2004 Indian Ocean earthquake and tsunami

On 26 December 2004, a very strong earthquake happened under the ocean near the west coast of Aceh in Indonesia. This earthquake was one of the most powerful ever recorded and lasted for many minutes. Because it happened under the water, it caused huge waves, called a tsunami, to rush toward the shores around the Indian Ocean.

The tsunami waves were as tall as a ten-story building in some places. They crashed into coastal towns and villages in 14 countries, including Indonesia, Sri Lanka, India, and Thailand. Sadly, many people lost their lives, and many more were left without homes or jobs. This event was the deadliest tsunami in history and caused a lot of damage.

The world came together to help the people affected by this disaster. People and countries gave more than $14 billion to support recovery efforts. Scientists also learned a lot from this event about how earthquakes and tsunamis work, which helps them try to prevent future disasters.

Earthquake

The 2004 Indian Ocean earthquake was first thought to have a strength of 8.8, but later studies showed it was between 9.2 and 9.3. It happened about 160 kilometers off the west coast of northern Sumatra, at a depth of 30 kilometers below the sea. The earthquake caused a big tsunami with waves up to 30 meters high, affecting many places around the Indian Ocean.

The earthquake happened where two pieces of the Earth's crust, called plates, moved past each other. One plate moved under another, causing the seafloor to rise and push a lot of water away. This created huge waves that traveled far. The earthquake was felt in several countries, including Bangladesh, India, Malaysia, Myanmar, Thailand, Sri Lanka, and the Maldives.

Historical comparisons

See also: List of megathrust earthquakes

Big earthquakes like the 2004 Indian Ocean earthquake happen where plates move under each other. This type of earthquake can release a lot of energy. The 2004 earthquake was one of the biggest ever recorded, releasing about one-eighth of all the energy from earthquakes in the 100 years from 1906 to 2005. It was similar in size to the Great Alaskan earthquake in 1964 and the Great Chilean earthquake in 1960.

Other very big earthquakes happened in Kamchatka, Russia, in 1952 and in Tōhoku, Japan, in 2011, but they did not cause as many deaths because fewer people lived near the affected coasts.

Tectonic plates

Main article: Plate tectonics

The 2004 earthquake was very big because a long piece of the Earth's crust moved about 15 meters along where the Indian plate moves under the Burma plate. This movement happened in two stages over several minutes. The Indian plate is moving northeast and meets the Burma plate at the Sunda Trench. When the Indian plate moves under the Burma plate, it gets deeper and deeper until heat and pressure cause water to come out, creating volcanoes.

The earthquake also pushed the seafloor up by several meters, moving a lot of water and causing the tsunami. This pushed the sea level up a little bit all around the world.

Aftershocks and other earthquakes

See also: List of earthquakes in Indonesia and List of earthquakes in 2004

Many smaller earthquakes, called aftershocks, happened after the main earthquake. Some were as strong as magnitude 7.2 and continued for months. The earthquake also caused changes in the ground that made two volcanoes in Aceh more active.

Energy released

The 2004 earthquake released a huge amount of energy, about 1.1×10¹⁷ joules. This made the whole Earth shake a little bit. The earthquake changed the Earth's rotation very slightly, making days a tiny bit shorter.

The earthquake caused the ground to move up and down all around the world. It also moved some islands a little bit and changed the shape of the seafloor. Satellites measured how the water level changed in the ocean, which helps scientists understand what happened.

After the earthquake, scientists found that the seafloor had changed a lot. Big pieces of rock had moved and fallen, creating new shapes on the ocean bottom.

Assessment of potential earthquakes in the future

Before the 2004 quake there were three arguments against a large earthquake occurring in the Sumatra region. After the quake it was considered that earthquake hazard risk would need to be reassessed for regions previously thought to have low risk based on these criteria:

1. The subducting plate at the location of the 2004 quake is older and more dense. Before the 2004 earthquake it was thought that only the subduction of young and buoyant crust could produce giant earthquakes.
2. Slow plate motion. Previously it was thought that the convergence rate had to be fast.
3. Before the 2004 quake it was thought that giant earthquakes only occurred in regions without back-arc basins.

Tsunami

The sudden rise of the seabed during the earthquake caused massive waves, leading to a tsunami that struck the coasts around the Indian Ocean. Tsunamis behave differently in deep water compared to shallow water near coastlines. In deep water, they form low, broad humps that travel quickly, but in shallow water, they slow down and become large, destructive waves.

Scientists found that the tsunami reached heights of up to 30 meters (100 feet) in some areas when it came ashore. The waves caused widespread damage and reached far inland in many places. Because the earthquake was far away, the tsunami took from fifteen minutes to seven hours to reach different coastlines. Areas closer to the earthquake were hit quickly, while others, like Sri Lanka and the east coast of India, were hit about 90 minutes to two hours later.

The tsunami was felt as far as Struisbaai in South Africa, about 8,500 kilometers (5,300 miles) away, where a 1.5-meter-high (5 feet) tide surged ashore about 16 hours after the earthquake. It also reached Antarctica, where tidal gauges recorded oscillations of up to a meter (3 feet 3 inches).

Despite the delay between the earthquake and the tsunami, nearly all victims were surprised because there were no tsunami warning systems in the Indian Ocean to detect tsunamis or warn people living around the ocean. Tsunamis are more common in the Pacific Ocean due to earthquakes in the "Ring of Fire," but they are rare in the Indian Ocean despite frequent earthquakes in Indonesia. The last major tsunami was caused by the eruption of Krakatoa in 1883.

The first warning sign of a possible tsunami is the earthquake itself. However, tsunamis can strike thousands of kilometers away where the earthquake is felt only weakly or not at all. In the minutes before a tsunami hits, the sea sometimes recedes temporarily from the coast, which was observed on the eastern earthquake rupture zone, such as the coastlines of Aceh, Phuket island, and Khao Lak in Thailand, Penang island in Malaysia, and the Andaman and Nicobar islands. This rare sight reportedly induced people, especially children, to visit the coast to investigate and collect stranded fish on as much as 2.5 kilometers (1.6 miles) of exposed beach, with unfortunate results. However, not all tsunamis cause 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, close to the epicenter. Island folklore recounted an earthquake and tsunami in 1907, and the islanders fled to inland hills after the initial shaking and before the tsunami struck. These tales and oral folklore from previous generations may have helped the survival of the inhabitants. On Maikhao Beach in north Phuket City, Thailand, a 10-year-old British tourist named Tilly Smith had studied tsunamis in geography at school and recognized 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, a biology teacher from Scotland, also recognized 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 of the Andaman Islands to be badly affected by the tsunami and even feared the already depopulated Onge tribe could have been wiped out. Many of the aboriginal tribes evacuated and suffered fewer casualties, however. Oral traditions developed from previous earthquakes helped the aboriginal tribes escape the tsunami. For example, the folklore of the Onges talks of "huge shaking of ground followed by high wall of water". Almost all of the Onge people seemed to have survived the tsunami.

Indonesia

Aceh

The tsunami devastated the coastline of Aceh province, about 20 minutes after the earthquake. Banda Aceh, the closest major city, suffered severe casualties. The sea receded and exposed the seabed, prompting locals to collect stranded fish and explore the area. Local eyewitnesses described three large waves, with the first wave rising gently to the foundation of the buildings, followed minutes later by a sudden withdrawal of the sea near the port of Ulèë Lheuë. This was succeeded by the appearance of two large black-coloured steep waves which then travelled inland into the capital city as a large turbulent bore. Eyewitnesses described the tsunami as a "black giant", "mountain" and a "wall of water". Video footage revealed torrents of black water, surging by windows of a two-story residential area situated about 3.2 kilometers (2.0 miles) inland. Additionally, amateur footage recorded in the middle of the city captured an approaching black surge flowing down the city streets, full of debris, inundating them.

The level of destruction was extreme on the northwestern areas of the city, immediately inland of the aquaculture ponds, and directly facing the Indian Ocean. The tsunami height was reduced from 12 meters (39 feet) at Ulèë Lheuë to 6 meters (20 feet) a further 8 kilometers (5.0 miles) to the north-east. The inundation was observed to extend 3–4 kilometers (1.9–2.5 miles) inland throughout the city. Within 2–3 kilometers (1.2–1.9 miles) 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. The area toward the sea was wiped clean of nearly every structure, while closer to the river, dense construction in a commercial district showed the effects of severe flooding. The flow depth at the city was just at the level of the second floor, and there were large amounts of debris piled along the streets and in the ground-floor storefronts. In the seaside section of Ulèë Lheuë, the flow depths were over 9 meters (30 feet). Footage showed evidence of back-flowing of the Aceh River, carrying debris and people from destroyed villages at the coast and transporting them up to 40 kilometers (25 miles) inland.

A group of small islands: Weh, Breueh, Nasi, Teunom, Bunta, Lumpat, and Batee lie just north of the capital city. The tsunami reached a run-up of 10–20 meters (33–66 feet) on the western shorelines of Breueh Island and Nasi Island. Coastal villages were destroyed by the waves. On Weh Island, strong surges were experienced in the port of Sabang, yet there was little damage with reported runup values of 3–5 meters (9.8–16.4 feet), most likely due to the island being sheltered from the direct attack by the islands to the south-west.

Lhoknga is a small coastal community about 13 kilometers (8.1 miles) 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. The locals reported 10 to 12 waves, with the second and third being the highest and most destructive. Interviews with the locals revealed that the sea temporarily receded and exposed coral reefs. In the distant horizon, gigantic black waves about 30 meters (98 feet) high made explosion-like sounds as they broke and approached the shore. The first wave came rapidly landward from the south-west as a turbulent bore about 0.5–2.5 meters (1.6–8.2 feet) high. The second and third waves were 15–30 meters (49–98 feet) high at the coast and appeared like gigantic surfing waves but "taller than the coconut trees and was like a mountain". The second wave was the largest; it came from the west-southwest within five minutes of the first wave. The tsunami stranded cargo ships, barges and destroyed a cement mining facility near the Lampuuk coast, where it reached the fourth level of the building.

Meulaboh, a remote coastal city, was among the hardest hit by the tsunami. The waves arrived after the sea receded about 500 meters (1,600 feet), followed by an advancing small tsunami. The second and third destructive waves arrived later, which exceeded the height of the coconut trees. The inundation distance is about 5 kilometers (3.1 miles). Other towns on Aceh's west coast hit by the disaster included Leupung, Lhokruet, Lamno, Patek, Calang, and Teunom. Affected or destroyed towns on the region's north and east coast were Pidie Regency, Samalanga, Panteraja, and Lhokseumawe. 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 such a natural phenomenon. Helicopter surveys revealed entire settlements virtually destroyed, with destruction extending miles inland. Only a few mosques remained standing.

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 of Sumatra, near Banda Aceh, and reached 51 meters (167 feet).

The tsunami heights in Sumatra:

• 15–30 meters (49–98 feet) on the west coast of Aceh
• 6–12 meters (20–39 feet) on the Banda Aceh coast
• 6 meters (20 feet) on the Krueng Raya coast
• 5 meters (16 feet) on the Sigli coast
• 3–6 meters (9.8–19.7 feet) on the north coast of Weh Island directly facing the tsunami source
• 3 meters (9.8 feet) on the opposite side of the coast of Weh Island facing the tsunami

Sri Lanka

The island country of Sri Lanka, located about 1,700 kilometers (1,100 miles) from Sumatra, was ravaged by the tsunami around two hours after the earthquake. The tsunami first struck the eastern coastline and subsequently refracted around the southern point of Sri Lanka (Dondra Head). The refracted tsunami waves then inundated the southwestern part of Sri Lanka after some of its energy was reflected from impact with the Maldives. Civilian casualties here were second only to those in Indonesia, with approximately 35,000 killed. The eastern shores of the country were the hardest hit since it faced the epicentre of the earthquake, while the southwestern shores were hit later, but the death toll was just as severe. The southwestern shores are a hotspot for tourists and fishing. The degradation of the natural environment in Sri Lanka contributed to the high death tolls. Approximately 90,000 buildings and many wooden houses were destroyed.

The tsunami arrived on the island as a small brown-orange-coloured flood. Moments later, the ocean floor was exposed for as much as 1 kilometer (0.62 miles) in places, which was followed by massive second and third waves. Amateur video recorded at the city of Galle showed a large deluge flooding the city, carrying debris and sweeping away people while in the coastal resort town of Beruwala, the tsunami appeared as a huge brown-orange-coloured bore which reached the first level of a hotel, causing destruction and taking people unaware. Other videos recorded showed that the tsunami appeared like a flood raging inland. The construction of seawalls and breakwaters reduced the power of waves at some locations.

The largest run-up measured was at 12.5 meters (41 feet) with inundation distance of 390–1,500 meters (1,280–4,920 feet) in Yala. In Hambantota, run-ups measured 11 meters (36 feet) with the greatest inundation distance of 2 kilometers (1.2 miles). Run-up measurements along the Sri Lankan coasts are at 2.4–4.11 meters (7 feet 10 inches – 13 feet 6 inches). Waves measured on the east coast ranged from 4.5–9 meters (15–30 feet) at Pottuvill to Batticaloa at 2.6–5 meters (8 feet 6 inches – 16 feet 5 inches) in the north-east around Trincomalee and 4–5 meters (13–16 feet) in the west coast from Moratuwa to Ambalangoda.

Sri Lanka tsunami height survey:

• 9 meters (30 feet) at Koggala
• 6 meters (20 feet) at Galle port
• 4.8 meters (16 feet) around the Galle coast
• 8.7 meters (29 feet) at Nonagama
• 4.9 meters (16 feet) at Weligama
• 4 meters (13 feet) at Dodanduwa
• 4.7 meters (15 feet) at Ambalangoda
• 4.7 meters (15 feet) at Hikkaduwa Fishery Harbour
• 10 meters (33 feet) at Kahawa
• 4.8 meters (16 feet) at North Beach of Beruwala
• 6 meters (20 feet) at Paiyagala

A regular passenger train operating between Maradana and Matara with over 1,750 passengers was derailed and subsequently overturned by the tsunami, claiming at least 1,000 lives in the largest single rail disaster death toll in history. Estimates based on the state of the shoreline and a high-water mark on a nearby building place the tsunami 7.5–9 meters (25–30 feet) above sea level and 2–3 meters (6 feet 7 inches – 9 feet 10 inches) higher than the top of the train.

Thailand

The tsunami travelled eastward through the Andaman Sea and hit the south-western coasts of Thailand, about 2 hours after the earthquake. Located about 500 kilometers (310 miles) from the epicentre, at the time, the region was popular with tourists because of Christmas. Many of these tourists were caught off-guard by the tsunami, as they had no prior warning. The tsunami hit during high tide. Major locations damaged included the western shores of Phuket island, the resort town of Khao Lak in Phang Nga Province, the coastal provinces of Krabi, Satun, Ranong and Trang and small offshore islands like Ko Racha Yai, the Phi Phi islands, the Surin Islands and the Similan archipelago. Approximately 8,000 people were killed.

Thailand experienced the second largest tsunami run-up. The tsunami heights recorded:

• 6–10 meters (20–33 feet) in Khao Lak
• 3–6 meters (9.8–19.7 feet) along the west coast of Phuket island
• 3 meters (9.8 feet) along the south coast of Phuket island
• 2 meters (6 feet 7 inches) along the east coast of Phuket island
• 4–6 meters (13–20 feet) on the Phi Phi Islands
• 19.6 meters (64 feet) at Ban Thung Dap
• 5 meters (16 feet) at Ramson
• 6.8 meters (22 feet) at Ban Thale Nok
• 5 meters (16 feet) at Hat Praphat (Ranong Coastal Resources Research Station)
• 6.3 meters (21 feet) at Thai Mueang District
• 6.8 meters (22 feet) at Rai Dan

The province of Phang Nga was the most affected area in Thailand. The quiet resort town of Khao Lak is located on a stretch of golden sandy beach, famed for its hotels overlooking the Andaman Sea and hilly rainforests. A video, taken by a local restaurant manager from a hill adjacent to the beach, showed that the tsunami's arrival was preceded by a sudden retreat of the sea exposing the seafloor. Many tourists and locals can be seen trying to gather fish. Moments later, the tsunami arrives as a wall of foaming water that slams into the coast, washing away numerous people who had no time to escape. Another amateur video, captured by a German family at beach level, showed the tsunami appearing as a white horizontal line in the distant horizon, gradually becoming bigger (bore-like), engulfing a jet skier and lifting two police boats. A maximum inundation of approximately 2 kilometers (1.2 miles) was measured, the inundated depths were 4–7 meters (13–23 feet) and there was evidence that the tsunami reached the third floor of a resort hotel. The tsunami in Khao Lak was bigger due to offshore coral reefs and shallow seafloor which caused the tsunami to pile-up. This was similar to eyewitness accounts of the tsunami at Banda Aceh.

Khao Lak also experienced the largest tsunami run-up height outside of Sumatra. The highest-recorded tsunami run-up was measured 19.6 meters (64 feet) at Ban Thung Dap, on the south-west tip of Ko Phra Thong Island and the second-highest at 15.8 meters (52 feet) at Ban Nam Kim. Moreover, the largest death toll occurred at Khao Lak, with about 5,000 people killed.

In addition, the tsunami inflicted damage to the popular resort town of Ao Nang in Krabi Province. Video footage showed that the tsunami appeared as multiple white surfs which violently lifted up yachts and boats, eventually crashing onto beaches. Footage captured at Koh Lanta showed a wall of water swamping the beach, while another video taken at another location showed a large surfing wave-like tsunami approaching the shore, lifting up a yacht and flooding the beach. At Koh Sriboya, the tsunami advanced inland as a turbulent medium bore, while at Koh Phayam, Ranong Province, the tsunami appeared as a wall of water.

At Phuket Province, the island province's western beaches were struck by the tsunami. At Patong Beach, a popular tourist destination, the tsunami first arrived as a small flood, which swept away cars and surprised people. About 10 minutes later, the sea receded for a while before the tsunami arrived again as a large wall of water looming over the skyline and flooding the coast. Another video from Kamala Beach showed the tsunami flooding the ground floor of a restaurant sweeping away an elderly couple. On Karon Beach, Kamala Beach and Kata Beach, the tsunami came in like a surging flood inland carrying people and cars. On some locations, a coastal road, which was built higher than the shore, protected a hotel which was behind it. On the east coast of Phuket Island, the tsunami height was about 2 m. In one river mouth, many boats were damaged. The tsunami moved counter-clockwise around Phuket Island, as was the case at Okushiri Island in the 1993 Hokkaido earthquake. According to interviews, the second wave was the largest. The tsunami heights were 5–6 meters (16–20 feet) and the inundated depth was about 2 meters (6.6 feet). The tsunami surprised many tourists at Koh Racha Yai, where it flooded the resorts. About 250 people perished directly in the tsunami.

The Phi Phi Islands are a group of small islands that were affected by the tsunami. The north bay of Phi Phi Don Island opens to the north-west in the direction of the tsunami. The measured tsunami height on this beach was 5.8 meters (19 feet). According to eyewitness accounts, the tsunami came from the north and south. The ground level was about 2 m above sea level, where there were many cottages and hotels. The south bay opens to the south-east and faces in the opposite direction from the tsunami. Furthermore, Phi Phi Le Island shields the port of Phi Phi Don Island. The measured tsunami height was 4.6 meters (15 feet) in the port. Amateur camcorder footage taken by Israeli tourists showed the tsunami advancing inland suddenly as a small flood, gradually becoming more powerful and engulfing the whole beach and resort, with the tsunami carrying a yacht out to sea.

Moreover, the tsunami was detected by scuba divers around offshore islands like the Similan Islands and the Surin Islands. The divers reported being caught in a violent, swirling current suddenly while underwater. Local camcorder footage showed the tsunami surging inland and flooding camping equipment at the Similan Islands while the tsunami caught tourists unaware at the Surin Islands, and dragging them out towards the sea.

India

The tsunami reached the states of Andhra Pradesh and Tamil Nadu along the southeastern coastline of the Indian mainland about two hours after the earthquake. At the same time, it arrived in the state of Kerala, on the southwestern coast. There were two to five tsunamis that coincided with the local high tide in some areas.

The tsunami runup height measured in mainland India by Ministry of Home Affairs includes:

• 3.4 meters (11 feet) at Kerala, inundation distance of 0.5–1.5 kilometers (0.31–0.93 miles) with 250 kilometers (160 miles) of coastline affected
• 4.5 meters (15 feet) at the southern coastline of Tamil Nadu, inundation distance of 0.2–2 kilometers (0.12–1.24 miles) with 100 kilometers (62 miles) of coastline affected
• 5 meters (16 feet) at the eastern coastline of Tamil Nadu facing tsunami source, inundation distance of 0.4–1.5 kilometers (0.25–0.93 miles) with 800 kilometers (500 miles) of coastline affected
• 4 meters (13 feet) at Pondicherry, inundation distance of 0.2–2 kilometers (0.12–1.24 miles) with 25 kilometers (16 miles) of coastline affected
• 2.2 meters (7.2 feet) at Andhra Pradesh, inundation distance of 0.2–1 kilometers (0.12–0.62 miles) with 985 kilometers (612 miles) of coastline affected

Along the coast of Tamil Nadu, the 13 kilometers (8.1 miles) Marina Beach in Chennai was battered by the tsunami which swept across the beach taking morning walkers unaware. Amateur video recorded at a resort beach showed the tsunami arriving as a large wall of water as it approached the coast and flooding it as it advanced inland. Besides that, a 10 meters (33 feet) black muddy tsunami ravaged the city of Karaikal, where 492 people died. The city of Pondicherry, protected by seawalls was relatively unscathed. Local video recorded that before the arrival of the tsunami, people had swarmed the beach to investigate fish that had been stranded on the sand. Furthermore, at the coastal town of Kanyakumari, the seabed was exposed briefly before a large wall of water can be seen on the horizon and subsequently flooding the town. Other footage showed the tsunami dramatically crashed into the Vivekananda Rock Memorial. The worst affected area in Tamil Nadu was Nagapattinam district, with 6,051 fatalities caused by a 5 meters (16 feet) tsunami, followed by Cuddalore district, with many villages destroyed. Most of the people killed were members of the fishing community. Velankanni, a coastal town with a Catholic Basilica and a popular pilgrimage destination was also one of the worst hit by the tsunami that struck at around 9.30 am on that Sunday, when pilgrims who were mostly from Kerala among others were inside the church attending the Malayalam Mass. The rising sea water did not enter the shrine, but the receding waters swept away hundreds of pilgrims who were on the beach. The shrine's compound, nearby villages, hundreds of shops, homes and pilgrims were washed away into the sea. About 600 pilgrims died. Rescue teams extricated more than 400 bodies from the sand and rocks in the vicinity and large number of unidentified bodies were buried in mass graves.

Kerala experienced tsunami-related damage in three southern densely populated districts, Ernakulam, Alappuzha, and Kollam, due to diffraction of the waves around Sri Lanka. Conversely, the southernmost district of Thiruvananthapuram experienced negligible impact, a result of the wide-angle turn required for diffracted waves to reach the peninsular tip. The most severe destruction was concentrated along narrow land strips situated between the Arabian Sea to the west and the Kerala backwaters to the east, where the geography restricted inland evacuation. Initial tidal recession preceded the surge, with the highest fatality rate recorded in the Alappad panchayat—including the villages of Cheriazheekkal and Azheekal—where waves reached heights of 4 meters (13 feet) and caused approximately 131 deaths.

Many villages in Andhra Pradesh were destroyed. In the Krishna District, the tsunami created havoc in Manginapudi and on Machalipattanam Beach. The most affected was Prakasam District, recording 35 deaths, with maximum damage at Singarayakonda. Given the enormous power of the tsunami, the fishing industry suffered the greatest. Moreover, the cost of damage in the transport sector was reported in the tens of thousands.

The tsunami run-up was only 1.6 meters (5.2 feet) in areas of Tamil Nadu shielded by the island of Sri Lanka but was 4–5 meters (13–16 feet) in coastal districts such as Nagapattinam in Tamil Nadu directly across from Sumatra. On the western coast, the runup elevations were 4.5 meters (15 feet) at Kanyakumari District in Tamil Nadu and 3.4 meters (11 feet) each at Kollam and Ernakulam districts in Kerala. The time between the waves ranged from about 15 minutes to 90 minutes. The tsunami varied in height from 2 meters (6.6 feet) to 10 meters (33 feet) based on survivors' accounts. The tsunami travelled 2.5 kilometers (1.6 miles) at its maximum inland at Karaikal, Puducherry. The inundation distance varied between 1,006–500 meters (3,301–1,640 feet) in most areas, except at river mouths, where it was more than 1 kilometer (0.62 miles). Areas with dense coconut groves or mangroves had much smaller inundation distances, and those with river mouths or backwaters saw larger inundation distances. Presence of seawalls at the Kerala and Tamil Nadu coasts reduced the impact of the waves. However, when the seawalls were made of loose stones, the stones were displaced and carried a few metres inland.

Andaman and Nicobar Islands

Due to close proximity to the earthquake, the tsunami took just minutes to devastate the Andaman and Nicobar Islands. The Andaman Islands were moderately affected while the island of Little Andaman and the Nicobar Islands were severely affected by the tsunami.

In South Andaman Island, based on local eyewitnesses, there were three tsunami waves, with the third being the most destructive. Flooding occurred at the coast and low-lying areas inland, which were connected to open sea through creeks. Inundation was observed, along the east coast of South Andaman Island, restricted to Chidiyatapu, Burmanallah, Kodiaghat, Beadnabad, Corbyn's Cove and Marina Park/Aberdeen Jetty areas. Several near-shore establishments and numerous infrastructures such as seawalls and a 20 MW diesel-generated power plant at Bamboo Flat were destroyed. At Port Blair, the water receded before the first wave, and the third wave was the tallest and caused the most damage.

Results of the tsunami survey in South Andaman along Chiriyatapu, Corbyn's Cove and Wandoor beaches:

• 5 meters (16 feet) in maximum tsunami height with a run-up of 4.24 meters (13.9 feet) at Chiriyatapu Beach
• 5.5 meters (18 feet) in maximum tsunami height and run-up at Corbyn's Cove Beach
• 6.6 meters (22 feet) in maximum tsunami height and run-up of 4.63 meters (15.2 feet) at Wandoor Beach

Meanwhile, in the Little Andaman, tsunami waves impinged on the eastern shore about 25 to 30 minutes after the earthquake in a four-wave cycle of which the fourth tsunami was the most devastating with a wave height of about 10 meters (33 feet). The tsunami destroyed settlements at Hut Bay within a range of 1 kilometer (0.62 miles) from the seashore. Run up level up to 3.8 meters (12 feet) have been measured.

In Malacca, located on the island of Car Nicobar, there were three tsunami waves. The sea was observed to rise suddenly before the onset of the first wave. The first wave came 5 minutes after the earthquake, preceded by a recession of the sea up to 600–700 meters (2,000–2,300 feet). The second and third waves came in 10-minute intervals after the first wave. The third wave was the strongest, with a maximum tsunami wave height of 11 meters (36 feet). Waves nearly three stories high devastated the Indian Air Force base, located just south of Malacca. The maximum tsunami wave height of 11 meters (36 feet). Inundation limit was found to be up to 1.25 kilometers (0.78 miles) inland. The impact of the waves was so severe that four oil tankers were thrown almost 800 meters (2,600 feet) from the seashore near Malacca to the Air force colony main gate. In Chuckchucha and Lapati, the tsunami arrived in a three-wave cycle with a maximum tsunami wave height of 12 meters (39 feet).

In Campbell Bay of Great Nicobar Island, the tsunami waves hit the area three times with an inundation limit of 250–500 meters (820–1,640 feet). A rise in sea level was observed before the first wave came within 5 minutes of the earthquake. The second and third waves came in 10-minute intervals after the first. The second wave was the strongest. The tsunami waves wreaked havoc in the densely populated Jogindar Nagar area, situated 13 kilometers (8.1 miles) south of Campbell Bay. According to local accounts, tsunami waves attacked the area three times. The first wave came five minutes after the mainshock (0629 hrs.) with a marginal drop in sea level. The second wave came 10 minutes after the first one with a maximum height of 4.8 meters (16 feet) to 8 meters (26 feet) and caused the major destruction. The third wave came within 15 minutes after the second with lower wave height. The maximum inundation limit due to tsunami water was about 500 meters (1,600 feet).

The worst affected island in the Andaman and Nicobar chain is Katchall Island, with 303 people confirmed dead and 4,354 missing out of a total population of 5,312. The significant shielding of Port Blair and Campbell Bay by steep mountainous outcrops contributed to the relatively low wave heights at these locations, whereas the open terrain along the eastern coast at Malacca and Hut Bay contributed to the great height of the tsunami waves.

Reports of tsunami wave height:

• 1.5 meters (4 feet 11 inches) at Diglipur and Rangat at North Andaman Island
• 8 meters (26 feet) high at Campbell Bay on Great Nicobar Island
• 10–12 meters (33–39 feet) high at Malacca (in Car Nicobar Island) and at Hut Bay on Little Andaman Island
• 3 meters (9.8 feet) high at Port Blair on South Andaman Island

Maldives

The tsunami severely affected the Maldives at a distance of 2,500 kilometers (1,600 miles) from the epicentre. Similar to Sri Lanka, survivors reported three waves with the second wave being the most powerful. Being rich in coral reefs, the Maldives provides an opportunity for scientists to assess the impact of a tsunami on coral atolls. The significantly lower tsunami impact on the Maldives compared to Sri Lanka is mostly due to the topography and bathymetry of the atoll chain with offshore coral reefs, deep channels separating individual atolls and its arrival within low tide which decreased the power of the tsunami. After the tsunami, there was some concern that the country might be submerged entirely and become uninhabitable. However, this was proven untrue.

The highest tsunami wave measured was 4 meters (13 feet) at Vilufushi Island. The tsunami arrived approximately two hours after the earthquake. The greatest tsunami inundation occurred at North Male Atoll, Male Island at 250 meters (820 feet) along the streets.

Local footage recorded showed the tsunami flooding the streets up to knee level in town, while another video taken at the beach showed the tsunami slowly flooding and gradually surging inland.

The Maldives tsunami wave analysis:

• 1.3–2.4 meters (4 feet 3 inches – 7 feet 10 inches) at North Male Atoll, Male Island
• 2 meters (6 feet 7 inches) at North Male Atoll, Huhule Island
• 1.7–2.8 meters (5 feet 7 inches – 9 feet 2 inches) at South Male Atoll, Embudhu Finothu
• 2.5–3.3 meters (8 feet 2 inches – 10 feet 10 inches) at Laamu Atoll, Fonadhoo Island
• 2.2–2.9 meters (7 feet 3 inches – 9 feet 6 inches) at Laamu Atoll, Gan Island
• 2.3–3 meters (7 feet 7 inches – 9 feet 10 inches) at North Male Atoll, Dhiffushi Island
• 2.2–2.4 meters (7 feet 3 inches – 7 feet 10 inches) at North Male Atoll, Huraa Island
• more than 1.5 meters (4 feet 11 inches) at North Male Atoll, Kuda Huraa Island

Myanmar

In Myanmar, the tsunami caused only moderate damage, which arrived between 2 and 5.5 hours after the earthquake. Although the country's western Andaman Sea coastline lies at the proximity of the rupture zone, there were smaller tsunamis than the neighbouring Thai coast, because the main tsunami source did not extend to the Andaman Islands. Another factor is that some coasts of Taninthayi Division were protected by the Myeik Archipelago. Based on scientific surveys from the Irrawaddy Delta through Taninthayi Division, it was revealed that tsunami heights along the Myanmar coast were between 0.4–2.9 meters (1 foot 4 inches – 9 feet 6 inches). Eyewitnesses compared the tsunami with the "rainy-season high tide"; although at most locations, the tsunami height was similar or smaller than the "rainy-season high tide" level.

Tsunami survey heights:

• 0.6–2.3 meters (2 feet 0 inches – 7 feet 7 inches) around the Irrawaddy delta
• 0.9–2.9 meters (2 feet 11 inches – 9 feet 6 inches) at Dawei area
• 0.7–2.2 meters (2 feet 4 inches – 7 feet 3 inches) around Myeik
• 0.4–2.6 meters (1 foot 4 inches – 8 feet 6 inches) around Kawthaung

Interviews with residents indicate that they did not feel the earthquake in Taninthayi Division or the Irrawaddy Delta. The 71 casualties can be attributed to poor housing infrastructure and additionally, the fact that the coastal residents in the surveyed areas live on flat land along the coast, especially in the Irrawaddy Delta, and that there is no higher ground to which to evacuate. The tsunami heights from the earthquake were not more than 3 meters (9.8 feet) along the Myanmar coast, the amplitudes were slightly large off the Irrawaddy Delta, probably because the shallow delta caused a concentration in tsunami energy.

Somalia

The tsunami travelled 5,000 kilometers (3,100 miles) west across the open ocean before striking the East African country of Somalia. Around 289 fatalities were reported in the Horn of Africa, drowned by four tsunami waves. The hardest-hit was a 650 kilometers (400 miles) stretch of coastline between Garacad (Mudug region) and Hafun (Bari region), which forms part of Puntland province. Most of the victims were reported along the low-lying Xaafuun Peninsula. The Puntland coast in northern Somalia was by far the area hardest hit by the waves to the west of the Indian subcontinent. The waves arrived around noon local time.

Consequently, tsunami runup heights vary from 5 meters (16 feet) to 9 meters (30 feet) with inundation distances varying from 44 meters (144 feet) to 704 meters (2,310 feet). The maximum runup height of almost 9 meters (30 feet) was recorded in Bandarbeyla. An even higher runup point was measured on a cliff near the town of Eyl, solely on an eyewitness account.

The highest death toll was in Hafun, with 19 dead and 160 people presumed missing out of its 5,000 inhabitants. This was the highest number of casualties in a single African town and the largest tsunami death toll in a single town to the west of the Indian subcontinent. Small drawbacks were observed before the third and most powerful tsunami wave flooded the town.

Other locations

The tsunami also reached Malaysia, mainly on the northern states such as Kedah, Perak and Penang and on offshore islands such as Langkawi island. Peninsular Malaysia was shielded by the full force of the tsunami due to the protection offered by the island of Sumatra, which lies just off the western coast.

Bangladesh escaped major damage and deaths because the water displaced by the strike-slip fault was relatively little on the northern section of the rupture zone, which ruptured slowly. In Yemen, the tsunami killed two people with a maximum runup of 2 meters (6.6 feet).

The tsunami was detected in the southern parts of east Africa, where rough seas were reported, specifically on the eastern and southern coasts that face the Indian Ocean. A few other African countries also recorded fatalities; one in Kenya, three in Seychelles, ten in Tanzania, and South Africa, where two were killed as a direct result of the tsunami—the furthest from the epicentre.

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.

Impact

Countries affected

Main article: Countries affected by the 2004 Indian Ocean earthquake and tsunami

The tsunami caused a lot of damage and loss of life in many places. In total, around 227,898 people died in 14 countries. Indonesia was hit hardest, with about 170,000 deaths. The tsunami reached as far as the east coast of Africa, causing damage there too.

Many children were among those who died because they were less able to escape the rising waters. In some areas, more women died than men because they were looking after children or waiting for family members.

Environmental impact

The earthquake and tsunami also hurt the environment. Forests, coral reefs, and wetlands were damaged. Water supplies were polluted, and soil was made salty by the ocean water. This made it hard to grow crops in some places.

Scientists and experts helped clean up the damage and protect the environment. They worked on restoring coral reefs and mangroves, which can help protect coastlines from future storms and waves.

Economic impact

The tsunami caused big problems for local economies, especially for fishing and tourism. Many boats and fishing tools were destroyed, and people lost their jobs. In some places, the damage made it hard to grow food or welcome tourists for a while.

Countries worked to bring tourists back and fix the damage, but it took time to recover.

Historical context

See also: Library damage resulting from the 2004 Indian Ocean earthquake

The 2004 earthquake and tsunami was one of the deadliest natural disasters in history. It was the strongest earthquake recorded since 1900 and caused more deaths than any other tsunami before it.

Other effects

After the tsunami, many people felt very upset and needed help to cope with what happened. In some places, families had trouble burying their loved ones because there were no bodies to bury.

The disaster also affected politics in some countries. In Indonesia, it helped bring peace talks to an end to a long conflict. In Sweden, leaders were criticized for how they responded to the tragedy.

The tsunami changed the Earth a little, shifting the North Pole and slightly changing the planet's shape. It also made the day a tiny bit shorter.

Humanitarian response

Main article: Humanitarian response to the 2004 Indian Ocean earthquake

After the tsunami, many places needed help because buildings were damaged, and people needed food and clean water. Health workers worried about diseases like cholera, diphtheria, dysentery, typhoid, hepatitis A, and hepatitis B. Countries around the world gave more than US$14 billion to help fix things. Australia gave US$819.9 million, Germany gave US$660 million, and Japan gave US$500 million. The United States first gave US$35 million, then increased it to US$350 million, and later asked to give even more.

The World Food Programme gave food to over 1.3 million people. Many people donated money to charities. In the United Kingdom, people gave about £330 million, which is nearly US$600 million. This was much more than the government gave.

In popular culture

Film and television

Several films and television shows have covered the tsunami. These include Children of Tsunami: No More Tears, The Wave That Shook the World, Tsunami: The Aftermath, Dasavathaaram, Tsunami: Caught on Camera, Hereafter, Hafalan Shalat Delisa, The Impossible, Kayal, and Tsunami: Race Against Time.

Literature

Books such as Paint the Sky with Stars: Selected Poetry in Remembrance of the Boxing Day Tsunami 2004, The Killing Sea, Wave by Sonali Deraniyagala, and On the Island explore the impact of the tsunami through stories and memories.

Music

Songs like "12/26" by Kimya Dawson and "Where the Wave Broke" by Burst remember the event and honor those affected.