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Ultra-Plinian Eruptions

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View overlooking extensive flat ground covered with trees and meadows
View of Yellowstone's Central Plateau (caldera) from Mt Washburn. Yellowstone National Park, Idaho, Montana, and Wyoming.

NPS photo by John Good.

Introduction

Ultra-Plinian eruptions are the largest of all volcanic eruptions, and are so voluminous that large calderas form above vacated magma chambers. These eruptions are more intense and have a higher eruption rate than Plinian ones and form higher eruption columns. These eruptions produce thick pyroclastic flows that cover vast areas and may produce widespread ash-fall deposits.

Large Calderas

caldera size comparison illustration
The giant crater (“caldera”) formed by the eruption and collapse of Yellowstone Supervolcano 640,000 years ago dwarfs the crater on top of Mt. St. Helens and the caldera of Mt. Mazama.

Modified from “Beauty from the Beast: Plate Tectonics and the Landscapes of the Pacific Northwest,” by Robert J. Lillie, Wells Creek Publishers, 92 pp., 2015, www.amazon.com/dp/1512211893.

The centers that produce the largest eruptions (e.g., that have a volume in excess of 200 cubic miles or 1,000 cubic kilometers) are known as supervolcanoes. These supervolcanoes are typically massive calderas, such as the Lava Creek eruption 640,000 years ago that formed the Yellowstone caldera which covers an area 30 miles by 45 miles (50 by 70 km).

  • Typical magma composition: silicic (rhyolitic)

  • Description: Colossal, Mega-colossal, Apocalyptic

  • Eruption Products: tephra, pumice, fallout ash, pyroclastic flows

  • National Park examples: Mount Mazama in Crater Lake National Park, and the entirety of Yellowstone National Park

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Part of a series of articles titled Volcanic Eruption Styles.

Previous: Plinian Eruptions

Crater Lake National Park, Valles Caldera National Preserve, Yellowstone National Park

Last updated: July 18, 2022