Winter Mountain Hazards

Avalanches, Crevasses and Cold Exposure are Backcountry Threats

Aug 30, 2009

Know how to travel safely on a glacier, perform avalanche search and rescue, carry sufficient equipment for wilderness first aid and shelter from the elements.

Skiers, mountaineers, snow-shoers and other recreationists traveling in the backcountry in winter should be well prepared. Make plans based on research of routes, conditions, forecasts and the skill level of the party. The group needs to be equipped for traveling safely in big mountain terrain and have wilderness survival skills and equipment for unforeseen incidents.

Avalanche Awareness

Avalanches are classified on an international scale. Size 1 avalanches are relatively harmless to people. At the other end of the spectrum, size 5 avalanches are the largest snow avalanches known. They could destroy a village or a forest of 100 acres and typically involve a shifting snow mass of 100,000 tonnes.

It is the union of terrain, weather and snow variables that make avalanches possible.

To travel safely in avalanche terrain it is necessary to be able to recognize avalanche slopes, have an idea about snow stability and the impact past, present and future weather conditions have on the avalanche risk. Avalanche bulletins are issued at ski fields.

Even a small avalanche can have very serious consequences if one is caught in the wrong place, at the wrong time e.g. standing on a steep slope above an ice cliff.

Safe Glacier Travel

Glaciers are the large tracts of permanent but constantly flowing ice on a mountainside. They are characterized by fractures known as crevasses that build up in areas of tension. These fractures that can be several hundred meters deep are often disguised by surface snow and pose a threat to mountain travelers.

Finding the least crevassed route on a glacier will provide the easiest and safest route. Typically this is through the center of the glacier where it is flattest.

Snow bridges that cover crevasses can provide access across these deep ice grooves when frozen. It can be difficult to gage the depth of any given snow bridge so mountain enthusiasts, especially mountaineers typically travel roped together on glaciers. Appropriate use of the rope during glacier travel ensures any fall by a climber into a crevasse will be checked by their rope partner or partners. Typically a rope team of two or more people travel with at least 10 meters (33 feet) of rope between them. Spare rope can be carried in rope coils around the chest that are tied off securely. This spare rope can then be used for crevasse rescue in the event of a deep crevasse fall.

When traveling through crevassed terrain in roped, crevasse travel mode it is important to cross crevasse bridges at 90 degrees to the crevasse edge and keep the rope taut between climbers.

Every individual on a rope team should have the equipment and know-how for self rescue (prussiking) and crevasse rescue of another team member.

Cold Weather Exposure

In winter, a small incident or accident in the mountains can soon be compounded by exposure to cold. The three classic contributors to cold exposure also known as Hypothermia are wet, wind and cold. It is essential for a party to be equipped with the means to create shelter in the event of being trapped or benighted in winter. Emergency shelters such as a Bothay Bag, bivy sac or tent should be carried. On snow, the best shelter (except in exceptionally dry or wet snow) is a snow cave.

Immediate action should be to get the patient to good shelter, rewarm them slowly and give warm food and hot drinks if possible. Hypothermia is considered mild if the core temperature is between 32°C (89.60°F) and 35°C (90 °F). Core temperatures of less than 32°C represent severe hypothermia.

Prevention is always preferable to cure. This involves taking due care before setting out on a winter escapade to ensure the group is appropriately dressed, equipped and prepared mentally and physically with appropriate survival skills. Everyone in the group should know what is expected of them in the event of an avalanche, a crevasse fall, an injury or other incident and have the skills and equipment to react effectively.

The copyright of the article Winter Mountain Hazards in Winter Sports is owned by Lisa Auer. Permission to republish Winter Mountain Hazards in print or online must be granted by the author in writing.