Earth · Pressure and gas

Volcano Eruption Simulator

Peer inside a volcano's magma chamber. Turn up the pressure, dissolve more gas into the melt, and change how thick the magma is to discover why some eruptions ooze gently while others blow the mountain apart.

A cross-section of a volcano showing the magma chamber, conduit and crater, with gas bubbles rising and an eruption when pressure is high.
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Raise pressure above 60% and gas above 40% to make the volcano erupt.

How it works

Magma is molten rock that is less dense than the solid rock around it, so it slowly rises.

Dissolved gases stay trapped while pressure is high. As magma climbs, pressure drops and the gas expands — like opening a shaken bottle of fizzy drink.

Thin, runny magma lets gas escape gently and produces lava flows. Thick, sticky magma traps the gas until it explodes.

Fun facts

The word volcano comes from Vulcan, the Roman god of fire.

Lava can reach about 1,200°C — hot enough to melt copper.

Olympus Mons on Mars is the largest volcano in the solar system, roughly the size of Arizona.

Volcanic soil is exceptionally fertile, which is why millions of people farm beside volcanoes.

Frequently asked questions