Subsidence crater
Encyclopedia
A subsidence crater is a hole or depression
left on the surface of an area which has had an underground (usually nuclear
) explosion. Many such craters are present at the Nevada Test Site
, which is no longer in use for nuclear testing.
Subsidence craters are created as the roof of the cavity caused by the explosion
collapses. This causes the surface to depress into a sink (which subsidence craters are sometimes called). It is possible for further collapse to occur from the sink into the explosion chamber. When this collapse reaches the surface, and the chamber is exposed atmospherically to the surface, it is referred to as a chimney.
It is at the point that a chimney is formed through which radioactive fallout
may reach the surface. At the Nevada Test Site, depths of 100 to 500 m (328.1 to 1,640.4 ft) were used for tests.
When the material above the explosion is solid rock, then a mound may be formed by broken rock that has a greater volume. This type of mound has been called "retarc", "crater" spelled backwards.
When a drilling oil well encounters high-pressured gas which cannot be contained either by the weight of the drilling mud or by blow-out preventers, the resulting violent eruption can create a large crater which can swallow up a drilling rig. This phenomenon is called "cratering" in oil field slang.
Depression (geology)
A depression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms.Structural or tectonic related:...
left on the surface of an area which has had an underground (usually nuclear
Underground nuclear testing
Underground nuclear testing refers to test detonations of nuclear weapons that are performed underground. When the device being tested is buried at sufficient depth, the explosion may be contained, with no release of radioactive materials to the atmosphere....
) explosion. Many such craters are present at the Nevada Test Site
Nevada Test Site
The Nevada National Security Site , previously the Nevada Test Site , is a United States Department of Energy reservation located in southeastern Nye County, Nevada, about northwest of the city of Las Vegas...
, which is no longer in use for nuclear testing.
Subsidence craters are created as the roof of the cavity caused by the explosion
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...
collapses. This causes the surface to depress into a sink (which subsidence craters are sometimes called). It is possible for further collapse to occur from the sink into the explosion chamber. When this collapse reaches the surface, and the chamber is exposed atmospherically to the surface, it is referred to as a chimney.
It is at the point that a chimney is formed through which radioactive fallout
Nuclear fallout
Fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and shock wave have passed. It commonly refers to the radioactive dust and ash created when a nuclear weapon explodes...
may reach the surface. At the Nevada Test Site, depths of 100 to 500 m (328.1 to 1,640.4 ft) were used for tests.
When the material above the explosion is solid rock, then a mound may be formed by broken rock that has a greater volume. This type of mound has been called "retarc", "crater" spelled backwards.
When a drilling oil well encounters high-pressured gas which cannot be contained either by the weight of the drilling mud or by blow-out preventers, the resulting violent eruption can create a large crater which can swallow up a drilling rig. This phenomenon is called "cratering" in oil field slang.
See also
- Underground nuclear testingUnderground nuclear testingUnderground nuclear testing refers to test detonations of nuclear weapons that are performed underground. When the device being tested is buried at sufficient depth, the explosion may be contained, with no release of radioactive materials to the atmosphere....
- Chagan (nuclear test)Chagan (nuclear test)Chagan was a Soviet underground nuclear test conducted at the Semipalatinsk Test Site on January 15, 1965.Chagan was the first and largest of the 124 detonations in the Nuclear Explosions for the National Economy program, designed to produce peaceful nuclear explosions for earth-moving purposes...
- Sedan (nuclear test)Sedan (nuclear test)Storax Sedan was a shallow underground nuclear test conducted in Area 10 of Yucca Flat at the Nevada National Security Site on 6 July 1962 as part of Operation Plowshare, a program to investigate the use of nuclear weapons for mining, cratering, and other civilian purposes...
- CamoufletCamoufletA camouflet, in military science, is an artificial cavern created by an explosion. If the explosion reaches the surface then it is called a crater....
- Glory hole (mining), specifically the subsidence crater produced by underground block caving.
