Science Sheds Light on Russia's Dyatlov Pass Mystery

Even those who don't have a sweet tooth for conspiracy theories might have heard about the infamous Dyatlov Pass incident, where a group of Russian hikers met their end under circumstances shrouded in mystery. While a Soviet criminal investigation has concluded that they died following an unidentified "compelling natural force," no one really knows what happened that night.

From yetis to aliens, many conspiracy theories have been discussed online, and now a new study indicates that a snow slab avalanche is responsible for the mysterious deaths, restoring a previously rejected theory with simulations.

The research was published in the journal Communications Earth & Environment. 

The incident

In a nutshell, this is how it went: On 1 February 1959, the hikers decided to set up a camp on the slope of the mountain Kholat Syakhl. Following midnight, they cut their way out of their tent from the inside and ran almost naked and barefoot towards the forest downslope at a temperature below −25°C (-13°F).

They were found dead some days later. Four hikers had severe thorax or skull injuries; two were found with missing eyes, and one missing a tongue. The main cause was determined to be hypothermia.

The Investigative Committee of the Russian Federation concluded in 2015 and in 2019 that a snow avalanche was to blame; however, it was rejected by the public and relatives of the hikers with four main counterarguments against it.

Now, Johan Gaume at the WSL Institute for Snow and Avalanche Research in Davos, Switzerland, and Alexander Puzrin at the Institute for Geotechnical Engineering in Zurich, Switzerland, have come up with a new theory backed with simulations to explain the mysterious injuries.

An unusual avalanche

In the counterarguments, it was first said that the slope's angle wasn't enough for an avalanche, and second was that there were no traces of one found afterward. The researchers stated that this could have been to due the unique local topography. While it seemed that the slope wasn't angled enough, the ground underneath had step-like curves that could have made it more angular, which is enough to cause an avalanche, but one that wouldn’t leave characteristic traces.

The third argument was focused on the possible trigger, and the fourth was that the injuries sustained were more severe than those typical of avalanches.

"We use data on snow friction and local topography to prove that a small slab avalanche could occur on a gentle slope, leaving few traces behind," Gaume said. "With the help of computer simulations, we show that the impact of a snow slab can lead to injuries similar to those observed. And then, of course, there’s the time lag between the team cutting into the slope and the triggering of the event. That’s the main focus of our article."

"Previous investigators have been unable to explain how, in the absence of any snowfall that evening, an avalanche could have been triggered in the middle of the night. We had to come up with a new theory to explain it."

The katabatic wind

In this new theory, researchers explain that it was the katabatic wind that changed everything. The katabatic wind is known to speed downhill with force, potentially placing more snow gradually uphill from the tent.

The researchers simulated the dynamics of this avalanche and sought answers to questions like how long it could take to break off after a cut in the slope, which was made by the hikers to set up the tent, was aided by katabatic winds.

The simulations showed that that the requirements for the avalanche release could be reached between 7.5 and 13.5 hours after the cut.

"If they hadn’t made a cut in the slope, nothing would have happened,” said Puzrin, co-author of the study. "That was the initial trigger, but that alone wouldn’t have been enough. The katabatic wind probably drifted the snow and allowed an extra load to build up slowly. At a certain point, a crack could have formed and propagated, causing the snow slab to release."

The team also simulated the potential damage a snow slab could do to a human body and found that the reported injuries could have been caused by the victims getting caught between the falling slab and the snow underneath the tent.

This study, while illuminating, doesn't solve the mystery completely since questions such as why their bodies were found almost a mile away still remain. "The truth, of course, is that no one really knows what happened that night,” says Puzrin. “But we do provide strong quantitative evidence that the avalanche theory is plausible."