I keep watching the real-time data list from the USGS and it is scary... many after-shocks are above 4.0... so many are in the 5 range, with quite a few are in the 6 range! 
http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/quakes_all.php

http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/quakes_all.php