Near-coast tsunami waveguiding: phenomenon and simulations

Abstract. In this paper we show that shallow, elongated parts in a sloping bottom toward the coast will act as a waveguide and lead to large enhanced wave amplification for tsunami waves. Since this is even the case for narrow shallow regions, near-coast tsunami waveguiding may contribute to an explanation that tsunami heights and coastal effects as observed in reality show such high variability along the coastline. For accurate simulations, the complicated flow near the waveguide has to be resolved accurately, and grids that are too coarse will greatly underestimate the effects. We will present some results of extensive simulations using shallow water and a linear dispersive Variational Boussinesq model.