Unnoticed by most in the world, in Yellowstone National Park there is a huge chunk the size of Chicago that over the past decade has been inflating and deflating by several inches.
That area is the Norris Geyser Basin. It’s the hottest, oldest, and most dynamic thermal area in the park. From 2013 to 2015, researchers were baffled to see it rising 5.9 inches each year.
Thanks to GPS data and satellite radar, experts discovered that magma intrusions that were trapped below the basin’s surface cause the deformation. The pressure of magma making its way to the surface pushed the rocks to create a pulsating effect.
Although magma intrusion is a common occurrence all over Yellowstone, this is the first time scientists were able to track an entire episode.
Situated in the northwest of Wyoming, Yellowstone National Park houses bursting geysers, bubbling pools, and steam vents. Its area is larger than Rhode Island and Delaware combined at 3,472 square miles.
While most of the park is in Wyoming, there are parts that spill over into Idaho and Montana.
The park houses a “supervolcano” that experts say last erupted roughly 640,000 years ago. However, the new study shows that the area beneath the surface still has an active flow of magma.
The Norris Geyser uplift started in 1996 but stopped between 2013 and 2014 following a magnitude 4.9 earthquake in the area. The ground then started to return to its natural depth.
But it started rising again in 2016 and went on for two years. For now, it seems the uplift has paused.
Dan Dzurisin, one of the study’s authors, wrote: “Modeling…suggests the 1996–2004 uplift was caused by an intrusion of magma about 14 km [8.7 miles] beneath Norris.
“When magma intrudes the crust it cools, crystallizes, and releases gases that had been dissolved in the melt.
“Gas escape lowers the pressure in the magma, causing the surface to subside… But rising gases can become trapped under an impermeable layer of rock, causing the kind of rapid uplift seen at Norris from late 2013 until the [magnitude] 4.9 earthquakes in March 2014.
“It seems likely the quake created microfractures that allowed gases to escape upward again, resulting in subsidence that ended in 2015.
“The third uplift episode from 2016 to 2018 suggests rising gases became trapped again, this time at a slightly shallower depth.”
Dzurisin added that this activity is nothing to be alarmed about because it’s a common occurrence throughout the park.
“For the first time, we’ve been able to track an entire episode of magma intrusion, degassing, and gas ascent to the near-surface. For those in the know, like you, that’s awesome—not alarming,” he explained.
Replaced!