An avalanche is a mass of snow and ice falling suddenly down a mountain slope and often taking with it earth, rocks and rubble of every description (WMO, 1992).

Thousands of avalanches occur every year, killing an average of 500 people worldwide. Avalanches occur when massive slabs of snow break loose from a mountainside and shatter like broken glass as they race downhill. These moving masses can reach speeds of 130 km/hour within about five seconds. They cannot always be predicted but the weather conditions, which make them more likely, can be forecast in advance. Most accidents now occur because people ignore warnings.  The majority of avalanche incidents are due to slab avalanches with skiers involved. Avalanches are bigger, travel greater distances and are triggered earlier in the year. These changes can be attributed clearly to rising temperatures, which have reached 0.2 to 0.4 degrees annually in some parts of the Himalayas.

Avalanche protection and control measures include early warning which is key (EAWS). By way of controlled explosions, artificial avalanche triggering aims temporarily to safeguard possible starting zones (SLF). Defensive structures prevent the formation of avalanches. In order circumstances, when an avalanche is released, it can be diverted or intercepted by a dam. Other means of protection against avalanches include physical structures for buildings and snow sheds (SLF).

Avalanche risk factors

  • Quick changes in weather, snowpack and terrain.
  • Increasing human populations: winter sports lovers at ski resorts and developers building in vulnerable locations.
  • Climate change.

Vulnerable areas

  • Human settlements in avalanche-prone zones.
  • Rural mountainous villages with no early warning systems.
  • Human settlements with no forest cover.
  • Skiing populations and tourists not educated in avalanche risk.

Risk reduction measures

  • Not constructing buildings, roads, etc. in avalanche hazard areas.
  • Early warning systems at local and national levels.
  • Information on avalanches, their impacts and risks for tourism information offices.
  • Tree planting to protect against the release of avalanches.
  • Building codes and appropriate materials to reinforce resilience.
  • Raising awareness, educating and training residents and visitors on what to do before, during and after an avalanche.

Latest Avalanche additions in the Knowledge Base

SLF researchers have been mapping snow depths in detail over a large area. The new technique yields important basic data.
WSL Institute for Snow and Avalanche Research SLF
This study analyzed temporal changes in snow avalanches and examined the impacts of climate change on snow avalanches under continental snow climate conditions along the transportation corridor in the Tianshan mountains.
International Journal of Disaster Risk Science
RAMMS (Rapid Mass Movement Simulation) is a long-standing simulation tool for avalanches, rockfall and debris flows. The SLF's RAMMS research group is now working on further modules for this software package.
WSL Institute for Snow and Avalanche Research SLF
With a view to capitalising on this potential for monitoring purposes, researchers at the WSL Institute for Snow and Avalanche Research SLF have developed a method to automatically, quickly and reliably map avalanches in optical satellite images.
WSL Institute for Snow and Avalanche Research SLF
Avalanche on a mountain close to a building
The ceiling of a cold chamber in MSU’s Subzero Research Laboratory was chilled to minus 58 degrees Fahrenheit, simulating a clear night so frigid it sucks warmth and water vapor from snow to form the feathery, glittering ice crystals known as surface hoar
Montana State University
This paper is a preliminary assessment of the glacier avalanche and debris flow disaster that occurred on 7 February 2021 in Uttarakhand, India. The researchers make some observations on the causes and effects of the particular disaster.
Natural Hazards (Springer)
Human experts will continue to produce the avalanche bulletin in future, but computer assessments based on weather data and other measurements have a valuable role to play as a “second opinion”.
WSL Institute for Snow and Avalanche Research SLF
Cover page of the journal pre-proof
This paper addresses the visual communication issues with a focus on natural hazards which vary in time and space or purely in space. This study is a follow up of a previous study on the efficacy of communication of avalanche warnings.
International Journal of Disaster Risk Reduction (Elsevier)