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Yellowstone geologist discusses a “new” thermal area

tern lake thermal area 2.jpeg
Michael Poland
(Left) Aerial view of the new extension of the Tern Lake thermal area, with steam rising in the center. (Right) Forward Looking InfraRed image of the thermal area, with the field of view indicated by the red box in the visible aerial view. Warmest areas are bright white and yellow, while cooler areas are purple.

Yellowstone National Park is filled with thermal areas. Some of the most iconic include the exploding steam from Old Faithful, the rainbow colors in the Grand Prismatic Spring, and the golden terraces at Mammoth Hot Springs.

About 20 years ago, scientists discovered a new thermal area in the park. It was actually by accident – the area is off the beaten path in the eastern side of the park. But some infrared satellite imagery showed that the area had warm ground, which indicated things were changing. Twenty years later, scientists are still studying the TernLake thermal area to further understand it.

Jefferson Hungerford, a Yellowstone National Park geologist and volcanist, spoke with Wyoming Public Radio’s Caitlin Tan about the Tern Lake thermal area.

Caitlin Tan: Could you describe, if you were standing in the area 20 years ago, what it might have looked like? And then if you're standing there now what it looks like?

Jefferson Hungerford: Basically 20 years ago, you wouldn't even think something was going to happen there. It was just forested like other areas right around it. And then over time, you'd start to see trees dying off, and the area would start to expand. The trees kind of standing there are dead and losing their foliage and this area of dead trees would kind of just grow. And then, the area might even elevate just a wee bit as more heat comes into the system.

And then the area that was really hot would start to turn orange, red, or brown. And you would see in the morning steam coming off this area, and then the trees would be laying [on the ground] about now starting to basically get cooked. The trees start to carbonize, like charcoal, right around the steam areas. You come to 2020 or 2019 and the area is no longer treed. All you have are trees that are knocked over. And now you see just brown dirt and heat. You can really feel the heat coming out of the ground. So it goes from a nice forested area to an area that's steaming.

CT: To someone who doesn't understand the science behind it, it kind of sounds scary that something like this can just kind of pop up. Is that anything people should be worried about?

JH: No. This is what we would expect out of the system as we know it. We expect these systems to be ephemeral. These systems are very active, and they're going to turn on and turn off and turn on and turn off all the time. They are the surface expression of the heat coming off the volcanic system lying below. So we don't expect anything big out of the system anytime soon. But the hazard is that these features are very hot right at the boiling temperature on the surface. So the hazard here to humans is interaction with that hot water. It will burn you and give you third-degree burns in a nanosecond if you were to touch it.

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Caitlin Tan
Wyoming Public Media
A view of the Grand Prismatic Spring in Yellowstone National Park.

CT: So have we ever seen a thermal area like this just kind of pop up in our lifetimes?

JH: Yeah. This actually happens more often than you would think. These geothermal systems are very, very dynamic – they come up, and then they will die off. But these areas are really, in geologic time, ephemeral. They're around for a wee bit, and then they might die off. Some might become really well-established but they will be in constant change.

We have a dynamic system here. The ground is either constantly uplifting, or deflating, or subsiding. And then we have a whole bunch [of earthquakes], between 1,500 and 3,000 earthquakes in the area a year. So this is a really dynamic system, and all that activity affects the systems. We look at things that have been around since we were here in the 1870s or so – like Old Faithful and some of these other predictive systems – those are not kind of the norm of this larger geothermal system. What we expect is sporadic activity. That's more the norm, and, again, ever changing. If you look at the hill above Porcelain Basin and Norris Geyser Basin, that hill is constantly changing, and we expect change in these systems.

CT: Do we know why an area might go dormant or turn off kind of suddenly?

JH: I would say we've got a bit to learn before we can actually forecast an area to turn on or turn off.

CT: It's so cool to think that we've known about Yellowstone for so long and yet there's still so much to learn, and that we’ll probably never be done learning about what's happening there.

JH: Yeah. I'm pretty certain I'm going to retire and there will still be a lot to learn. Yeah, it's a beautiful system. It's one of the most fascinating systems on planet Earth, and it's one of the biggest ones too. It's created some of the biggest eruptions that we know of.

Caitlin Tan is the Energy and Natural Resources reporter based in Sublette County, Wyoming. Since graduating from the University of Wyoming in 2017, she’s reported on salmon in Alaska, folkways in Appalachia and helped produce 'All Things Considered' in Washington D.C. She formerly co-hosted the podcast ‘Inside Appalachia.' You can typically find her outside in the mountains with her two dogs.
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