I think the strange thing is this type of disaster has been well telegraphed by scientists repeatedly. In Hawaii everytime there is an Earthquake in the pacific basin they instantly decided whether to trigger a tsunami warning. I guess there is no such warning in the Indian ocean.
In theory this type of thing could happen anywhere. Two weeks or so ago there was a big quake in Antarctica but because is a was a horizontal shift rather than vertical there was no tsunami. This quake was massive and vertical (by about 10 metres on the sea bed so any witness to the quake would have known there was huge trouble on the way.