Last year, a very compelling theory was set to solve the enduring mystery of the Dyatlov Pass Incident where, in 1959, nine experienced hikers died on the slopes of Kholat Syakhl Mountain ("Death Mountain” in the local indigenous Mansi language). The hikers, the study put forward, were caught in a rare slab avalanche.

When rescuers went looking for them a month after the incident, they found first their tent cut open from the inside with most of the supplies and clothes still in there. Some of the bodies were recovered the day after near the remains of a fire. Others were found months later in a ravine.

Soviet authorities at the time established that three died due to physical trauma and the other six of hypothermia. Being caught in the avalanche is a good explanation, hitting a third of the group while the rest met their demise as they fled in unsuitable clothing.

While the explanation fitted the peculiarities of the case, not everyone was convinced. The main criticism was that such avalanches were not seen on the mountain. Well, since the publication, authors Johan Gaume and Alexander M. Puzrin conducted three more expeditions to Kholat Syakhl, founding video evidence of two recent avalanches. The findings are reported in the journal Communications Earth & Environment.

Slab avalanches are peculiar because the top layer of snow is bonded together in a slab which sits on top of a weaker layer. They need to stretch across a sufficiently large area on a slope with an angle greater than 30 degrees in order to form, making them quite rare.

“The critics took aim at two key aspects of our theory, arguing that the slope wasn’t steep enough and the conditions weren’t right for an avalanche to be triggered. People living in the area swore that they’d never seen an avalanche on the Dyatlov Pass,” Gaume, from the Ecole Polytechnique Fédérale De Lausanne, said in a statement.

“Most of the criticism came from relatives and conspiracy theorists. We felt as though many people were rejecting our scientific approach because they wanted to maintain a shroud of mystery around the tragic fate that befell the hikers.”

The two expeditions that took place in 2021, one in summer and one in winter, looked first at the angle of the slope (which was greater than 30 degrees) and then at snow conditions which suggested that avalanches were indeed possible. The third expedition in January 2022, led by Oleg Demyanenko and Dmitriy Borisov, actually filmed evidence of two recent snow-slab avalanches.

The researchers stress that they do not claim to explain everything about the tragic end of the nine hikers of the Dyatlov Pass, but they are confident that their explanation is a solid one that makes sense when it comes to the natural conditions of the mountain.