Tsunami Special

the Indian context Tsunami is a water wave caused due to tectonic activities un-der water and travels across oceans with very high speed and can inflict great damage to life and property at the shores. The recent Sumatra earthquake of magnitude 9.0 triggered the most devastating tsunami of the recorded history causing a death toll of more than 150,000. Many regions around the globe, especially the Pacific Ocean have witnessed many damaging tsunamis in the past. Countries around the Pacific Ocean have developed an early warning system that has been very effec-tive for the last 50 years. Tsunamis have not been so frequent in the Indian Ocean, therefore lack of awareness has been a major cause for the great dev-astation caused by the tsu-nami of 26 December 2004. This feature gives a brief back-ground about tsunamis. What is a Tsunami? Tsunami is a word of Japanese language meaning ‘harbour wave’, which is used to de-scribe the large waves pro-duced by an abrupt shifting of the sea floor which results in vertical displacement of the overlying water. When these waves reach the land by trav-elling large distances across the ocean, they cause devasta-tion on the coasts. These waves move at a speed, V, that is equal to the square root of the product of the acceleration of gravity, g, and the water depth, D, that is V = D.g. With typical water depth in ocean at about 3000 to 4000 m, a tsunami travels at about 200 m/s, or over 700 km/h. Typically, in deep ocean tsunami has very large wave length (distance from crest to crest) running into 100-200 km and the wave height of less than 1 m. As the rate at which a wave loses its energy is inversely related to it