely "wobble" on its axis.

• The earthquake caused a rise in the seafloor by several metres, displacing an estimated 30km3 of water and triggering devastating tsunami waves.

• The tsunami waves radiated outwards along the entire 1,600km length of the rupture and reaching as far as Mexico, Chile, and the Arctic.

• The earthquake had aftershocks of up to magnitude 6.6 that continued to shake the region daily for three or four months.

• The earthquake's impact on the topography of the seabed was revealed by a survey using a high-resolution, multi-beam sonar system.The 2004 Indian Ocean earthquake and tsunami caused a massive displacement of water resulting in a tsunami that devastated the coastlines of many countries. The tsunami was caused by the sudden vertical rise of the seabed by several meters during the earthquake, which displaced massive volumes of water. The tsunami behaved differently in deep water than in shallow water, forming only a low, broad hump in deep ocean water but slowing down to form large destructive waves in shallow water near coastlines. The total energy of the tsunami waves was equivalent to about 5 megatons of TNT, which is more than twice the total explosive energy used during all of World War II. The tsunami was noticed as far as 8,500 km away in South Africa, and it produced small but measurable tsunamis along the western coasts of North and South America. Despite a delay of up to several hours between the earthquake and the impact of the tsunami, nearly all of the victims were taken by surprise as there were no tsunami warning systems in the Indian Ocean to detect tsunamis or to warn the general population living around the ocean. The tsunami devastated the coastline of Aceh province, about 20 minutes after the earthquake. The greatest run-up height of the tsunami was measured at a hill between Lhoknga and Leupung, on the western coast of the northern tip. The high fatality rate in the area was mainly due to lack of preparation of the community towards a tsunami and limited knowledge and education among the population regarding the natural phenomenon.Tsunami Impacts in South Asia

• The 2004 Indian Ocean earthquake, which measured 9.1-9.3 on the Richter scale, triggered a massive tsunami that caused widespread destruction across South and Southeast Asia.

• The tsunami struck the west coast of Sumatra, Indonesia, first and reached a height of 51 meters (167 feet).

• Sri Lanka, located about 1,700 km (1,100 mi) from Sumatra, was hit around 2 hours after the earthquake, with approximately 35,000 people killed.

• The eastern shores of Sri Lanka were hardest hit while the southwestern shores were hit later, but the death toll was just as severe.

• Thailand, located about 500 km (310 mi) from the epicenter, was also hit about 2 hours after the earthquake, with approximately 8,000 people killed.

• The worst-affected area in Thailand was Khao Lak, which experienced the largest tsunami run-up height outside of Sumatra and the largest death toll of about 5,000 people.

• Phuket Island, Thailand, experienced a tsunami height of about 2 m on the east coast and 5-6 m on the west coast.

• The Phi Phi Islands, a group of small islands, were affected by the tsunami, with the highest recorded tsunami height of 5.8 m.

• India was hit about 2 hours after the earthquake, with two to five tsunamis that coincided with the local high tide in some areas.

• The worst-affected area in India was Nagapattinam district, with 6,051 fatalities caused by a 5 m (16 ft) tsunami.

• The Andaman and Nicobar Islands were severely affected by the tsunami, with Little Andaman and the Nicobar Islands being hit the hardest.Impact of the 2004 Indian Ocean earthquake and tsunami

• The earthquake and tsunami caused a total of 227,898 deaths, making it one of the ten worst earthquakes in recorded history and the single worst tsunami in history.

• Indonesia was the worst affected area, with most death toll estimates at around 170,000.

• Relief agencies reported that one-third of the dead appeared to be children.

• The tsunami severely affected the Maldives, with the highest tsunami wave measured at 4 m (13 ft) at Vilufushi Island.

• The tsunami caused moderate damage in Myanmar, with the highest tsunami wave height of 2.9 m (9.6 ft) along the Myanmar coast.

• The hardest-hit area in Somalia was a 650 km (400 mi) stretch of the coastline between Garacad and Xaafuun, which forms part of the Puntland province.

• Tidal surges also occurred along the Western Australian coast that lasted for several hours, resulting in boats losing their moorings and two people needing to be rescued.

• The tsunami caused severe damage to ecosystems such as mangroves, coral reefs, forests, coastal wetlands, vegetation, sand dunes, and rock formations, animal and plant biodiversity, and groundwater.

• The spread of solid and liquid waste and industrial chemicals, water pollution, and the destruction of sewage collectors and treatment plants threatened the environment even further.

• The environmental impact took a long time and significant resources to assess, and it caused the death of plants and important soil micro-organisms.

• The tsunami destroyed thousands of rice, mango, and banana plantations in Sri Lanka and will take years to recover.

• The United Nations Environment Programme (UNEP) worked with governments in the region to determine the severity of the ecological impact and develop strategies for reef-monitoring and rehabilitation of marine environments and coral reefs in the Maldives, Seychelles, and other areas.

• The International Water Management Institute 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.