Tsunami flow measurement using the video recorded during the 2011 Tohoku tsunami attack

The 2011 Tohoku earthquake tsunami totally devastated the communities of Sanriku coast. Because of the destruction of tsunami observation facilities, such as tide gauges, there are difficulties to understand local tsunami characteristics. The author analyzed the videos recorded at two sites to identify the local tsunami inundation characteristics. The video analysis based on 2-D projective transformation and field measurements enables to estimate the tsunami front and flow velocities precisely, e.g. 8 m/s on Sendai plain and 6 m/s at Onagawa town. The results contribute to understand the local tsunami flow characteristics that were not documented by the observation.