Tsunami hazards - assessment of exposure of Sri Lanka

Abstract

The coastal belts of several Indian Ocean countries including Indonesia, Sri Lanka, India and Thailand suffered massive loss of life and damage to property due to the tsunami unleashed by the great earthquake in the Sunda trench on 26 December 2004 which is now called as Indian Ocean Tsunami. In the context of Sri Lanka the extent of inundation and the associated damage varied significantly with the local near shore wave height, topography and the resistance offered to the overland flow and due to the lack of preparedness and unawareness about tsunamis, death toll and the damage was quite high around two third of the coastal zone of the country.As indicated by the Indian Ocean Tsunami and subsequent tsunami alerts in 2005 and 2007, it will be important to assess the risk of tsunamis for Sri Lanka from possible undersea earthquake zones around the country to mitigate the adverse effects of a future tsunami. That kind of study should assess the exposure of the country in terms of tsunami arrival time, nearshore wave height and extent of inundation for possible tsunami scenarios which could affect the country. Also according to the geographical location of the country, Sri Lanka is threatened by far field tsunamis with tsunami travel time of hours. So the ideal tsunami impact mitigation measure is an early warning and evacuation system. Therefore this study was focussed on assessing the exposure of Sri Lanka to potential tsunami events from Sunda trench and arranging the information from such assessment to be effectively utilized by an early warning system and evacuation system.