The Boxing Day 2004 Earthquake: A Holiday's Worst Nightmare
In order to explore what a tsunami is and how tsunamis are formed, we will use the 2004 Sumatran Tsunami to illustrate exactly how earthquake events can produce such destructive outcomes. You will rely on topics covered in Unit 1 (modules 2 and 3) to help understand the plate tectonics responsible for earthquake activity, but we will use USGS’s Pacific Coastal and Marine Science Center to explore the specific geologic details that gave rise to the tsunami. The day after Christmas (December 26, 2004), a large magnitude earthquake occurred just west of the island of Sumatra along a subduction boundary between two tectonic plates. The date couldn’t be worse for such an event to occur; with thousands of people on holiday in the region and with very few people working in government offices, it was a recipe for disaster. Tourists from all over the world were vacationing in seaside resorts in Thailand, Indonesia, India, and elsewhere. Unplugged as they were, it was next to impossible to inform them or the residents of the region of the impending hazard once the earthquake and tsunami were detected. The result was that over 150,000 people lost their lives. But, how? Let’s take some time and work through a series of questions whose answers can be found on the website.
Figure 5.31: Screen capture from the USGS. Lampuuk on the island of Sumatra before and after the Banda Aceh earthquake on Boxing Day, 2004 (December 26, 2004). Lampuuk is located on the northwestern most peninsula of the island. The image on the left shows the area prior to the tsunami and, on the right, the area after the tsunami. Tsunami waves swept from west to east across this region in complex patterns. Significant infrastructure including roads, agricultural areas, residential and beach front areas were obliterated during this event. Moreover, significant erosion pushed the shoreline inland and resulted in subsidence that contributed to continued land loss after the tsunami.
Credit: USGS: Tsunamis and Earthquakes
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.