Case study: The Indian Ocean Tsunami, 2004

How are tsunamis created?

• Most are caused at convergent plate boundaries - the ocean plate subducts under the continental plate causing friction.

• This eventually leads to them being stuck; energy builds up due to the compressional forces.

• When the energy exceeds the friction, the plates snaps back into position - this energy leads to a large volume of water displacement.

• The waves created can travel up to a large distances. When water slows down, and the height of the wave increases by several metres and the waves get closer together. This is why when water retreats, its a sign of tsunami.

When did the tsunami occur?

26th December 2004

What was the magnitude of the earthquake?

9.0 Richter

Which plates were involved?

The sudden slippage of the Indo-Australian plate under the Eurasian plate

What were the immediate impacts of the tsunami?

• The waves destroyed homes and hotels - two million people lost their jobs

• 294,000 people were killed/missing - deadliest since 1900

• Over 5 million people were left homeless without resources

• Mass graves had to be built in Indonesia and Hindu funerals were held for unidentified bodies.

• Malaria and cholera spread quickly, worsened by the lack of safe water lack of food

• Tourism industry declined - job opportunities

How many people died in Indonesia?

150,000 - because it was closest to the epicentre

How many people died in Sri Lanka?

Over 30,000 died

What were the factors that made the earthquake devasting?

• The earthquake’s magnitude was massive - made it difficult to control

• There were no early warning systems because tsunamis aren’t common in the Indian Ocean. The Pacific has a DART system where surface buoys which measure the changes in pressure and wave speed, set up by the Pacific nations (after the Chili tsunami in 1960).

• Most of the island chains are low-lying - couldn’t protect from wave

• Densely populated fishing villages and tourists towns were built right up to the coastline (removal of mangrove) - more at risk due to exposure.

What number of tsunamis were recorded outside the Pacific region?

19 out of the 157

What was a big issue with recovery in this tsunami?

The countries impacted were extremely poor so they didn’t have the resources to coordinate an effective response. They had to rely on foreign assistance.

What was the response like?

• Charity relied agencies and foreign governments coordinated a massive recovery programme.

• The UK alone donated £32 mil and the govt donated £50 mil.

• Globally, over £700 mil had been donated

• Emergency aid were delivered - but the remoteness of communities but the remoteness of communities, political instability and destruction of local infrastructure meant that manly resources couldn’t be distributed

What were the mitigation tactics implemented after the event?

• Early warning systems (mitigating against vulnerability) - tsunamis don’t usually occur straight after the earthquake, so with these warning systems, evacuations can occur quickly, saving lives.

• Hazard mapping - this can help predict the tsunami damage - govts can use this to prioritise evacuations, plan infrastructure or not allow for settlement buildings.

• Public awareness and perception - Many people in the affected areas were unaware of the signs of the tsunamis due to its rareness - but not every country could afford this system.

What was the issue with the Indonesia tsunami in 2018?

• More than 1000 people died and three waves hit Palu within three minutes

• None of the buoys work - Indonesia doesn’t have the infrastructure to continuously fix and monitor the buoys and warning system.

What long term mitigation techniques have been put in Sri Lanka?

They’ve highlighted clear signs to higher ground and huge efforts were placed in educate people took place

What has occurred in Indonesia with the natural environment?

Mangrove was regrown and tourism and fishing industries haven’t resettled there strategy to prevent further losses