2011 年 67 巻 1 号 p. 63-66
An earthquake of magnitude 9.0 occurred off the Pacific coast of Tohoku, Japan, on March 11, 2011. It generated a tsunami 130 km off the northern coast of Japan. The tsunami first reached the Japan mainland 20 min after the earthquake and attacked over 1,300 km along the Pacific coast, inundating over 400 km2 of land. As of 14 July, estimated fatalities were 16,011 with additional 5,242 missing. This tsunami was the first case that the modern and well-developed tsunami countermeasures faced such an extreme event.
A nationwide tsunami survey has been conducted by joint research groups of 299 researchers among 64 different universities/institutes. Inundation heights and run-up heights measured at 5,247 points in total. On the Sendai plain, the maximum inundation height was 19.5 m, and the tsunami propagated as a bore more than 5 km inland. Along the ria coast, about 50-200 km to the north of Sendai, the narrow bays caused focusing tsunami and generated the largest inundation heights and run-ups. The maximum run-up height measured 40.4 m, resulting in the catastrophic destruction of towns and cities.
