On the issue of the atheistic response to such a disaster, there seems little hope (or even obligation) for the unbeliever to make sense of any of this.
Isn't it correct to say that for the materialist, there is no sense to be made of anything - evil and good are not real, but mere constructs fabricated in the hyperdeveloped nervous systems of one subset of hominids? For the atheist, there is no evil - nor good - because there is no morality, no justice, no reason, no right or wrong.
It's just chemical determinism and physics.
And isn't it question-begging to use the presence or occurrence of evil as an argument against God from the atheistic perspective - since, to the atheist, claims of the existence of evil have no rational basis (indeed, rationality itself has no basis for the atheist, but that's another topic...)?
Like it or not, rationally, the question of God's existence as it relates to the presence of physical tragedy in time-space is entirely the province of the believer and the question really is not does the presence or occurrence of evil say something about whether or not God exists, since that is already decided when we raise the question of evil in the first place, but, rather, what kind of God is it?