If Yellowstone’s volcanic system erupted, how could it impact Colorado?

DENVER ( KDVR ) — If you think the air quality in Denver is bad now, imagine if there were a large volcanic explosion at Yellowstone National Park.

On Tuesday, visitors at the park fled when a hydrothermal explosion occurred a few miles north of the famous Old Faithful geyser. No one was injured, but the event destroyed a nearby boardwalk and prompted officials to close the Biscuit Basin area of the park.

But not to worry, the phenomenon is a normal, common occurrence at Yellowstone, happening once or more each year . Officials with the U.S. Geological Survey told Nexstar that hydrothermal explosions like the one that occurred this week are “not a sign of impending volcanic eruptions.”

Still, the explosion sparked conversation on the internet about what would happen if this were a sign of the “big one,” and what would happen if the volcanic system at Yellowstone were to erupt.

The Yellowstone Volcano Observatory said a large eruption at Yellowstone “will not lead to the end of the human race ,” however it would have global impacts and would impact the entire state of Colorado.

How would a large eruption at Yellowstone impact Colorado?

According to the USGS, a “supereruption” at Yellowstone would have regional effects, including falling ash and short-term changes to the global climate that would last years or even decades.

The closest states, like Montana, Idaho and Wyoming, could be affected by destructive pyroclastic flows , which are a mix of lava blocks, pumice, ash and volcanic gas that flows around a volcano after an eruption.

The rest of the country, however, would be impacted by the resulting volcanic ash.

“Thick ash deposits would bury vast areas of the United States, and injection of huge volumes of volcanic gases into the atmosphere could drastically affect global climate,” according to the USGS .

USGS scientists Larry Mastin and Jacob Lowenstern, as well as National Science Foundation researcher Alexa Van Eaton, published their research about 10 years ago on where volcanic ash would fall if a supereruption were to happen in the present day.

In order to understand what would happen in the modern day, scientists modeled where ash has been found from previous big eruptions at Yellowstone, which happened most recently 640,000 years ago.

Scientists used historical evidence and modern-day weather patterns to create a model of where the ash from a hypothetical supereruption would fall.

“Models have been used for decades to forecast ashfall during eruptions. But only in recent years have tephra models like Ash3d been developed that use a 3-D, time-changing wind field, enabling us to model eruptions that last weeks and spread ash across an entire continent,” a USGS article about the study said.

With the model, USGS scientists learned that “supereruptions distribute ash in a fundamentally different pattern than smaller eruptions.” Supereruptions create an umbrella cloud of ash and volcanic debris that are much less affected by winds than smaller eruptions.

As a result, thick ash would be dispersed in all directions away from the eruption site, gradually thinning out with distance.

The USGS model shows that southern Colorado would get ash that’s about 1 inch to 4 inches thick, and the northern half of the state would get ash that’s about 4 inches to 12 inches thick.

The USGS notes that most “doomsday” scenarios portray far worse impacts than what scientists believe would happen.

The Yellowstone Volcano Observatory said Yellowstone is behaving normally , as it has over the past 140 years. Yellowstone has not erupted in some 70,000 years, and the odds of a large eruption in the coming centuries are very low.

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