Updated:01/29/2021 01: 31h
On January 27, 1959, a group of ten hikers consisting mainly of students from the Ural Polytechnic Institute, led by Igor DyatlovThe 23-year-old went on a 14-day expedition to Gora Otorten, a mountain in the northern part of the Soviet province of Sverdlovsk. At that time of year, such a route was considered very dangerous, with temperatures as low as -30 ° C, but all the members of the expedition were experienced skiers. Only one of them, Yuri Yudin, decided to back down two days later. He never saw his companions again.
When the group did not return to the place of departure, the town of Vizhay, on the appointed date, a rescue team set out to search for them. On February 26, they found the tent, badly damaged, on the slopes of Kholat Syakhl, which translates as “Mountain of Death”, about 20 km south of the destination of the expedition. The young people’s belongings had been left behind. Further down the mountain, under an old Siberian cedar, they found two bodies dressed only in socks and underwear. Later, three other bodies, including Dyatlov’s, appeared between the tree and the place where the store was. Apparently they had died of hypothermia while trying to return to the camp. Two months later, the four remaining bodies were discovered in a ravine under a thick layer of snow. Several of the deceased had serious injuries.
What happened 60 years ago in the Urals is one of the great mysteries in the history of Russia. The Soviet authorities investigated the case but closed it three months later, concluding that a “Irresistible natural force” it had killed the hikers. In the absence of survivors, the sequence of events for the night of February 1 to 2 has not been clear to this day and has given rise to innumerable more or less fanciful theories, from the Yeti to secret military experiments, with the KGB involved. Now, two avalanche experts have studied the mystery and believe they have solved it.
Avalanche by surprise
Johan Gaume, director of the Snow and Avalanche Simulation Laboratory (SLAB) at the Federal Polytechnic School of Lausanne (EPFL) in Switzerland, had never heard of this story until a journalist from the “New York Times” called him to ask an expert opinion. The files on the case had just been revived by the Russian Prosecutor’s Office.
“I started writing equations and figures on my board, trying to understand what could have happened in purely mechanical terms,” he recalls. The first thing he deduced was that an avalanche took the group by surprise while they slept in the tent. This theory, which is the most plausible, was also exposed by the Russian Public Ministry after the investigation was reopened in 2019 at the request of the victims’ families. But the lack of evidence and the existence of strange elements failed to convince a large part of Russian society.
Intrigued, Gaume contacted Russian professor Alexander Puzrin, an expert on landslides. Together they reviewed Soviet archives open to the public, spoke with other scientists and experts on the incident, and developed analytical and numerical models to reconstruct the possible avalanche.
According to Gaume and Puzrin, this is what happened in 1959: the hikers had done a cut in the snowy slope from the mountain to pitch his tent, but the avalanche did not occur until several hours later.
“One of the main reasons why the avalanche theory is still not fully accepted is that the authorities have not provided an explanation of how it happened,” says Gaume. In fact, there are a number of points that contradict that theory: First, the rescue team did not find any obvious evidence of an avalanche or its deposition. So the average angle of the slope over the tent site, less than 30 °, was not steep enough for an avalanche. Also, if an avalanche did occur, it was triggered at least nine hours after the slope cut was made. And finally, the chest and skull injuries seen in some victims were not typical of avalanche victims.
In their research, published in the journal “Communications Earth & Environment”, Gaume and Puzrin attempt to address these points. ‘We used data on snow friction and local topography to show that a small avalanche of slabs (which often form in windblown snow) could occur on a gentle slope, leaving few traces. With the help of computer simulations, we show that the impact of a snow slab can cause injuries similar to those observed, ”explains Gaume.
One of the most important factors in the tragedy was the presence of katabatic winds, that is, winds that carry air down a slope under the force of gravity. These winds could have carried the snow, which would then have accumulated uphill from the store due to a specific terrain feature that the team members were unaware of. “If they hadn’t cut the slope, nothing would have happened. That was the initial trigger, but that alone wouldn’t have been enough. The katabatic wind probably blew away the snow and allowed an extra load to slowly build up. At a certain point, a crack may have formed and propagated, causing the snow plate to come loose, ”says Puzrin.
However, both scientists are cautious of their findings and make it clear that much of the incident remains a mystery. The truth, of course, is that nobody really knows what happened that night. But we provide strong quantitative evidence that the avalanche theory is plausible, ”continues Puzrin.
The two models developed for this study, an analytical one to estimate the time required to trigger an avalanche, and a numerical one to estimate the effect of avalanches on the human body, will be used to better understand natural avalanches and associated risks. Gaume and Puzrin’s work is a tribute to Dyatlov’s team, which faced an “irresistible force” of nature.