It's been years so I can't recall the name or find a source, but I recall reading at the time that there was in fact an engineer working on Fukushima's design that loudly protested that the sea wall and related preparations were inadequate based on historical records. Basically that they planned for the 100 year event but should have planned for the 1000 year event. It also wouldn't have been a huge cost burden. Putting the gensets on piers would have prevented the worst of it.