A groundburst is the detonation of an explosive device such as an artillery shell

Shell (projectile)

A shell is a payload-carrying projectile, which, as opposed to shot, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot . Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used...

, nuclear weapon

Nuclear weapon

A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

 or air-dropped bomb

Bomb

A bomb is any of a range of explosive weapons that only rely on the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy...

 that explodes upon hitting the ground. These weapons are set off by (fuses

Fuse (explosives)

In an explosive, pyrotechnic device or military munition, a fuse is the part of the device that initiates function. In common usage, the word fuse is used indiscriminately...

) 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.