It's amazing how many after shocks have occurred and how frequently! In the first hour, here's what happened:
The earthquake occurred at 06:34, 8.8 mag
The first aftershock occurred at 6:52, 6.2 mag (18 minutes after the last shake)
The next aftershock occurred at 7:12, 6.0 mag (20 minutes after the last shake)
The next aftershock occurred at 7:19, 5.4 mag (7 minutes after the last shake)
The next aftershock occurred at 7:33, 5.6 mag (14 minutes after the last shake)
The next aftershock occurred at 7:37, 6.0 mag (4 minutes after the last shake)
and it continues. Since the quake there have been 50 aftershocks!
See the complete list here, and at the bottom of the screen click on 'last 30 days earthquakes':
http://www.iris.edu/dms/seismon.htm