Planned for this Thursday at 10 am: The ShakeOut Drill, what's being called the largest earthquake practice drill in U.S. History. Perhaps you've seen the flyers up at your school or office. According to the official web site, the drill is based on a potential magnitude 7.8 earthquake on the southern San Andreas Fault (that's 5,000 times larger than that July 29th earthquake that happened in Southern California). More via the web site: "It’s not a matter of if an earthquake of this size will happen—but when. And it is possible that it will happen in our lifetime." We'll post more about the exact details of the drill, but in the meantime, watch two videos.