Melt-Freeze Crust

A Melt-Freeze Crust is a potential layer of weakness between snow layers which can be the cause of slab avalanches.

The layer can be created in two instances:

• When the temperature is high enough allowing snow to melt thus creating melt water which is re-frozen creating a frozen layer.
• When rain falls and freezes on the existing snow creating the same frozen layer.

The layer becomes a potential weakness when subsequently buried under further snow. Once the tensile stresses are exceeded the layer will fracture allowing the overlying slab of snow to move down the mountain under gravity. The initial slab may be as large as 10,000m² and 10 metres thick.