ABSTRACT
A tsunami causing disturbance in the ocean will generally consist of a group of waves having periods of 5-60 mins with irregular amplitudes. Figure 14.1 shows the tsunami wave generated by an earthquake. Figure 14.2 shows a record taken at Sanfransisco after 1964 Alaskan earthquake which shows remarkable water level oscillators heights. Figure 14.3 shows the water column height at Rat Island Alaska tsunami of 2003. Generally speaking tsunami waves in the open sea are of the order of 1 m or less. Consider a simple case study-Assume a typical period of 30 minutes and considering the mean ocean depth as 4000 m the wave celerity C can be expressed as
C gd= = 9 81 4000. ( ) = 62.64 m/s (14.1) where d = ocean depth, g = acceleration due to gravity L (wave length) = CT = 62.64 × 1800, with T = Time period in seconds.
