According to interviews, the leading wave produced an initial depression, and the second wave was the largest. [52] 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. The rupture proceeded at about 2.8 km/s (1.7 mi/s; 10,000 km/h; 6,300 mph), beginning off the coast of Aceh and proceeding north-westerly over about 100 seconds. 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.

The seismic waves of the earthquake were felt across the planet; as far away as the U.S. state of Oklahoma, where vertical movements of 3 mm (0.12 in) were recorded. [83][84][85], At Port Blair, the water receded before the first wave, and the third wave was the tallest and caused the most damage. [96] An initial report by Siti Fadilah Supari, the Indonesian Minister of Health at the time, estimated the death total to be as high as 220,000 in Indonesia alone, giving a total of 280,000 fatalities. An even higher runup point was measured on a cliff near the town of Eyl, solely on an eyewitness account. The Indian Plate is part of the great Indo-Australian Plate, which underlies the Indian Ocean and Bay of Bengal, and is moving north-east at an average of 60 mm/a (0.075 in/Ms).

In one area of the Strait, water depths were previously up to 1,200 m (4,000 ft), and are now only 30 m (100 ft) in some areas, making shipping impossible and dangerous. [59], The tsunami devastated the northwestern coastlines of Sumatra, especially in the Aceh province, about 20 minutes after the initial earthquake. 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; in this case near Ecuador). Flooding occurred at the coastlines of the islands and low-lying areas inland, connected to open sea through creeks.

A second team found similar evidence of previous tsunamis in Aceh, a province at the northern tip of Sumatra; radiocarbon dating of bark fragments in the 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 ripple effect could especially be felt in the inland provinces of Thailand, such as Krabi, which acted as a starting point for many other tourist destinations in Thailand.

Major damage occurred in two narrow strips of land bound on the west by the Arabian Sea and on the east by the Kerala backwaters. The highest death toll was in Hafun, with 19 dead and 160 people presumed missing out of its 5,000 inhabitants. Chennai: Vintage car rally organised to create awareness about refugees, Kamala Harris' ancestral village in Tamil Nadu celebrates her victory, Madhya Pradesh: Girl climbs atop hoarding to marry boy against mother's wish, J&K youth don't have option but to pick up arms, says Mehbooba Mufti, Drug case: NCB raid at Bollywood actor Arjun Rampal’s house, Tejashwi will be next Bihar CM, says Tej Pratap Yadav, 20 Best Traditional Diwali Recipes and Homemade Sweets, Kamala Harris reveals her love for indian food, Air Quality Monitors To Give Info About The Air You Breathe, Diwali sweets for diet-conscious people: 10 Options, Terms of Use and Grievance Redressal Policy. The time between the waves varied from about 15 minutes to 90 minutes. The Indian Ocean Tsunami warning system was formed in early 2005 to provide an early warning of tsunamis for inhabitants around the Indian Ocean coasts. The Colombo-based 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. with a marginal drop in sea level. On Pulau Weh, however, the island experienced strong surges in the port of Sabang, yet there was little damage with a reported runup values of 3–5 m (9.8–16.4 ft), sheltered from the direct tsunami attack by the islands to the south-west. The only other recorded earthquakes of magnitude 9.0 or greater were off Kamchatka, Russia, on 4 November 1952 (magnitude 9.0)[22] and Tōhoku, Japan (magnitude 9.1) in March 2011. Although the extreme western edge of the Ring of Fire extends into the Indian Ocean (the point where the earthquake struck), no warning system exists in that ocean. [39], In February 2005, the Royal Navy vessel HMS Scott surveyed the seabed around the earthquake zone, which varies in depth between 1,000 and 5,000 m (550 and 2,730 fathoms; 3,300 and 16,400 ft). The city experienced the highest number of human casualties, with about 167,000 people perishing directly from the tsunami. The 2004 tsunami travelled via Andaman Sea and hit the south-west coast of Thailand, which was about 500 km (310 mi) from the epicentre.

[41] These satellites carry radars that measure precisely the height of the water surface; anomalies in the order of 500 mm (20 in) were measured.

Moreover, the cost of damage in the transport sector was reported in the tens of thousands. The eastern shores of Sri Lanka were hardest hit since they face the epicentre of the earthquake. [145] The announcement was a false alarm, and the Home Affairs minister withdrew their announcement. An oceanic trench several kilometres wide was exposed in the earthquake zone.[40]. Besides these factors, the number of lives lost was influenced by exposure to previous disasters and local disaster management capability. Much of the ecological expertise has been rendered from work with the Great Barrier Reef, in Australia's northeastern waters. The magnitude 8.7 2005 Nias–Simeulue earthquake, which originated off the coast of the Sumatran island of Nias, is not considered an aftershock, despite its proximity to the epicentre, and was most likely triggered by stress changes associated with the 2004 event. 14", "Asia-Pacific | 'Hundreds feared dead' in Burma", "The 2004 Indian Ocean Tsunami Disaster: Evaluation of UNICEF's response (emergency and recovery phase). Specifically, the Andaman Islands were moderately affected while the island of Little Andaman and the Nicobar Islands were severely affected by the tsunami. Within 2–3 km (1.2–1.9 mi) of the shoreline, houses, except for strongly-built reinforced concrete ones with brick walls, which seemed to have been partially damaged by the earthquake before the tsunami attack, were swept away or destroyed by the tsunami. Banda Aceh, the closest major city was particularly affected, suffering severe casualties. [152], Nations all over the world provided over US$14 billion in aid for damaged regions,[153] with the governments of Australia 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 offering US$343 million, Norway and the Netherlands offering both US$183 million, the United States offering US$35 million initially (increased to US$350 million), and the World Bank offering US$250 million. [89], Interviews with local people indicate that they did not feel the earthquake in Taninthayi Division or Ayeyarwaddy Delta. [17] Although the Pacific Tsunami Warning Center has accepted these new numbers, the United States Geological Survey has so far not changed its estimate of 9.1. Video footage revealed black torrents of water moving at high speed, rolling by windows of a two-story residential area situated about 3.2 km (2.0 mi) inland. Several near-shore establishments and numerous infrastructures such as seawalls and a 20 MW diesel-generated power plant at Bamboo Flat were extensively damaged. [125], Countries in the region appealed to tourists to return, pointing out that most tourist infrastructure is undamaged. Approximately 90,000 buildings, many wooden houses, were destroyed.[73]. [62], Lhoknga is a small coastal community about 13 km (8.1 mi) south-west of Banda Aceh, located on a flat coastal plain in between two rainforest-covered hills, overlooking a large bay and famous for its large swathe of white sandy beach and surfing activities. [74], The Phi Phi Islands are a group of small islands that were affected by the tsunami.

The volcanic activity that results as the Indo-Australian Plate subducts the Eurasian Plate has created the Sunda Arc. Tsunami survey in Andaman and Nicobar group of Islands.

Governments and non-governmental organizations feared that the final death toll might double as a result of diseases, prompting a massive humanitarian response. The exact amount is not yet known, but theoretical models suggest the earthquake shortened the length of a day by 2.68 microseconds, due to a decrease in the oblateness of the Earth.

[70] In Hambantota, tsunami run-ups measured 11 m (36 ft) with the greatest inundation distance of 2 km (1.2 mi). According to interviews, the leading wave produced an initial depression, called a tsunami drawback or "disappearing sea" effect and the second wave was larger.

The first wave came 5 minutes after the earthquake, preceded by the recession of seawater up to 600–700 m (2,000–2,300 ft).