Yellowstone has been struck by some 200 earthquakes in just two weeks, as experts say the the supervolcano is “under strain”.
The tremors took place between February 8 and February 15 near the huge caldera, but tension beneath the surface continues to rumble on.
The latest came today at 5.24 AM local time, when a small 2.7 tremor struck the region.
There have been four quakes of such magnitude in as many day.
A spate of small tremors around a volcano usually signifies that magma and gasses beneath the surface are beginning to navigate their exit.
Portland State University Geology Professor Emeritus Scott Burns has said: “If you get swarms under a working volcano, the working hypothesis is that magma is moving up underneath there.”
But Michael Poland, scientist-in-charge of the USGS Yellowstone Volcano Observatory in Vancouver, Washington, played down fears of a Big One.
He told Live Science: “This is what Yellowstone does; this is Yellowstone being Yellowstone.
“It experiences swarms all the time.
“This particular area, especially, is a hotbed of swarm seismicity, and it has been for quite a while.
“One of the potential explanations for why this area is so swarmy is that the whole crust in the area is still adjusting to the big earthquake in 1959.”
The Yellowstone Caldera supervolcano last erupted 700,000 years ago but experts say it should blow every one million years or so.
If the Wyoming volcano were to erupt an estimated 87,000 people would be killed immediately and two-thirds of the USA would immediately be made uninhabitable.
The large spew of ash into the atmosphere would block out sunlight and directly affect life beneath it creating a “nuclear winter”.
The massive eruption could be a staggering 6,000 times as powerful as the one from Washington’s Mount St Helens in 1980 which killed 57 people and deposited ash in 11 different states and five Canadian provinces.
If the volcano explodes, a climate shift would ensue as the volcano would spew massive amounts of sulphur dioxide into the atmosphere, which can form a sulphur aerosol that reflects and absorbs sunlight.
In a recent article for the Billings Gazette, David Mencin and Glen Mattioli, geodesists with UNAVCO, a nonprofit university-governed consortium, said Yellowstone is “under strain”.
The duo say they are using “Global Positioning System, borehole tiltmeters, and borehole strainmeters” to measure minute changes in deformation at Yellowstone.
The say “the strain signal is larger than would be expected if the crust under Yellowstone were completely solid”.