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Differences Between Mud Volcanoes & Phreatomagmatic Volcanoes

The mountainous structure of a volcano is responsible for unleashing massive amounts of energy, lava and ash during an eruption. Mud and phreatomagmatic are words that best describe a type of eruption, rather than a volcano itself. Although the term mud volcano has nothing to do with actual volcanic activity, but rather an eruption from vents within the earth. A mud volcano is characterized by the eruption of mud and fine sediments, while a phreatomagmatic volcanic eruption involves both water and magma.

Mud Volcano Basics
- Mud volcanoes are also called oil volcanoes or gas volcanoes because they spew materials from within the earth, similar to a magmatic volcano. Mud and fine sediment are pushed through a vent in the earth due to pressurized gas and steam. When the pressure becomes too great, the mud volcano erupts. Lava is not involved. There are many places across the globe where you can find mud volcanoes, including China, Pakistan, Trinidad and the United States, in Yellowstone National Park. Humans are responsible for the creation of a mud volcano called Sidorajo, found in East Java, Indonesia. This mud volcano was caused by faulty drilling practices in the search for oil.
Mud Volcano Characteristics
- Mud volcanoes share few characteristics with phreatomagmatic eruptions. The mud that is ejected from the mud volcano is not as hot as lava, in fact, often times it is cool, although just as deadly. A mud volcano releases mud, slurry, fine solids, water, hydrocarbon fluids and gases. The gas released from a mud volcano is 86 percent methane but also contains nitrogen and carbon dioxide. Occasionally, oil and oil traces come from a mud volcano. As the mud is released, it hardens on the surface, forming a mound. Mud volcanoes can be between 16 and 1,600 feet in height.
Phreatomagmatic Volcanoes
- Phreatomagmatic volcanoes describe a type of eruption that occurs when magma is pushed to the surface due to heated water. A typical volcanic eruption is known as a magmatic eruption, in which liquid magma is driven to the surface by gases. Phreatomagmatic volcanoes push older materials, rock, steam, magma and gas to the surface in a violent eruption. The erupted materials are called phreatic. This occurs when water comes through fissures in the earth's crust and interacts with rising magma. Thus, an explosion occurs. In April of 2000, a phreatomagmatic eruption occurred at Mt. Usu in Japan.
Phreatomagmatic Eruptions
- The phreatomagmatic eruption is typically very brief, as the source of water is likely limited. However, these eruptions are still violent and dangerous, unlike a mud volcano. A phreatomagmatic eruption will leave a scar on the earth's surface due to a violent eruption. As the water source begins to exhaust itself, the phreatomagmatic eruption will cease, as opposed to a typical magmatic eruption where the eruption stops when the magma stops rising.

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