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Calderas

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aerial photo of a summit caldera with snow and clouds
Aniakchak Caldera in Aniakchak National Monument on the Aleutian Peninsula in Alaska was formed by a Colossal (VEI 6) eruption 3,700 years ago at the site of a former composite volcano. The preexisting volcano was largely destroyed when its summit collapsed.

NPS photo by M. William.

Introduction

Calderas are collapse features that form during large-volume volcanic eruptions when the underlying magma chamber is partially emptied and the ground above it subsides into it. Calderas may form in both silicic (dacitic to rhyolitic) and mafic (basaltic to andesitic) volcanic systems, leading to two main types of calderas. In addition to the composition of magma erupted, these calderas are also differentiated on the basis of whether the eruptions that produced them were effusive (nonexplosive) or explosive.

  • Explosive calderas form during eruptions of silicic magmas that emit large-volume ash-flow tuffs and form Ultra-Plinian eruptive columns.

  • Nonexplosive calderas form on the summit of shield volcanoes during especially large eruptions of lava flows at either the summit or along flank rift zones.

Calderas are large, generally with a diameter greater than 0.6 miles (1 km). The largest calderas are tens of miles (kms) wide. A defining characteristic of calderas is that they have diameters that are much wider than their included vents.

Calderas are both landforms that are parts of other volcanoes and a type of volcano in their own right. Resurgent calderas, the largest type of caldera, are not associated with any individual volcanic edifice, but are characterized by broad volcanic plateaus with voluminous ash-fall and pyroclastic-flow deposits (ignimbrites).

Calderas are excavational (or inverse) volcanoes with relief below the general land surface because they form from subsidence (or foundering) of the surface. In this way, they are the opposite of constructional volcanoes like cinder cones, composite volcanoes, and shield volcanoes that form from the accumulation of lava and tephra.

Explosive Calderas

photo of crater lake
The Crater Lake caldera was formed by the climatic eruption of Mount Mazama 7,700 years ago. The collapse of the summit reduced the height of the volcano from approximately 12,000 ft (2,700 m) to 8,156 ft (2,486 m) above sea level.

John St. James photo.

Explosive calderas result from violent eruptions of great quantities of silicic magmas. These eruptions produce massive eruption columns that extend into the stratosphere and voluminous pyroclastic flows. Eruptions that produce explosive calderas generally range from 6 (Colossal) on the Volcanic Explosivity Index (VEI) to 8 (Apocalyptic) super eruptions.

The different types of explosive calderas vary in size, eruption magnitude, diameter, age, and whether they formed at summit of a preexisting volcano.

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Nonexplosive Calderas

Photo of a barren summit crater with patches of snow
USGS webcam image taken from the north rim of Mokuʻāweoweo, the summit caldera of Mauna Loa volcano.

USGS photo, Hawaiian Volcano Observatory.

Nonexplosive calderas are located at the summit of most large shield volcanoes, like Kīlauea and Mauna Loa in Hawai’i Volcanoes National Park. They form during VEI 0-1 (Effusive to Severe) eruptions that drain the shallow magma chambers located beneath them. Nonexplosive calderas can contain pit craters, which are smaller collapse structures, as well as lava lakes that can be active for periods of time.

Shield volcanoes can experience several cycles of caldera collapse and subsequent infilling by lava flows.

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National Park Sites with Calderas

National Park Sites with Calderas
ParkCaldera TypeCompositionAgePrimary SignificanceIn Park

  1. Aniakchak National Monument, Alaska—[Geodiversity Atlas] [Park Home] [npshistory.com]

  2. Bandelier National Monument, New Mexico—[Geodiversity Atlas] [Park Home] [npshistory.com]

  3. Bering Land Bridge National Preserve, Alaska—[Geodiversity Atlas] [Park Home] [npshistory.com]

  4. Big Bend National Park, Texas—[Geodiversity Atlas] [Park Home] [npshistory.com]

  5. Channel Islands National Park, California—[Geodiversity Atlas] [Park Home] [npshistory.com]

  6. Chiricahua National Monument, Arizona—[Geodiversity Atlas] [Park Home] [npshistory.com]

  7. Coronado National Monument, Arizona—[Geodiversity Atlas] [Park Home] [npshistory.com]

  8. Crater Lake National Park, Oregon—[Geodiversity Atlas] [Park Home] [npshistory.com]

  9. Gila Cliff Dwellings National Monument, New Mexico—[Geodiversity Atlas] [Park Home] [npshistory.com]

  10. Hawai’i Volcanoes National Park, Hawai’i—[Geodiversity Atlas] [Park Home] [npshistory.com]

  11. Katmai National Park, Alaska—[Geodiversity Atlas] [Park Home] [npshistory.com]

  12. National Park of American Samoa, American Samoa—[Geodiversity Atlas] [Park Home] [npshistory.com]

  13. Saguaro National Park, Arizona—[Geodiversity Atlas] [Park Home] [npshistory.com]

  14. Valles Caldera National Preserve, New Mexico—[Geodiversity Atlas] [Park Home] [npshistory.com]

  15. Wrangell-St. Elias National Park and Preserve, Alaska—[Geodiversity Atlas] [Park Home] [npshistory.com]

  16. Yellowstone National Park, Wyoming—[Geodiversity Atlas] [Park Home] [npshistory.com]

Part of a series of articles titled Volcano Types.

Aniakchak National Monument & Preserve, Bandelier National Monument, Bering Land Bridge National Preserve, Big Bend National Park, Channel Islands National Park, Chiricahua National Monument, Coronado National Memorial, Crater Lake National Park, Gila Cliff Dwellings National Monument, Hawaiʻi Volcanoes National Park, Katmai National Park & Preserve, National Park of American Samoa, Saguaro National Park, Valles Caldera National Preserve, Wrangell - St Elias National Park & Preserve, Yellowstone National Park more »

Last updated: July 18, 2022