‘Tsunami’ is simply a Japanese word meaning ‘harbour wave’ in English. Tsunamis are also known as seismic sea waves or tidal waves which form in the sea due to large scale displacement of water in an ocean or a large lake over a very short duration, giving rise to gravity waves.
Tsunamis are generally caused by earthquakes under water, volcanic eruptions and other underwater explosions like detonations of underwater nuclear devices.
Tsunamis could also be triggered by submarine landslides, glacier calvings, meteorite impacts and other disturbances above or below water.
Tsunamis can vary from a few meters to few tens of meters, savagely attacking coastlines and causing devastation to property and loss of life. When these waves travel long distances and reach shallow waters, their amplitude increases exponentially. Therefore, the devastating potential of the Tsunami multiplies. At any given place, the amplitudes depends upon several factors including the magnitude of the event, the type of faulting, depth of water column and bathymetry (equivalent to topography) of the coast.
The waves of a tsunami do not resemble normal sea waves, because their wavelength is much longer. A tsunami resembles a rapidly rising tide initially and thus, they are often referred to as tidal waves.
The tsunami which occurred in the Indian Ocean in 2004 was one of the deadliest natural disasters in human history with at least 290,000 people killed or missing in 14 countries bordering the Indian Ocean.
