it's quite a small country
It's not that small. Larger than Germany, smaller than Sweden.
If the accident had been West of Tokyo it would have been incredibly, stupendously bad
Perhaps, but if by "west" you mean the Japan Sea coast, the tsunami risk is substantially lower.
Top Ten Things Overheard At The ANSI C Draft Committee Meetings: (8) I'm on the committee and I *still* don't know what the hell #pragma is for.