Tsunami Damages of Nakoso Coast due to the 2011 Tohoku Pacific Ocean Earthquake

Abstract

佐藤愼司１・武若 聡２・劉 海江３・信岡尚道４ Shinji SATO, Satoshi TAKEWAKA, Haijiang LIU and Hisamichi NOBUOKA Coastal damages due to the 2011 Tohoku Tsunami were investigated on the basis of field surveys on the Nakoso Coast, Fukushima Prefecture. Seawall heights, inundation heights, runup heights and ground elevations were surveyed by using VRS type RTK-GPS’s. A clear contrast in the damage was identified depending on the height of seawalls; damages were relatively small where the tsunami overtopped the seawall by about 1m while devastating damages including the collapse of seawalls were observed where the overtopped tsunami height exceeded 2m above the crown of seawalls. Disappearance of the sand bar at the river mouth, deformation of barrier islands and tsunami invasion into rivers and the role of coastal forest in damping tsunami flow were also described. 1.