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Emergency Management

Avalanches

A snow avalanche is a swift, downhill-moving snow mass. The amount of damage is related to the size of the slide, type of avalanche, the composition and consistency of the material in the avalanche, the force and velocity of the flow, and the avalanche path. Avalanches usually occur on steep slopes, usually 35 to 60 degrees.   Avalanches can occur outside the optimum slope angle range, but are not as common.

Avalanches take more lives nationwide than any other natural disaster event. Most avalanche deaths result from snow sport activities such as skiing, snowboarding, adn snowmobiling.  It is common for the victim to trigger the fatal avalanche. Avalanches tend to occur repeatedly in localized areas and can shear trees, cover communities and transportation routes with packed snow and debris, destroy buildings, and cause severe personal injury or death.

Avalanches in Juneau have received much attention in recent years.  Steep slopes, heavy, wet snow, and relatively warm temperatures combine every year to create conditions that are conducive to avalanches, especially from January to March.  In the past 100 years, more than 70 buildings near downtown Juneau have been struck by avalanches. Large avalanche paths surround the city, especially near the Behrends and White subdivisions, and along Thane Road.

Click the map below for a larger version:

 

What You Can Do

Backcountry travelers:

• All backcountry travelers should take, at minimum, a basic avalanche awareness course before traveling.
• Know your terrain: be aware of slope angles and other aspects of terrain that may indicate avalanche danger.
• Always carry a probe, beacon, and shovel when traveling in avalanche terrain.
• Avoid high-marking and other high-risk activities.
• Carry a cell phone and/or radio. Remember that cell phones and radios do not work well in mountainous terrain, though.
• If possible, tell someone where you are going and when to expect you back.

Residents:

• Be aware of where avalanche paths are.
• Pay attention to the weather; the level of avalanche danger changes every day.
• Carry a beacon whenever traveling in avalanche zones. For residents living in the highest hazard areas, this might mean wearing an avalanche beacon all the time. Remember that the beacon only works if you are actually wearing it!
• Consider reinforcing the structure of your home to withstand avalanche impact loads.
• Consider evacuating your home during times of high avalanche danger if you live in the path of a slide.