Experimental Study on Detached Breakwaters' Effect on Tsunami Disaster Mitigation

Abstract

In recent years, the risk of occurrence of tsunamis generated by near shore earthquakes, such as, Tokai, Tonankai, Nankai and off-Miyagi is considered to be higher than before as well as off shore tsunami traveling long distance, e.g., the 2010 Chilean tsunami. Tsunami force onto vertical walls, such as seawalls, has been studied in detail. Detached breakwaters are widely applied in front of seawalls especially in Japan. However, effect of such kind of detached breakwaters to reduce run-up and wave force onto seawalls has not been studied. In our study, hydraulic model tests have been systematically and carefully carried out using solitary tsunami waves with and without detached breakwaters to evaluate the effectiveness of detached breakwaters from the viewpoint of reducing run-up and wave pressure onto seawalls.