I feel the earth move

We just had an EARTHQUAKE, people! At about 5:30 a.m., the house did some sort of wild dance, and I had no idea what was going on. Sometimes we hear the trains, but they don't shake the house. Sometimes we get a pretty good shock from a live fire exercise out on the range, but that is accompanied by a LOT of noise, and there was no noise to go along with this feeling. No, it was an earthquake--5.4 on the Richter scale, too, so while it wasn't a major catastrophe, it also wasn't one that's easily slept through.