Regarding my point...

Agreed with your point. The presence or absence of focusing features MUST be considered for any specific location. But even in the 1960s the shoreline and seafloor topology was pretty well known for Japan. So therefore, for a stretch of shore line like Sendai historical records should be consulted for the average heights of tsunamis in areas without focusing features and then a healthy margin of safety should be applied for the case of a nuclear power plant. That likely would have resulted in a significantly higher wall at Sendai, as the detailed historical record would likely show 5 to 6 meter tsunamis in this area.

But TEPCO likely functioned as an arm of G.E. in all of this and GE likely did not want to have the cost of even a six meter sea wall added to the cost of constructing the plant. They wanted to sell reactor cores and "expertise". Given the US corporate attitude towards risk during the '60s I would expect that the advice given by G.E. would have been to minimize the issue of tsunami dangers and put the responsibility for protecting from them on the whole society via the national government.

"It is not necessary to have hope in order to persevere."