Goa The events associated with the Great Tsunami of

Tsunamis are shallow-water waves, a special kind of surface gravity waves that occur in the oceans. They are called "shallow" because they occur in depths of water that are smaller than half of the wavelengths associated with the waves. The ocean, on average, is 4,000 m deep. Hence, wavelengths associated with shallow-water waves are at least 8 km in the open sea. The phase velocity of these waves is √gh, where g is the acceleration due to gravity (9.81 m/s2) and h is the depth of water. As the phase velocity is independent of wavelength, these waves are non-dispersive. In the open sea, their phase velocity is about 200 m/s, i.e. about 750 km/hr. This is roughly the speed at which a jet aircraft normally cruises. The speed of particle motion associated with shallow water waves observed over the open sea is much weaker. For linear waves, it is of the order of (gη/√gh), where is the perturbation of the ocean surface. The particle motions associated with shallow-water waves are along ellipse