Structure of volcanoes

Volcanoes have distinctive features:

  • magma chamber - this is where the molten rock is stored beneath the ground
  • main vent - this is the channel (or channels) through which magma travels to reach the Earth's surface
  • secondary vent - some magma may escape through the side of the volcano, particularly if the main vent becomes blocked
  • crater - this is found at the top of the volcano and magma erupts from here
Magma comes from the magma chamber under the volcano. It travels through the main vent to the crater. Secondary vents on the side of the volcano may also form. The magma may erupt as volcanic bombs.
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Magma is the name given to molten material inside the earth (volcano) whereas lava is the name given to molten material which is often ejected from a volcano and then cools and solidifies.