Scientists have used artificial 'earthquakes' to uncover new details about magma lurking a few thousand metres below Yellowstone, one of the world’s most closely monitored supervolcanoes.
In the new study, researchers from the University of Utah and the University of New Mexico deployed a truck-mounted Vibroseis – essentially a massive mechanical vibrator – to generate controlled seismic waves across Yellowstone National Park.
These waves, captured by 650 ground sensors, allowed scientists to peer through layers of rock and reveal the volcanic structure close to the surface.
“In a sense, we’re causing our own earthquakes, and we record all that data on the seismometers,” said Dr Jamie Farrell, a geologist at the University of Utah and co-author of the study. “Because we used so many sensors, we can capture a much sharper image of what’s going on underground.”
All this shaking revealed that the top of the magma pockets is 3.8 km – or about 12,500 feet – below the Earth’s surface.
Surprisingly, 86 per cent of this chamber is made up of solid rock. The remaining 14 per cent contains pockets of molten rock mixed with gases and liquids – far from the giant pool of magma that many may imagine.
“Generating artificial seismic waves to find out what is going on underground is nothing new and has been used by fossil fuel hunters for many decades,” Bill McGuire, Professor Emeritus of Geophysical and Climate Hazards at University College London, told BBC Science Focus. McGuire was not involved in this research.
“This is the first time, however, that it has been used at Yellowstone to determine the depth of the shallowest magma.”
Yellowstone, located in Wyoming, US, last erupted 630,000 years ago, with catastrophic consequences and some fear another eruption is overdue. However, while the study found magma less than 4km from the surface, it also confirmed that Yellowstone was not in danger of erupting any time soon.
“There is no giant void of magma here, waiting to come out,” McGuire explained. “Instead, the magma is contained in tiny pockets in hot rock. These are not fully connected up, so don’t form a critical mass, which would be needed prior to an eruption.”
Study co-author Mike Poland, of the US Geological Survey and chief scientist at the Yellowstone Volcano Observatory, said in a statement: “Yellowstone in many ways is a laboratory volcano, and what we learn at Yellowstone can be used to better understand volcanoes in other parts of the world that are a lot more active, but are harder to study.”
McGuire said: “Another super-eruption could be building somewhere on the planet – just not here.”
Read more:
- The thought experiment: What would happen if the supervolcano under Yellowstone erupted?
- Earth's supervolcanoes are waking up. Here's what that means for the planet
- What would happen if all volcanoes on Earth erupted at once?
About our expert:
Prof Bill McGuire is the Emeritus Professor of Geophysical and Climate Hazards at University College London's Department of Earth Sciences. McGuire is also a science writer and broadcaster, whose next book, The Fate of the World: How Our Future is Written in the Past, is due to be published in 2026.
