SUMMARY: Fun dynamic data. In color! Dogs are useless!
Whenever you feel an earthquake, you can report it at this USGS site. Then you can watch the responses pour in from thousands and thousands of people who feel even weak earthquakes, and very quickly get a picture of how weak and minor it was--and be amazed at how widely people feel them. I love watching the picture grow in the minutes after a quake.
My renter came downstairs at 9:00 and said, "Did you feel it?" I didn't! Drat! Usually if I'm sitting at my computer, I do, but not this time. Online, the quake hadn't even come up on the various web sites yet, but within a couple of minutes, it did: Reported as a 4.1 near Alamo (about 45 minutes from here by freeway). So we filled in his impressions of the quake and hit Submit. At that time, we were among the first 25 responders. Within 15 minutes, there were 2500 responses; 5 minutes later, there were over 3000. It'll probably slack off considerably now.
But think what an amazing tool the Internet is for collecting that kind of info! Just astonishing.
See the map of this quake.
Meanwhile, I got no tips from my dogs (as usual) that anything was going on. But then, there are zillions of little quakes every day (see all from the last week) that they probably feel more than we do and just dismiss out of hand. I know I would if I were a dog.