Encyclopedic Entry

The caldera at Crater Lake.

Photograph by Bates Littlehales

Calderas in Space
Earth isn't the only planet that has calderas. Other planets have them as well, including Venus and Mars. The moon also has calderas.

Yellowstone is Still Hot
Yellowstone National Park sits over a hotspot, a place in the Earth's crust where magma sits close to the surface. The Yellowstone Supervolcano, which sits over the hotspot, has had three caldera-forming eruptions: 2.1 million years ago, 1.3 million years ago and 640,000 years ago.

Magma continues to build beneath Yellowstone. It's a question of when, not if, it erupts again. (Chances are good that we have 90,000 years or so before that happens, but geologists monitor the area just in case!)

A caldera is created after a volcano erupts. The eruption blasts away the top of the volcano or causes it to collapse inward. The circular "dent" that results on top of the volcano is a caldera, which can be several kilometers wide. A caldera-causing eruption is the most devastating type of volcanic eruption. It permanently alters the environment of the surrounding area.

A caldera is not the same thing as a crater. Craters are smaller and more circular. They are usually created by explosions of rock during an eruption. Calderas are formed when magma empties from a chamber beneath the volcano. When this happens, the land around the crater may collapse. This collapse forms a caldera. Calderas are circular like craters, but may have parts of their sides missing because land collapses unevenly.

Crater Lake in the U.S. state of Oregon is in a caldera, not a crater, thats about 10 kilometers (6 miles) wide. It resulted from an eruption that occurred more than 7,000 years ago. The volcano's magma chamber collapsed, then filled with water from rain and snow, creating the lake. Crater Lake is the deepest lake in the United States.

The Tengger Caldera in Java, Indonesia, is over 800,000 years old and is 16 kilometers (10 miles) wide. It is part of a group of calderas resulting from the eruption of five volcanoes that are called the "Tengger complex."

The Yellowstone Caldera, located in Yellowstone National Park in the U.S. state of Wyoming, is the result of the Yellowstone Supervolcano. This enormous volcano complex last erupted about 640,000 years ago. The Yellowstone Caldera is more than 72 kilometers (45 miles) long.

Vocabulary

Term Part of Speech Definition Encyclopedic Entry

basin

Noun

a dip or depression in the surface of the land or ocean floor.

Encyclopedic Entry: basin

collapse

Verb

to fall apart completely.

eruption

Noun

release of material from an opening in the Earth's crust.

magma

Noun

molten, or partially melted, rock beneath the Earth's surface.

Encyclopedic Entry: magma

volcano

Noun

an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.

Credits

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Writers

Kim Rutledge
Melissa McDaniel
Diane Boudreau
Tara Ramroop
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

Illustrators

Tim Gunther
Mary Crooks, National Geographic Society

Editors

Kara West
Jeannie Evers

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

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