Magma chamber

A magma chamber is a large pool of liquid rock under the surface of the Earth.

The molten rock, or magma, in such a chamber is less dense than the surrounding rock. This produces buoyant forces on the magma that tend to drive it upwards.

If the magma finds a path to the surface, then the result may be a volcanic eruption. Many volcanoes sit over magma chambers. These chambers are hard to detect if they are deep within the Earth. Most of those known are close to the surface.

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