Complex volcano

A volcano with an irregular structure formed by multiple vents, overlapping volcanic edifices, or successive episodes of activity. Its shape and internal structure reflect a history of shifting eruptive centers.

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Volcanic vent: An opening through which magma, gases, and volcanic fragments reach Earth’s surface. Multiple vents can give a complex volcano several distinct eruptive centers.
Magma chamber: A subsurface region where molten rock accumulates beneath a volcano. Changing magma storage can redirect eruptions among different vents.
Mount Etna: An active stratovolcano on the Italian island of Sicily, with summit and flank vents. Its long-lived activity and multiple eruptive centers have built a complex edifice.
Stratovolcano: A steep-sided volcano built from alternating layers of lava and fragmental deposits. A stratovolcano can be one component of a complex, rather than the whole multi-center structure.
Volcanic edifice: The landform built by volcanic eruptions around one or more vents. Overlapping edifices are one source of a complex volcano’s irregular outline.
Dike (geology): A sheet of igneous rock formed when magma cuts across preexisting rock layers. Dikes can open new pathways that move activity away from an older vent.
Mount Vesuvius: An active volcano near Naples, Italy, formed within the older Somma caldera. The younger cone and older caldera rim form a nested volcanic structure.
Shield volcano: A broad, gently sloping volcano built mainly by repeated fluid lava flows. Its commonly broad, unified profile contrasts with an irregular complex edifice.
Lava dome: A steep-sided mound formed when viscous lava accumulates near a volcanic vent. Dome growth can add local relief and new eruptive centers to a complex structure.
Volcanic fissure: A long crack in Earth’s crust through which lava and volcanic gases can erupt. Fissure eruptions can build separate cones across a broad volcanic area.