Yellowstone’s heat may be coming from deeper underground than thought

USA TODAY

Yellowstone National Park: It's hard not to be impressed by all of the incredible natural wonders the world's first national park has to offer. Because an active volcano lies beneath Yellowstone National Park, the site has more than 10,000 hydrothermal features such as mudpots, hot springs and geysers — including the famous "Old Faithful." Plus, there are nearly 300 waterfalls and an incredible array of wildlife — including elk, moose, bison and bears — in this 3,472-square-mile park that straddles Wyoming, Montana and Idaho.

Although there are some hidden expenses to watch out for when visiting, it costs only $30 for a seven-day vehicle pass ($50 if you include a pass to nearby Grand Teton National Park). There are a few times during the year when entrance fees to all national parks are waived, however. And currently all fourth graders can visit national parks for free as part of the Every Kid in a Park program, making it a great family vacation idea.

There's lots of heat underneath Yellowstone National Park, and where it comes from has fueled debates among geologists for decades.

Now, a new study says the volcanic activity at the park could be driven by what's called a "mantle plume," — a 200-mile-wide column of potentially warm, upwelling material — that rises from deeper underneath the Earth's surface than had been thought.

The study was published this week in Nature Geoscience.

Mantle plumes are themselves contentious because seismic images of the Earth’s interior have failed to clearly identify these plume-like features that trace all the way down to the deep mantle.

Geologists Peter Nelson and Stephen Grand of the University of Texas used seismic data to take a look the mantle beneath North America. The authors found a long, thin, sloping zone within the mantle through which seismic waves travel more slowly — and which may indicate the presence of unusually warm material.

The zone extends almost continuously through the mantle, rooted in the core–mantle boundary beneath Mexico and running northeastward up to Yellowstone National Park.

"Our results strongly support a deep origin for the Yellowstone hotspot, and also provide evidence for the existence of thin thermal mantle plumes that are currently beyond the resolution of global tomography models," the authors wrote in the study.

This finding implies the volcanic activity at Yellowstone, which includes hydrothermal springs and explosive geysers like the famous "Old Faithful," as well as super-eruptions in the geologic past, could all ultimately be driven by this deep-mantle plume rising up from above the Earth’s core.

None of this means that an eruption of the Yellowstone supervolcano is predicted let alone imminent, as at least one British tabloid, the Daily Express, claimed.

It's true that underneath Yellowstone National Park lies a "supervolcano," one that blows its top with a massive supereruption every few hundred thousand years.

There is no indication, however, that such an eruption is imminent, or that the volcano is "due" for an eruption. "The probability of such a large eruption occurring in any given year is 1 in 730,000," Christy Till, an Arizona State University geologist, said last year.

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