Theories Discussion > General Discussion

Avalanche theory

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Axelrod:
It should also be added that an avalanche does not guarantee death or any injuries. Especially an avalanche at low angles of inclination.
Many people do not suffer after the avalanche. Rescuer Sogrin got out of the avalanche (and snow slab) 2 times.

Ziljoe:
I think there are several avalanche theories and various interpretations of that theory , not just G&P's model.

If there's a 1% chance of a snow slide or avalanche then there's a possibility.

I'm not sure how the terrain roughness anchors a slab slide though? (This is where my lack of knowledge comes in). If a interpolation technique is used to create the terrain surface , would that not be the opposite of what G and P are suggesting? Also, I'm not sure where run off comes in?.

I think the theory of the slab slide is to do with the different layers of snow that build up on the slope through the season. Hard snow, wet snow , freezing , mild temperatures etc. The angles of these layers will be different depending on the conditions of each season and weather variables. All creating weak and strong layers. Like lots of tiny ball bearings between thicker slabs. ( I'm sure there's more technical words within avalanche experts).

As I understand it , it's about the sheer force between the different layers of snow and not the actual ground terrain, the snow does not break away from the ground surface to cause the slide but slides on a smooth slope.

I would explain it like sheets of glass at different thicknesses, different strengths and density lying on top of each other  , a little more and a little less at different parts.

When a vertical cut is made, it leaves a potential for a slide, if the wind is blowing from the ridge and carrying snow , it deposits it on these layers above the tent, at some tipping point one of the layers gives way as the weight of new snow, wind etc exceed the adhesion between the snow layers , it's not a giant avalanche. 

It would be great to see if you can model this on your computer. I think there's a lot of maths involved for snow models though.

gunmat:
Thank you for your response. I cannot delve further into my analysis here because it requires sketches and images, which I cannot post here.

When I mention interpolation techniques, it refers to how a terrain model is constructed. It starts with data points containing elevation data along with plane coordinates. Then, interpolation is used between the points to build a surface. There are many different interpolation techniques that can be used, depending on the purpose of the model. Different interpolation techniques can yield very different surfaces. The surface is used to calculate the terrain slope. If one desires a model that is visually appealing, interpolation techniques that provide a smoother and more "fancy" surface can be used. However, such a model can deviate significantly from a model built using triangulation, for example. That's why I want the original data points so that a model can be built that can be used by others in future studies of the phenomenon and for illustrations of the accident.

The slope of the avalanche path determines whether an avalanche can occur. Everything else are parameters that nuance the possibilities of avalanches. Avalanches do not release on horizontal terrain, regardless of snow conditions and layering, but they release with great certainty on a slope of 45 degrees.

Vegetation and large rocks peaking above snow act as anchors to hold the snow in place and prevent it from sliding.

It is not necessary at all to use complicated equations to identify areas with potential avalanche danger.

Ziljoe:
Thanks gunmat .

I've had a Google at interpolation techniques and I think I have a general understanding. My observations are this is not what Gaume and Puzrin claim ( I read something the film frozen and software) . The media are awful at reporting and publishing data and the Dyatlov pass is one example. It's just to get clicks or views for adverts. I don't think anyone believes it to be the solution,it was just put forward as an unchallenged article to potentially solve the mystery. If it gets readers or views, the journalist has done their job I suppose.

However, I would debate  your point.

"The slope of the avalanche path determines whether an avalanche can occur. Everything else are parameters that nuance the possibilities of avalanches. Avalanches do not release on horizontal terrain, regardless of snow conditions and layering, but they release with great certainty on a slope of 45 degrees."

I don't think this is what is being proposed by G&P. There is no natural avalanche path in the area of the tent, I don't think that's what they are putting forward. Its more like if you have a slope of grass and earth at a slight angle and you dig/cut a hole/pit into it , would it potentially collapse?. Nothing would happen if one didn't dig into it?.

It would seem the slope has had years of erosion with bare stones and streams, the natural process of run off,wind, rain and gravity etc.

I don't think the slope alone determines an avalanche, there are weather conditions and interactions and G&P do mention this.

The depth of the snow and it's layers are quite important, I think , possibly more at less steep angles. This is where I would think calculations do get complicated. There's a science to it and people are taught how to avoid the risks, especially when skiing .

Depending on how we interpret the avalanche theory will give us different conclusions, personally I think a small localised snow slide or collapse may have given an impression of worse to come for the hikers , then they just decided to move to the forest quickly until the best opportunity to return.

I look forward to seeing your software model. 

gunmat:
"Apologies for not being able to debate slope angle and the other parameters triggering an avalanche. Slope angle is clearly the most crucial parameter regarding avalanche release. I have studied G&P's two publications on the Dyatlov mystery, so I have a fairly good understanding of their theory. To build the model, I need the data points, but it seems no one knows where they are."

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