Tukivyöry

Tukivyöry is a Finnish term that translates to "snow avalanche" or more specifically, a "slab avalanche." It refers to a type of avalanche that occurs when a cohesive layer of snow, known as a slab, breaks off from the underlying snowpack and slides down a slope. This cohesive layer can be formed by wind, which deposits snow in drifts and compacts it, or by temperature changes causing melt-freeze cycles.

Slab avalanches are often triggered by a relatively small disturbance, such as a skier, snowboarder, or even a loud noise, which can exceed the strength of the weakened bond between the slab and the base layer. The fracture line, where the slab breaks away, can be sharp and distinct. Once released, the slab can travel a significant distance and gain considerable momentum, making it particularly dangerous.

The stability of the snowpack is a critical factor in the formation of tukivyöry. Avalanche professionals assess snowpack layers and their bonding to predict the likelihood of slab avalanches. Factors contributing to instability include rapid temperature fluctuations, new snow falling on an old, weak layer, and persistent weak layers within the snowpack. Understanding these conditions is crucial for safety in mountainous or snowy terrain.