Local Mountain Rescue service organized a course about avalanches in Dom na Zelenici mountain hut, 1536 m and we, trainees of Alpine Club Tržič, attended. 3 hours of theoretical lectures and 3 more of practical examples were perfect and we found out many new things. We also tried some of the avalanche equipment like avalanche beacons, probes, shovels, ...
Some useful information:
|The death rate from avalanches remains fairly constant, around 60% of victims on extraction. This is largely due to the average response time of the search and rescue services.|
THE FOUR PHASES OF THE AVALANCHE SURVIVAL CURVE (from here)
Survival PhaseIn the first 15 minutes 93% of avalanche victims are still alive, indeed most of the deaths occur during the fall either by hitting rocks or trees or being carried over cliffs or by being crushed or suffocated by the weight of snow. Wet snow avalanches, characteristic of spring, are most likely to suffocate or crush skiers during this phase but it is less common for skiers to be caught these.
Asphyxiation PhaseIn this half hour period, two thirds of victims will die from asphyxiation. Apart from wet snow avalanches the snow encasing victims contains a significant amount of oxygen and is permeable. If a victim has protected or can clear airways and can breath (that is the weight of snow is not compressing the lungs or thorax) they can usually breath. During this period the surrounding air will either be exhausted or the victims respiration will condense and freeze slowly rendering the surrounding snow impermeable.
Waiting PhaseBetween 45 minutes and rescue the victim will probably have found an air pocket and is in a phase of relative security which will allow them to survive for a considerable period. Death is either from slow asphyxia or hypothermia. With an adequate air supply hypothermia is slowed down.
Rescue PhaseBetween being rescued and arrival and recovering in hospital the risk of hypothermia is great. Hypothermia begins when the body temperature drops below 35° C (body temperature is around 36.5/37.0° C) and it is extremely rare for a victim to survive once their body temperature drops to 29° C. The survival phase is critical, when the body is cooled it will divert blood from the extremities to the vital organs, when the body is warmed blood will return to the extremities but at too low a temperature this will cool the vital organs causing death by thermal shock.
CONCLUSIONThe basic message is that to survive an avalanche you have to be rescued within 15 minutes, with half an hour to wait before the rescue services arrive on the scene this comes down to your friends. Your life depends on carrying and being proficient in the use of avalanche transceivers and having snow probes and shovels. In ideal conditions it will take around 5 minutes to locate a victim with a transceiver and 10 to 15 minutes to dig them out from the average depth of burial which is 1 meter.
|Red sky on descent|
|Our instructors and we, trainees|
Hike to the course