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What is a Volcano Conduit?

Volcanoes are essentially fissures, or vents, in the crust of the Earth, that sporadically eject gas, lava, ash and rock. Volcanic eruptions range the spectrum from disastrous explosions to slow, mellow discharges of lava. A conduit serves a crucial role in the eruption process, and certain activities inside the conduit can help determine the nature of the eruption and types of materials erupted.

Basic Definitions
- Most volcanoes lie near boundaries of tectonic plates or hot spots, where geological forces periodically push magma from deep underground toward the Earth̵7;s surface. A conduit is the pipe or passageway at the core of the volcano. Magma and other volcanic materials travel through this channel. Once it has erupted, magma is known as lava.
Structure and Layout
- The conduit connects two important pieces of a volcano: the magma chamber and the vent. The magma chamber, or reservoir, is the location in which magma accumulates and resides until the volcano is ready to erupt. The vent is the opening at the Earth̵7;s surface through which lava and other materials are expelled from the volcano. Magma flows upward through the conduit, from the chamber and out through the vent.
Eruption Impacts
- During an eruption, the pressure of fluids within a volcano fluctuates. This action may push conduit walls apart, or, conversely, draw them together, distorting portions of the conduit and in turn acting to influence fluid flow. Post-eruption, lava can sometimes cool within the conduit, creating a plug. This may, in some cases, cause extra pressure to build within the volcano, so that the next eruption is highly explosive. Alternatively, a plug may contribute to a volcano going extinct.
Effect on Emissions
- Activity occurring inside a volcano conduit prior to an eruption can effect the amount of ash and other material expelled from the volcano during the eruption. As pressure toward an eruption builds, particles inside the conduit collide with one another. The deeper their position within the conduit, and the greater the length of time they remain in it, the more often they collide. These collisions break them apart into smaller and smaller pieces, resulting in substantial emissions of fine-grained ash. Ash dispersal can have far-reaching impacts, including disruptions to air traffic and influences on weather patterns. On the other hand, particles nearer the surface which collide less frequently remain intact and are associated with less ash, instead containing hefty chunks of rock.

Nature