Ground burst

A ground burst is the detonation of an explosive device such as an artillery shell, nuclear weapon or air-dropped bomb that explodes at ground level. These weapons are set off by fuses that are activated when the weapon strikes the ground or something equally hard, such as a concrete building, or otherwise detonated at the surface.

In the context of a nuclear weapon, a ground burst is a detonation on the ground, in shallow water, or below the fallout-free altitude. This condition produces substantial amounts of nuclear fallout. An air burst or a deep subterranean detonation, by contrast, makes little fallout.