Plate Tectonics- Seismicity Case Study

Indonesian Boxing Day Earthquake & Tsunami, 2004

Key Facts

• Date: 26th December 2004
• Magnitude: 9
• Indian Ocean
• Eurasian and Australian Plates
• Strongest earthquake for 40 years

Location

On 26 December 2004 a tsunami occurred in the Indian Ocean. 
Thirteen countries were affected, the worst being Indonesia. Indonesia was hit by the tsunami first. Forty-five minutes later the tsunami reached Thailand.

Causes

• 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 the 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.

Economic Impact

• Local economies were devastated, the overall impact to the national economies was minor.
• The two main occupations affected by the tsunami were fishing and tourism. The impact on coastal fishing communities and the people living there, some of the poorest in the region, had been devastating with high losses of income earners as well as boats and fishing gear.
• While the tsunami destroyed many of the boats vital to Sri Lanka's fishing industry, it also created demand for fibreglass reinforced plastic catamarans in boatyards of Tamil Nadu. Since over 51,000 vessels were lost to the tsunami, the industry boomed. However, the huge demand has led to lower quality in the process, and some important materials were sacrificed to cut prices for those who were impoverished by the tsunami.

Environmental impact

• Severe damage on ecosystems such as mangroves, coral reefs, forests, coastal wetlands, vegetation, sand dunes and rock formations, animal and plant biodiversity and groundwater.
• The spread of solid and liquid waste and industrial chemicals caused water pollution and the destruction of sewage collectors and treatment plants threaten the environment.

Social Impact

• 250,000 deaths
• PTSD
• 2 million people were made homeless
• Starvation and disease
• No access to clean water - contamination from sewage and decomposing bodies
• Due to the many deaths and destruction, the people of South East Asia have found it hard to return to a normal way of life.

Responses

• Short-term aid, such as water purification tablets, temporary housing and medical supplies were given from international countries.
• The governments of the affected countries reacted reasonably quickly but were reliant in many cases on OUTSIDE AID due to the magnitude of the disaster and the lower level of economic development of the places affected. Countries sent aid teams immediately.
• An early warning system for Tsunami has now been put in place in the Indian Ocean, through co-operation from many governments.
• The UK government's Disasters and Emergency Committee established an emergency fund almost immediately.
• The DEC Earthquake/Tsunami disaster appeal fund stood at £32 million, up £7 million in one night from the 31st of December. At one point the DEC was receiving around £15,000 a minute in donations via the phone and Web
• MEDCs such as the UK sent dog teams, forensic experts and equipment to help identify bodies and clean up after the Tsunami.