Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
volcano
References & Edit History Quick Facts & Related Topics
Images & Videos
Mount St. Helens volcano
Magma streaming down a volcano.
Snow-capped Mount Fuji rises above a layer of mist, with a bridge and calm water in the foreground under a pink and blue sky in Japan. Cross-sectional diagram showing three tectonic plates at ocean ridges, transform faults, and a subduction zone. The image illustrates rising magma forming rift and subduction volcanoes, convection currents in the mantle, and features such as ocean trenches, extinct and hot-spot volcanoes, and the movement of plates above a molten core and low-velocity mantle layer. World map displaying the locations of volcanoes and thermal fields that have been active in the past 10,000 years, marked with red dots. Dense clusters are visible along the Pacific Ring of Fire, including the west coasts of the Americas, eastern Asia, and island arcs in the Pacific, as well as scattered sites in the Mediterranean, East Africa, and the Atlantic.
What It's Like to Visit an Active Volcano
seismic sensor pahoehoe Mount St. Helens eruption.
Types of Volcanic Eruptions Explained
At a Glance
default image
volcano summary
Quizzes
Taj Mahal, Agra, India. UNESCO World Heritage Site (minarets; Muslim, architecture; Islamic architecture; marble; mausoleum)
Wonders of the World Quiz
Hawaiian volcanic crater, Hawaii
Volcanoes Quiz
Related Questions
Feedback
Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).
Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

External Websites
Britannica Websites
Articles from Britannica Encyclopedias for elementary and high school students.
Mount St. Helens volcano
Mount St. Helens volcano Mount St. Helens volcano, viewed from the south during its eruption on May 18, 1980.

volcano

geology
Written by
Robert W. Decker
Professor Emeritus, Dartmouth College, Hanover, New Hampshire. Coauthor of Volcanoes.
Robert W. DeckerAll
Fact-checked by
Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
Britannica Editors
Last updated
•History

volcano, vent in the crust of Earth or another planet or satellite, from which issue eruptions of molten rock, hot rock fragments, and hot gases. A volcanic eruption is an awesome display of Earth’s power. Yet, while eruptions are spectacular to watch, they can cause disastrous loss of life and property, especially in densely populated regions of the world. Sometimes beginning with an accumulation of gas-rich magma (molten underground rock) in reservoirs near Earth’s surface,...

Discover the world with Britannica

Subscribe to Continue Reading

Free Trial | No Ads | Exclusive Content
Explore Subscriptions
DNA
Right
Mobile