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magma chamber
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A cross-sectional diagram showing how a geyser and hot spring form above a magma chamber. Arrows illustrate heat rising from magma, groundwater moving through porous rock, and steam or hot water reaching the surface as a geyser or hot spring. Labels identify each layer and process. hot springs and epithermal veins
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magma chamber

geology
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A cross-sectional diagram showing how a geyser and hot spring form above a magma chamber. Arrows illustrate heat rising from magma, groundwater moving through porous rock, and steam or hot water reaching the surface as a geyser or hot spring. Labels identify each layer and process.
geyser and hot spring Groundwater percolates through porous rock into fractures deep underground, where heat from a nearby magma chamber superheats the pressurized water to a temperature above the boiling point of water at surface pressure. In hot springs the rising superheated water is cooled below the boiling point by groundwater before reaching the surface. In geysers the superheated water collects in underground pockets. There a small drop in pressure caused by the release of water at the surface flashes the superheated water into steam, which expands and ejects a column of steam and water into the air. When the supply of steam and hot water is exhausted, the spouting stops and the cycle begins again.

A magma chamber is an underground space, typically deep beneath the Earth's surface, that holds magma. Magma, which is molten or partially molten rock, forms from the melting of Earth's mantle and crust. This magma can rise from the chamber towards the surface.12

Volcanic eruptions are often linked to plate tectonics. When one tectonic plate slides beneath another, heat is generated, melting rock to form magma. This magma then rises and may collect in magma chambers closer to the surface. As a chamber fills, internal pressure can increase. If this upward pressure exceeds the downward pressure from the overlying rock, cracks may form, allowing magma to erupt at the surface as lava. Some volcanoes also form at hotspots, where rising magma melts through the crust, such as in Hawaii.2

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4 Britannica Sources
  1. magma chamber
  2. What Causes a Volcano to Erupt?
  3. volcano - Fissure vents
  4. volcano - Other volcanic structures and features

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