Case study: tsunami
On Sunday 26 December 2004, a magnitude 9 earthquake occurred off the West Coast of Northern Sumatra in the Indian Ocean. This caused the Indian Ocean tsunami that affected 13 countries and killed approximately 230,000 people.
This tsunami was particularly devastating because:
The earthquake which caused the tsunami was magnitude 9.
The epicentre [epicentre: The point on the Earth's surface directly above the focus of an earthquake. ] was very close to some densely populated coastal communities, eg Indonesia. They had little or no warning. The only sign came just before the tsunami struck when the waterline suddenly retreated, exposing hundreds of metres of beach and seabed.
There was no Indian Ocean tsunami warning system in place. This could have saved more people in other countries further away from the epicentre.
Many of the countries surrounding the Indian Ocean are LEDCs [LEDCs: A less economically developed country (LEDC). This type of country is less wealthy or has lower standards of health and education than many other countries.] so they could not afford to spend much on preparation and prevention.
In some coastal areas, mangrove forests [mangrove forests: Tropical evergreen trees which help protect coastal zones.] had been removed to make way for tourist developments [tourist development: Things that are built for holiday makers to use.] and therefore there was less natural protection.
Social impacts of the tsunami (effects on people)
230 000 deaths.
1.7 million homeless.
5-6 million needing emergency aid, eg food and water.
Threat of disease from mixing of fresh water, sewage and salt water.
1,500 villages destroyed in northern Sumatra.
Economic impacts of the tsunami (effects on money and jobs)
Fishing industry devastated – boats, nets and equipment destroyed. An estimated 60% of Sri Lanka’s fishing fleet destroyed.
Reconstruction cost billions of dollars.
Loss of earnings from tourism - foreign visitors to Phuket dropped 80% in 2005.
Communications damaged, eg roads, bridges and rail networks.
Environmental impacts of the tsunami
Farm land ruined by salt water.
8 million litres of oil escaped from oil plants in Indonesia.
Mangrove forests along the coast were destroyed.
Coral reefs [coral reefs: Underwater structures found in warm seas. ] and coastal wetlands damaged.
Responses to the tsunami
Non-Governmental Organisations (NGOs) and local authorities typically have immediate and secondary responses to devastation of this kind.
Search and rescue.
Emergency food and water.
Re-establishing infrastructure [infrastructure: The basic structures needed for an area to function, for example roads and communications. ] and communications.
Re-building and improving infrastructure and housing.
Providing jobs and supporting small businesses.
Giving advice and technical assistance.
Responses to the 2004 Indian Ocean tsunami can also be divided into short and long term:
In many areas local communities were cut off and had to help themselves.
The authorities ordered quick burial or burning of the dead to avoid the spread of disease [disease: Illness affecting plants and animals.] .
Food aid was provided to millions of people, eg from the World Food Programme.
$7 billion (just under £4.5billion) of aid was promised by foreign governments – but there were complaints that not all money pledged was given.
The British public gave £330 million through charities, eg the average Actionaid donation was £84 – their best ever response.
Reconstruction [reconstruction: The rebuilding of an area after damage has been caused, eg following an earthquake.] is still taking place.
International scale: an Indian Ocean tsunami warning system has now been set up.
Local scale: some small-scale sustainable [sustainable: When something is able to keep going over time without harming people or the environment.] development projects have been set up by charities to aid recovery and help local people help themselves to rebuild and set up small businesses.
Case study: Boxing Day Tsunami, 2004
On 26 December 2004 a tsunami occurred in the Indian Ocean. It was the result of the Indio-Australian Plate subducting below the Eurasian Plate. It was caused by an earthquake measuring more than magnitude 9. The earthquake caused the seafloor to uplift, displacing the seawater above.
- In open ocean the tsunami measured less than 1 metre high.
- The tsunami travelled at speeds up to 800km per hour.
- When the Tsunami reached the shores, the height of the wave increased to 15 metres in some areas.
- A quarter of a million people died.
- Two million people were made homeless.
- People were swept away in the waters, which arrived rapidly and with little warning.
- Thirteen countries were affected, the worst being Indonesia.
- Indonesia was hit by the tsunami first. Fourty-five minutes later the tsunami reached Thailand.
- Mangrove swamps helped to act as a barrier to reduce the energy of the water in some areas.
- Short-term aid, such as water purification tablets, temporary housing and medical supplies were given from international countries.
- Islands reliant on tourism and fishing, such as the Maldives, had to rebuild their industries.
- An early warning system between countries surrounding the Indian Ocean has been set up.
Now try a Test Bite.
Map of Indian Ocean tsunami 2004
Back to Natural hazards index