JACKSON, Wyo. — Roaring Mountain, a thermal area between Norris Geyser Basin and Mammoth Hot Springs in Yellowstone National Park (YNP), is a place to keep on the radar.

Norris Geyser Basin is known as one of the hottest and most acidic of YNP’s hydrothermal areas. According to Yellowstone Volcano Observatory’s (YVO) Yellowstone Caldera Chronicles, which was published last week and written by Scientist in Charge Michael Poland, Roaring Mountain has no geysers present but has its surface dotted with numerous steam and gas vents.

Roaring Mountain is known as an acid-sulfate thermal area, with gases emitted at or above boiling temperatures with acidity that has altered the rock in the area into clay minerals.

“The area of intensely hot ground—easily viewable from space!—makes Roaring Mountain one of the most intense thermal areas in the park despite its overall small size, with more than 100 megawatts of geothermal radiative power output,” Poland writes.

While Roaring Mountain “roared” in the second half of the 1800s as gas escaped from the area and was audible a mile or more away, activity slowed in the late 1890s. Then, in 1902, a thermal event occurred.

“The sound could be heard far away once again, and increased heat emissions killed trees over an area of up to a half a square mile,” Poland writes.

Poland suggests this event was similar to an event at Norris Geyser Basin in 2003, where temporary heating killed trees and formed new thermal vents. He tells Buckrail this event caused the entire Back Basin to be closed for a season, with several boardwalks rerouted.

Poland also tells Buckrail that this type of “thermal unrest” is common in YNP. In 2018 and 2023, minor increases in thermal emissions and geyser activity caused boardwalks to be closed at Geyser Hill, near Old Faithful.

“So what happened in 1902 is pretty characteristic of Yellowstone thermal areas in general,” Poland says. “There is always potential for a ‘thermal event’ pretty much in any thermal area in Yellowstone. They are amazingly common.”

After the 1902 event, thermal emissions quieted and have remained quiet. However, days where traffic and wind are light might still afford visitors the opportunity to hear the sounds from Roaring Mountain. And Poland says if there is a thermal event in the Roaring Mountain area in the future, it would likely show up as an increase in heat emissions and changes in the discharge of what’s known as fumaroles, or steam vents that are the hottest hydrothermal features in YNP.

Poland notes that this type of event is never anomalous for the area. With changes typically happening in the Park every year, the possibility of Roaring Mountain roaring once again is something to keep an ear out for.

YNP requires all visitors to stay on boardwalks and designated trails for safety. This past July, Poland told Buckrail that staying on the boardwalks was a critical factor to no one getting injured during the Biscuit Basin hydrothermal explosion.

YNP also prohibits touching thermal features, swimming or soaking in hot springs or bringing pets into thermal areas. Toxic gases in some hydrothermal areas can also accumulate to dangerous levels, so visitors should monitor themselves and leave an area immediately if they feel sick.

YELLOWSTONE NATIONAL PARK — While the dust settles after Tuesday’s Biscuit Basin hydrothermal explosion, Scientist-in-Charge of the Yellowstone Volcano Observatory Michael Poland spoke to Buckrail about the event and what it means for Yellowstone National Park (YNP) visitors.

YNP closed the area to visitors immediately following the explosion on Tuesday, July 23, and then announced on Wednesday, July 24, that Biscuit Basin would remain closed for the rest of the visitor season.

“It was probably a pretty easy decision to make,” Poland said. “One, the boardwalk was destroyed, and two, the park is cautious and takes visitor safety extraordinarily seriously.”

Poland noted that it was extremely lucky that no injuries were reported after the explosion, and said things might have gone differently if any visitors had gone rogue. This event should encourage visitors to heed signage about staying on the boardwalks.

“These are spectacular places and you really have to be careful where you walk,” he said. “The park puts a lot of effort into putting the boardwalks in places that are not thermal ground.”

Poland said he wouldn’t be surprised if the boardwalk layout around Biscuit Basin saw some adjustments. After a young visitor detected extra-hot ground under the boardwalk at Norris Geyser Basin in 2003 by removing his flip-flop and placing a bare foot on the near-boiling ground, Poland said, Yellowstone rerouted the boardwalk to avoid the newly dangerous area.

“Clearly the plumbing system just changed really drastically,” Poland said. “There have been times when an event like this happens and it leads to a fundamental change to how that feature will behave. Maybe it starts to have eruptions really regularly. These things are dynamic features; they can change.”

Changes to these features are a chief concern of the Yellowstone Volcano Observatory, and Poland’s team is prioritizing hydrothermal hazard research. Recently installed sensors in Norris Geyser Basin logged a similar event in April of this year, and Poland hopes more sensor installation is in the cards. Even if the instruments can confirm that a hydrothermal event has occurred after the fact, though, the technology might not yet be as helpful in predicting them.

“I’m not hyper-confident that we’re ever gonna see a signal that will allow us to say, ‘Uh oh, a hydrothermal explosion is coming,’ because that transition from water to steam happens instantaneously,” he said.

For now, Poland is grateful for the heightened visitor awareness, especially since no one was injured.

“Hydrothermal hazards are the most underappreciated hazards in Yellowstone,” Poland said. “I’m hopeful this hazard won’t be dismissed, especially by visitors, now that [footage of the July 23 explosion] is out there.”

The U.S. Geological Survey shared a video with other insights from Poland.

Figure 1. Bison lying on its side with feet perpendicular to its body. All 5 bison were lying in a similar position.

Introduction

On March 10, 2004, Bear Management personnel noticed an unusual grouping and position of bison carcasses near Norris Geyser Basin. On March 11, 2003, YNP geologists joined bear management biologists (Travis Wyman and Susan Chin) to investigate 5 bison along the Gibbon River. The adults and calves were lying on their sides with their feet perpendicular to their bodies (Figure 1). The unusual position of the carcasses led biologists to suspect that the bison had died very rapidly, as a group. Biologists established that the bison had been dead for approximately one week. Reconnaissance of the area showed that the 5 bison died along the Gibbon River and downstream of multiple gas vents. Areas with multiple gas vents are associated with thermally baked ground, minimal vegetation and sulfur deposits. Multiple gas vents occur uphill from the bison carcasses on both sides of the Gibbon River.

Data

Bison Management personnel (Doug Blanton and others) visited the site on March 10th, collecting incisors and tail hair. Members of the Bear Management team examined the 5 bison on March 11th and collected samples of blood, lung, liner and windpipe. The Bear Management team also examined body fat and bone marrow for each carcass. Body fat was present on all bison. Bone marrow was pink and solid for 4 bison. One calf had red and gelatinous bone marrow.

Number Animal Age Tissue Teeth Body Fat 1 Bison Calf No Yes Yes 2 Bison Adult No Yes Yes 3 Bison Adult No Yes Yes 4 Bison Yearling No Yes Yes 5 Bison Calf Yes Yes Yes

Within the thermal area, an Orion Multi-Gas Detector measured concentrations of hydrogen sulfide and oxygen. Concentrations of hydrogen sulfide (H2S) varied from a high of greater than 200 ppm to 0 ppm (Figures 2 and 3, Table 2). Concentrations of greater than 200 ppm H2S were found at a vent immediately upstream from the bison carcasses (Figures 2 and 3). A second vent in the thermal area emitted steam with 177 ppm of H2S (Table 2). Within the thermal area, the air contained 56 ppm of H2S (Table 2). On the top of a small hill (Table 2), the gas meter measured 0 ppm H2S in the gentle wind. Downstream from the thermal area, the gas meter measured 1 ppm H2S (Table 2). Oxygen varied from 16 % (within a vent) to 20.8 % (within the air). On the morning of March 11th, there was a gentle breeze mixing the air.

Yellowstone Volcano Observatory published this blog post on June 12, 2023. It’s part of a weekly column written by scientists and collaborators of the observatory. This contribution is from Kiernan Folz-Donahue, Physical Science Technician with Yellowstone National Park. Edits by EarthSky.

Recent thermal activity at Yellowstone geyser

Since late May 2023, there’s been a general increase in thermal and geyser activity at Geyser Hill, near the famous Old Faithful geyser in Yellowstone National Park.

The recent activity started on May 24, 2023. That’s when observers on Geyser Hill in Yellowstone’s Upper Geyser Basin, near Old Faithful, witnessed something that hadn’t been seen for two years: an eruption of Aurum Geyser. This medium-sized but charismatic geyser lies at a bend of the boardwalk that circles Geyser Hill, in front of a shallow pool filled with geyser eggs (smooth pebbles made of layers of mineral precipitated from geyser water).

According to citizen scientist observations, Aurum was witnessed erupting nearly 30 times over the subsequent 14 days, throwing water about 6 meters (20 feet) in the air.

Aurum’s awakening was not the only change on Geyser Hill in last the few weeks. The same day Aurum erupted, the popular Beehive Geyser erupted twice. Beehive typically erupts about every 18-22 hours, although with substantial variation. On May 24, a series of eruptions began with a shorter interval of about 15–16 hours. Small features became more active, too.

By May 30, a small geyser known as UNNG-GHG-17, in the runoff channel of Doublet Pool, began erupting for the first time since 2018. It was throwing water about 1 meter (3 feet) into the air. And it settled on a frequency of about once every 90 minutes for the first few days of its reawakening.

The changes are reminiscent of those that occurred in the same area in 2018 and are a testament to the dynamic nature of Yellowstone’s geyser basins.

Citizen scientists helped monitor

The unusual activity on Geyser Hill attracted community interest. Citizen scientist Graham Meech watched “17” erupt 20 times over a period of two days, carefully noting eruption times and how the intervals between eruptions varied. Meech’s data cover a critical period in the eruptive cycle of “17” that would otherwise not have been captured before park service personnel could put monitoring equipment on the geyser.

When “17” began to erupt again, a new feature – dubbed UNNG-GHG-17a – broke through the surface. “17a” is located about 3 meters (10 feet) southeast of “17” and next to a boardwalk.

As the new feature erupted, it churned up broken bits of sinter (rock made of minerals precipitated from geyser water) and tossed out debris, some of which landed on the boardwalk.

By June 5, the hole from “17a” had grown to a diameter of 0.75 m (2.4 feet).

Meech noted on May 30 that the activity of “17” and “17a” was closely linked, with “17a” consistently erupting about 8 minutes after “17”.

Just a few days later, the new geyser’s behavior was markedly different. Whereas before the geyser would drain between eruptions, park geology staff visiting the site on June 5 found a mostly stagnant pool filled to the brim with water.

“17” and “17a” started having some eruptions independent of each other, and the intervals between eruptions lengthened. Preliminary analysis of temperature logger data indicates that “17a” had 13 eruptions on June 2, with an average interval of 1.8 hours between eruption. By June 5 this had dropped to 7 eruptions, with an average interval of 3.7 hours.

The activity occurring on Geyser Hill bears a remarkable similarity to activity that occurred in the same area in September 2018. That time period included a rare eruption of Ear Spring that brought decades worth of human trash to the surface, including coins, hats, cans, a cinder block, and a baby’s pacifier. In fact, it was during this period that the feature known as “17” first formed!

Not over yet

The unusual conditions of the May 2023 event have not ended. While activity at “17” and “17a” slowed down, a previously existing feature near Doublet Pool, half under the boardwalk, sprang to life. Named by some “Snow Globe” for the way it churns up small flakes of sinter, this feature began erupting, throwing 88 °C (191 °F) water at least a foot or two in the air, with some droplets landing on the boardwalk.

Activity at this feature was near-constant on June 4, with eruptions reported about every 90 seconds. Then, on June 7, a new vent a few inches west of “Snow Globe” opened up, splashing out water in frequent eruptions, and draining with a whirlpool.

As a result of this unusual activity, a boardwalk closure was put into effect between Sponge Geyser and Doublet Pool to protect visitors and staff from tossed rocks and boiling water.

Yellowstone National Park geology staff have responded to the May 2023 Geyser Hill event by placing temperature dataloggers and other monitoring equipment near “17,” “17a,” and the feature by Doublet Pool.

They hope that these data will not only document the unusual activity, but also aid park staff in determining when it is safe to lift boardwalk closures.

Yellowstone is dynamic

Changes like those now occurring on Geyser Hill occur frequently in Yellowstone’s geyser basins. Besides the September 2018 event on Geyser Hill, a major thermal event occurred in 2003 at Norris Geyser Basin, with the formation of several new features, eruptions of previously non-erupting pools, and a general increase in surface temperatures.

This activity ultimately forced the rerouting of several boardwalks in the area. There was also the observation of a new thermal area that formed in the past 20 years near Tern Lake, on the east side of the park.

In most geologic contexts, change is almost imperceptibly slow. This is not the case in hydrothermal areas, which are incredibly dynamic. By the same token, it is hard to predict the course this particular thermal event will take. Geyser Hill could rapidly cool off and return to its “normal” activity, or additional features could form or continue to grow.

The most constant thing about Yellowstone’s geyser basins is their changeability.

ACKNOWLEDGEMENT: Tracking hydrothermal activity is a time-consuming effort that has benefitted greatly from community involvement. The observations discussed in this article include input from Graham Meech, Lori and Steve Walker, Shannan Marack, AJ Ferrara, and several other members of Yellowstone National Park staff and the public.

Bottom line: Since late May 2023, there’s been a general increase in thermal and geyser activity in Yellowstone National Park.

Via USGS