Michael Stiassnie: Tsunami calculations

An idealized mathematical model of tsunami evolution in deep sea and across the continental shelf is proposed. The initial value problem in deep sea is related to the well known Cauchy- Poisson problem, and the tsunami propagation across the continental shelf is derived using the linearized shallow water equations.

When analyzing different cases of tsunamis in deep sea it was found that tsunamis evolve into two basic wave types. One resembles a single wave and the other a wave packet. The analysis of different cases of tsunamis at the shoreline reveals that the continental shelf, due to its geometrical properties, serves as a tsunami amplifier, producing tsunami amplitudes up to 20 times larger than those at the edge of the continental shelf.

A comparison with tsunami measurements suggests that the idealized model may be used for a reliable assessment of the principle hydrodynamic properties of the tsunami, such as the tsunami amplitude and its half- period.

The new mathematical model for tsunami evolution is used to derive a synthetic tsunami database for the southern part of the Eastern Mediterranean coast. Information about coastal tsunami amplitudes, half-periods, currents, and inundation levels is presented.

Michael Stiassnie is professor at the Department of Civil and Environmental Engineering, Technion – Israel Institute of Technology.