TSUNAMI DISASTER MITIGATION OF INLAND EMBANKMENT STRUCTURE

Abstract

 The 2011 Tohoku tsunami was about 2 to 3 times larger than the assumed tsunamis in Iwate, Miyagi, and Fukushima in Japan; consequentially, coastal structures could not completely prevent damages. Therefore, in Japan, we had to take into consideration tsunami disaster mitigation by inland embankment structures. In the present study, we have studied the optimal distance between a coastal levee and an inland embankment by using some cases of tsunami inundation simulations. In the results, the following conclusions have been obtained. (1) Inland embankments can reduce the damaged area by 30% in the case of an input tsunami that lasts for 10 min and has an amplitude of 10 m. (2) A non-optimal location of the embankment reduces its mitigation effects drastically and may even increase the damaged area. (3) The optimal distance between coastal and inland embankments changes significantly if the period or the amplitude of an input wave is different.