Avalanche: Snowpack Failure Dynamics (3D) — Slab / Weak Layer Crack Propagation

Snowpack

Slope angle θ 35°

Slab thickness h 0.60 m

Weak-layer strength 1400

Temperature gradient 8 °C/m

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Driving stress τ

0 Pa

Weakest margin

Fractured area

Status

Stable

Effective weak-layer strength (after faceting)

1400

How it works

Each cell of the buried weak layer carries a shear strength τ_s, weakened by faceting from a temperature gradient: kinetic-growth (faceted) crystals form when the gradient exceeds roughly 10 °C per metre of snow, and their poorly-bonded structure sheds strength as the gradient climbs.

τ_drive = ρ·g·h·sinθ·cosθ
τ_eff(cell) = τ_s · (1 − facet(∇T)) · (1 − 0.15·noise)
local stress = τ_drive + Σ skier loads + concentration·(failed neighbours)

A cell fails when the local stress — including the extra concentration produced by already-failed neighbours, the same stress-riser effect that drives real crack-tip propagation — exceeds its own effective strength. Failure doesn't need to happen everywhere at once: once a crack nucleates at the weakest cell, its neighbours see elevated stress and tend to fail next, so the fracture front propagates across the slope. Once the connected fractured region covers enough of the slab, the whole block detaches and accelerates downhill under a = g(sinθ − μcosθ).

Click the slab to plant a skier — a localized load that raises stress in a small radius and is often enough to nucleate the first crack on a marginal slope.
Temperature gradient — higher values simulate near-surface or basal faceting, silently eroding the weak layer's strength even while the slider for strength itself stays put.

Click the slab to drop a skier load · drag to orbit · scroll to zoom

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