Recently the Asahi News reported the following:
On the 17th, the investigation done by Prof. Fuminhiko Imamura (tsunami engineering) of the Tohoku University found that the tsunami came from the East Japan great earthquake had a height of ten meters when it reached the Arahara district in Sendai City Wakabayashi Ward where a death toll of several hundreds people was confirmed. It was said that this was the world's largest class tsunami seen at plain part. The tsunami was about three times the height that Miyagi Prefecture had prepared for; it went beyond the tide embankment and the sea wind protection forest, and hit the villages.
In the Arahara district, there were signs that the tsunami was up to ten meters in height at some part of the school building of the elementary school where the residents had escaped into. From the Arahara district to Natori City, almost the whole region had marks of a tsunami that was ten meters in height. Tsunami could not be amplified easily at the plain part, but it could be amplified in the Sanriku coast etc. , and there was a possibility that it was amplified more than twice than those seen at the plain part. According to Mr Imamura, it was said that the biggest tsunami generated at the plain part was over ten meters and that was observed at the Indian Ocean in 2004.
At Miyagi prefecture, the assumption was based on the biggest tsunami seen previously due to the Miyagi Prefecture off-shore earthquake (synchronization type); at this region, the expectation was 2 to 3 meters. Although a five-meter tide embankment together with a pine forest with a width ranging from 50 to a few hundreds meters was prepared, this tsunami was three times bigger. The ferro-concrete building assumed to be unbreakable in the tsunami was destroyed in the fishing port in Natori City. Mr. Imamura said ｢An exceptional strong tsunami had came. I had been involved in the disaster prevention measures and I think it is embarrassing.｣
Natural disasters are difficult to predict, a ten-meter tsunami is something beyond expectation.