Satomi Hayashi

Understanding the Extreme Tsunami Inundation in Onagawa Town by the 2011 Tohoku Earthquake, Its Effects in Urban Structures and Coastal Facilities

The 2011 Tohoku Tsunami is considered to be one of the most tragic events in Japans disaster history, and represents an important milestone for the research community regarding the investigation of the characteristics of tsunami inundation. A thorough analysis of tsunami inundation was conducted using numerical modeling, and measurements from a video recorded from the rooftop of a building in Onagawa in Miyagi Prefecture. In this study, we analyze the destruction of buildings using numerical simulations and tsunami fragility functions. Numerical results for the locations at which the tsunami eyewitness video was recorded are compared with measurements. In addition, we considered the effect of the breakwater in Onagawa bay to evaluate its contribution to reducing overland tsunami inundation depths. The results of our simulations show that the maximum inundation depth due to the first incoming wave was over 16 m, and over 500 buildings were washed away with this first wave. This result is consistent with the video data. Further, we found that the breakwater, which was not originally designed against tsunami waves, reduced the maximum tsunami inundation depth at least by 2.0 m in Onagawa town.

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.

Contribution of earth observation and modelling to disaster response management: Methodological developments and recent examples

The paper outlines new research findings and hereof generated products in the field of earth observation and modeling technologies to support emergency response measures. Based on the recent earthquake and tsunami disaster in Japan (March 2011) examples will be given for new methodological developments and products to support emergency response strategies more effectively.