Difference between tsunami and other water waves
May 24, 2010 I Coastal area issues, Great Tsunami, tsunami report.Tsunamis are different from wind-generated waves, which many of us may have observed on a local lake or at a coastal beach, in that they are characterized as shallow-water waves, with long periods and wave lengths.The wind-generated swell one sees at a California beach, for example, seeded by a storm out in the Pacific and rhythmically rolling in, one wave after another, might have a period of about 10 seconds and a wave length of 150 m.
A tsunami, on the other hand, can comprise a wavelength in excess of 100 km and period on the order of one hour.
As a result of their long wave lengths, tsunamis usually behave as shallow-water waves.A wave becomes a shallow-water wave when the ratio between the water depth and its wave length gets very less.Shallow-water waves travel at a speed that is equal to the square root of the product of the acceleration of gravity (9.8 m/s/s) and the water depth.