5. What are the consequences of a tsunami?

The destruction caused by tsunamis stems mainly from the impact of the waves, the flooding, the erosion of shorelines, foundations of buildings, bridges and roads. Damage is magnified by floating debris, boats and cars that crash into buildings. Strong currents sometimes associated with tsunamis, add to the destruction by freeing log booms, barges and boats at anchor. Additional damage takes the form of fires from tsunami-related oil spills and of pollution from released sewage and chemicals. The above results in loss of life, socio-economic, environmental and cultural heritage resources.

One of the major consequences of tsunami is the loss of human life. The 2004 Indian Ocean Tsunami destructively struck 12 countries – Indonesia, Sri Lanka, India, Thailand, Maldives, Malaysia, Myanmar, Bangladesh and, in Africa, Somalia, Kenya, Tanzania and the Seychelles – causing unprecedented destruction in terms of scale and geographical distribution. Most of the coasts the tsunami swamped were home to poor coastal communities, and it destroyed basic services, critical infrastructure, administrative capacity and livelihoods. Most shocking was the Indian Ocean tsunami’s death toll, which was by far the highest in recorded history. Worst hit was Indonesia, followed by Sri Lanka and India. Only major earthquakes and diseases and wars have claimed more human lives (Table 1).
Country Dead Missing
Indonesia 125,598 94,574
Thailand 5,395 3,001
Sri Lanka 30,957 5,637
India 10,749 5,640
Myanmar 61 ­
Maldives 82 26
Malaysia 68
Somalia 298
Tanzania 10
Bangladesh 2
Kenya 1
TOTAL 173,221 108,878

There are three factors of destructions from tsunamis: inundation, wave impact on structures, and erosion. Agricultural areas are fully flooded and destroyed beyond recovery for many years to come. Strong, tsunami-induced currents lead to the erosion of foundations and the collapse of bridges and seawalls, infrastructures. Flotation and drag forces move houses and overturn railroad cars. Considerable damage is caused by the resultant floating debris, including boats and cars that become dangerous projectiles that may crash into buildings, break power lines, and may start fires. Fires from damaged ships in ports or from ruptured coastal oil storage tanks and refinery facilities can cause damage greater than that inflicted directly by the tsunami. Of increasing concern is the potential effect of tsunami draw down, when receding waters uncover cooling water intakes of nuclear power plants. For 2004 Indian Ocean Tsunami total destruction figures are presented below:

Destruction figures for 2004 Indian Ocean Tsunami (source: “Tsunami Teacher”, www.unesco.org)

Tsunami impacts on the environment in many ways, from the death of marine life to the destruction of livestock, plant life and the impact on geological features as well as damage to mangroves, coral reefs and vegetation. Of great concern are damage to marine habitats and the impacts on coastal towns that are intertwined with fragile marine systems.

Tsunami-induced environmental problems include:

  • Ground water contamination.
  • Damage to coral reefs, sea grass beds and mangrove ecosystems. o Salinisation of soils and damage to vegetation and crops.
  • Tsunami-generated waste and debris. o Impacts on sewage collection and treatment systems.
  • Damage to protected areas. o Coastline erosion and inundation.
  • Changes in river hydrology.
  • Loss of livelihoods based on natural resources or ecosystem services.

Archaeological sites, historical ruins, naturally beautiful places are lost under the impact of tsunami forces and due to inundation.