Tsunami impacts on Sri Lanka—lessons for disaster reduction on coasts

The Indian Ocean region experienced its most devastating natural disaster through the action of a Tsunami, resulting from of an Earthquake off the coast of Sumatra on 26th of December 2004. This was a global event where tide gages in all oceans recorded oscillations related to the tsunami. Direct impact of the tsunami was limited to the countries of the Indian Ocean with over 250,000 deaths in the region and many millions homeless. Tsunamis are not a rare occurrence as historical records indicate that there have been over 1100 tsunamis recorded around the world with the majority occurring in the Pacific Ocean. Estimating a return period for the December 2004 event is difficult since an earthquake of the exact characteristics has not occurred previously and is not likely to occur in the future. However, for insurance purposes, the recurrence interval for a similar destructive tsunami is estimated to vary between 150-500 years. Prior to the December 2004 event, tsunami as a coastal hazard was neglected in coastal management, planning and development in Indian Ocean countries but is now considered to be a major factor in coastal planning and development – subsequent to the disaster. However, data required for the development of mitigation actions are non-existent and an international cooperative effort is required to acquire these data sets, particularly the coastal topography.