Propagation of tsunami on a linear slope between two flat regions. Part II reflection and transmission.

Abstract

Reflection and transmission of long sinusoidal tsunami waves are investigated for a sea with a linearly sloping region sandwitched by a flat shelf and an outer ocean having a constant depth. Both the coefficients are derived as a function of period, incident angle and dip angle. It is found that the coefficients strongly depend on the period of incident wave and that the existence of a slope affects the tsunami wave form. Particularly, a gentle slope contributes a selective reflection and transmission of wave component of tsunami. The ratio of the amplitude at the coast to that of the incident wave from the outer sea was also investigated taking into account of a rigid coast. It is noted that the only resonance period amounting to 70min is expected in the case of north east Japan.