A deadly supervolcano lies under Yellowstone -- here's what would happen if it erupted

Flickr / Howard IgnatiusThe Old Faithful geyser at Yellowstone.
  • Yellowstone National Park sits atop a supervolcano.
  • Even though the area’s still active, scientists don’t think Yellowstone’s supervolcano will erupt anytime soon (at least not in the next thousand years).
  • But if it did, the eruption could have a major impact on the surrounding areas, spreading ash for hundreds of miles around the western half of the US.

Yellowstone National Park is best known for its Old Faithful geyser and its stunning wildlife.

But the national park also sits atop a supervolcano. You can see some of the evidence of its active state in the hydrothermal activity that bubbles up, including Old Faithful, which shoots water every few hours.

Because the area’s still active, researchers have been trying to determine when the volcano might erupt again. According to research presented in 2017, the supervolcano’s transition from not a problem to eruption might happen faster than experts had previously realised.

Even so, it’s too early to determine an exact time scale of when the supervolcano will erupt, and scientists still don’t think Yellowstone’s supervolcano will erupt anytime soon (at least not in the next thousand years).

What is a supervolcano?

Supervolcanos are characterised as volcanic centres that have had eruptions that covered more than 240 cubic miles. The US has two: one at Yellowstone and another at Long Valley in California.

Yellowstone has had three major events in the past 2.1 million years, which led to the creation of the calderas, or large volcanic craters.

Screen Shot 2016 07 11 at 1.29.10 PMBI Video

It has been hundreds of thousands of years since a major volcanic eruption. The last one was about 174,000 years ago, and it led to the West Thumb Geyser Basin, which extended the Yellowstone Lake.

What would happen if it were to erupt again?

Scientists don’t think Yellowstone’s supervolcano would be erupting any time soon (at least not in the next thousand years). The odds of it erupting within a given year are one in 730,000, according to the US Geological Survey. So if you’re planning a trip there, you shouldn’t be too concerned.

If it did erupt, it could have some pretty extreme effects on the surrounding areas.

For starters, the eruption could emit ash that would expand over 500 miles. For comparison, this map shows the area that the ash reached in the 1980 Mount St. Helens eruption in Washington.

Screen Shot 2016 07 11 at 1.28.44 PMBI Video

Molten lava more than 1,000 degrees oozing from an eruption might be less of a concern than the ash. The eruption would likely cover the ground with as much as 4 inches of grey ash, which could be detrimental to crops growing in the Midwest.

Along with the ash, the supervolcano would spew a whole bunch of gasses, including sulphur dioxide, a gas that can lead to acid rain as well as global cooling as it reflects the sun away from the Earth.

The explosion likely wouldn’t wipe out human life, but it certainly would be destructive, especially to the western half of the US.

In the meantime, researchers are keeping a close watch on Yellowstone to check for warning signs that an eruption might be underway.

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