Tsunamis are rare events but can be extremely deadly. In the past 100 years, 58 of them have claimed more than 260,000 lives, or an average of 4,600 per disaster, surpassing any other natural hazard. The highest number of deaths in that period was in the Indian Ocean tsunami of December 2004. It caused an estimated 227,000 fatalities in 14 countries, with Indonesia, Sri Lanka, India and Thailand hardest-hit.
Just three weeks after that the international community came together in Kobe, in Japan’s Hyogo region. Governments adopted the 10-year Hyogo Framework for Action, the first comprehensive global agreement on disaster risk reduction.
They also created the Indian Ocean Tsunami Warning and Mitigation System, which boasts scores of seismographic and sea-level monitoring stations and disseminates alerts to national tsunami information centers.
Rapid urbanization and growing tourism in tsunami-prone regions are putting ever-more people in harm’s way. That makes the reduction of risk a key factor if the world is to achieve substantial reductions in disaster mortality — a primary goal of the Sendai Framework, the 15-year international agreement adopted in March 2015 to succeed the Hyogo Framework.
In December 2015, the UN General Assembly designated 5 November as World Tsunami Awareness Day.
World Tsunami Awareness Day was the brainchild of Japan, which due to its repeated, bitter experience has over the years built up major expertise in areas such as tsunami early warning, public action and building back better after a disaster to reduce future impacts.
The date for the annual celebration was chosen in honor of the Japanese story of Inamura-no-Hi”, meaning the burning of the rice sheaves”. During an 1854 earthquake, a farmer saw the tide receding, a sign of a looming tsunami. He set fire to his entire harvest to warn villagers, who fled to high ground. Afterwards, he built an embankment and planted trees as a buffer against future waves.
The UN General Assembly has called on all countries, international bodies and civil society to observe the day, in order to raise tsunami awareness and share innovative approaches to risk reduction. It also asked the UN Office for Disaster Risk Reduction (UNISDR) to facilitate the observance of World Tsunami Awareness Day in collaboration with the rest of the United Nations system.
For the second year in a row, the World Tsunami Awareness Day will align with the International Day for Disaster Reduction and the “Sendai Seven Campaign” and will focus in 2017 on Target B of the Sendai Framework for Disaster Risk Reduction, which aims at reducing the number of affected people globally by disasters.
2004 Indian Ocean earthquake and tsunami
The 2004 Indian Ocean earthquake occurred at 00:58:53 UTC on 26 December with the epicenter off the west coast of Sumatra, Indonesia. The shock had a moment magnitude of 9.1—9.3 and a maximum Mercalli intensity of IX (Violent). The undersea megathrust earthquake was caused when the Indian Plate was subducted by the Burma Plate and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean, killing 230,000—280,000 people in 14 countries, and inundating coastal communities with waves up to 30 meters (100 ft) high. It was one of the deadliest natural disasters in recorded history. Indonesia was the hardest-hit country, followed by Sri Lanka, India, and Thailand.
It is the third-largest earthquake ever recorded on a seismograph and 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 centimeter (0.4 inches) and triggered other earthquakes as far away as Alaska. Its epicenter was between Simeulue and mainland Indonesia. The plight of the affected people and countries prompted a worldwide humanitarian response. In all, the worldwide community donated more than US$14 billion (2004) in humanitarian aid. The event is known by the scientific community as the Sumatra—Andaman earthquake. The resulting tsunami was given various names, including the 2004 Indian Ocean tsunami, South Asian tsunami, Indonesian tsunami, the Christmas tsunami, and the Boxing Day tsunami.
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 systems in the Indian Ocean to detect tsunamis or to warn the general population 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”, 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 the 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 eruption of 1883. It should be noted that not every earthquake produces large tsunamis; on 28 March 2005, a magnitude 8.7 earthquake hit roughly the same area of the Indian Ocean but did not result in a major tsunami.
The first warning sign of a possible tsunami is the earthquake itself. However, tsunamis can strike thousands of kilometers away from 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, which was observed on the eastern side of the rupture zone of the earthquake such as around the coastlines of Aceh province, Phuket island and Khao Lak area in Thailand, Penang island of Malaysia and the Andaman and Nicobar islands. 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 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.
Reportedly, scuba divers near the abundant coral reefs in Thailand and the Maldives were caught off guard by violent, swirling underwater currents. The divers described the experience like being in a ‘washing machine’. Coral reef animals such as fish were also absent as the tsunami passed by.
One of the few coastal areas to evacuate ahead of the tsunami was on the Indonesian island of Simeulue, very 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 northern Phuket, Thailand, a 10-year-old British tourist named Tilly Smith had studied tsunami 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. 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 a high wall of water”. Almost all of the Onge people seemed to have survived the tsunami