Avalanche prediction model a boon for rescuers and filmmakers

When animators turn to science to build accurate simulations of snow and nature; a scene from Disney's 'Frozen'. Keystone

A Swiss researcher has created a 3D model of the workings of so-called ‘snow slab’ avalanches that could help to better predict their extent – and help filmmakers achieve more realistic animations.

Johan Gaume of the Swiss Federal Institute of Technology in Lausanne (EPFL) created the model – published in detail in Nature magazine on Friday – based on the fact that snow in an avalanche can behave both like a solid and a fluid.

Gaume, who also works with the WSL Institute for Snow and Avalanche Research SLFExternal link, worked with mathematicians in California – some of whom had worked with Disney in designing the snow in animated film Frozen – to build his model.

In particular, he wanted to simulate the conditions of a ‘snow-slab’ avalanche: one which happens when there is a weak and fragile snowpack layer underneath a dense top layer of snow called the slab.

Such avalanches are hard to predict, deadly, and are often triggered by skiers or walkers.

The extra weight can cause a crack to appear and spread in the weak bottom layer of snow, an EPFL media releaseExternal link explains. This further weakens it, to such an extent that it can no longer support the top slab, which slides across the weaker layer to bring about the avalanche.

“The collisions, frictions, and fractures that the solid snow experiences as the top layer slides downward and breaks apart lead to a collective behaviour characteristic of a fluid,” the statement reads.

The key breakthrough was thus to be able simulate, using a so-called continuum approach, the dynamics of collapse of this fluid-type bottom layer.

Gaume says that the model, “in addition to deepening our knowledge of how snow behaves”, could also help to “assess the potential size of an avalanche, the runout distance and the pressure on any obstacles in the avalanche’s path more accurately”.