How does magma rise to the surface?

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Main topic: Science
Other topics: Volcanoes
Short answer:
  • Because of the pressure created by very high temperatures and the fact that it weighs less than the surrounding hard rock.
  • As magma ascends toward the planet's surface, the pressure decreases.
  • Bubbles form as a result of gases that have dissolved in the solution. The expansion of the bubbles makes the magma lighter, rising quickly to the surface.
Illustration of Magma Chamber, Source:

Rock that has melted or is in the process of melting and may be found deep inside the earth is called magma.[1] The typical composition of this combination includes the following components:[2]

  • A heated liquid foundation is known as the melt
  • Minerals crystallized by the melt
  • Solid rocks integrated into the melt from the constraints around it
  • Dissolved gases

The lower region of the earth's crust and the higher part of the mantle are where magma is found to have its beginnings. The majority of the mantle and crust are composed of solid material. Lava is the term used to describe the material produced when magma is expelled from a volcano or other vent. Igneous rock is the name given to rock that was once magma but has since solidified.[3]

The earth has three distinct layers. The core is the very hot heart of the planet, the mantle is the thick layer in the middle, and the crust is the outermost layer on which life may exist.

Core-mantle differentiation processes

Magma rises upward due to high temperature and pressure of bubble expansion that gas molecules make[edit]

The rocks begin to melt as they go higher (or when water is added).  These globules flow upward and combine into more giant proportions that continue to move higher. It's possible that they'll gather in a magma chamber, or they may rise vertically. As the magma rises, the gas molecules inside it start to come out of the solution and produce bubbles; these bubbles also expand. At some point, the pressure from these bubbles becomes more significant than the solid rock surrounding them. As a result, the solid rock around it cracks, which makes it possible for magma to reach the surface.[4][5]

Magma rise cause Decompression Melting at the earth’s tectonic plate separations[edit]

When tectonic plates diverge from one another at divergent borders, decompression melting often occurs. The movement of the fissure enables the buoyant magma found more profound in the earth to ascend and fill the gap created by the reduced pressure. After then, the rock transforms into a new crust. Additionally, decompression melting occurs at mantle plumes, which are columns of hot rock that ascend from the higher-pressure core of the earth to the lower-pressure crust.[6]

Tectonic plate boundaries

The very hot molten rock in the mantle typically does not make it through the several miles of crust that make up the earth on which we walk. The molten mantle begins to slide through only at specific locations where the crust is split or broken (known as fissures), such as at the edge of a tectonic plate boundary.[7][8]

New landform develops through magma decompression melting when located beneath the ocean[edit]

When the plumes, referred to as hot spots, are found under the water, they force magma onto the seabed. These volcanic mounds have the potential to develop into volcanic islands, given millions of years of activity.

Because of this heat, magma becomes extraordinarily fluid and dynamic material, capable of creating new landforms and engaging in physical and chemical changes in various situations.[9][10]


  1. "Magma | National Geographic Society". Retrieved 2022-11-03.
  2. "Magma's Role in the Rock Cycle | National Geographic Society". Retrieved 2022-11-03.
  3. "Volcanoes: The Nature of Volcanoes". Retrieved 2022-11-03.
  4. "What makes the magma come out of the chamber and how does magma form?". Volcano World. 2010-05-06. Retrieved 2022-11-03.
  5. Administrator (2020-03-04). "Frequently Asked Questions". Retrieved 2022-11-03.
  6. "Magma's Role in the Rock Cycle | National Geographic Society". Retrieved 2022-11-03.
  7. "4.3: Magma Generation". Geosciences LibreTexts. 2019-11-04. Retrieved 2022-11-03.
  8. "What Is The Process Of Subduction?". WorldAtlas. 2018-03-06. Retrieved 2022-11-03.
  9. "Magma's Role in the Rock Cycle | National Geographic Society". Retrieved 2022-11-03.
  10. "4.3: Magma Generation". Geosciences LibreTexts. 2019-11-04. Retrieved 2022-11-03.