Science
How does a volcano work?
A volcano works as an opening in Earth's crust where molten rock, ash, and gas escape from below. Deep heat melts rock into magma, which is lighter than the solid rock around it, so it rises and erupts at the surface as lava.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a volcano works.
Step by step
- 1Intense heat deep inside Earth melts rock into magma.
- 2Magma is less dense than the surrounding rock, so it rises.
- 3Trapped gases build pressure that can drive explosive eruptions.
- 4Erupted magma at the surface is called lava.
- 5Most volcanoes sit where Earth's tectonic plates meet.
Frequently asked questions
- What makes a volcano erupt?
- Rising magma and the gases dissolved in it build pressure; when it overcomes the rock above, magma and gas burst out as an eruption.
- What's the difference between magma and lava?
- It's the same molten rock — called magma while underground and lava once it erupts onto the surface.
- Why are some eruptions explosive and others gentle?
- Thick, gas-rich magma traps pressure and erupts violently; runny, low-gas magma lets gas escape and oozes out as flowing lava.