The fatal events that unfolded on the slopes of Russia’s Kholat Syakhl, or “Dead Mountain,” sometime in the night between February 1 and 2, 1959, have generated decades of speculation about the fates of nine hikers who died under mysterious circumstances that remain unexplained to this day.
The Dyatlov Pass incident, named after expedition leader Igor Dyatlov, has spawned all manner of explanations for the eerie deaths of the group, ranging from an avalanche, to secret military experiments, to encounters with supernatural beasts. The avalanche hypothesis is considered the most likely, but there are still many problems with this natural explanation, including the lack of evidence that the area now known as Dyatlov Pass was vulnerable to avalanches that night. There were also the strange and grisly injuries, and the radiation detected on some recovered clothing. Indeed, Russian prosecutors reopened the case in 2019 to settle outstanding doubts.
A pair of scientists based in Switzerland now propose solutions to some of the kinks in the avalanche theory, which are “in agreement with the autopsy results” from more than 60 years ago, according to a study published on Thursday in Communications Earth & Environment.
Johan Gaume, head of the Snow Avalanche Simulation Laboratory at École polytechnique fédérale de Lausanne, and Alexander Puzrin, chair of geotechnical engineering at ETH Zurich, pored over Soviet archives about the incident and applied the latest avalanche research and simulations to the bizarre incident.
The researchers demonstrate that a type of snowslide called a “slab avalanche” could account for some of the gaps in this hypothesis, including the presence of injuries on some of the hikers that aren’t normally associated with avalanche victims. But though Gaume and Puzrin bolster the general consensus that the ill-fated hikers were killed by natural causes, the team does not claim that they have solved this legendary puzzle.
“Personally we do not believe that the mystery can ever be solved because no one survived to tell the story,” said Gaume in a short documentary about the paper, also released on Thursday. “What we did in our paper is to show the plausibility of the avalanche hypothesis based on solid physical and experimental evidence.”
Dyatlov and his companions—all experienced young hikers—began their trek on January 27 as a group of ten, but one of the group, Yuri Yudin, turned back on the second day due to chronic pains. Over a week after the hikers were supposed to complete the trip, a rescue team was dispatched which eventually found the group’s abandoned tent, weirdly cut open from the inside, on a shallow slope.
The hikers had all died after retreating down the slope, some of them wearing nothing more than underwear. It’s clear most of the group froze to death in the punishing winter temperatures of roughly -25°C ( -13°F). However, when all of the bodies were recovered after a period of months, strange injuries suggested that hypothermia was not the whole story.
“While hypothermia was determined to be the main cause of death, four hikers had severe thorax or skull injuries, two were found with missing eyes and one without tongue; some were almost naked and barefoot, traces of radioactivity were found on some of their clothes, and signs of glowing orange spheres floating in the sky were reported that night,” according to the study.
Gaume and Puzrin acknowledge that these blunt traumatic injuries are “not typical for avalanche victims” in the study. Most people perish in avalanches by asphyxiation under the heavy snow, and spinal injuries are more common than thorax and skull trauma. The avalanche theory has also been challenged by the slope where the tent was pitched, which Dyatlov may have selected precisely because it was not dangerously angled or visibly avalanche-prone.
Slab avalanches, in contrast, could still batter such a slope, the researchers argue. These events occur when a dense slab of snow sits over a weaker snow layer until some form of trigger releases it, and they can occur on slopes with angles of fewer than 30 degrees.
Gaume and Puzrin propose that a cut that Dyatlov and his companions made in the snow to protect their tent from the wind was this trigger; the fact that snow slabs can take a while to reach a critical mass may explain why several hours passed between the group setting camp and the disaster that would eventually end all their lives.
The researchers suggest that a slab avalanche could have been relatively small, yet still deadly, which would account for the lack of evidence of a major snowslide encountered by rescuers weeks later. Even a small slab could weigh hundreds of pounds. If the hikers who sustained the worst injuries were lying down in the tent, they would be especially exposed to the bone-crunching trauma of an unexpected slab slide.
“Dynamic avalanche simulations suggest that even a relatively small slab could have led to severe but non-lethal thorax and skull injuries, as reported by the post-mortem examination,” Gaume and Puzrin said in the study.
The team backed up all their assumptions with analytical models of slab avalanches and three-dimensional numerical simulations of the injuries that might result from slabs tumbling onto the tent and the hikers inside it. As to the remaining enigmas about this storied incident, they “will always remain an intrinsic part of the Dyatlov Pass Mystery,” the researchers said.
One thing is crystal clear, however: If you are an outdoor enthusiast, do not assume that a shallow slope will save you from an avalanche disaster.
The study’s results imply “that building a tent even on a relatively mild slope (less than 30°) can be dangerous and should not be recommended when combined with a cut in the slope,” Gaume and Puzrin cautioned in the study. “Instead, digging a snow cave may be a safer solution, as confirmed by the increasing use of this practice for winter camping in recent decades.”