It is true that God is sovereign over literally everything, including natural phenomena (Psalm 29:3; 115:3; Jeremiah 10:10). It is also true that national sin can bring national judgment, even among "heathen" nations (i.e. nations other than Israel; Genesis 15:16; Proverbs 14:34; Amos 12, etc. ad inf.).
However, I would not attach any such one-for-one significance to these calamities, lest I fall under the judgment incurred by Job's three "friends," who thought they could interpret every act of Providence for others.
Here is one reason why I am reluctant: another Biblical principle is this, and you may make bank on it: the greater the privilege, the greater the responsibility (Amos 3:2; Luke 12:48; Romans 2:1-2).
I say that to say this: if any nations on earth today deserve complete eradication because of their deliberate, defiant and arrogant rejection of abundantly-available truth from God, America would have to be right at the top of the list.
So let's not point fingers. Instead, let's humble ourselves, repent, and get to faith-born work.
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!