Soviet investigators examine the tent belonging to the Dyatlov Pass expedition on February 26, 1959. The tent had been cut open from inside, and many team members had fled in socks or bare feet.
A 62-year-old adventure mystery that has prompted conspiracy theories around Soviet military experiments, Yetis, and even extraterrestrial contact may have its best, most sensible explanation yet—one found in a series of avalanche simulations based in part on car crash experiments and animation used in the movie Frozen.
In an article published today in the journal Communications Earth and Environment, researchers present data pointing to the likelihood that a bizarrely small, delayed avalanche may have been responsible for the gruesome injuries and deaths of nine experienced hikers who never returned from a planned 200-mile adventure in Russia’s Ural Mountains in the winter of 1959.
Film recovered from the scene shows the last photograph taken by the Dyatlov team of members cutting the snow slope to erect their tent.
In what has become known as the Dyatlov Pass incident, ten members of the Urals Polytechnic Institute in Yekaterinburg—nine students and one sports instructor who fought in World War II—headed into the frigid wilderness on a skiing and mountaineering expedition on January 23, 1959.
One student with joint pain turned back, but the rest, led by 23-year-old engineering student Igor Dyatlov, continued on. According to camera film and personal diaries later found on the scene by investigators, the team made camp on February 1, pitching a large tent on the snowy slopes of Kholat Saykhl, whose name can be interpreted as “Dead Mountain” in the language of the region’s Indigenous Mansi people.
The nine—seven men and two women—were never heard from again.
When a search team arrived at Kholat Saykhl a few weeks later, the expedition tent was found just barely sticking out of the snow, and it appeared cut open from the inside. The next day, the first of the bodies was found near a cedar tree. Over the next few months, as the snow thawed, search teams gradually uncovered more spine-chilling sights: All nine of the team members’ bodies were scattered around the mountain’s slope, some in a baffling state of undress; some of their skulls and chests had been smashed open; others had eyes missing, and one lacked a tongue.
Each body was a piece in a grim puzzle, but none of the pieces seemed to fit together. A criminal investigation at the time blamed their deaths on an “unknown natural force,” and the Soviet bureaucracy kept the case quiet. The lack of detail about this shocking event, an apparent massacre that transpired in a deeply secretive state, gave rise to dozens of long-lived conspiracy theories, from clandestine military tests to Yeti attacks.
In the wake of renewed media interest and pervasive outlandish hypotheses, Russian authorities recently reexamined the case around the Dyatlov Pass incident and concluded in 2019 that an avalanche was primarily responsible for the nine deaths. Key scientific details were absent from the report, however, including a clear explanation as to how an avalanche could have taken place with no documented evidence of its occurrence left behind. This led to continued doubts around the seemingly pat explanation from a government long infamous for its lack of transparency.
People love to invent implausible scenarios about death in the wilderness, because we will never know 100 percent what happened.
Many argued that the avalanche theory, initially proposed in 1959, still didn’t seem to stack up: The team’s tent encampment was cut into the snow on a slope with an incline seemingly too mild to permit an avalanche. There was no snowfall on the night of February 1 that could have increased the weight of the snow burden on the slope and triggered a collapse. Most of the blunt force trauma-like injuries and some of the soft tissue damage were atypical of those caused by avalanches, whose victims usually asphyxiate. And if an avalanche had occurred, why was there a gap of at least nine hours, according to forensic data, between the team members cutting the slope for their encampment and the eventual avalanche?
That curious delay was of particular interest to Alexander Puzrin, a geotechnical engineer at ETH Zürich, one of Switzerland’s federal institutes of technology. He had recently published a paper explaining how, strange though it may seem, an earthquake can trigger an avalanche with a gap ranging from mere minutes to several hours between the two events. While Puzrin grew up in Russia, he learned of the Dyatlov Pass story only a decade ago. He was fascinated by the infamous incident and what may have caused it, but was understandably wary of tackling the question solo.
Johan Gaume, head of the Snow Avalanche Simulation Laboratory at EPFL, another Swiss federal technical institute in Lausanne, got to know Puzrin around the time of the 2019 Russian inquiry into what happened at Dyatlov Pass. Suspecting the avalanche delay issue held one of the keys to solving the mystery, they teamed up to create analytical models and computer simulations to try and replicate the obfuscated hours that stole the mountaineers’ lives.
The scientific investigation came with an added benefit from Puzrin’s wife, who is Russian. “When I told her that I was working on the Dyatlov mystery, for the first time she looked at me with real respect,” he says.
The shallow slope argument against an avalanche was tackled early on: It turned out not to be all that shallow after all. The undulating topography on Kholat Saykhl, covered by snowfall, made the slope appear mild, but it was actually closer to 30 degrees, the rule-of-thumb minimum requirement for many avalanches. Reports dating back to the site’s initial investigation also describe an underlying snow layer on the mountain that didn’t clump together, providing a weak, slippery base that a lot of overlying snow could easily slide over.