What type of eruption will occur if Yellowstone erupts again?

The most likely explosive event to occur at Yellowstone is actually a hydrothermal explosion—a rock-hurling geyser eruption—or a lava flow. Hydrothermal explosions are very small; they take place every few years and form a crater a few meters across. Every few thousand years, a hydrothermal explosion will form a crater as much as a few hundred meters across.

Though the worst-case scenario for a giant Yellowstone eruption is indeed bad and could have global implications, most past eruptions at Yellowstone were not highly explosive. Of the past 50 or so eruptions, almost all were simple lava flows. If they occurred tomorrow or next year, they would have minimal direct effect outside Yellowstone National Park.

As for the worst-case scenario, even previous Yellowstone supereruptions did not cause extinctions, and ash fallout on the other side of the continent was minimal.

Yellowstone is routinely monitored for signs of volcanic activity. These methods include using seismographs to detect earthquakes and using GPS (Global Positioning System) to detect ground motion. The USGS has not detected any signs of activity that suggest an eruption is imminent.

Learn more at the website for the Yellowstone Volcano Observatory.

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What is a supervolcano?

The term "supervolcano" implies a volcanic center that has had an eruption of magnitude 8 on the Volcano Explosivity Index (VEI), meaning that at one point in time it erupted more than 1,000 cubic kilometers (240 cubic miles) of material. Eruptions of that size generally create a circular collapse feature called a caldera . The largest eruption at...

When will Yellowstone erupt again?

We do not know. Future volcanic eruptions could occur within or near Yellowstone National Park for the simple reason that the area has a long volcanic history and because there is hot and molten rock, or magma, beneath the caldera now. USGS scientists monitor Yellowstone for signs of volcanic activity using seismographs (to detect earthquakes) and...

What would happen if a "supervolcano" eruption occurred again at Yellowstone?

Such a giant eruption would have regional effects such as falling ash and short-term (years to decades) changes to global climate. Those parts of the surrounding states of Montana, Idaho, and Wyoming that are closest to Yellowstone would be affected by pyroclastic flows, while other places in the United States would be impacted by falling ash (the...

When was the last time there was volcanism at Yellowstone?

The most recent volcanic activity consisted of rhyolitic lava flows that erupted approximately 70,000 years ago. The largest of these flows formed the Pitchstone Plateau in southwestern Yellowstone National Park. Learn more about the eruptive history of Yellowstone at our Yellowstone Volcano Observatory website .

Is Yellowstone monitored for volcanic activity?

Yes. The Yellowstone Volcano Observatory (YVO), is a partnership between the United States Geological Survey (USGS), Yellowstone National Park, the University of Utah, the University of Wyoming, UNAVCO, the Montana Bureau of Mines and Geology, the Idaho Geological Survey, and the Wyoming State Geological Survey. YVO closely monitors volcanic...

How much volcanic activity has there been at Yellowstone since the most recent giant eruption?

Since the most recent giant ( caldera-forming ) eruption 631,000 years ago, approximately 80 relatively nonexplosive eruptions have occurred. Of these eruptions, at least 27 were rhyolite lava flows in the caldera, 13 were rhyolite lava flows outside the caldera, and 40 were basalt vents outside the caldera. The most recent volcanic eruption at...

How far in advance could scientists predict an eruption of the Yellowstone volcano?

The science of forecasting a volcanic eruption has significantly advanced over the past 25 years. Most scientists think that the buildup preceding a catastrophic eruption would be detectable for weeks and perhaps months to years. Precursors to volcanic eruptions include strong earthquake swarms and rapid ground deformation and typically take place...

Can you release some of the pressure at Yellowstone by drilling into the volcano?

Scientists agree that drilling into a volcano would be of questionable usefulness. In addition to the enormous expense and technological difficulties in drilling through hot, mushy rock, drilling is unlikely to have much effect. At near magmatic temperatures and pressures, any hole would rapidly become sealed by minerals crystallizing from the...

Could a large Yellowstone eruption significantly change weather patterns?

If another catastrophic caldera-forming Yellowstone eruption were to occur, it would probably alter global weather patterns and have enormous impacts on human activity (especially agricultural production) for many years. At this time, however, scientists do not have the ability to predict specific consequences or durations of possible global...
Filter Total Items: 7
Date published: December 19, 2018

Which U.S. volcanoes pose a threat?

USGS Volcanic Threat Assessment updates the 2005 rankings.

Date published: May 17, 2017

EarthWord–Phreatic Eruption

This EarthWord is straight up steampunk...

Date published: May 10, 2017

The Complex Dynamics of Geyser Eruptions

Despite two centuries of scientific study, basic questions persist about geysers—why do they exist? What determines their behavior?

Date published: August 22, 2016


Look! In the sky! It’s a bird, it’s a plane! Wait, run, it’s this week’s EarthWord!

Date published: October 5, 2015

EarthWord: Fumarole

Fumaroles are openings in the earth’s surface that emit steam and volcanic gases, such as sulfur dioxide and carbon dioxide. They can occur as holes, cracks, or fissures near active volcanoes or in areas where magma has risen into the earth’s crust without erupting. A fumarole can vent for centuries or quickly go extinct, depending on the longevity of its heat source.

Date published: May 30, 2008

What Makes an Old Geyser Faithful?

New research suggests that how often Old Faithful and other Yellowstone geysers erupt may depend on annual rainfall patterns.

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May 26, 2016

Forecasting Ashfall Impacts from a Yellowstone Supereruption

  • Yellowstone is one of a few dozen volcanoes on earth capable of "supereruptions" that expel more than 1,000 cubic km of ash and debris.
  • The plumes from such eruptions can rise 30 to 50 km into the atmosphere, three to five times as high as most jets fly.
  • Yellowstone has produced three supereruptions in the past 2.1 million years. The most recent was
January 22, 2014

The Yellowstone Volcano: Past, Present and Future

Public Lecture on Yellowstone Volcano by Jake Lowenstern at Menlo Park, CA on January 23, 2014. The Q&A at the end of the talk can be found on the original source video (Source URL).

video thumbnail: Volcano Hazards
July 30, 2012

Volcano Hazards

The United States has 169 active volcanoes. More than half of them could erupt explosively, sending ash up to 20,000 or 30,000 feet where commercial air traffic flies. USGS scientists are working to improve our understanding of volcano hazards to help protect communities and reduce the risks.

Video Sections:

  • Volcanoes: Monitoring Volcanoes
Image: Active Lava Flow
July 22, 2010

Active Lava Flow

Flows continue to be active south of the Kalapana access road, heading in a generally eastward direction. These breakouts were active just a few hundred meters east of the County lava viewing area.

Image: Lava Flow
April 27, 2010

Lava Flow

Lava, on its southward journey to the ocean, crossed and buried the County lava viewing trail. The viewing area was relocated a short distance back from the flow margin.

Image: Lava Flow
April 20, 2010

Lava Flow

Surface flows on the coastal plain were active a couple hundred meters (yards) from the current viewing trail at the end of Highway 130. The flows are burning along the margin of a large kipuka mauka of the viewing trail.

Image: Lava flow breakout
April 8, 2010

Lava flow breakout

Lava flow breakout

video thumbnail: Yes! Yellowstone is a Volcano (Part 1 of 3)
January 29, 2009

Yes! Yellowstone is a Volcano (Part 1 of 3)

USGS Scientist-in-Charge of Yellowstone Volcano Observatory, Jake Lowenstern, answers
the following questions to explain volcanic features at Yellowstone: "How do we know Yellowstone is a
volcano?", "What is a Supervolcano?", "What is a Caldera?","Why are there geysers at Yellowstone?",
and "What are the other geologic hazards in Yellowstone?"


video thumbnail: Yellowstone Eruptions (Part 3 of 3)
January 29, 2009

Yellowstone Eruptions (Part 3 of 3)

USGS Scientist-in-Charge of Yellowstone Volcano Observatory, Jake Lowenstern, answers
the following questions to explain volcanic eruptions at Yellowstone: When was the last supereruption at
Yellowstone?", "Have any eruptions occurred since the last supereruption?", "Is Yellowstone overdue for
an eruption?", "What does the magma below indicate about a

video thumbnail: Yellowstone Volcano Observatory (Part 2 of 3)
January 29, 2009

Yellowstone Volcano Observatory (Part 2 of 3)

USGS Scientist-in-Charge of Yellowstone Volcano Observatory, Jake Lowenstern, answers
the following questions to provide a tour of the Yellowstone Volcano Observatory: "What is YVO?", "How
do you monitor volcanic activity at Yellowstone?", "How are satellites used to study deformation?", "Do
you monitor geysers or any other aspect of the Park?", "Are