The somewhat fanciful illustration above reflects the art of man as well as the actual event - but the event did happen; cities and landscapes were devastated and people died, en masse, in an instant - all because of a natural upheaval that could certainly be interpreted as God's will ... or not.
The Bible tells of many historical disruptions in the natural world that resulted in heavy loss of life that were the will and working of God, the greatest, by far, being the story of the flood in Noah's day that left only eight people alive on the whole earth. It was God's judgement on a sinful world and it was foretold for well over a hundred years. Noah found grace in the eyes of the Lord; his warnings were apparently discounted.
The story of the flood has been discounted by most modern historians, geologists and even theologians but evidences around the world of massive depositions of sedimentary material embedded with billions of fossil creatures obviously caught in an instant by some catastrophic, hydraulic circumstance, tend to support 'flood geology' ... at least in the minds of those willing to entertain the possibility of a global flood - perhaps just the possibility of a God who can and will intervene in the world of men. Global, God-ordained catastrophism was the pre-darwinian interpretation of the fossil record, in fact.
Other catastrophes mentioned in the Bible were said to have had world-wide effects (during the Exodus, for instance) and still others were very specifically targetted and of limited scope (such as the sudden annihilation of the Assyrian army surrounding Jerusalem in 701 B.C. - 185,000 casualties!). God's use of the natural world is literally an old story. No wonder we ask the question.
What is the answer?
God uses nature to display His creative power and He uses the power of nature to work His will ... and He has told us of it and warned us of it when He has. The warnings are future and dire; the record is past and clear (for those who will receive it). No divine warning of the recent disaster was received to our knowledge so no assignation of the divine imprimatur would bring Him any glory and therefore it is likely not assignable to that category of event. God's work is always purposeful and the purpose is always His glory.
That said, there are warnings implicit in the wake of a natural disaster like the recent earthquakes and tidal waves in Asia. The primary warning is that we are ephemeral; our next breath is a gift and our existence on this earth is not contractually firm. Another lesson is that we are truly miniscule players on a great stage. Prosperity and power tend to obscure some very basic truths of our existence and the grace of God in an age often referred to as 'The Age of Grace' has tended to make us complacent. The grace of God may also be that He has just warned a complacent world of these basic truths ... and of the reality of past and promised judgements.
Do natural disasters reflect His will? They may - or they may not. It's a good question but we have to remember, stuff happens.
The great lesson may simply be: be ready.