Exploring the myths of the Yellowstone supervolcano

Editor's note: These stories were produced for High Country News by students in the University of Montana's online news class. They will be running over a period of two weeks in the Range blog. See a list of all the stories here.

By Tor Haugan

When bestselling alternative-history writer Harry Turtledove published a recent novel, Supervolcano: Eruption, that described a devastating explosion of the Yellowstone supervolcano, he brought to life the fantasies of a subset of geologic doomsdayers.

Christopher C. Sanders is one of these Cassandras. On Jan. 1, 2009, at the tail end of a Yellowstone earthquake swarm in late 2008 and 2009, Sanders, who identifies himself as a geologist and whose website displays the logo of the United States Geological Survey, did not hesitate: He ordered an evacuation of Yellowstone National Park.

"I ask that some politicians or everyone that can get together with your politicians, your friends or local advisers and ask that everybody leaves the caldera, the surface of Yellowstone National Park, immediately,” he says in a video warning he posted on YouTube. “We have a potential eruption on our hands.”

But Sanders had no authority to order an evacuation, or anything like it. Despite the logos on his website, the man has no affiliation with either the USGS or the National Park Service. Nor did the earthquake swarm indicate a potential volcano eruption. In fact, earthquake swarms are common in the park. They have occurred as recently as January 2010, when the northwestern edge of the Yellowstone Caldera started to experience what became the second-largest swarm ever recorded in the park.

Sanders’ 2009 warning was just one of perhaps hundreds of recent rumors about the Yellowstone volcano that are circulating through cyberspace. They begin in chat rooms and on websites, announcing to the masses that the country's first national park sits atop a sleeping dragon that could awake and start wreaking havoc at any moment. Despite all the fuss, however, officials with the Yellowstone Volcano Observatory, a collaborative effort of the USGS, Yellowstone National Park and the University of Utah that monitors the geological processes of Yellowstone, see no signs of an impending catastrophic eruption.

IS AN ERUPTION OVERDUE?

One of the most prevalent rumors about the Yellowstone Caldera is that the volcano is overdue to go off. But “there’s no clock down there,” says Jacob Lowenstern, USGS geologist and the scientist in charge of the Yellowstone Volcano Observatory. “There’s no guarantee it will erupt in that kind of manner. The worst-case scenario is not the most likely.”

Yellowstone sits atop three overlapping calderas, which were created by three volcanic eruptions. (A caldera is a large depression in the earth, usually formed by the collapse of land following an eruption.) The last one occurred 640,000 years ago, and it created the park’s predominant geological feature, the Yellowstone Caldera. The two previous ones occurred 1.3 million and 2.1 million years ago. Even though the spacing between eruptions has been somewhat varied, many people believe that the eruptions take place every 600,000 years. That would make the volcano’s eruption 40,000 years overdue.

But even if the interval hypothesis held water, 600,000 years is not an accurate figure, Lowenstern says. The average interval based on past eruptions is actually more than 700,000 years, which gives us a bit more time before we need to start panicking about the next massive eruption.

“There’s no guarantee that any given volcano will continue to live forever,” Lowenstern says. “So at Yellowstone, three major eruptions might be all we get.”

IS THE GROUND RISING?

There is another factor behind the recent speculation about an impending eruption: A bulge on the floor of Yellowstone Lake. The lake covers 136 square miles, and most of it is located within the Yellowstone Caldera.

“The bulge is a bit of a newspaper misunderstanding,” Lowenstern says. “There are features that are domed up, and there is no knowledge that the doming is recent.”

There are, however, some GPS data that indicate recent uplift (PDF) across the Yellowstone Caldera. Scientists point to magma or hot water and steam below the earth’s surface as possible causes.

According to a study published in 2010 (PDF), the Yellowstone Caldera rose about 7 centimeters a year between 2004 to 2006, although that rate eventually decreased.

This kind of ground change has been happening ever since Yellowstone became a park and even many years before it was created, Lowenstern says.

“It happens all over the world in caldera systems,” he says, and does not indicate an impending eruption.

The results of this study continue to be analyzed. But other studies look beyond human observations. Some websites with doomsday predictions report that many animals are leaving Yellowstone National Park or dying as a result of toxic volcanic gases. Others point to the so-called Mayan calendar, which many say predicts an apocalypse in 2012.

“If they’re dying or migrating, it has nothing to do with volcanic risk,” Lowenstern says. In fact, animals like bison are often on the move; they have seasonal migrating patterns.

“Yellowstone is very quiet at the moment,” Lowenstern says. “I don’t think the Mayans knew a whole lot about Yellowstone.”

THE REALITY

Henry Heasler, Yellowstone National Park’s chief geologist, has also heard his share of predictions involving the eruption of the Yellowstone supervolcano.

“I don’t think any of those have come true,” he says dryly, “because we’re all still here.”

Earthquake swarms, ground deformation, the release of geothermal gases and changes in hydrothermal systems (which create tourist attractions like mud pots and geysers) can indicate a potential large volcanic eruption. In Yellowstone, this is unlikely, since these events are mostly unrelated to one another.

Pointing to these signs as evidence of an impending eruption is akin to singling out shortness of breath as the harbinger of a heart attack when no other symptoms are present, Heasler says. There’s a whole range of warning signs for eruptions, just as there are for diseases, and they have to occur in roughly the same place and at about the same time for there to be cause for alarm.

But if all these signs did occur at one time, the potential for a large and devastating eruption, akin to the one Turtledove's book imagines, could be very real.

“It would be catastrophic, and a big, caldera-forming eruption would cause global change in atmosphere and temperature and travel patterns and everything,” Heasler says.

Post-eruption atmospheric change can happen when sulfur, which is present in magma, is released during eruptions and injected into the stratosphere. Scientists have found that such injections of sulfur have led to a cooling of the Earth’s surface and a warming of the stratosphere. Sulfur also reacts with chemicals in a way that promotes ozone depletion. Based on evidence from past volcanoes, a future eruption could cause temperature changes that disrupt the delicate balance needed to keep wildlife, livestock, crops and humans alive and healthy.

As evidenced by the recent mass speculation, the prospect of a real, massive explosion is both fascinating and frightening to contemplate. But for the most part, the information on the Web and even scientific articles on the topic has been taken out of context, says Heasler. Still, he believes in paying attention to the rumors and even tries to clarify misconceptions that are born online.

“The great thing about the Internet is that it’s anarchy,” he says. “Anybody can say anything. That’s both a blessing and a curse.”

His advice? Consider the source before you get too excited; look carefully at its credentials and reputation.

And, as a dedicated park employee, he encourages all who are interested in the topic to investigate in person, if they can.

“If someone says all the fish are dead in Yellowstone Lake,” he says, “come and see for yourself.”

Essays in the Range blog are not written by High Country News. The authors are solely responsible for the content.

Images:

The Yellowstone Caldera experienced an uplift of about 7 centimeters per year between 2004 and 2006, but the rate has decreased since then. Caldera systems around the world have been known to go through periods of uplift. Photo courtesy Flickr user nicolas.boullosa.

A bulge 2,000 feet long and 100 feet tall sits at the bottom of Yellowstone Lake, although there’s no indication it’s grown recently. Photo courtesy Flickr user Amy the Nurse.