Holy hole, Batman!

Worst November Ever was pretty worst, but now it seems to be rolling into December.

A friggin' sinkhole has opened up in my back yard. Oh, not a big one -- maybe a foot across. But it goes down for a good three feet. There's a concrete wall along one side, and it's four or five feet from the house, so I assume it's an old cistern or septic tank. The question is ... why now?

I keep picturing those sinkholes in places like Florida that swallow whole houses.