SCIENCE

A new study of ancient ash suggests the “sleeping giant” could develop the conditions needed to blow in a span of mere decades. (Nat Geo News)

What is the Yellowstone supervolcano? Use our super resource (including downloadable maps, videos, and photos) to learn more.

Discussion Ideas

• The geologic feature beneath Yellowstone National Park is described as a “supervolcano.” How does a supervolcano differ from a regular volcano?
  • A supervolcano is just what it sounds like—a really, really powerful volcano.
    • Supervolcanoes are loosely described as volcanoes that produce more than 1,000 cubic kilometers (240 cubic miles) of gas, ash, magma, and rock. (This is a magnitude 8 on the Volcanic Explosivity Index (VEI).)
    • “Supervolcano” can describe the volcano itself (like Yellowstone), a singular volcanic eruption (sometimes called a “supereruption”), or a long-lasting (million-year!) series of eruptions and lava flows.
    • Supervolcanoes form as magma in the Earth’s mantle rises to the crust but is unable to break through it. A massive magma chamber develops (take a look at the Yellowstone magma plume here) until the chamber can no longer contain the enormous pressure and violently erupts. Learn more about magma and magma chambers with our resource here.

 

• Where are the world’s supervolcanoes?
  • Supervolcanoes are found around subduction zones, hot spots, and rock formations known as “large igneous provinces.” Examples:
    • subduction zone. La Pacana, part of the Central Volcanic Zone of the Andes, is a supervolcano formed as the Nazca plate subducts beneath the South American plate.
    • hot spot. The Yellowstone supervolcano sits over the Yellowstone hot spot. The Yellowstone hot spot has remained stable for millions of years, while the North American continent has drifted southwest.
    • large igneous province. The volcanic event that produced the “Siberian Traps” in northern Russia lasted more than a million years and is sometimes associated with the Permian-Triassic extinction event, in which 96% of marine species and 70% of terrestrial species were wiped out.

 

• Volcanologists estimate supereruptions happen about every 100,000 years. When was the last time the world experienced the eruption of a supervolcano?
  • About 26,500 years ago, the Oruanui eruption sent about 1,170 cubic kilometers (281 cubic miles) of ejecta into the atmosphere.
    • The Oruanui eruption is associated with the still-very-active Taupo Volcanic Zone of the North Island of New Zealand. The Taupo supervolcano is part of a back-arc basin, a depression on the ocean floor formed as an ocean trench created by subduction (here, the Tonga Trench) migrates “backward” toward the overriding plate. The Tonga Trench, to the northeast of New Zealand, is created as the Pacific plate is subducted beneath both the Tonga and Kermadec plates. (FYI, because subduction is our favorite geologic process: that subduction is happening fast—24 centimeters (9.4 inches) a year. That’s the fastest plate velocity on Earth!)

 

• Why do volcanologists and other scientists think the Yellowstone supervolcano may erupt sooner than we thought?
  • A new analysis of crystals from past eruptions shows that the volcano’s massive magma chamber can refill much, much faster than previously thought. According to Nat Geo, “critical changes in temperature and composition built up in a matter of decades. Until now, geologists had thought it would take centuries for the supervolcano to make that transition.”

 

• When was the last time the Yellowstone supervolcano erupted? Read through our great, student-friendly article for some help.
  • According to our article, Yellowstone has produced three colossal eruptions within the past 2.1 million years. The last eruption occurred about 70,000 years ago.

 

• Previous eruptions at Yellowstone spewed tons of volcanic debris that covered most of the continental U.S. Should we be worried about the new research predicting a possible earlier eruption?
  • Not yet. Yellowstone is still considered dormant, and is one of the best-monitored volcanoes in the world. Sensors and satellites are constantly looking for changes in Yellowstone’s geology, and right now, the supervolcano does not seem to pose a threat. Learn more about how the Yellowstone Volcano Observatory is keeping track of its “sleeping giant” with our video series here, here, and here.

 

 

 

TEACHERS TOOLKIT TEXT SET

Nat Geo: Yellowstone Supervolcano May Rumble to Life Faster Than Thought

Nat Geo: When a Sleeping Giant Awakes

Nat Geo: Yellowstone Volcano Observatory (second video) (third video)

Nat Geo: What is a hot spot?

Nat Geo: What is a volcano?