When we think of Yellowstone National Park, we think of a traditional family vacation spot in America's heartland. There are canyons, rivers, forests, hot springs, geysers, and even a few bison roaming around. But a new study by researchers at the University of Utah recently uncovered what's going on under the surface – for the first time, they've been able to map the active volcanic system that makes Yellowstone such a hot spot for seismic activity.
1. Yellowstone leaves Mount St. Helens in the Dust
There's a "Supervolcano" in there, sitting on top of multiple magma chambers in the Earth's crust. It's what keeps Old Faithful on a regular schedule.
Eruptions of volcanos the size of the Yellowstone Caldera are thousands of time larger than regular volcanic eruptions, and typically spew so much lava and volcanic ash that they trigger a long-lasting change to the weather, like a small ice age. Other supervolcanoes include Lake Taupo in New Zealand, La Garita Caldera in Colorado, and Mount Tambora in Indonesia. Mount Tambora erupted in 1815, and 1816 became known to Indonesians as the "Year Without a Summer." For comparison's sake, the Mount St. Helens eruption of 1980 doesn't even come close to 'supervolcano' status.
2. It Caused The Ice Age (Maybe)
The Yellowstone Caldera last erupted 640,000 years ago, and may have caused the last ice age, right around the time Homo erectus was evolving into Homo neanderthalensis.
Lava was flowing from Yellowstone as recently as 70,000 years ago, but the Homo sapiens of the time were probably distracted by the eruption of the Toba supervolcano in Indonesia, which wiped out almost all human life of the age.
3. Magma Chambers Bring Heat Up From The Mantle
A newly discovered magma chamber connects a smaller pool in the upper crust to a mantle hotspot down below Yellowstone, according to new research published in Science. We knew there was a small magma chamber near the top and that there was a magma hotspot nearby, but those two phenomena couldn't account for all the molten rock below Yellowstone or all the carbon dioxide escaping everywhere. "This provides a complete picture of the magma system," Fan-Chi Lin, an assistant professor of geology and geophysics at the University of Utah, and coauthor of the new study, says.
4. It's Sitting on 11 Grand Canyons
The newly discovered magma chamber, which is 12 to 28 miles below the surface, would fill the 1,000-cubic-mile Grand Canyon 11.2 times, while the smaller chamber above it would only fill the canyon roughly 2.5 times. Most of that space is filled with hot, solid, sponge-like rock, with only a fraction of the space filled with actual molten rock.
5. Yellowstone Is The Best Studied Supervolcano to Date
It might help us understand other volcanoes and how they work: "I'm not aware of any other study being able to see these kind of lower crust magma body," Lin says. "The reason is that Yellowstone is a very unique place within the U.S. continent."
6. We Use Earthquakes to "See" the Magma Chambers
We can't actually see the magma chambers, we have to infer their presence from seismic movement elsewhere.
"An extensive seismology study across the U.S. allows us to connect local and distant earthquake data, we need to combine these two types of data together," Lin adds. "Most other locations around the world do not have this kind of seismic station," which is why no other volcanoes have this kind of data. They use earthquakes within Yellowstone to study the shallow crust structure, but for the deeper structure you need signals from further away, like Japan, China and Europe, he said.
7. The Supervolcano May Erupt Again
Unfortunately, this study won't help us predict it. "We kind of know what happened in the past, but predicting eruptions will probably remain very challenging," Lin concludes. "Volcanoes are very complex systems."
Yellowstone is closely monitored and researchers can usually tell about a week to a month beforehand if a volcano is going to blow, based on increasing seismic activity, CO2 emissions and ground uplift, he says.