Roaring Mountain’s quiet ‘might not last forever’
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.
