Despite persistent rumors, the Yellowstone caldera is not a “supervolcano,” nor is it about to cause a super eruption.
BY AMANDA LOUDIN
If there was ever an “overused, misrepresentative and misapplied” term, according to Mike Poland, it’s “supervolcano.” Sometimes, he admits, trying to squelch the rumors surrounding Yellowstone’s volcanic activity can get downright depressing. But as the scientist-in-charge at the Yellowstone Volcano Observatory, Poland is passionate about sharing the truth of the matter, and so he—and others like him— continue to educate and inform the public wherever and whenever they can.
Here’s what they’re up against: Some 631,000 years ago, Yellowstone experienced a massive eruption from a caldera, the name for the basin-shaped volcanic depression with a diameter ranging from one to 30 miles across. This was a “super eruption,” but not a super volcano. In fact, according to Poland, “There’s no such thing as a supervolcano.”
About 20 years ago, the term super volcano began entering scientific articles, seeping into the public’s imagination. Add to it the 2005 British- Canadian disaster film—actually named Supervolcano—that centered on a massive eruption at Yellowstone, and the term caught fire.
These days, with social media to fuel the rumor mill, folks like to chat about Yellowstone’s “supervolcano” being overdue for a massive, civilization-ending eruption. “People’s minds like to go to disaster scenarios,” says Madison Myers, assistant professor in the department of earth sciences at Montana State University. “When I tell people what I do for a living, the first question I get is ‘When will the super eruption occur at Yellowstone?’ They’re almost disappointed when I tell them it’s not going to happen in their lifetime.”
If and when the caldera actually erupts in the distant future, however, it will likely be more of a whimper than a bang.
What’s Really on Tap
One thing is for certain: the rumor mills crank up anytime there’s increased seismicity around Yellowstone, or anywhere in the West, for that matter. “We see spikes in rumors whenever there are higher than average numbers of quakes, or large quakes anywhere in the country,” Poland says. “The 2019 Ridgecrest, California, quake, for instance, or the 2020 central Idaho earthquake kicked the chatter into high gear.”
On average, somewhere around 1,500 earthquakes occur annually in Yellowstone, and in some years, upwards of 3,000. But an uptick in earthquakes does not equate to an impending super eruption.
A number of components need to come together, according Wyoming state geologist Erin Campbell, including the tilt of the surface near the volcano and its elevation, the release of gases like sulfur dioxide, and even the amount of water vapor the volcano is releasing. “When activity is close to the surface, there’s nothing to be concerned about,” Campbell says. “Volcanoes are not like tornadoes; they give you plenty of clues well in advance of an eruption.”
The Yellowstone caldera is one of the most highly monitored volcanoes in the United States, under the close watch of multiple organizations. “At this time, we have no evidence that an eruption is taking place soon,” Myers says. “If something changed, we would know about it and be able to react to it with plenty of time.”
“When activity is close to the surface, there’s nothing to be concerned about,” Campbell says. “Volcanoes are not like tornadoes; they give you plenty of clues well in advance of an eruption.”
Scientists study eruptions in two general categories, according to Myers, the first being effusive, or a lava flow, which hugs the ground and moves slowly. “Think Hawaii,” she says, adding that an effusive eruption is considered low hazard and evacuation isn’t too difficult. It’s just not quite electrifying.
“It’s like watching paint dry,” Myers says, “but there’s some level of excitement associated with that release of gases.”
The second type is explosive, which is what most people think of when they picture an eruption. These involve magma higher in viscosity and with a higher gas content. Eventually, Yellowstone will experience one of these, but nothing indicates that will take place anytime soon. “The magma chamber would need to be primed for that to happen, and that would take a while, probably centuries,” Poland says. “It would be accompanied by unmistakable signs of unrest, far more extreme than anything we’ve witnessed before.”
Given all that, what’s a scientist to do about getting the correct messaging to the public? “We do our best to put out lots of good information, including monthly video updates, weekly articles, annual reports of activity and so forth,” Poland says. “And we try to fight misinformation that we see on social media.”
It can be an overwhelming job, however, and experts face an uphill battle in numbers. “It’s really difficult for every scientist who has dedicated a career to this, because for every one of us, there’s 1,000 others on the internet spreading bad information,” says Wyoming’s Campbell.
Another layer is a general mistrust in government in some circles, according to Poland. “I frequently have people say they don’t trust me because I work for the government,” he says. “So, I push back and encourage them to find experts not on the government payroll, like a geology department at a university.”
At the end of the day, consistency in messaging is the approach the experts take and that means dispelling fear about a supervolcano in Yellowstone. “My approach is one person, one rumor at a time,” Poland says. “I trust that in the end common sense will prevail.”
Amanda Loudin is a new Colorado resident and freelance writer who covers health and science, the outdoors and travel—sometimes all in one article.