We must be very cautious about saying that God judged a nation's sin by causing a specific disaster to take place -- because we simply don't know. Jesus called Satan "the prince of this world" (John 16:11), and no doubt he is the author of all kinds of evil and destruction.
But what we do know is this: God can use tragic events to turn us to Himself. After all, it's easy to go through life without ever thinking about God, as long as our way is smooth and we think we can handle our problems on our own. But what happens when our lives are in danger, or we come up against something we can't solve? Then we should realize that we need God after all, and -- perhaps for the first time in our lives -- we'll turn to Him and seek His help.
I often think, for example, of Jonah in the Old Testament. He fled from God and wanted nothing more to do with Him, but then a fierce storm came, and Jonah was cast into the sea and swallowed by a giant fish. Then Jonah repented and God forgave him -- but it took a fierce storm to bring him to that point.
Don't wait until something like this happens to you before you turn to God! God loves you; He loves you so much that His Son, Jesus Christ, was willing to die for you. By faith ask Him to come into your life, and then make it your goal to live for Him every day.