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 upon hitting the ground. 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.
Ground shock
Ground shock, or water shock will result from nuclear explosions on (or near) the surface of ground or water. This ground shock can damage or destroy hardened structures. In water this shock will be damaging to nearby vessels and may also produce a surface wave to limited ranges. A crater is formed by an explosion at (or near) the ground surface. The size of the crater depends on the type of ground material and how close to the ground surface the explosion occurs.