i was just guessing but looks like i was right
Mike Blanpied, USGS associate coordinator for the earthquake hazards program, says there could be more aftershocks any magnitude up to 5. “Aftershocks could go on for days, weeks, or even months. They’re most likely to be felt under the next three or four days,” Blanpied said.
http://www.washingtonpost.com/blogs/blogpost/post/earthquake-aftershock-felt-in-virginia-more-likely-to-come/2011/08/23/gIQA0i9TZJ_blog.html