My approach to these things is that God may very well be doing something on the mega scale, or it may just be that some places are more at risk to having these type of disasters (like there are only a few places on earth where you can get an earthquake in the M9 range, due to geography).
From my point of view of living the Christian life on a day to day basis, it doesn't matter. What matters is how I respond. Is my neighbor in need? God wants me to respond like a child of God to these who are his children, too. Although sometimes I wonder about the eschatology of it all, what matters most is that when he comes, he finds me being the faithful servant.
Most important from my point of view is that he never catches me being like the Pharisee in the parable of the Pharisee and the Tax Collector, pointing fingers at other people's unworthiness, and for me, I can slip into that trap, so I have to be vigilant and humble.
Off to fight the good fight!
That's right. And a day will come when earthquakes will have immediate eschatological significance; but the overall scene at that point will be, in my understanding of Biblical prophecy, pretty unambiguous.
So I picture myself in dialogue with someone from this country:
Q -- Is this earthquake a direct judgment of God for my people's sin?
A -- I don't know. But God is sovereign, and in His hand is your own life-breath, as well as that of your nation... as well as my own.
Q -- Should we should I repent of our sin and put our faith in Jesus as Lord, Savior, and God?
A -- Yes.
That is how I see God at work in these kinds of situations. I believe that the earth is of God's design; therefore I believe that thingies like fault lines and other geological imperfections exist for a reason...not to punish us, but to challenge us when disasters inevitably occur.