There was apparently a reasonably large earthquake last night - a 5.7 at 8:47pm PDT near Greenville CA - see http://earthquake.usgs.gov/earthquakes/eventpage/nc71996906#summary.

Not being from around here, I am still, even after 13 years, not quite used to earthquakes. And in fact, I'm not always sure when I feel one and/or what to do.