Science
How does a geyser work?
A geyser works when underground water, heated by Earth's deep heat, builds up pressure until it erupts in a jet of steam and water. Water trapped in narrow channels boils, and the sudden pressure release sends it bursting to the surface.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a geyser works.
Step by step
- 1Groundwater seeps down near hot volcanic rock.
- 2The deep water heats well past normal boiling, held down by pressure.
- 3Eventually some flashes to steam, expanding violently.
- 4The expansion blasts water and steam up through the vent.
- 5After erupting, the system refills and the cycle repeats.
Frequently asked questions
- What makes a geyser erupt?
- Underground water heated past boiling by volcanic rock builds pressure until some flashes to steam and violently forces water up and out.
- Why are geysers rare?
- They need a precise combination of abundant groundwater, intense underground heat, and a particular plumbing of narrow channels.
- Why do some geysers erupt on a schedule?
- Their underground chambers refill and reheat at a fairly steady rate, so pressure builds to the eruption point at regular intervals.