The researchers modeled how such winds could build snow above the tent, and how long it would take to reach a critical load that would cause the top plate to slide off the weaker layer now that the structural integrity was cutting through. “That was how the load increased,” Gaume says. “Because there was no other way – there is no snow at night.” About after midnight, enough weight built up above the weak layer that it suddenly collapsed and sent the plate into the tent. It would have been a relatively small avalanche – perhaps 16 feet by 16 feet – that the researchers simulated with inspiration from the Disney snow model. That would have been enough to fill the hole the campers had dug in the snow, but not enough that the rescue team would have been able to find clear signs of an avalanche 26 days later.
Here we see the disturbance caused not by an imaginary snowman, but by the combination of the cutting above the tent and the snow being put down by the wind.
Video: Guame et al.However, an avalanche does not have to be large to seriously damage the human body. Hikers trapped in one will usually just suffocate. But in this case, none of the nine victims died of suffocation, and some had severe trauma to the chest and head.
This can also be explained by the dynamics of the flat avalanche and the downward wind. While it did not snow during the incident, the catabatic winds would have yielded a much more dangerous type of deposit above the tent. “The wind eroded and transported the snow, which was made of very small crystals,” says Gaume. ‘And then when it settles down, [the crystals] is very compacted. It could create a dense snow sheet that weighs perhaps £ 25 per cubic foot. And even more unfortunate for our adventurers, they laid down their skis as a floor for their tent and created a hard surface for the snow to push them against.
Gaume and Puzrin went even further by modeling what this trauma might look like. To calibrate their simulation, they used data from old accident tests in the automotive industry used using human corpses, rather than dummies. (To be honest, it was the 1970s, which was a … different time.) They modeled the release of simulated snowballs of different sizes on a digital model of a human body and compared it to the collision test results. “What we saw was that it would not be fatal, but that it would cause moderate to severe injuries,” Gaume says. (Below you can see the damage that a piece of snow can do a meter over.)
Because the snow put down by the wind would have been very dense, even a small avalanche could have seriously injured the campers in the tent.
Video: Guame et al.From this they concluded that the mountaineers survived the initial pressure of the snow and cut their way out of the tent, although some of them were seriously injured. But if they were to escape a relatively small avalanche, why would they flee more than half a mile away instead of holding on to digging out their supplies, especially their boots? Investigators found that the group had stored another set of supplies in the forest so that they might leave in a panic. “You start pitching the tent from the inside to get out,” Gaume says. ‘You see there was an avalanche, and then you might have been afraid of a second avalanche. And so they decided that the best option was probably to go to the forest, make a fire and try to find the stock. ‘