2014 Volume 70 Issue 1 Pages 50-64
The 2011 Tohoku-oki tsunami caused sea-level rise at about 20 m height along the coast of Fukushima resulting in devastation on significant power plants including Fukushima No. 1 nuclear power plant. This paper investigated the process of tsunami inundation on Haramachi thermal plant located on the north Fukushima coast in order to ascertain the cause of the larger tsunami height in Fukushima coast than that in the neighboring coasts from field investigations and 2-D numerical simulations. The numerical simulation and inverse wave-ray analysis revealed two significant characteristics of Tohoku-oki tsunami. Firstly, the wave source of Tohoku-oki tsunami covers areas which have the same travel time to Fukushima coast so that tsunamis from wide source areas overlapped at Fukushima coast. Secondly, the tsunami wave concentrated at the coast due to the refraction on the sea-bed topography offshore Fukushima. Additionally, the overlapping of the incident tsunami and the reflected tsunami from the coast caused local sea-level rise near the plant, resulting in reinforcement of the inundated flow. This paper also examined cost-effective measure against future tsunamis. Raising the ground level at where superposition of tsunami occurs can be an effective measure against future regular tsunamis on Haramachi plant. The complement and radical measures, however, is needed for rare giant tsunamis such as Tohoku-oki tsunami.
PROCEEDINGS OF COASTAL ENGINEERING, JSCE
PROCEEDINGS OF THE JAPANESE CONFERENCE ON COASTAL ENGINEERING
