Deep beneath Earth's surface, temperatures become hot enough to melt some rock into magma. This magma slowly gathers inside underground spaces called magma chambers.
Volcanoes begin deep underground long before anyone can see an eruption at Earth's surface.
Pressure Builds
As more magma enters the chamber, gases become trapped inside it. These gases create enormous pressure underground.
When the pressure becomes stronger than the surrounding rock, magma is forced upward through openings called vents.
Volcano Eruptions
Not every volcano erupts the same way. Shield volcanoes usually have gentle lava flows, while composite volcanoes can produce powerful explosions of ash, gas, and lava.
Scientists study volcanoes to understand when eruptions might happen and how to keep nearby communities safe.
Knowledge Check
Where does magma collect before a volcanic eruption?