Scientists have made new insights into cracks under the surface of snow that could help to predict when slab avalanches might occur.
These avalanches are often triggered by skiers and account for many skiing accidents.
It was previously thought slab avalanches were caused by shear cracks, in which one layer of snow slides off another.
But a team at the University of Edinburgh report today that the main cause of slab avalanches could be fractures under the surface known as anticracks.
These cause a layer of snow to crumble inwardly.
Anticracks have been found to cause fractures over large distances in snow. They can spread not only on steep slopes but on gentle slopes and even on the flat.
This type of crack is known to play a role in earthquakes, but their relevance for snow avalanches was a surprise to the researchers.
Joachim Heierli, of the University of Edinburgh’s Centre for Materials Science and Engineering, said: “It was thought that slab avalanches were caused by a section of snow simply slipping off other layers. However, when we took a closer look, we saw that something quite different was going on.
“Our discoveries complete a piece of the puzzle of how avalanches occur – we hope this will help to pinpoint dangerous tell-tale signs and so avoid unnecessary dangers to people on mountains.”
The research is published in the journal Science.
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