Better the more prosaic Stuff Happens. Because the earth’s plates moved and jostled the water and those power plants were in the wrong place.
But how about this. What if the Singularity (that moment, supposedly coming in 2045, when the computers we’ve built get smarter than we are) has already happened, somewhere else? What if the Singularians landed here and explained everything – they collided some stars and made a neat little world where creatures crawled out of oceans and came together in countries and tried out different ways of governing themselves and made art and music and fought wars – and everything was going along in a quite fascinating way until it seemed like too much went wrong all of a sudden in Japan.
We’re so sorry! they’d say. With this free will that God gave us, we’re not perfect.
I know, I’m just moving the Why question up a level. Ultimately, Stuff Just Happens, Stuff that’s beyond our (or the Singularians’) capability to understand.