A volcano is an opening in the Earth's crust. It allows hot magma, ash and gases to escape from below the surface.

Diagram showing key parts of a volcano
  • Magma chamber - large underground pool of magma
  • Lava - magma, once it reaches the surface
  • Crater - bowl-shaped basin in the top of the volcano
  • Vent - central tube which magma travels through
  • Secondary cones - eruptions from other vents may build up secondary cones on the flanks
  • Ash, steam and gas - material thrown out by the volcano
  • Volcanic bombs - larger material thrown out by the force of eruption