Did "an entire unnamed mountain" collapse into itself near Casper, Wyoming at the end of 2025 and were emergency crews from several states mobilizing? No, that's not true: A viral post and image making that claim originated on a satirical Facebook page. Earlier there was a (much smaller) collapse in Wyoming's Teton mountains but that happened over 250 miles from Casper.
The viral story appeared in a Facebook post (archived here) published by a page named "Casper Planet" on December 6, 2025 It read:
Wyoming Mountain Collapses Into Itself, Area Closed as Search Crews Mobilize
Casper, WY - A geological event that experts are already calling "one of the strangest in modern history," an entire unnamed mountain west of Casper reportedly collapsed inward early Friday morning, forming a massive crater and sending shockwaves through surrounding communities.
Local ranchers said they heard what sounded like a "deep thunderclap underground" just before the peak seemed to sink straight down, leaving behind a bowl shaped void nearly a mile wide. Emergency officials quickly closed the region to the public as reports surfaced of at least two hiking groups believed to have been in the area at the time.
Wyoming Conservation Services, Natrona County Emergency Management, and search and rescue teams from across the state are already on scene, with additional specialized crews from Colorado, Montana, and Idaho currently en route. Federal geological teams are also being deployed to determine whether the collapse was caused by seismic activity, a long hidden cavern system, or something "significantly more unusual," according to officials.
Residents across central Wyoming reported feeling the tremor, with some describing a brief vibration followed by a low rumble that lasted nearly ten seconds.
Authorities are urging the public to avoid the area entirely until stability assessments are complete. Officials say the primary focus now is locating potential survivors and securing the perimeter around what one responder described as "a mountain that folded like a camp chair."
More updates will be released as information becomes available.
This is what the image in the post looked like on Facebook at the time of writing:
(Source: Facebook screenshot taken on Sun Dec 7 11:13:08 2025 UTC)
However the Casper Planet Facebook page has an about tab (archived here) with a disclaimer in the bio that clearly reads:
Delivering the Snews that doesn't matter directly to your Snews feed. Did we say this is satire? Well it is, names/locations are made up
The vehicles visible on the ground in the image in the viral post also appeared oddly deformed and misshapen, in a way that is typical of imagery generated using artificial intelligence.
Despite the satire disclaimer the joke post did appear in Google News search results as the top result when looking for news articles with the phrase "wyoming mountain collapse" (archived here):
(Image: screenshot of Google News search for "wyoming mountain collapse")
Those search results did contain several news reports about a collapse involving the "Grand Teton's Second Tower" that started in 2022 in the Teton mountains. But that collapse was much smaller in scale and it happened over 250 miles from Casper, Wyoming.
