This is not the biggest earthquake / tsunami they've ever dealt with.
I do not see Death swooping down on them and wiping them out.
Though to my mind theres only one other instance I can think of that compares with it. I could be badly mistaken but If I'm not, around 1680 a huge tsunami hit and completely buried a town there. I mean it wiped it off the map outright. I know it was in the 1600s.
I do however see the danger of the nuclear plants. If they leak radiation for longer than a few days, with Japans population concentrations, it is likely to be a rather huge problem. (not that I'm down on nuclear power outright or anything, I'm not).
It is a ring of fire nation. Earthquakes will come and go, but I'm glad that this one wasn't on the island itself, that would have been devastating beyond what this one is. All we can do is keep our back straight, keep a stiff upper lip, and try doggedly to fix whatever problems arise.