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New theory on avalanches

Slab avalanches are the most common type to kill people and now Scottish scientists have fresh research on how they may occur.

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The common cause of a slab avalanche is when the snow cracks and then one layer of snow slides off another one below. It’s often thought these cracks were caused by skiers or snowboarders passing over a weak bond in the snow.

However researchers at the University of Edinburgh believe they could be caused by fractures under the surface.  These so-called “anti-cracks” then crumble inwards like a deck of cards.  The full findings have been published in the journal, Science.

“It was thought that slab avalanches were caused by a section of snow simply sliding off another layer.  However we took a closer look and saw that something quite different was going on,” says Jauchim Heierli from the Centre of Materials, Science and Engineering at the University of Edinburgh.

Further research is needed for any conclusive proof but it is an interesting development in the debate.

In Switzerland  around 25 people die in avalanches each winter on average.  Last year though despite the high levels of snow only 11 perished. It was the same sharp fall in fatalities across other Alpine countries.  It’s believed the main reason for this was the stability of the snow pack rather than the behaviour of skiers and snowboarders.

The high levels of snow that fell early in the season was followed by high fluctuations in temperatures that caused the snow to bond well and form a solid base.

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