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How does a volcano work?
Quick answer
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.
Step by step
- Intense heat deep inside Earth melts rock into magma.
- Magma is less dense than the surrounding rock, so it rises.
- Trapped gases build pressure that can drive explosive eruptions.
- Erupted magma at the surface is called lava.
- Most volcanoes sit where Earth's tectonic plates meet.
People also ask
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.
What causes a volcano to erupt?
Rising magma and the pressure of trapped gases force molten rock up through a weak point in Earth's crust.
Where do volcanoes usually form?
Mostly along the edges of tectonic plates, where the crust is cracked and magma can rise.
Part of the guide: Nature & Earth: Living Things and Rocks →