MTPR

Yellowstone Boardwalk Closed, But Thermal Activity Nothing To Worry About

Sep 26, 2018

Last week, Yellowstone National Park saw thermal activity that hasn't been recorded in the area in decades.

The normally still and calm Ear Spring in the Upper Geyser Basin, not far from Old Faithful, sent out its largest burst of water in recorded history. The National Park Service has closed some areas of the boardwalk to accommodate additional new thermal features that have formed. And all this comes at the same time that Steamboat Geyser in the Park's Norris Geyser Basin, has erupted more, annually, than in at least three decades

Last Friday, MTPR reporter Nick Mott talked with Wendy Stovall, the deputy scientist in charge of the Yellowstone Volcano Observatory, about these changes deep in the earth and what they could mean for the park as a whole.

Wendy Stovall: There has been an eruption of Ear Spring, which we believe is the largest recorded eruption of Ear Spring. It's a water eruption. And it threw out lots of water, rocks and then many artifacts, like human-derived artifacts that have collected there over the years.

Nick Mott: When you say collected there, how'd they get there?

WS: Either people threw them in or they blew in or they were accidentally dropped in. There's coins, lots of different coins that were thrown out during this eruption. There's an old pacifier that looks like a very old variety of a pacifier, like from a century ago even. Part of a cinder block was tossed out. Old cans, soda cans that have the seam down the side with the old peel-off pop tops. Just some odd things coming out of there.

NM: How high did the eruption send all the stuff flying?

WS: Twenty to 30 feet.

NM: And you said this is the largest recorded eruption ever of Ear Spring?

WS: Yeah, there was an eruption that happened in 1957 that - it's stated that the eruption went up to about 15 feet. But we don't really know for sure. There wasn't a rigorous, detailed field observation that happened at that time.

NM: Is the park expected to keep seeing this kind of activity in the area?

WS: Ear Spring has been boiling since that time. And there are several other features in the Geyser Hill area that have also changed. Some features have less water in them than normal. A couple of different pools are boiling where they didn't use to be boiling and some other features are erupting more frequently than they have before, like Goggles Geyser. North Goggles Geyser has been erupting more frequently. And then there's also a new thermal feature that has popped up underneath the boardwalk really close to Pump Geyser. There's an area of ground that's probably six to eight feet in diameter that is swelling - that's rising and lowering and there's a new thermal feature that's there that's occasionally bursting out water. So there's spouters of water that are coming up right underneath the boardwalk in that area. So that's why the National Park Service has chosen to close the boardwalk.

NM: Describe to me what we would see at Ear Spring before this started happening and what we would see now.

WS: Ear Spring is shaped like an ear. And before this eruption happened there were these bacterial mats. So the ground surrounding Ear Spring was covered in like a spongy looking, yellowish orange material, in some places it was white, and a clear pool that you could look down into. And now the bacterial mats have essentially been boiled away so the hot water that's been boiling out of Ear Spring is too hot for the bacteria that live in these mats to survive.

NM: What's happening beneath the earth to cause all this?

WS: So there's a plumbing system beneath the surface, much like the plumbing system that's in your house. And Old Faithful itself has a separate plumbing system than what is on Geyser Hill. And there's water that comes from rain and snow that supplies the water of the system. And then there's heat that comes from the magmatic system that's kilometers below the surface. The heat kind of travels up and the water is there and the water goes through fractures down and then the water is reheated and that pushes the water back up to the surface. So it's like this cyclic convection of water going down through cracks and then rising back up to the surface and then they form in two different reservoirs at the surface around Geyser Hill.

NM: How normal is this particular change?

WS: Changes happen in thermal areas at volcanoes, annually. So this is something that goes on all over the place. We've already seen it this year at another thermal area in the park at Norris Geyser Basin where there's been increased activity at Steamboat and changes in some of the activity of the spring surrounding it. So this is just part and parcel of what happens in an active hydrothermal system at any volcano.

NM: I know when a lot of people here about changes in thermal activity in Yellowstone they worry about volcanic activity under the ground. Is there anything to worry about?

WS: There is nothing to worry about as far as volcanic activity at Yellowstone. The difference to think about is that the hydrothermal system is really in the very top of the crust of the earth and it's only the top 10 to a couple of hundred feet of the surface of the crust. And then, the magma is several miles below the surface. So in that hot water system, one thing that can happen is hydrothermal explosions, which is just a very rapid transition from water to steam and that creates an explosive steam eruption. And sometimes during those explosive steam eruptions, rocks and other debris can get thrown about. So those are very small, localized hazards that could occur and that is also one of the reasons why the park has chosen to close the boardwalks so people are not around just in case there is a steam explosion.

NM: I see. So there could be an explosion, but it'd be a really small, local one that there isn't really much to worry about.

WS: Right. They are known to happen and they do happen in Yellowstone frequently enough to be a concern. We have a geology crew out there monitoring the situation and they certainly will keep everybody informed as changes occur.