Avalanches Problems are a fairly recent advance in the structuring and differentiation of the different causes for which Avalanches can occur.
In this way, not only the causes and therefore the meteorological agents that produce the instabilities are differentiated, but also their distribution on the ground.
- Storm Slab
- Wind Slab
- Persistent weak layers
- Wet snow
In this section, we find the avalanches of punctual departure of dry snow and the storm slab that are created by differences in the structure of the recent snow and, or changes in the temperature that affects the slab.
- Increased thickness of snow thus increasing the load
- + 30cm precipitation
- Usually lasts 1 to 3 days
- Recent avalanches ALARM!!
The wind is the architect of the mountain and is capable of transporting a lot of snow. This mechanical action breaks the glass and creates wind plates. For this task, the most effective wind force is 25 – 40 km/h. Moderate!
- Snow Transport Visible on Ridges and Terrain
- Snow with some cohesion
- Variability in mantle depth
- Duration 1 – 2 days
- Slab avalanches in characteristic places, fissures ALARM!
PWL Persistent weak layers
Weak layers form on the snow surface and are buried by new snow. The slab builds on top, gradually accumulating over several storm cycles until the critical threshold is reached.
- Persistent weak layer within the mantle (Tests like CT and ECT work very well)
- Read BPA weak layer distribution
- Difficult to manage
- Lasts from days to months
- Typically located in specific aspects or elevation bands, but sometimes generalized.
Wet slab Avalanches
The mantle or weak layer is affected by liquid water which decreases the cohesion. Crack propagation occurs before a complete loss of cohesion produces an avalanche of loose, wet snow.
- Water from melting or rain weakens the bonds between layers
- Duration hours
- Overcast sky, especially at night and early morning
- High temperature / strong solar radiation
- S SE SW and W aspects by radiation or by elevations depending on the rain (It can also affect all elevations and orientations)
The entire snow cover slides over smooth ground, such as grass or rock slab. The mantle slowly deforms downward until the stress results in a fault and a crack opens and stops there or an avalanche occurs.
- Places with little roughness meadows stone slabs typical places
- You can appear at any time and persist throughout the winter
- Duration Hours, days, months
- They imply the presence of water between the mantle and the ground
- They are natural avalanches not accidental!
Formation of Avalanches AST 1 Get informed.