Where do avalanches most often occur? Snow avalanche

A snow avalanche is a mass of snow falling or sliding from steep mountain slopes and moving at a speed of 20-30 m/s. The fall of an avalanche is accompanied by the formation of a pre-avalanche air wave, which produces the greatest destruction. Avalanche-prone regions of Russia are: the Kola Peninsula, the Urals, the North Caucasus, Eastern and Western Siberia, and the Far East.
The causes of a snow avalanche are: prolonged snowfall, intense snow melting, earthquakes, explosions and other types of human activity that cause shaking of mountain slopes and air fluctuations. “Descent” snow avalanches can cause destruction of buildings, engineering structures, and cover roads and mountain paths with compacted snow. Residents of mountain villages, tourists, climbers, geologist, border guards and other categories of the population caught in an avalanche may be injured and find themselves under thick snow.

What to do if you are in a danger zone

Follow the basic rules of behavior in avalanche areas:

• do not go to the mountains in snowfall and bad weather;
• when in the mountains, monitor the weather changes;
• When going out into the mountains, be aware of possible avalanche sites in the area of ​​your path or walk.

Avoid areas where avalanches may occur. They most often descend from slopes with a steepness of more than 30°, if the slope is without bushes and trees - at a steepness of more than 20°. With a steepness of more than 45°, avalanches occur with almost every snowfall. Remember that during avalanche periods, rescue teams are created in the mountains.

Preventive measures

In conditions of the threat of avalanches, control over the accumulation of snow in avalanche-prone areas is organized, artificial avalanches are triggered, protective structures are built in avalanche-prone areas, rescue equipment is prepared and rescue operations are planned.
In any weather, you should not cross (cross) ravines with slopes of more than 30°, and after a snowfall, you can cross ravines with slopes steeper than 20° only after 2-3 days. Remember that the most dangerous period for avalanches is spring and summer, from 10 a.m. to sunset.

What to do in case of an avalanche

If an avalanche breaks high enough, quickly walk or run out of the way of the avalanche to a safe place or take cover behind a rock ledge, in a recess (you cannot hide behind young trees).
If it is impossible to escape from the avalanche, free yourself from things, take a horizontal position, tucking your knees to your stomach and orienting your body in the direction of movement of the avalanche.

What to do if you are caught in an avalanche

Cover your nose and mouth with a mitten, scarf, collar; When moving in an avalanche, use swimming movements of your hands to try to stay on the surface of the avalanche, moving towards the edge where the speed is lower. When the avalanche has stopped, try to create space near your face and chest, it will help you breathe. If possible, move towards the top (the top can be determined using saliva, allowing it to flow out of the mouth).
If you find yourself in an avalanche, do not scream - the snow completely absorbs sounds, and screams and meaningless movements only deprive you of strength, oxygen and warmth. Don’t lose your composure, don’t let yourself fall asleep, remember that they are looking for you (there are cases when people were rescued from an avalanche on the fifth and even thirteenth day).

What to do after an avalanche

If you find yourself outside the avalanche zone, report the incident by any means to the administration of the nearest populated area and begin searching and rescuing the victims.
After getting out from under the snow, inspect your body on your own or with the help of rescuers and, if necessary, provide yourself with help. When you reach the nearest populated area, report the incident to the local administration. Go to a health center or doctor, even if you think you are healthy. Next, act as directed by the doctor or rescue team leader. Inform your family and friends about your condition and whereabouts.

Snow avalanche - this is a mass of snow falling or sliding from steep mountain slopes and moving at a speed of 20-30 m/s. An avalanche is accompanied by the formation of a pre-avalanche air wave, which produces the greatest destruction.

The causes of a snow avalanche are: prolonged snowfall, intense snow melting, earthquakes, explosions and other types of human activity that cause shaking of mountain slopes and fluctuations in the air environment. Avalanches can destroy buildings, engineering structures, and fill up roads and mountain paths. Residents of mountain villages, tourists, climbers, geological prospectors, border guards, people working and vacationing in the mountains can be caught in an avalanche, risking injury and ending up under thick snow (Fig. 3).

The basic rules of behavior in avalanche areas are:

Do not go to the mountains in snowfall or bad weather;

While in the mountains, monitor the weather changes;

Before heading out into the mountains, find out where avalanches may occur in your area.

Avoid areas where avalanches may occur. Most often these are slopes with a steepness of more than 30°; if the slope without bushes and trees is more than 20°. With a steepness of more than 45°, avalanches occur with almost every snowfall. The most dangerous period is spring and summer, from 10 a.m. to sunset. When encountering a snow avalanche, you need to know some rules of behavior in this situation (Diagram 23).

After an avalanche, If you find yourself outside its zone, report the incident by any means to the administration of the nearest locality and begin searching and rescuing the victims. If you get caught in an avalanche and free yourself from under the snow, inspect your body and, if necessary, provide yourself with help. When you reach the nearest populated area, report the incident to the local administration. Go to a health center or doctor, even if you think you are healthy. Inform your family and friends about your condition and whereabouts.

Test your knowledge by checking your answers to the tests with the answers given at the end of the textbook.

1. In what sequence will you try to act if, while at home, you suddenly felt shocks, rattling glasses, dishes, and there was no time to run out of the building:

a) turn off electricity, gas, water, move away from windows and pieces of furniture that may fall, take a safe place in the doorway;

b) call the emergency service, turn off the electricity, gas, water, take a seat by the window;

c) close the windows and doors and take a safe place in the closet.

2. Signs of an approaching earthquake may include:

a) bluish glow inner surface houses, sparking of nearby (but not touching) electrical wires, the smell of gas in areas where this had not been noted before, flashes in the form of scattered lightning lightning;

b) sudden changes in weather conditions, self-ignition and spontaneous combustion of flammable substances and materials, heavy precipitation in the form of rain or snow;

c) a short circuit in the electrical network, an incomprehensible hum, the swinging of the chandelier and the shaking of the glass in the windows.

3. You are trapped under a rubble as a result of an earthquake. The left leg was damaged by a fallen structure, but is free and you can move your toes and feet. There is some free space in the room, but the exit is blocked. What is the order of your actions:

a) give yourself first aid, install supports under the structures above you, find warm clothes or a blanket to cover yourself with, scream, call for help, knock with metal objects on pipes and slabs;

b) give yourself first aid and begin to clear the rubble towards the exit from the room;

c) install supports under the structures above you, try to approach the window opening, if you find matches, try to make a small fire to warm up and look around.

4. The most suitable places for shelter in a building during an earthquake:

a) places under the window sill, inside cabinets, wardrobes, corners formed by internal partitions;

b) places under firmly fixed tables, next to beds, near columns, openings in main internal walls, corners formed by main internal walls, doorways;

c) ventilation shafts and ducts, balconies and loggias, spaces inside storage rooms and built-in closets.

5. When a volcano erupts, being in close proximity to it, you must:

a) run away perpendicular to the direction of movement of the lava flows;

b) protect the respiratory system, go to shelter;

c) take cover behind a large stone.

6. The greatest danger during a volcanic eruption is:

a) blast wave and scattering of debris;

b) water and mud-stone flows;

c) sudden temperature fluctuations;

d) clouds of ash and gases (“scorching cloud”),

7. The safest places in case of landslides, mudflows, landslides, avalanches:

a) mountain slopes, where landslide processes are not very intense, gorges and recesses between mountains;

b) hills located on the opposite side of the mudflow-hazardous direction, mountain slopes and hills not prone to the landslide process;

c) valleys between mountains with mudflow and avalanche areas, large trees with thick trunks, large stones behind which you can hide.

8. While at home in a mudflow-prone area, you heard a radio message about the threat of a mudflow. You have 30 minutes left. Your actions:

a) collect all valuable property in the yard and hide it indoors, hide yourself in the cellar;

b) tightly close the ventilation and other openings, all doors and windows, you will go out onto the mountainside through a gorge or a small valley;

c) leave the building and head to a safe place, warn your neighbors about the threat of a mudflow, and go out onto a mountain slope located in a direction that is safe from mudflows.

9. The most dangerous period for avalanches is considered to be:

a) winter, in the moments after precipitation;

b) winter and autumn, from 14:00 to sunset;

c) spring and summer, from 10 a.m. to sunset.

10. While passing through an avalanche-prone area in the mountains, you and a group of tourists saw a sudden avalanche. The risk of being caught in an avalanche is great. Your actions:

a) quickly begin an organized exit from the avalanche-hazardous area;

b) divide into several groups, each of which will begin to independently descend into the valley;

c) use ropes to secure yourself to large stones;

d) take cover behind a rock or its ledge, lie down and press yourself to the ground, covering your head with your hands.

when stopping an avalanche, clear a space in front of your face and chest, create space for breathing;

It’s useless to scream - the snow completely absorbs sounds, save your energy, don’t let yourself fall asleep;

determine the top and bottom (let the saliva flow out of your mouth) and quickly get out, moving the snow under your feet and trampling it down.

PREVENTIVE ACTIONS IN under conditions of avalanche threat, control over the accumulation of snow in avalanche-prone areas is organized, artificial avalanches are triggered, protective structures are built in avalanche-prone areas, rescue equipment is prepared and rescue operations are planned.

In any weather, you should not cross (cross) ravines with slopes steeper than 30o, and after snowfall, you can cross ravines with slopes steeper than 20o only after 2-3 days.

HOW TO ACT IN THE EVENT OF AN AVALANCHE

If an avalanche breaks high enough, quickly walk or run out of the way of the avalanche to a safe place or take cover behind a rock ledge, in a recess (you cannot hide behind young trees). If it is impossible to escape from an avalanche, free yourself from things, accept the horizontal

position, tucking your knees to your stomach and orienting your body in the direction of the avalanche movement.

WHAT TO ACT IF YOU ARE OVERHAUL BY AN AVALANCHE

Don’t lose your composure, don’t let yourself fall asleep, remember that they are looking for you (there are cases when people were rescued from an avalanche on the fifth and even thirteenth day).

A heavy snow avalanche falling on you makes you lose consciousness. When you gradually regain consciousness, you need to try to free one of your hands and press it to your nose so that there is a small space for breathing.

Then try to bring your other hand closer to your face so that you can shovel snow away from your respiratory organs.

You can tell which way is up and which way is down by looking at the saliva in your mouth. If saliva fell in front of you, it means that you are lying upside down in relation to the surface of the earth. If saliva remains on your lips, you are lying upside down. Body position is checked in the same way by spitting to the sides.

When you determine your position, you should try to stretch your arm up. If your hand does not come out, you need to try to make a through hole so that air can flow through it.

If you find yourself upside down in a rubble, you need to try to dig out space around you so that you can turn over.

You must not panic, do not breathe deeply, and do not make fast and sudden movements, as this increases the heart rate and the lungs need more air. Conserving your strength, make your way up, moving the snow under your feet and trampling it down.

If you managed to dig a through passage, but were unable to get out all the way, you need to scream in order to attract the attention of rescuers by screaming during search and rescue operations. They will definitely find you.

HOW TO ACT AFTER AN AVALANCHE

If you find yourself outside the avalanche zone, report the incident by any means to the administration of the nearest populated area and begin searching and rescuing the victims. After getting out from under the snow on your own or with the help of rescuers, inspect your body and, if necessary, help yourself. When you reach the nearest populated area, report the incident to the local administration. Go to a health center or doctor, even if you think you are healthy. Next, act as directed by the doctor or rescue team leader. Inform your family and friends about your condition and whereabouts.

• 1. How to avoid an avalanche

  Avalanches can be avoided if you know a few simple rules and follow them. You need to choose your ski route as carefully as possible. Before, having accelerated well, you fly down the mountain, it is better to look around and analyze the possible danger, and what can be expected from the slope today. It is better to wait out an intense snowfall; in addition, for some time after it it is also better not to go to the slope until the snow settles or avalanches occur. It is better to cross a dubious slope one at a time without stopping. In this case, it is necessary to move as far as possible from the place of a possible avalanche. As a rule, the path along the crest of the ridge is safe, but under no circumstances should you go onto the ledge of the cornice. Very often, avalanches are caused by a person going out onto an avalanche-prone slope. The most dangerous are treeless slopes. Therefore, in order to avoid getting into an avalanche, you must follow some rules of behavior:

  • it is necessary to ski in specially designated areas, for example, at the ski resort on the street. Flotskoy, Nevelsk or village. Gornozavodsk;
  • You cannot go out onto very snowy slopes, much less climb them.

  2. Behavior in an avalanche.

  If you get caught in an avalanche, there is no need to be scared. It is important to try to stay on the surface of the avalanche flow and move towards its edge. If the avalanche is small, you can “hide” from it: temporarily slow down your movement on a natural barrier and let the bulk of the snow flow through. If an avalanche has grabbed your legs and is dragging you down, you need to make swimming movements with your arms, trying to swim to the surface. In addition, you need to cling to any obstacle along the way. If you still plunge into an avalanche flow, then you simply need to cover your face with your hands, creating space for breathing. At the moment the avalanche stops, you need to do everything to form an air cavity around your head and chest before the avalanche compacts. When the flow stops, you need to try to break the snow and raise one hand. There are cases when this saved the lives of people caught in an avalanche.

  3. Rescue operations.

  People caught in an avalanche can die from severe injuries as the avalanche flow moves and hits trees, rocks, and uneven terrain. However, in most cases, death occurs from suffocation. Snow gets into the victim's mouth and presses on her chest. When the avalanche flow stops, the snow is deposited so densely that the person becomes so helpless and cannot move either his arms or legs. The only way to save the life of a person caught in an avalanche is quick and properly organized rescue operations.

  The chances that a person buried in an avalanche will survive quickly decreases as the time until they are removed from the snow increases. According to statistics, when digging out a person caught in an avalanche, about 70% remain alive after ten minutes, after an hour the chance of survival is 30%, and after two hours - less than 20%.

  There are exceptional cases where people who were dug up after three days or more survived, but this happens extremely rarely. Usually two hours is the limit of time during which a person who has fallen asleep can remain alive. The snow, due to its porosity, contains enough air, but within two hours an ice mask forms around the face of a person covered by an avalanche, which prevents breathing. Group members should mark the place where they are last time saw the missing person on the surface. And if the group is large enough, someone should go for help, urgently call rescuers and ambulance and others at this time must look for the missing person. The area below this point should be especially carefully examined using an avalanche probe or other rod. In addition, you need to inspect the slope to find any traces - fragments of equipment or scraps of clothing. You also need to look close to these traces, as well as in places where a person could get into: natural terrain barriers, trees in the path of the avalanche, especially large piles of snow at turns and places where part of the avalanche stops. When a person caught in an avalanche is found, first of all, it is necessary to clear the victim’s mouth of snow and give him artificial respiration.

Every year, many people die under them, either because they ignore the danger or because they know little about avalanches.

Many of us don't take the threat of avalanches seriously until someone is killed or injured in one. The sad fact is that people caught in an avalanche usually provoke it themselves. Skiers cut slopes, climbers walk in avalanche times. Moreover, the victims are often professionals in their field, but they neglect the avalanche danger. This article provides basic knowledge about avalanches.

Potential threats

An avalanche can move at a speed of 200 kilometers per hour. Such a force can smear you against trees and rocks, grind you into rocks, make a mess of your insides and impale you on your own skis or snowboard. About one third of all avalanche victims die due to injury.

If you were not injured by an avalanche, you will be struggling with a mass of snow as dense as concrete, which squeezes your body. An avalanche, which begins as snow dust, heats up from friction with the slope as it moves down, melts a little and then freezes tightly around your body. All this mass is enough to squeeze all the air out of your lungs.

If you manage to create an air pocket around you before the snow settles, you have a good chance of survival. If you and your friends have an avalanche transmitter and know how to use it, then your chances of survival are even greater. However, this is where the race against time begins. Most people are unable to survive an avalanche for more than 30 minutes (Black Diamond AvaLung backpacks can extend that time to up to one hour), so it makes sense to purchase and learn how to use avalanche transmitters. A must-have item for winter freeride enthusiasts. About 70% of avalanche victims die from asphyxiation.

The best protection against avalanches is, of course, knowledge of avalanche conditions and slopes, and avoidance of dangerous situations.

Types of avalanches

Loose avalanches.

Such avalanches form when there is little or no grip on the snow cover. As a rule, such avalanches begin from one point either on the surface of the slope or close to it. Such avalanches gain greater snow mass and momentum while moving down the slope, often forming a triangular-shaped path behind them. The causes of such avalanches can be blocks of snow falling onto the slope from the cliffs above or melting snow cover.

Such avalanches occur on dry and wet snow and occur both in winter and summer. Winter loose avalanches usually occur during or after a snowfall. In warmer seasons, wet, loose avalanches are caused by snow or melt water. These avalanches are dangerous both in winter and summer.

Reservoir avalanches.

These avalanches pose much more danger. Sheet avalanches form when one layer of snow slides off the bottom layer and rushes down the slope. Most freeriders end up in such avalanches.

They are caused by snowfalls and strong winds, which deposit layers of snow that change over time. Some layers are tracked and held together, while others, on the contrary, are weakened. Weak layers are often grainy or made up of very light snow (powder) so that other layers cannot grip them.

An avalanche occurs when the top layer, called the "plank", is not sufficiently bonded to the underlying layer and is set in motion by some external factor, usually a skier or climber. Unlike loose avalanches, which start from a single point, sheet avalanches increase in depth and width, usually along a separation line at the top of the slope.

Avalanche release on Cheget:

Factors contributing to avalanches.

Terrain.

Slope steepness: Pay attention to the steepness of the slope when you are skiing or climbing. Avalanches often occur on slopes steeper than 30-45 degrees.

Slope side: In winter, southern slopes are much more stable than northern slopes, as the Sun melts and compacts the snow. Unstable layers of “deep rime,” dry, icy snow that does not adhere to adjacent layers, are most often located on northern slopes. Therefore, be vigilant when you see a tempting northern slope with excellent powder, because they are more dangerous than southern slopes, due to the fact that they do not receive enough solar heat to compact the snow over the winter. At the same time, in spring and summer, southern slopes melt more, which leads to dangerous wet avalanches. Warmer weather at this time of year hardens the snow on northern slopes, making them safer.

Terrain hazards: snow cover, most often, is not stable on convex slopes, rock ledges, boulders or trees where the snow cover is interrupted, leeward slopes or under eaves. It is best to avoid bowls, circuses and pits where snow can accumulate after an avalanche (avalanche discharges). Steep, narrow couloirs (or gullies) tend to accumulate a lot of snow and pose a huge danger to hikers and skiers who get caught in them. Often, it is impossible to get out of such places due to the steep side slopes, so in the event of an avalanche there is nowhere to run.

Weather

Precipitation: snow is least stable after snowfalls or rains. A large amount of snow falling in a short period of time is a sign of avalanche danger. Heavy snowfall, especially wet or dense snow falling on powder, creates unstable layers in the snowpack. Rain seeps through and heats the lower layers of the snowpack and also reduces friction between the layers, making them less stable. After heavy snowfall, you should wait at least two days before going to avalanche areas.

Wind: Another indicator of snow cover instability is wind. Often strong winds carry surface snow from one slope to another part of the ridge, where the snow falls down, forming an avalanche. Pay attention to the intensity and direction of the wind throughout the day.

Temperature: A large number of problems with snow cover are caused by temperature fluctuations. The formation of snow crystals can vary due to temperature differences between the surface and overlying layers, different layers in the center of the cover, and even between the air temperature and the upper snow layer. A particularly dangerous snow crystal, due to its inability to bond with other crystals, is “frost.”

"Rime Snow"

Frost snow (a Western term) is also called sugar snow by the bourgeoisie, due to its similarity to granulated sugar, and can be located at any depth or several depths of deep snow cover. Often a sharp increase in temperature leads to wet avalanches, especially in spring, so be careful when it gets warm in the mountains.

Snow cover

Snowfalls occur one after another throughout the winter. Temperature changes cause metamorphosis of snow crystals. If the composition of the snow remains the same, then the snow cover is uniform and stable. Snow becomes dangerous and unstable when layers of different types of snow form within the snowpack. To every freerider it is imperative to check snow layers for stability, especially on slopes of 30-45 degrees.

How to test a slope for avalanche danger:

Human factor

While terrain, weather and snow cover play a big role in triggering avalanches, it is important to remember that ego, emotions and herd mentality can seriously cloud your judgment and lead you to make rash decisions. In fact, according to a recent survey of Canadian avalanche experts, respondents cited 'human error' and 'poor terrain selection' as the main causes of avalanche accidents. Most avalanches are caused by people!

Typical mistakes when making decisions:

• Familiar places: It is most likely that you will take risks in a place that is familiar to you. Conditions, however, can change from minute to minute, so treat any terrain as if you were seeing it for the first time.
• OK: encouragement from a group can put a lot of pressure on you. “Everything will be fine, relax!” Even if you feel that something is wrong, in order to please the group you may take unnecessary risks.
• Get to the place at any cost: if you want to get to your destination too much, you may act contrary to your common sense and ignore signs of danger, concentrating only on your goals. Foreign climbers call this phenomenon “summit fever.”
• "We have an expert with us": You imply that there is someone else in your group with more experience than you. You think so based on the fact that this person was in this place before you or he underwent some kind of special training. It's better to ask than to guess.
• Existing trails: you can feel safe because you see a well-trodden path ahead of you. In our mountains, I was once walking along a seemingly excellent path, but I felt that the slope under the path was very unreliable. Just because someone has been here before you doesn't mean it's safe to walk here.
• "Virgin Fever": You can turn a blind eye to the signs avalanche danger when there is fresh, deep and untouched snow in front of you. Don't give in to temptation!
• “Others have passed!”: it's very easy to give in" herd instinct” and go up a dangerous slope when other people have already passed in front of you. Always assess the situation as if you are alone. Tell me if you feel something is wrong.