In terms of
nuclear explosions and other large
bombs, the term
ground zero (sometimes also known as
surface zero as distinguished from ) describes the point on the Earth's surface closest to a detonation. In the case of an explosion above the ground,
ground zero refers to the point on the ground directly below the nuclear detonation and is sometimes called the
hypocenter. Generally, it is also used in relation to
earthquakes,
epidemics, and other
disasters to mark the point of the most severe damage or destruction.