Tsunamis are a specific secondary effect and can have devastating effects in coastal areas.

A tsunami is a huge wave which is caused by volcanic or earthquake activity under the ocean which eventually reaches the coast and creates devastating impacts. For this section of the unit you need to know a case study of one tsunami event and its causes, effects and responses. You will have to know about the 2004 Boxing Day tsunami.


The Boxing Day tsunami happened at 7.59am on the 26th December 2004 and was the result of the Indo-Australian plate being subducted beneath the Eurasian plate 240km off the coast of Indonesia. The earthquake measured 9.1 on the Richter scale according to the USGS and caused a 20m uplift all along the 1,000km fault line.

Explaining the causes of a tsunami

Video of the causes


Social Economic Environmental

  • Over 220,000 people died in 14 countries
  • 650,000 were seriously injured
  • Up to 2million were made homeless
  • Identification of the dead on such a massive scale was difficult
  • Families grieving for lost family members
  • Livelihoods destroyed
  • Diseases such as cholera and dysentary spread due to the lack of sanitation and contaminated floodwaters
  • Public buildings including schools and hospitals were wiped out in some areas
  • 1,500 settlements were wiped out in Banda Aceh
  • Coastal tourist hotels damaged
  • Railway lines and roads washed away
  • Fishermens’ boats were destroyed
  • Crops destroyed/farming land flooded
  • Hotels lost income
  • Highest wave to come ashore was over 25m
  • Coral reefs damaged
  • Thousands of rice, mango and banana plantations in Sri Lanka destroyed
  • Water wells contaminated by seawater and dirt
  • Debris washed up on beaches
  • Places as far away as Fiji, American Samoa, New Zealand and Hawaii which lie up to 12,000km from the tsunami, saw the seas rise.
  • In India saltwater from the ocean contiminated freshwater supplies


Short-term responses:

  • Rescue services and emergency teams were swamped by the scale of the disaster. Injured peopple were untreated for days as wounds turned gangrenous and conditions worsened. Bodies littered the street before being buried in mass graves.
  • Over $7 billion was provided by governments and charities in the aid effort and to help with reconstruction.
  • Immediate response from the international community was to send fresh water, water purification tablets, food, sheeting and tents. Medical teams and forensic scientists also came.
  • UK government promised £75 million and public donations of £100 million followed.
  • Up to 5 million people had to be relocated into temporary refugee camps and had to be provided with shelter, food and water.
  • Took months to simply clear the debris before rebuilding could start again.

Long-term responses:

  • Indonesian government relocated people straight from the refugee camps into new homes. The building of these new homes took a lot longer than expected due to the lack of building materials and destruction of main transport routes.
  • A tsunami early warning system has now been installed in the Indian Ocean at a cost of $20 million (how the early warning system works, animation of system)

“Aid relief chaotic” – BBC article criticising the responses to the tsunami