If the massive supervolcano underneath Yellowstone National Park ever erupted, it could spew ash over most of the United States. Of course, the Yellowstone Caldera (as it is formally known) hasn't erupted in about 70,000 years — and it only seems to erupt around every 700,000 years — so it seems unlikely that it will happen again anytime soon. All the same, researchers constantly study the underground volcano looking to understand its behavior. You know, just in case.

Even though the volcano doesn't erupt, it's still quite active, producing the park's famous mud pits and geysers and boiling rivers as heat escapes from beneath the surface. That drives constant change in the park. "The heat from the Yellowstone volcano is what drives the hydrothermal system," Yellowstone geologist Henry Heasler told the Casper Star-Tribune. "It gets hot and rises, and the magma chamber, or reservoir, is at a relatively shallow depth."

Interestingly, that shallow depth causes some changes that cause some people to worry unnecessarily: the very ground in Yellowstone swells and deforms in places. Over the several months a section of the park about 6 miles wide has risen about 1.4 inches and moved nearly half an inch southeast. The Yellowstone Volcano Observatory, operated by the U.S. Geological Survey, says this is completely normal, though. "Episodes of ground deformation, which occur commonly in Yellowstone and at other dormant volcanoes around the world, pose no direct volcanic hazards, nor do they imply that an eruption is pending," reads a recent news release. "They do, however, create a scientific opportunity to better understand the geologic processes at work in Yellowstone and elsewhere. YVO and other scientists are pursuing this opportunity, and will continue to monitor the ground deformation closely."

Among those scientists studying the Yellowstone volcano are University of Wyoming professor of isotope geology Ken Sims, who was in the park this past November with a team of researchers. Using equipment to detect radon and acid levels, Sims told the Star-Tribune that he hopes to figure out what causes the park's well-known steam eruptions. If they can determine the cause, then maybe scientists can also anticipate when certain regions would become volatile (and when tourists should be kept away).

The fact that things change so quickly in Yellowstone offers geologists unique opportunities. "Geology in general is a hard thing to observe," Jacob Lowenstern, lead scientist at the Yellowstone Volcano Observatory, told the Star-Tribune. "It's like watching a rock decompose. In a place like Yellowstone, there are a lot of things that are sped up. That's the truly amazing thing about it."

Studying the volcano also offers a chance to examine the very forces that may have created life on Earth. In fact, an enzyme discovered in a Yellowstone geyser in the 1960s later led to new technologies to study DNA and save lives. (I interviewed one of the scientists behind that discovery a few months ago.)

Even though Yellowstone hasn't erupted in millennia, the researchers are still careful. "When we work in a place that hasn't erupted in 70,000 years, you need to watch and wait and pay attention to what the Earth is saying," Lowenstern told the paper.

What can we learn from the giant volcano under Yellowstone National Park?
Just because this volcano hasn't erupted in 70,000 years doesn't mean it isn't full of new information for the scientists who study it.