Propagation and Inundation Characteristics of the 2011 Tohoku Tsunami on the Central Sanriku Coast

Abstract

Propagation and inundation characteristics of the 2011 Tohoku tsunami on the central Sanriku coast are investigated through field surveys and numerical simulations using offshore wave recordings as incident wave conditions. The numerical model successfully reproduces the extent of flood areas as well as the distribution of tsunami heights along the intricate coastline except for run-up of extreme heights over steep slopes. The survey and computed results suggest significant variations of tsunami heights along the coastline. Their positive dependency on topographic slopes implies that the incoming tsunami propagates in standing wave mode to precipitous sites while in progressive wave mode accompanied 1250004-1 Coast. Eng. J. 2012.54. Downloaded from www.worldscientific.com by UNIVERSITY OF CALIFORNIA @ SAN DIEGO on 06/04/15. For personal use only. T. Shimozono et al.by wave breaking over gentle slopes. Temporal-spatial analysis of wave properties in different bays reveals that the inner bay topography provides a clear contrast to inundation characteristics. The impacting waves have extreme heights due to the funnel effect and local wave resonances causing highly transient flooding in narrow V-shaped bays whereas tsunami surges over longer periods across innermost shores of U-shaped bays to produce large horizontal velocities during both run-up and backwash phases.

Nationwide Post Event Survey and Analysis of the 2011 Tohoku Earthquake Tsunami

“…The most of numerical results reasonably agree with the southern part of Sanriku (lower than 39.0 • N) and Aomori Prefecture (higher than 40.5 • N). The local comparisons between the survey and numerical results have been coducted by other people (e.g., Hokkaido area by Watanabe et al [2012]; Middle and South of Sanriku by Shimozono et al [2012]; Kakinuma et al [2012]; Tokyo area by Sasaki et al [2012]) qualitatively agree with our results. There are no significant differences between the other initial tsunami profiles, such as FS1, GSI2 or others above 39.0 • N around the northern part of Sanriku to Aomori Prefecutre.…”

“…The survey areas were gradually expanded to all of the Tohoku region after the middle of April. Survey groups measured local tsunami heights along the coast stretching 2,000 km from Hokkaido in the north to Okinawa in the south, with the exception of a 30 km zone around the Fukushima Daiichi Nuclear Power Plant [Watanabe et al, 2012;Ogasawara et al, 2012;Shimozono et al, 2012;Gokon and Koshimura, 2012;Kakinuma et al, 2012;Udo et al, 2012;Tanaka et al, 2012;Mikami et al, 2012;Sasaki et al, 2012].…”

Improvement of Tsunami Countermeasures Based on Lessons from The 2011 Great East Japan Earthquake and Tsunami — Situation After Five Years

“…However, the 2011 tsunami made a serious nationwide impact [Mori et al, 2012], mainly in the Tohoku region [Suppasri et al, 2012a,b;Gokon and Koshimura, 2012;Kakinuma et al, 2012;Mikami et al, 2012;Ogasawara et al, 2012;Shimozono et al, 2012] and in other regions, from Hokkaido in the north Tokyo in the south [Sasaki et al, 2012]. This tsunami event exposed hidden weaknesses in Japan's tsunami disaster countermeasures.…”

Dispersion and nonlinear effects in the 2011 Tohoku‐Oki earthquake tsunami

“…The characteristics of the inundation strongly depend on the shapes of the bays and the topography around the coast. Numerical simulations were conducted for reproducing and understanding the inundation process of the Tohoku tsunami [e.g., Shimozono et al, 2012;Sugawara et al, 2012].…”