A little shake

This afternoon there was a 4.9 magnitude earthquake, in the greater Los Angeles area. When it happened all my co-workers and I looked at each other, and just commented on the fact that it wasn't that big of an earthquake, and that it seemed to be a roller. We didn't even get out of our chairs. Then we discussed that the building we worked in is on rollers. If it was our first earthquake I seriously doubt we would of been that calm, or of blown it off like we did.