An explosion crater is a characteristically shaped hole formed when material is ejected from the surface of the ground by an explosive event just above, at, or below the surface.
A crater is formed by an explosive event through the displacement and ejection of material from the ground. It is typically bowl-shaped. High pressure gas and pressure waves are responsible for the creation of the crater by three processes

• plastic deformation of the ground
• projection of material (ejecta
  Ejecta
  Ejecta can mean:*In volcanology, particles that came out of a volcanic vent, traveled through the air or under water, and fell back on the ground surface or on the ocean floor...
  
  ) from the ground by the expansion of gases in the ground
• spallation
  Spallation
  In general, spallation is a process in which fragments of material are ejected from a body due to impact or stress. In the context of impact mechanics it describes ejection or vaporization of material from a target during impact by a projectile...
  
   of the ground surface

and two processes partially fill it back in

• fall-back of ejecta
• erosion and landslides of the crater lip and wall

The relative importance of the five processes varies depending on the height above or depth below the ground surface at which the explosion occurs, and the material composing the ground.

See also

• Maar
  Maar
  A maar is a broad, low-relief volcanic crater that is caused by a phreatomagmatic eruption, an explosion caused by groundwater coming into contact with hot lava or magma. A maar characteristically fills with water to form a relatively shallow crater lake. The name comes from the local Moselle...
  
  , an often flooded crater caused by volcanic explosion
• Subsidence crater
  Subsidence crater
  A subsidence crater is a hole or depression left on the surface of an area which has had an underground explosion. Many such craters are present at the Nevada Test Site, which is no longer in use for nuclear testing....
  
  , a depression in the ground formed by collapse of a void below the surface
• Impact crater
  Impact crater
  In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
  
  , a depression formed by excavation following a hypervelocity impact
• Pseudocrater
  Pseudocrater
  A pseudocrater is a volcanic landform which resembles a true volcanic crater, but differs in that it is not an actual vent from which lava has erupted...
  
  , a volcanic crater formed by a steam explosion