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Snow Slab Avalanche Stability Lab Blender 5.2

A cirque slope below a corniced ridge. Set the slope angle, slab, new snow, wind and weak layer; read the infinite-slope stability index S = strength / load, colour the slope by it, and see how far a Voellmy-Salm avalanche runs against the alpha-beta rule. Drag to orbit, wheel or pinch to zoom, right-drag to pan, click the slope for a local probe. Educational model: always read the official avalanche bulletin and follow local guidance before going into the mountains.

Presets

Live readouts

Slope and slab

New snow, wind and extra load

Weak layer and temperature gradient

Runout (Voellmy-Salm) and release

Map and display

Graphs

Stability index against slope angle for the current snowpack (S < 1: the weak layer is overloaded). Shaded: the classic 30-45 degree release range; the dot is the current slope

Avalanche path (fall line): terrain, alpha line from the top of the start zone, alpha-beta runout band (plus/minus one sigma = 2.3 deg), and the Voellmy-Salm stopping point

Voellmy-Salm speed along the path with the local slope angle (dashed). The dot follows the live avalanche

Experiment: critical slab depth against slope angle

Question: how thick must a slab be before it overloads a weak layer, and does the stability code agree with the closed form D_c = c / (ρ g (sinθ − cosθ tanφ))? For each angle the slab thickness is bisected until S = 1 (slab only, no new snow). The second series adds the 80 kg skier load of the load-spreading model, which needs a thinner slab: the margin that makes a skier a realistic trigger. Below θ = φ a cohesive weak layer never fails by gravity alone (infinite depth).

Numerical checks

The science