The word "Tsunami" is derived from the Japanese meaning "Harbour Wave". Tsunamis are often described as tidal waves but this view is incorrect since they have nothing to do with tides. Tsunamis are generated by offshore earthquakes, submarine landslides and also occasionally by undersea volcanic activity. In each case, a large water disturbance is created by large-scale underwater displacement of sediment or rock on the seabed, usually as a result of a fault or a landslide. The initial water movement is often characterized by a rapid draw-down or lowering of the sea surface at the coast as the water moves into the area of seabed displacement. Thereafter large kinematic waves are propagated outwards from the zone of seabed disturbance. The waves travel across the ocean at very high velocities, often in excess of 450km/hr, and possess very long wavelengths and periods. At the coast, the tsunami flood level (run-up) associated with a tsunami is partly a function of the dimensions of the propagated waves but it is also greatly influenced by the topography and bathymetry of the coastal zone and, as such, the waves can reach considerable