The term Ground Zero may be used to describe the point on the earth's surface where an explosion occurs. In the case of an explosion above the ground, Ground Zero refers to the point on the ground directly below an explosion (see hypocenter). The term has often been associated with nuclear explosions and other large bombs, but is also used in relation to earthquakes, epidemics and other disasters to mark the point of the most severe damage or destruction. Damage gradually decreases with distance from this point.
The term was also used to describe the site of the World Trade Center in New York City, which was destroyed in the September 11, 2001 attacks. The term had been applied to the site in the 1980s by the authors of messages that were stenciled on the sidewalks of Manhattan. Each stenciled message included an arrow that pointed towards the southern tip of the island and stated: "[Number] miles to Ground Zero," in apparent reference to the targeting of the financial district by the Soviet Union in the event of a nuclear war. The adoption of this term by the mainstream North American media with reference to the September 11th attacks began as early as 7:47 p.m. (EDT) on that day, when CBS News reporter Jim Axelrod said, Rescue workers also used the phrase "The Pile", referring to the pile of rubble that was left after the buildings collapsed.