Analysis of Tsunami Flow Velocities during the March 2011 Tohoku, Japan, Tsunami

Abstract

The March 2011 Tohoku, Japan, tsunami caused severe damage to many buildings, bridges, and lifelines along the Pacific coast of Japan. To analyze its effects on structures, the tsunami flow velocity and the tsunami flow depth are needed to estimate the force acting on structures. Videos recording tsunami flows are available on many websites. Ten cases of tsunami flow velocities and flow directions are analyzed from videos by estimating the movement distances of observed objects. The analyzed tsunami flow velocities are 3–5 m/s in Kamaishi City, 2 m/s in Ofunato City, 3–6 m/s in Kesennuma City and 1.5 m/s in Iwaki City. The analyzed velocities fall in the range of to . A case study of tsunami simulation is performed to estimate the velocity in Kesennuma City. At the same locations as the recorded videos, the tsunami flow velocities from the simulation agree the velocities from recorded videos.