What are avalanches and why are they dangerous

An avalanche is when a huge mass of snow suddenly breaks loose from a slope and rushes downhill at speeds up to 100–200 km/h. It can bury a person under several meters of snow, where survival chances drop sharply: after 15 minutes under the debris the probability of being rescued alive falls to 30–40%. Avalanches come in different types: dry (loose snow, fast and far-reaching), wet (triggered by warming, slower but very heavy), and slab (a strong upper layer sliding on a weak lower layer like a plate of glass).

Why do they release? The main reason is instability in the snowpack. Snow builds up in layers: fresh powder on top, but weaker layers of depth hoar, surface hoar, or old faceted snow can lie underneath. Add wind that forms hard wind slabs on lee slopes, and you have a classic recipe for disaster. Plus the human factor: one skier can become the “trigger” if they load a weak layer. In Russia, according to avalanche bulletins (lavina.ru), most incidents happen on slopes between 30–45 degrees — exactly the angles freeriders love. Remember: avalanches don’t choose victims — they simply follow the laws of physics.

The Avalanche Triangle: Key Risk Factors

To assess danger, use the “avalanche triangle” — three main elements: terrain, snowpack, and weather. The fourth is always the human factor.

Terrain first. Most avalanches occur on slopes of 25–45 degrees, with the sweet spot at 35–40°. Below that angle snow usually doesn’t slide; above it often releases spontaneously. Measure the angle with a clinometer app on your phone. Dangerous “traps” include: couloirs and gullies (funnel effect — snow piles up deep), cliffs and trees (you can get swept into or over them), depressions (deeper burial). Aspect matters too: north-facing slopes stay colder and weaker longer; south-facing warm up faster and become wet. Use maps to check slope angle, shape, and aspect. Avoid areas below cornices or above cliffs — even a small slide there can be fatal.

Second — the snowpack. Think of it as a layered cake: the top can look solid, but a weak layer (depth hoar, surface hoar, old faceted snow) hides below. Red flags: recent avalanches on similar slopes nearby (means yours is likely unstable too); shooting cracks in the snow surface (like spider webs — tension release); whumphing — that hollow “boom” when the snow collapses under your feet or skis. Dig a snow pit (1–2 m deep to the ground). Look at the layers, feel them, spot weak interfaces. Simple tests: compression test (tap the column and watch for collapse), extended column test (cut a block and load it). If you find instability — choose a different line.

Third — weather. Fresh snow >2 cm/hour or >25–30 cm in 24 hours significantly raises danger. Strong wind (>30 km/h) transports snow and builds wind slabs on lee aspects. Rapid warming or rain softens the pack and triggers wet slides. Sun on south-facing slopes also destabilizes. Check forecasts for the past week on Snow-Forecast.com (precipitation, temperature, wind at altitude) and Windy.com (wind transport patterns). New snow in the last 24–48 hours is always a warning sign.

And finally — the human factor. About 90% of avalanche accidents come from our mistakes: ignoring forecasts, group pressure (“everyone’s going, so I will too”), overconfidence. Always discuss the plan openly in the group: Plan A, B, and C. When in doubt — say “no”.