I looked at the code and the disaster creation calls are fairly obviously guarded by checks if disasters are enabled. Further, if disasters are enabled, the type of disaster is random, so it won't always be the same type.
This sounds like either a bug or an exploit. This does seem quite possibly caused by something I know about. (And other people, hence why I asked who was playing). Although, I'd be surprised if that was really the case. Or maybe I should be more surprised if it was caused by something else I don't know about that is more random. Hmm, the lag comments are interesting.