The bulge the size of Chicago has sparked fears it could erupt – but one scientist insists there are no major concerns yet, even as he keeps a watchful eye on its movements
A colossal bulge the size of 279 football fields has surged up inside Yellowstone National Park, and it’s showing no signs of slowing down.
The vast swell, which stretches roughly 19 miles across near the northern rim of the Yellowstone Caldera by Gibbon Falls, has lifted by an inch since last July. Its movement has reignited talk about the park’s slumbering supervolcano and whether it could be stirring beneath the surface.
But the man watching it says there’s no sign of an impending blast anytime soon. Mike Poland, scientist-in-charge at the Yellowstone Volcano Observatory, is closely tracking the growing dome.
“It’s an area over 19 miles across, give or take a few miles. Saying the uplift is the size of Chicago makes it sound incredibly grandiose, but I think it’s pretty stunning even if it’s not particularly unusual,” he told Cowboy State Daily.
The Greater Yellowstone Ecosystem is one of the most volatile landscapes on the planet, fuelled by constant volcanic, geothermal and hydrothermal forces that power its world-famous geysers and boiling hot springs.
So is this giant underground swell a warning that the supervolcano in northwest Wyoming is about to blow? “That doesn’t mean that the volcano is about to erupt,” he said. “It’s Yellowstone being Yellowstone.”
Ground deformation like this has happened before, with similar uplift episodes recorded between 1996 and 2000, and again in 2004 and 2020.
What’s different now is the technology. Scientists can monitor the changes in real time using satellites, radar and a network of GPS stations dotted across the park and surrounding region.
The result is a detailed map showing the bulge slowly expanding beneath the surface. “It’s a measure of how advanced our monitoring networks have gotten, and their sensitivity in detecting these small changes,” he said. “That’s the story of the year for me.”
Mike compared the phenomenon to inflating a giant balloon underground, which would be far too slow for visitors to notice, but clearly visible on scientific instruments.
“We can see things that are moving up and away from this area of uplift on radar maps and satellites we use to measure this sort of thing,” he said.
“We’ve got 17 GPS stations in Yellowstone, and many more in the surrounding area, and they could pinpoint exactly when this uplift started.”
Despite the dramatic imagery, earthquake numbers have actually been low. Yellowstone typically experiences between 1,500 and 2,500 quakes each year. However, just 1,119 were recorded last year.
The expert said: “That’s on the very low end of normal. The average range is 1,500 to 2,500 earthquakes in Yellowstone every year. This is the second straight year we’ve been at the very low end of the typical range.”
“We’re not really seeing other indications of anything to be concerned about. The difference here at Yellowstone is that a lot of the small earthquakes are driven by water interacting with minor tectonic faults. Water moving around causes those faults to move in small ways, giving you smaller magnitude earthquakes.”
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