Yellowstone National Park Volcano: Facts & History

Instructor: Betsy Chesnutt

Betsy teaches college physics, biology, and engineering and has a Ph.D. in Biomedical Engineering

Yellowstone National Park is a fascinating place on Earth. It also sits on top of one of the world's largest supervolcanoes! In this lesson, learn about the volcano that lies just under Yellowstone.

What's Really Under Yellowstone National Park?

Yellowstone National Park is a beautiful and unusual place. Throughout the park, there are hot springs where boiling water rises to the surface, geysers that spew hot water and steam hundreds of feet into the air, and unusual geologic features found nowhere else on Earth. To preserve its amazing natural landscape, Yellowstone was designated as the first national park in the United States in 1872.

Grand Prismatic Spring is one of the many hot springs that populate Yellowstone National Park
Grand Prismatic Spring at Yellowstone National Park

It is a habitat for many species of plants and animals, and millions of people have enjoyed visiting the park over the last 150 years. Top attractions include Grand Prismatic Spring and Old Faithful.

Old Faithful spews hot water and steam into the air about every ninety minutes
Old Faithful Geyser at Yellowstone National Park

However, just under the surface of Yellowstone, something big is hiding. Most of Yellowstone National Park is actually a huge volcanic crater, known as a caldera. It is so big that scientists refer to Yellowstone as a supervolcano!

Several times in the past, there have been massive volcanic eruptions at Yellowstone, leading to the development of the unusual geologic features that we can see today. Today, even though you don't see any lava coming out of the ground, there is still a massive pool of magma hiding just under the ground. This creates very high underground temperatures and pressures and causes hot water to be forced to the surface where it erupts from geysers and fills hot spring-fed pools. The area in and around Yellowstone still experiences earthquakes regularly, and one day, the volcano will likely erupt again.

Yellowstone National Park is actually the caldera of a giant supervolcano
yellowstone caldera

History of the Yellowstone Volcano

Over the past 2.1 million years, three major volcanic eruptions and many smaller ones have occurred at Yellowstone. The largest eruption, which happened 2.1 million years ago, deposited ash over much of North America, and scientists think that it sent so much ash into the air that global temperatures were lowered for years! The last major eruption occurred 640,000 years ago and, while it was not quite as powerful as the one 2.1 million years ago, it was still very destructive and deposited ash over many hundreds of miles.

Prehistoric eruptions at Yellowstone were much more powerful than any volcanic eruptions that have occurred in the last 200 years
prehistoric eruptions at yellowstone

What has caused all these volcanoes to erupt at Yellowstone? Deep inside the Earth, there is a region of the mantle known as a hotspot that is located directly underneath Yellowstone. This causes a lot of heat to build up under the ground, which leads to volcanic eruptions as well as the spectacular geysers and hot springs that Yellowstone is famous for.

The Yellowstone hotspot has not always been underneath Yellowstone. Although the hotspot has actually stayed in roughly the same place, the North American plate has been slowly moving, so the hotspot has slowly moved eastward across North America. Eruptions from this hotspot that have left their mark as a caldera have been recorded from 16.5 million years ago.

The hotspot currently under Yellowstone has changed place as the continental plate has been moving for millions of years. The map shows where the hotspot was located at different times (the numbers represent millions of years ago)
yellowstone hotspot over time

Possible Effects of an Eruption of the Yellowstone Volcano

Since the Yellowstone supervolcano has erupted many times in the past and is still an active volcano, it's pretty likely that it will erupt again at some time in the future. What might happen if it did erupt? To see what might happen following a future eruption, we can look back in time to see what happened when it erupted in the past.

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