Tsunami and wind-driven wave forces in the Mediterranean Sea

Abstract

The comparison between the impact forces generated from a tsunami wave and those from a wind-driven wave are presented here. Wind-driven wave forces are derived from established maritime theory going back to the nineteenth century. The understanding of tsunami impact forces is derived from more recent research correlated further by some recent model testing. The maritime theory on wave impact force for breaking and non-breaking waves is very well developed from breakwater/seawall engineering. It commenced with Stephenson and Hiro's nineteenth century rule of thumb equations, which was then followed in the twentieth century by Sainflou's theory (1928) for standing waves in deep water. Minikin's studies in the 1950s yielded results for breaking waves and noted high dynamic localised loads and these was followed in 1985 by Goda's equations applicable for both breaking and non-breaking waves. At Alderney, typical impact pressures of 40 t/m2 (400 kN/m2) for 20 m/s waves were recorded, although a Ciria document published in 1992 notes that the average wave pressure on sea walls varies from 150 kN/m2 down to 50 kN/m2 pressure. Users are cautioned about the extremely high wave forces associated with the Minikin method. In 1984, Blackmore and Hewson developed a method to estimate an average wave pressure from broken wave loads. The present analysis which was undertaken for the bathymetry and climatological data of the Mediterranean Sea then outlines the Malta scenario. It can act as a guide to structural engineers in selecting suitable values for the impact pressures that vertical walls may be subjected to for the cases of wind-driven or tsunami waves.