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Volcano's Deadly Warning

Anatomy of a Volcano

 

Intro | Ash | Lava flow | Lava dome | Lava | Vent | Tephra | Caldera | Lahar |  Fissure  | Dike | Magma

Volcano's Deadly Warning homepage

Fissure
Diagram of a volcano

Fissure
On volcanoes, a fissure is an elongated fracture or crack at the surface from which lava erupts. Fissure eruptions typically dwindle to a central vent after a period of hours or days. Occasionally, lava will flow back into the ground by pouring into a crack or an open eruptive fissure, a process called drainback; sometimes lava will flow back into the same fissure from which it erupted.

Left: A close-up of a crack in the volcanic surface of a cooled lava flow from the crater of Mt. St. Helens.

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NOVA Home Find out what's coming up on air Listing of previous NOVA Web sites NOVA's history Subscribe to the NOVA bulletin Lesson plans and more for teachers NOVA RSS feeds Tell us what you think Program transcripts Buy NOVA videos or DVDs Watch NOVA programs online Answers to frequently asked questions