Application of Improved Numerical Techniques to the Tsunami Response of Island Systems

Abstract

A finite-difference numerical model based on the classical linear long-wave equations has been developed to study the tsunami response of multiple-island systems. The first application of this model was to the Hawaiian Islands. Early results were satisfactory. However, one drawback to the model was the use, at the outer open boundaries of the basin, of a radiation condition which allowed only wave energy approaching the boundary at a normal angle to pass out of the basin without reflection. Recently, an improved boundary condition has been employed which takes into account the radial propagation of scattered waves near the boundary. The earlier model tests were repeated using this new condition. The major features of the results remained relatively unchanged. Certain secondary features of the response. which had made analysis of model results quite complicated, were either eliminated or greatly reduced.