When Will Yellowstone Erupt? Supervolcano Could Rumble to Life Far Faster Than We Thought

Yellowstone supervolcano last erupted 640,000 years ago. Jim Urquhart/Reuters

Before the Yellowstone supervolcano next erupts, we might have only a few decades to prepare—not thousands of years, as previously thought. By analyzing the last eruption to take place, a team of researchers has estimated how long it took for the required amount of magma to build up in the main chambers. The preliminary findings show it happened startlingly fast.

The last major eruption at Yellowstone—one of the world's largest active supervolcanoes—took place around 640,000 years ago, sending about 240 cubic miles of volcanic ash, dust and rock into the sky.

If an eruption were to talk place today, experts estimate a blanket of ash would cover most of the U.S. "Ash-fall thicknesses of centimetres throughout the American Midwest would disrupt livestock and crop production, especially during critical times in the growing season," a 2014 report said. "Thick deposits could threaten building integrity and obstruct sewer and water lines. Electronic communications and air transportation would likely be shut down throughout North America. There would also be major climate effects."

To understand what goes on beneath Yellowstone before an eruption—in a bid to work out what might happen prior to the next one—researchers at Arizona State University analyzed the last big eruption, looking at crystals that show the changes that took place in the run-up to the event.

Hannah Shamloo, a graduate student at the university, and colleagues presented the team's preliminary findings at a volcanology conference in September. According to The New York Times, she said changes to the crystals indicate there was a fast increase in temperature at the site. The magma appears to have accumulated very quickly, and then an eruption occurred a few decades later. "It's shocking how little time is required to take a volcanic system from being quiet and sitting there to the edge of an eruption," Shamloo said.

The findings do not help scientists predict when the next eruption might take place. They could, however, serve as something of an early warning system. By monitoring what's going on underneath Yellowstone, they can track changes to the magma and be on alert if it starts accumulating.

Mike Poland, the scientist in charge of the Yellowstone Volcano Observatory at the U.S. Geological Survey, says the research is interesting, and while the results are preliminary, they potentially open the door to many more questions—including what processes actually trigger rapid magma movement and an eruption.

"I think it's important to note that these results say that the rejuvenation of Yellowstone's magma system may have occurred over decades prior to eruption," he tells Newsweek. "The research does not provide any information about what actually triggered the eruption.

yellowstone deformation
Ground deformation at Yellowstone National Park over the last two years. USGS

"One thing I would emphasize is that even if large eruptions are preceded by only decades of unrest, this is still something we are positioned to detect well in advance. Yellowstone is one of the best-monitored volcanoes in the world, with a host of seismic, deformation, thermal and geochemical sensors and satellite datasets always looking for changes," Poland says.

An example of this was the earthquake swarm that has been taking place at the supervolcano since June. Since it began, almost 2,500 earthquakes have been recorded at the site—making it the longest and most vigorous swarm since 1985.

"We see interesting things all the time, but we haven't seen anything that would lead us to believe that the sort of magmatic 'rejuvenation' event described by the ASU researchers is happening now," Poland says. "We're in a good position to see that sort of event thanks to the monitoring systems that are in place—seismicity (not just the numbers of earthquakes, but also their types) would change drastically, as would styles of deformation, and there would probably be significant thermal manifestations.

"The research does a great job of helping us understand the conditions that set up the last large eruption at Yellowstone. Hopefully, the researchers will continue their investigations to see what more the crystals they are studying can tell us, particularly about the specific conditions that led to the eruption."