Summary
An avalanche is a rapid flow of snow down a slope, such as a hill or mountain. Avalanches can be set off spontaneously, by factors such as increased precipitation or snowpack weakening, or by external means such as humans, animals, and earthquakes. Primarily composed of flowing snow and air, large avalanches have the capability to capture and move ice, rocks, and trees. Avalanches occur in two general forms, or combinations thereof: slab avalanches made of tightly packed snow, triggered by a collapse of an underlying weak snow layer, and loose snow avalanches made of looser snow. After being set off, avalanches usually accelerate rapidly and grow in mass and volume as they capture more snow. If an avalanche moves fast enough, some of the snow may mix with the air, forming a powder snow avalanche. Though they appear to share similarities, avalanches are distinct from slush flows, mudslides, rock slides, and serac collapses. They are also different from large scale movements of ice. Avalanches can happen in any mountain range that has an enduring snowpack. They are most frequent in winter or spring, but may occur at any time of the year. In mountainous areas, avalanches are among the most serious natural hazards to life and property, so great efforts are made in avalanche control. There are many classification systems for the different forms of avalanches, which vary according to their users' needs. Avalanches can be described by their size, destructive potential, initiation mechanism, composition, and dynamics. Most avalanches occur spontaneously during storms under increased load due to snowfall and/or erosion. The second largest cause of natural avalanches is metamorphic changes in the snowpack such as melting due to solar radiation. Other natural causes include rain, earthquakes, rockfall and icefall. Artificial triggers of avalanches include skiers, snowmobiles, and controlled explosive work. Contrary to popular belief, avalanches are not triggered by loud sound; the pressure from sound is orders of magnitude too small to trigger an avalanche.
About this result
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
Related courses (4)
ENV-524: Hydrological risks and structures
Le cours est une introduction à la théorie des valeurs extrêmes et son utilisation pour la gestion des risques hydrologiques (essentiellement crues). Une ouverture plus large sur la gestion des danger
ENV-617: Snow Science Winter School (WSL)
The modern techniques and methods to measure snow properties in the field and in the laboratory are introduced by specialists in the corresponding field. The methods are applied in the field and in th
ENV-525: Physics and hydrology of snow
This course covers principles of snow physics, snow hydrology, snow-atmosphere interaction and snow modeling. It transmits sound understanding of physical processes within the snow and at its interfac
Show more
Related lectures (25)
Snow Melt Dynamics: Phases, Energy Balance, and Water Movement
Explores snowmelt phases, energy balance, water dynamics, and transport complexities in snow.
Ice Lenses: Formation and Hydrological Impacts
Covers ice lens formation, water flow redirection, snowmelt fate, and runoff modulation.
Snow Measurements: Techniques and Analysis
Explores techniques for snow depth measurements, temperature sensors, snow stratigraphy, and crystal imaging.
Show more
Related publications (178)

A seasonal snowpack model forced with dynamically downscaled forcing data resolves hydrologically relevant accumulation patterns

Michael Lehning, Tobias Jonas, Dylan Stewart Reynolds

The Mountain snowpack stores months of winter precipitation at high elevations, supplying snowmelt to lowland areas in drier seasons for agriculture and human consumption worldwide. Accurate seasonal predictions of the snowpack are thus of great importance ...
Frontiers Media Sa2024

Impact of intercepted and sub-canopy snow microstructure on snowpack response to rain-on-snow events under a boreal canopy

Michael Lehning, Adrien Michel, Nander Wever, Daniel Nadeau, Benjamin Bouchard

Rain-on-snow events can cause severe flooding in snow-dominated regions. These are expected to become more frequent in the future as climate change shifts the precipitation from snowfall to rainfall. However, little is known about how winter rainfall inter ...
2024

Good enough: Intermediate complexity atmospheric models improve the representation of processes affecting seasonal snow

Dylan Stewart Reynolds

Snow plays a crucial role in processes regulating ecosystems, the climate, and human development. Mountain snowpack in particular has great relevance for downstream communities. Knowledge about the distribution and properties of the snowpack thus help in p ...
EPFL2024
Show more
Related concepts (14)
Debris flow
Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally have bulk densities comparable to those of rock avalanches and other types of landslides (roughly 2000 kilograms per cubic meter), but owing to widespread sediment liquefaction caused by high pore-fluid pressures, they can flow almost as fluidly as water.
Mass wasting
Mass wasting, also known as mass movement, is a general term for the movement of rock or soil down slopes under the force of gravity. It differs from other processes of erosion in that the debris transported by mass wasting is not entrained in a moving medium, such as water, wind, or ice. Types of mass wasting include creep, solifluction, rockfalls, debris flows, and landslides, each with its own characteristic features, and taking place over timescales from seconds to hundreds of years.
Mountaineering
Mountaineering, mountain climbing, or alpinism is a set of outdoor activities that involves ascending mountains. Mountaineering-related activities include traditional outdoor climbing, skiing, and traversing via ferratas that have become sports in their own right. Indoor climbing, sport climbing, and bouldering are also considered variants of mountaineering by some, but are part of a wide group of mountain sports. Mountaineering activity, involving such activities as mountain climbing and trekking, has traditionally been dominated by men.
Show more
Related MOOCs (1)
Fluid Mechanics
Ce cours de base est composé des sept premiers modules communs à deux cours bachelor, donnés à l’EPFL en génie mécanique et génie civil.