Science
What is Volcano?
A volcano is an opening in Earth's surface where molten rock, ash, and gases escape from deep underground. When the pressure of magma below builds up enough, it erupts — sometimes as gentle flows of lava, sometimes as violent explosions.
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Watch a 2-minute lesson with voice + animation that explains volcano.
Key things to understand
- 1Beneath the surface, intense heat melts rock into magma; once it reaches the surface it's called lava.
- 2Most volcanoes form at tectonic plate boundaries, where plates pull apart or one dives beneath another.
- 3Eruptions range from slow oozing lava to explosive blasts of ash and rock, depending on the magma's thickness and gas content.
- 4Over many eruptions, volcanoes build landforms — mountains, islands, and plateaus.
- 5The 'Ring of Fire' around the Pacific Ocean holds most of the world's active volcanoes.
Frequently asked questions
- What causes a volcano to erupt?
- Pressure. Magma is less dense than the surrounding rock and rises; dissolved gases expand as it nears the surface, and when the pressure exceeds what the rock above can hold, it erupts.
- What's the difference between magma and lava?
- It's the same molten rock — 'magma' while it's still underground, and 'lava' once it has erupted onto the surface.
- Are volcanoes always dangerous?
- Not always. Some erupt gently and predictably, and volcanic soil is very fertile. But explosive eruptions can be deadly, releasing ash, gas, and fast-moving flows.