A reference to an earthquake in biblical writings is not equivalent to an indication that they are caused by God. The bible doesn't say that, and the notion that God is sitting on his throne looking over all the universe and deciding to punish Sumatra for what America is doing to Terri doesn't fit.
Lots of lightening strikes everyday, too. Nature, or is God obsessed with zapping the planet?
I've made my decision and perhaps it doesn't fit the perspective of others. If we all agreed, this would be a boring forum.