To Ellis Krauss:

The tsunami last year had a height of 18m in Onagawa but in 1896 30m because the earthquake was very slowly so the wave got higher. Of course it happened only at the Sanriku coast. Look at the tsunami history of Tohoku you can see, tsunami happens ca. every 80years.
The last one happened 1933. Former METI Minister Kaeida said last year in a question from journalists at the FCCJ in Tokyo the government knew about the possibility of an earthquake over 8 in Tohoku.

Best

Siegfried Knittel