From The Times Dispatch:
Reports of the mysterious booms first felt in North Side neighborhoods are now coming from other city sections and beyond.
Folks from the Fan District, Lakeside, Short Pump and New Kent County all say they have sensed the shock.
Richmond leaders have even been contacted by officials from Fort Wayne, Ind., and several Canadian provinces where similar booms have been felt recently, city emergency services spokesman Bill Farrar said.
I should add that the local officials told residents that they had determined the cause of the "booms" but weren't going to share it with them. This story makes that statement less credible.