Do you have a source for the "about four meters" ?
Looking at the "predicted maximum level caused by tsunami O.P. 5.7 meter" caption leading via the blue arrow to the red dots just above the sea wall at http://www.tepco.co.jp/en/press/corp...s/110409e9.pdf
, I am wondering how tall that sea wall is. If the sea wall is 5.7 m high and the tsunami only "about four meter" high, should not the nuclear plant have been safe then ?
I would be glad to read more basic science on this topic : how tsunami height and tsunami "run up" are related with each other and possibly modelized, and how sea walls are designed to ensure some predicted level of protection.
What is the meaning of the "O.P." acronym ?