Ground zero

In terms of nuclear explosions and other large bombs, the term "ground zero" 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, the term "ground zero" is also used in relation to earthquakes, epidemics, and other disasters to mark the point of the most severe damage or destruction. The term is distinguished from the term zero point in that the latter can also be located in the air, underground, or underwater.

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