The researchers modeled how such winds could have built up snow above the tent, and how long it would have taken to reach a critical load that would cause the top plate of the weaker layer below to slide, now that its structural integrity had been compromised by the cut. “This was how the tax increased,” says Gaume. “Because there was no other way – no snow fell that night.” Sometime after midnight, enough weight had been built over the weak layer that it suddenly collapsed, sending the slab into the tent. It would have been a relatively small avalanche – maybe 5 by 5 meters – that the researchers simulated with inspiration from the Disney snow model. It would have been enough to fill the hole the campers dug in the snow, but not enough that the rescue team could 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 cut above the tent and the snow deposited by the wind.
Video: Guame et al.However, an avalanche does not have to be large to cause serious damage to the human body. Most of the time, hikers who get caught in it will likely just choke. But in this case, none of the nine victims died of asphyxiation, and some had severe chest and head trauma.
This can also be explained by the dynamics of the plate avalanche and the downward wind. Although it was not snowing at the time of the incident, the catabatic winds would have produced 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 when it turns off, [the crystals] are highly compacted. “This could have created a dense slab of snow weighing perhaps 25 pounds per cubic foot. And even more unfortunate for our adventurers, they had put their skis down as the floor for their tent, creating a hard surface for the snow to withstand. to press.
Gaume and Puzrin went even further by modeling what this trauma might have been like. To calibrate their simulation, they used data from old automotive crash tests, conducted with human cadavers instead of dummies. (To be fair, it was the 1970s, which was a… different time.) Then they modeled the release of simulated snow blocks of different sizes on a digital model of a human body, and compared that with the crash test results. “What we saw is that it wouldn’t be fatal, but it would cause moderate to severe injuries,” says Gaume. (Below you can see the damage a piece of snow three feet wide can do.)
Since the wind-deposited snow 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 snowfall and made their way out of the tent, although some of them were seriously injured. But if they had escaped a relatively minor avalanche, why would they flee half a mile further, instead of hanging around digging out their supplies, especially their boots? Researchers found that the group actually had another set of supplies stowed away in the forest, so perhaps they had left for them in a panic. “You start to cut the tent from the inside to get out,” says Gaume. “You see, there was an avalanche, and then you might be afraid of one second avalanche. And so they may have decided that the best option would probably be to go to the forest, make a fire, and try to find the supply. “