The term 'ground zero' is used for where a bomb hits.

The term 'Ground Zero' was, before Sept 11, normally associated with the point on the Earth directly below a nuclear explosion. At that time we didn't conceive that explosions of this magnitude could be accomplished with anything but bombs. You cannot deny that when the planes hit the WTC there were explosions; there was conflagration beyond the explosions. Ground Zero is the point on the surface of the Earth directly below those explosions.

However, apparently there has been some talk recently that the term "ground zero" predated the first nuclear explosions.