Magma Chamber
Magma chamber explained in an easy to understand way:
Imagine the frustration of trying to keep a soda bottle from fizzing over when you shake it. Just like that bottle, a volcano has a magma chamber beneath it which acts as a reservoir for molten rock, much like the carbonated liquid inside the sealed bottle. When the pressure builds up inside the bottle, it is similar to the pressure increasing in the magma chamber; if released suddenly, both result in an eruption—one with foam and the other with lava.
Practice Version
Magma Chamber: A large pocket of molten rock under a volcano. Magma chamber. A magma chamber is an underground pool of liquid rock beneath a volcano that can fuel eruptions.