Avalanche

AVALANCHE

Definition and General Information

An avalanche is the sudden and rapid movement of large masses of snow accumulated on sloping surfaces such as mountain slopes, caused by a loss of equilibrium either spontaneously or as a result of a triggering effect, flowing down the slope. Avalanches are the second most deadly natural phenomenon in Turkey after earthquakes.

For an avalanche to occur, the slope angle must be between 28° and 58°. Rugged, mountainous, and sloping terrain without vegetation cover is conducive to avalanche formation. Northern slopes, which remain in the shade, carry a potential avalanche risk during winter months because the snow takes longer to harden and a soft layer forms between two hard layers. The structure of the snow cover, wind, temperature, ground (rocky or treeless grassy ground is more risky) and the freezing of the interfaces between the snow layers are effective in avalanche formation.

Types of Avalanches:

Powder Avalanche: Consists of dry or loose snow. It can reach speeds of 400 km per hour and causes significant damage due to the air pressure it creates. Loss of life can occur due to the snow-air mixture pumped into the lungs before the pressure.
Slab Avalanche: Consists of hard, compacted snow. It is very difficult to predict and can occur at the slightest vibration, moving in blocks.
Heavy Snow Avalanche: Consists of wet, old snow and is usually seen at the end of winter.

A person trapped under an avalanche weighing tons has very little chance of survival. The survivors' chances of survival depend on being located and rescued quickly; someone found within the first 15–20 minutes has a 90% chance of survival.

Prevention Methods

Before the Disaster (Risk Reduction and Preparation)

Education and Information Acquisition:

The first requirement for avalanche protection is to learn about avalanche risk. The avalanche season in the areas visited, the risky areas, and avalanche testing methods should be learned.

Winter activities should not be undertaken without thoroughly learning how to open an avalanche profile and interpret snow layers.

Obtain the most reliable information from local residents; those living in the area are well aware of avalanche-prone locations.

Safety and Prevention:

Avoid going to the mountains for 5–10 days after periods of heavy rainfall; wait for the snow to settle and for any avalanches to occur.
Pass through avalanche-prone areas individually rather than in groups. This minimises the damage to the group and allows for quick intervention for any individual.
New settlements should not be built on avalanche and flood beds, and existing structures should be removed immediately.

Equipment: Avalanche search and rescue equipment (avalanche probe, avalanche shovel and Bieps/transceiver) must be obtained. Having a Bieps device for each team member increases the chances of survival.

During a Disaster (Response/Rescue)

Before Being Caught in an Avalanche:

If you see a powder snow avalanche, try to escape sideways before it reaches you.
If you are at the edge of a slab avalanche, try to separate yourself from the avalanche block by digging into the ground with your shovel before the avalanche gains speed.
If you cannot escape the avalanche, try to find a large rock to take shelter behind or a large tree to hold onto.

When Moving with the Avalanche:

Try to stay on the surface by making movements similar to swimming on your back.
Always move towards the edges.
Immediately discard any equipment that restricts your movement, such as walking sticks.
Try to prevent snow from entering your mouth and nose.

When Buried Under an Avalanche:

Do not panic. Before the snow movement completely stops (before the snow begins to freeze), try to kick the snow to reach or approach the surface.
Try to create an air pocket around your face with your hands.
Darkness can cause panic, which leads to rapid oxygen consumption, so breathe more slowly.

After the Disaster (Rescue and First Aid)

Rescue Organisation:

The search should begin immediately, as the first few minutes are critical.
One person should be sent to call for help after the first 15–20 minutes.
The first task of the search team is to determine the last known location of the missing person or persons.
During the search, a lookout should be posted to watch for the danger of new avalanches, and a safe area should be designated.
The search should be conducted using a Bieps device (if the casualty has one) or avalanche probes.

First Aid:

The first intervention for an injured person rescued from an avalanche is to open the airway. Snow and ice particles that have entered the throat during the slide should be cleared.
If the person is not breathing, artificial respiration (CPR) should be administered.
The casualty should be carefully extracted from under the avalanche and moved to a point where there is no avalanche risk; during this transfer, the casualty's position under the avalanche should be maintained.
There is a high risk of hypothermia. The patient should be laid in a place protected from the cold to increase their body temperature; attempts should be made to warm them using materials such as a sleeping bag and thick blankets.
Changing their clothes for dry ones will be beneficial.
Those who are conscious should be given warm drinks.
Applying heat to frostbitten areas, rubbing them, and bursting blisters is inadvisable.