Description of the snow avalanche. Types of avalanches. Prevention of the threat of falling into an avalanche. Characteristics of snow avalanches

10.03.2020

Avalanche - a rapid, sudden movement of snow and (or) ice down the steep slopes of mountains, posing a threat to human life and health, causing damage to economic facilities and the environment. Avalanches form on treeless mountain slopes, the slope of which is greater than 14°. This is a critical slope at which the snow constantly slides down. An avalanche begins when the layer of freshly fallen snow is 30 cm or when the thickness of the old snow is more than 70 cm. The steepness of the slope, most favorable for the formation of an avalanche, is 30-40 °.

Avalanche speed can reach from 20 to 100 m/s. Thus, an avalanche is a mass of snow falling or sliding off the steep slopes of mountains and moving at an average speed of 20-30 m/s. The fall of a snow avalanche is accompanied by the formation of an air pre-avalanche wave, which produces the greatest destruction.

The formation of an avalanche layer

The occurrence of avalanches is possible in all mountainous areas where snow cover is established. Avalanche-prone regions in Russia are the Kola Peninsula, the Urals, the North Caucasus, Eastern and Western Siberia, and the Far East.

The formation of avalanches occurs in the avalanche focus, which is a section of the slope and its foot, within which the avalanche moves.

Avalanches are caused by prolonged snowfalls, intense snowmelt, and explosions during road construction.

After heavy snowfalls in the mountains, there is a threat of avalanches. Warning about this with the help of special signs.

The impact force of a descending avalanche can reach from 5 to 50 tons per square meter. Descending avalanches can cause the destruction of buildings, engineering structures, cover roads and mountain paths with snow. Residents of mountain villages, tourists, climbers, geologists and other people who find themselves in the mountains and are captured by an avalanche can be injured and find themselves under a layer of snow.

Protection of the population from the consequences of avalanches

Of great importance for protecting the population from the consequences of snow avalanches is their forecasting. There is a special monitoring system for this.

The data received from the surveillance system is processed and presented as forecasts.

Based on the forecasts received, preventive measures are planned and implemented,

Under conditions of the threat of avalanches, they organize control over the accumulation of snow in avalanche-prone directions, cause artificial descent of emerging avalanches during their period of least danger.

Protective structures are being built in avalanche-prone directions, rescue equipment is being prepared and rescue work is being planned. The population is being warned about the danger of avalanches.

Means to prevent an avalanche

Rules of conduct for avalanche zones

Let's consider the recommendations of specialists of the Ministry of Emergency Situations of Russia, developed for the population living in avalanche zones. Follow the basic rules of behavior in avalanche areas: do not go to the mountains in snowfall and bad weather; being in the mountains, watch the weather change; when going out into the mountains, know the places of possible avalanches in the area of your path.

Rules of conduct in avalanche zones: 1 - in case of danger of an avalanche, listen to radio messages; 2 - if you find yourself in the mountains during an avalanche, try to escape from it; 3 - try to hide behind a rock ledge; 4 - once in the snow mass, make “swimming” movements with your hands

Information about avalanches can be found in the search and rescue service of the Russian Emergencies Ministry. And if you are going to be in an avalanche zone, report your intentions (register) to the search and rescue service of the Russian Emergencies Ministry.

Avoid areas where avalanches may occur. They most often descend from slopes with a steepness of more than 30 °; if the slope is without shrubs and trees - with a steepness of more than 20 °. With a steepness of more than 45 °, avalanches come down almost every snowfall.

Remember

The most dangerous period of avalanches is spring and summer from 10 am to sunset!

When an avalanche comes down, if there is a decent distance from you to it, you need to quickly leave the path of the avalanche to a safe place or take cover behind a rock ledge, in a recess.

If it is impossible to escape from an avalanche, get rid of all things and take a horizontal position; cover your mouth and nose with a mitten or scarf so as not to suffocate; in the snow mass, move your arms and legs (depict swimming) to stay on the surface; try to clear a layer of snow in front of you to make breathing easier.

When the avalanche has stopped, try to move up.

Do not lose your temper, do not fall asleep, save your strength, remember that they are looking for you (there are cases when people were rescued from an avalanche on the fifth and even on the thirteenth day)

Test yourself

Where do avalanches form?
List the causes of avalanches.

After lessons

Ask parents or other adults if they were present at the time of the avalanche. Based on their story, prepare a report on the topic "Personal safety during an avalanche."
Write down the main causes of avalanches in your safety diary. Give examples of these phenomena, the description of which you met in the literature, the media. You can use the Internet.

Workshop

You are in a mountainous area where avalanches are possible. What are your actions to maintain personal safety in a similar situation?

Unlike freeriders, who, riding on virgin slopes, literally climb on the rampage and release avalanches themselves, tourists and climbers are cautious and afraid. However, in mountain hiking and climbing, there is almost always such a risk. Therefore, the rules of behavior during an avalanche are taught by everyone who, one way or another, sets foot on the mountain slopes.

Unfortunately, the number of people who have been hit by an avalanche more than once and survived is extremely small. So there is practically no one to learn from the real practical experience of actions during an avalanche.

And even if you have completed avalanche safety courses, will you be able to remember everything you were taught in a real threat situation? The knowledge gained is more likely to be useful for search and rescue.

I consider it appropriate to draw an analogy with teaching driving skills - even the most theoretically savvy students, ideally “practicing” driving on the site, get lost and make mistakes in the city.

But when an avalanche comes down, the stress will be much greater, and, as you know, it turns off the brain and sharpens the instincts.

From the outside, I saw many avalanches, I dealt with only one - in Altai,. Fortunately, all members of our team were at the station (they were on insurance), which helped us to stay on the slope.

Therefore, without much experience, I rely on generally accepted safety precautions for being in dangerous areas and the rules of behavior during an avalanche, which everyone who is going to the mountains needs to know.

Avalanche situation and types of snow avalanches

The avalanche situation in the mountains is highly dependent on the weather. Certain weather conditions can be called avalanche harbingers.

So, within a day after a heavy snowfall, the risk of a dry avalanche (from fresh snow) is high.

During the thaw there is a threat of a wet avalanche (snow landslide). Since in such weather, water forms between the ground and snow or between layers of snow, which is a lubricant that allows the snow to move. A wet avalanche descends even on the ground.

Photo by Anton Shestakov. The descent of the visor from the Akkem wall (Belukha mountain)

During strong winds, cornices are inflated - pressurizations that break off when they reach their critical mass.

Photo by Dmitry Ryumkin. avalanche trail

Boards are a special kind of snow avalanches. The upper layer of snow slides over the lower one, because. between them is a layer of unstable cereals. A slight external influence is enough: a person's exit, a sharp sound, a rockfall. Boards can come off in any weather.

The most avalanche-prone slopes are slopes with a steepness of 20 to 50 degrees. On more gentle slopes, avalanches are less likely to occur. On steep slopes, snow does not accumulate, it melts immediately. Usually they are always naked, but sometimes they form supercharged visors, which can come off at any moment.

Photo by Dmitry Ryumkin. Descended boards blocked our path

It is impossible to assess the avalanche danger 100%. It's always on the slopes. Boards are generally unpredictable.

Avalanche safety

On the route, you constantly have to overcome avalanche sections, build it in such a way that it is almost impossible to bypass them all. Here are some quick rules that will help ensure avalanche safety, so it's best not to neglect them.

Organizational rules for overcoming avalanche areas:

move along the slope (up or down), do not traverse

if a traverse is unavoidable, then this section must be passed in turn

avoid driving along avalanche exits (these are bare areas of forest on a slope in the form of stripes)

do not go to the center of the circus

before passing through the avalanche area, unfasten the belt of the backpack so that it can be quickly dropped and the backpack itself in order to make it easier to search for the person caught in the avalanche by his scattered things

put an observer on the observation point, who, in the event of an avalanche, must give a signal, as well as monitor the location of participants located in avalanche areas

Usually, when they talk about what to do during an avalanche, they give a long list of actions. Remember at least the most basic rules of behavior during an avalanche.

I want to dwell on the topic of slope traverse. In real conditions, it is very rarely possible to traverse a slope in turn. This is only possible in a short area. If the section is long - a kilometer or more, then the group will not stretch like that, and if there are closed cracks on the slope, then it generally needs to be passed in a bunch.

I do not call for breaking the rules, but in the mountains they are often violated themselves. Therefore, when traversing a large avalanche area, you can do the following:

if the group is large, divide it into links of 4-5 people and pass at some distance between the links, but within sight;
if there is a margin of time, and the avalanche has not yet descended from the slope - wait, maybe it will come down next night or tomorrow (although no one is safe from a second descent). In my hiking and climbing it worked.
and most importantly, the avalanche area must be passed quickly, i.e. with the highest possible speed. You can relax and unwind later.

Behavior in an avalanche

get rid of the backpack, skis (although the tourist bindings will fly off by themselves) and ski poles;

cover your face with your hands, try not to get snow in your mouth and nose

Photo by Dmitry Ryumkin. Through the avalanche

Actions during an avalanche of the comrades of the victim:

Without panic, observe where the avalanche stopped and where the person was last seen.

Go down to the place where the participant was last seen, put a mark (for example, stick a ski pole).

Search from it and below to the place where the avalanche stops (because the avalanche blows down the slope), do not waste time walking around.

Avalanche equipment and supplies

Tourists and climbers rarely take special avalanche equipment with them. After all, we go to the mountains not to fall into an avalanche. This is an emergency.

However, such equipment exists. These are both the simplest devices known to us since ancient times, such as an avalanche cord, probe, shovel, as well as modern and expensive gadgets, such as a beeper.

Whether it makes sense to equip the group with expensive modern avalanche equipment is up to you, but stocking up on avalanche cords and learning how to act in avalanches in advance will still not hurt.

Avalanche cord - a long (10-15 meters) strip of a bright-colored line made of light synthetic material (so that snow does not stick).

She is tied to the participant with one end, and the other is thrown down the slope. If a participant gets caught in an avalanche, there is a chance that a light tape will remain on top of the snow, then the victim will be found and dug up in a matter of minutes.

The reliability of the method is 50/50 (the tape can wrap around a person rolling down a slope or get under the snow).

A modern gadget is a beeper or, in Soviet terms, a beacon. In tourism, it should be not only a transmitter, but also a receiver. Because rescue work will be carried out by their own comrades.

Or one avalanche scanner and beepers-transmitters are taken per group for everyone who wants to stay alive.

Avalanche search equipment can be replaced with improvised means. A probe that is used to search under the snow - arcs from a tent (it is better to wind them with adhesive tape at the grip points) or a ski pole with the ring removed. Avalanche shovel - an ordinary snow shovel, you can also dig with the heel of a ski.

I hope that you will be able to add something to the topic of avalanche safety for tourists and climbers, or to challenge my point of view.

Dmitry Ryumkin, specially for

Snow avalanches - landslides of masses of snow from the slopes. They are formed as a result of a violation of stability under the influence of internal processes occurring in it and external influences.

The occurrence of avalanches is possible on slopes with a steepness of more than 15° and with a snow cover thickness of more than 30 cm. from rooftops.

Areas in which the collapse of avalanches occurs regularly occupy more than 18% of the territory within Russia. Another 5% of the country's area are potentially dangerous zones, where the relief is favorable for avalanche formation, and in the event of the destruction of wood - natural protection against avalanches, or with an increase in the amount of solid precipitation - snow masses from the slopes will be possible to collapse. Significant differences in and on the territory of Russia lead to the fact that the avalanche regime here is more diverse than in any other.

In the high-mountainous regions of the Caucasus, Altai, and the peninsula, where sharply pronounced landforms with sharp peaks and jagged ridges are typical, avalanches form mainly in cirques, cirques, and complex denudation funnels with a rocky surface. The area of such avalanche flows can reach 250–300 ha, and their relative height is 1000–1500 m. The density of the avalanche network here is 8–15 avalanche flows per 1 linear kilometer of the valley bottom. The number of avalanche flows decreases with an increase in the relative height of the slopes, but their area, on the contrary, increases. In the low mountains, the share of avalanche collections - carts and cirques most often does not exceed 1%, but their area is quite large - in the Polar and Subpolar Urals they occupy up to 12% of the total area of avalanche collections.

In the middle and low mountains, denudation funnels and erosion incisions predominate. Thus, about 80% of all avalanche collections are denudation funnels with an average area of 6–8 ha. On the Udokan Ridge, 45% of avalanche collections are erosion incisions and denudation funnels with an area of 0.5–50 ha, and 25% are multi-chamber denudation funnels with an area of up to 250–300 ha.

Avalanche formation often occurs on undivided slopes. Avalanche collections of this type make up about 40% of the total on the Kolyma Highlands with an average area of about 10 ha and a maximum area of more than 120 ha, 30% - on the Udokan Ridge. The width of such slopes can exceed 3500 m, and the fall height is 500 m.
In the mid-mountain regions of Western Altai, on the western and northwestern slopes, the density of the avalanche collection network is 5–10 per 1 linear kilometer. For most of the middle mountains, the density of the network is 1–5 per 1 linear kilometer.

In the low mountains, the density of avalanche flows most often does not exceed 1 per 1 linear kilometer of the valley bottom. This value is typical for 40% of the avalanche-prone territory of the Caucasus.
On sea terraces, avalanches come down as a result of the collapse of snow cornices in gutters and on even slopes 20–200 m above sea level.

The lower altitudinal boundary of the distribution of avalanches rises to the south and to the inland regions. Right into the sea, avalanches collapse from terraces on the coast of the islands, the Far East. And on the northern macroslope, the lower limit of avalanches rises from 550–1250 m above sea level in the Western Caucasus to 1100–1300 m in the Central Caucasus and up to 900–1500 m in the Eastern Caucasus.

Avalanches are possible already at the first snowfalls and before the disappearance of the snow cover throughout almost the entire period of its occurrence. In the glacial belt, snowfall can occur all year round.

Most avalanches descend during or shortly after the end of snowfalls: in the Caucasus - this is 75% of all avalanches, in - more than 60%. Snowfalls with an increment of more than 30–40 cm are, as a rule, accompanied by massive catastrophic avalanches in a wide range of heights and orientations. In the highlands and in coastal areas, the role of avalanche formation increases. Snowfalls are associated with the first peak of avalanche activity, observed in most mountainous regions in December - January. The second peak of avalanche activity is observed during the spring snowmelt during wet avalanches. In inland regions, there are frequent cases of avalanche collapses caused by the weakening of bonds within the snow mass.

Every year, the number of days with avalanches is: in the Caucasus (Elbrus region), the Subpolar and Northern Urals, in the Khibiny - 30-40, on the Kamchatka Peninsula, on Sakhalin Island - 20-30, in the North-East of the Asian part of Russia, in, in Transbaikalia - 10–20. In various mountainous areas, in avalanche collections located favorably in relation to the prevailing winds, more than 20 avalanches can descend during the winter. Most often, avalanche collection “works” no more than once in the winter. The frequency of occurrence of avalanches reaching far to the bottom of the main valley can be 1 time in 50 or more years.

Most often, the volumes of avalanches do not exceed several thousand m3. The maximum volumes of recorded avalanches are: in the Caucasus - 5.9 million m3, in Altai and Sakhalin Island - 1.4 million m3, in the Khibiny - 1.125 million m3, on the Kamchatka Peninsula - more than 1 million m3. At the same time, in the North-East of the Asian part of Russia, in the Urals, they reach no more than 100 thousand m3, in the Byrranga mountains - 10 thousand m3. According to the Avalanche Cadastre, the maximum total run length for catastrophic avalanches is: in Altai - 2500 m, in Transbaikalia - 2220 m, on Sakhalin Island - 2500 m.

About 6 million people live in Russia on the territory where avalanches occur or are possible. 8 cities of the country and many other settlements are under direct threat. Only in Petropavlovsk-Kamchatsky within the city there are more than 90 avalanches. In another 36 cities there is a danger to communications. Snow mass collapses occur in recreation areas of the population of regional centers - Yuzhno-Sakhalinsk and. Avalanches hit the ski slopes, Dombai, Krasnaya Polyana, Khibiny. Routes of tourists and climbers pass through avalanche zones. Regularly, due to snow avalanches, traffic is disrupted on the Transcaucasian highway, the Krasnoyarsk-Kyzyl highway, the Kolyma highway and many other roads in different parts of the country. There are avalanche-prone areas on the Novokuznetsk-Abakan railways, on the BAM route, on Sakhalin Island. Power lines, oil and gas pipelines pass in the zone of action of avalanches.

More than 20 people die in avalanches every year in Russia. Cases of people dying in avalanches were noted in almost all mountainous regions of the country, as well as in flat areas - in, near Novosibirsk.

In order to protect the population and economic facilities, a whole range of anti-avalanche measures is used. Scientific and practical research in avalanche-prone areas is carried out by Moscow State University. M. V. Lomonosov, a number of academic and departmental institutions. As part of the Hydrometeorological Service, there are prognostic units and observation avalanche stations. The shelling of avalanche-prone slopes is carried out by anti-avalanche paramilitary services. The first protective engineering structures - galleries and walls - appeared in the middle of the 19th century on the Georgian Military Highway. With the appropriate organization of work, the effectiveness of anti-avalanche measures is high - in the Khibiny, as a result of warning descents, more than 25% of the total number of registered avalanches descends.

In the early 1990s, the number and quality of avalanche observations decreased significantly, and there was a serious lag behind many countries in the study of this dangerous natural phenomenon. The development of mountain territories (construction of structures, recreational development) is carried out without due regard for avalanche danger, which ultimately can lead to an increase in avalanche disasters.

A tiger in a lamb's skin called innocent, at first glance, white snow Matthias Zdarsky, an Austrian researcher who studied the question of what an avalanche is. Softly falling snow captivates even those who dislike winter - it's too beautiful a picture, like a fairy tale. Yes, and the crystal stars smoothly flying to the ground create a deceptive impression of fragility, defenseless tenderness. However, excessively active snowfalls are fraught with danger, and serious. After all, not only snowdrifts, but also avalanches can grow from small snowflakes. So what is an avalanche? The definition of this concept is given below. And now a little history.

A brief excursion into history

In all likelihood, an avalanche is a phenomenon that has existed for as long as the steep slopes of mountains, and Polybius also mentions the first large-scale snowfalls that caused the death of hundreds of people in the context of the history of the campaign of the Carthaginian army through the Alps. And in general, this mountain range, chosen by tourists and climbers, “behind” the longest chronicle of disasters. It is not for nothing that even in the 20th century, masses were celebrated in some areas in memory of those who died under snowy debris, because in this case an avalanche is pain and grief for the relatives and friends of those who suffered from its descent. It is also noteworthy that in one of the last winters of the First World War, more soldiers on the Austro-Italian front died from this than directly during hostilities. And December 16, 1916 went down in history as "Black Thursday", when six thousand people were missing in one day. Hemingway, who was in the Alps at the same time and described his definition of what an avalanche means, noted that winter avalanches are terrible, sudden and bring instant death.

The inhabitants of Norway, Iceland, Bulgaria, the United States, the Russian Federation, Canada, as well as Asian countries: Turkey, Nepal, Iran, Afghanistan, also suffered from the “white death”, and in the latter, the death toll is by and large not kept. Tens of thousands of lives and on account of the snow avalanches that broke from Mount Huascaran in Peru.

What is an avalanche? Etymology of the word

The ancient Romans called this phenomenon "a pile of snow." Each nation had its own definition. What does avalanche mean? This is a beautiful, exciting and dangerous natural phenomenon. The very meaning of the word “avalanche” is also interesting, in the origins of which is the Latin root lab, meaning “instability”, although it got into the Russian language through German, since the definition of Lavine existed in Old German. Xuan Zang poetically called them "white dragons", and in the time of Pushkin, avalanches were called avalanches. In the Alps and the Caucasus, the names of individual mountains, gorges and valleys are already "speaking". For example, the Lan forest or Zeygalan Hoch (“mountain from which avalanches always come down”). Sometimes the ability to read onomastics, although it does not tell everything about snow blockages, can save you from unforeseen circumstances.

What is an avalanche

An avalanche is a type of landslide, a significant mass of snow that moves or even falls from the slopes of mountains under the influence of gravity. It simultaneously creates an air wave, which accounts for a significant part of the destruction and damage that is almost inevitable in this natural disaster.

Having started its movement, the avalanche can no longer stop, sinking lower and lower and capturing accompanying stones, ice blocks, branches and uprooted trees on its way, turning from ebullient white snow into a dirty mass, remotely resembling a mudflow. The flow can continue its “fascinating journey” until it stops on gentle sections or at the bottom of the valley.

Factors affecting the convergence of snow masses from the mountains

The reasons causing the convergence of avalanches largely depend on the old snow - its height and density, the state of the surface under it, as well as on the growth of new masses of precipitation. The intensity of snowfalls, subsidence and compaction of the cover and air temperature also affect. In addition, a fairly long open slope (100-500 m) is optimally suited for the start of an avalanche path.

The main "architect" of this natural phenomenon is not in vain called the wind, since an increase of 10-15 cm is enough for the snow to melt. Temperature is also one of the most important factors that can provoke a disaster. Moreover, if at zero degrees the instability of snow, although it arises quickly, but also passes no less actively (it either melts or an avalanche descends). And when the low temperature is stable, the avalanche period increases.

Seismic vibrations can also activate the convergence of snow, which is not uncommon for mountainous areas. In some cases, flights of jet aircraft over dangerous zones are also enough.

In general, more frequent snow avalanches are indirectly or directly related to the rapid human economic activity, which is not always reasonable. For example, forests that have been cut down today used to serve as natural protection against snow landslides.

Periodicity

Depending on the frequency, intra-annual convergence (for the winter and spring periods) and the long-term average, which includes, respectively, the total frequency of avalanche formation, are distinguished. There are also systematic avalanches (annually or every 2-3 years) and sporadic ones, occurring a maximum of twice per century, which makes them especially unpredictable.

Movement, the focus of a natural phenomenon

The nature of the movement of snow masses and the structure of the focus determine the following classification: flume snow avalanches, special and jumping. In the case of the first, the snow moves either along the tray or along a certain channel. Special avalanches during movement cover the entire accessible area of the area. But with jumpers it’s already more interesting - they are reborn from flume, arising in places of uneven flow. The snow mass has to “jump”, as it were, to overcome certain sections. The latter type is capable of developing the greatest speed, therefore, the danger is very significant.

The snow is treacherous and may well creep up unnoticed and inaudibly, falling in an unexpected shock wave, destroying everything in its path. Features of the movement of these natural masses underlie another division into types. A formation avalanche stands out in it - this is when the movement occurs relative to the snow surface located below, as well as a ground avalanche - it slides directly on the ground.

scale

Depending on the damage caused, avalanches are usually divided into especially dangerous (they are also spontaneous) - the volume of material losses amaze the imagination with their scale, and simply dangerous - they impede the activities of various organizations and threaten the peaceful measured life of settlements.

snow properties

It is also important to note the classification associated with the properties of the snow itself, which is the basis of the avalanche. Allocate dry, wet and wet. The former are characterized by a high convergence rate and a powerful destructive air wave, and the masses themselves are formed at sufficiently low temperatures after significant snowfalls. A wet avalanche is snow that has chosen to leave the cozy slopes at above freezing temperatures. The speed of movement here is less than in the previous ones, however, the density of the cover is also greater. In addition, the base can freeze, turning into a hard and dangerous layer. For wet avalanches, the raw material is viscous, wet snow, and the mass of each cubic meter is about 400-600 kg, and the speed of movement is 10-20 m / s.

Volumes

Well, the simplest division is small and almost harmless, medium and dangerous to humans, as well as large ones, which on their way wipe buildings and trees from the face of the earth, turn vehicles into a pile of scrap metal.

Can avalanches be predicted?

It is extremely difficult to predict the convergence of avalanches with a high degree of probability, since snow is an element of nature, which, by and large, is practically unpredictable. Of course, there are maps of dangerous areas and both passive and active methods are being taken to prevent this phenomenon. However, the causes and consequences of avalanches can be different and very noticeable. Passive methods include special shield barriers, forest areas, observation points for dangerous areas. Active actions consist in shelling areas of possible collapses from artillery and mortar installations in order to provoke the convergence of snow masses in small batches.

Snow avalanches sliding down from the mountains in any of the options are No matter how small or large they are. It is extremely important to take into account all the factors influencing the emergence of snow masses and their movement along an indefinite route to unknown targets, so as not to sacrifice too expensive gifts to the elements.

All about avalanches: interesting facts

The speed of an avalanche can reach 100-300 km/h. A powerful air wave instantly turns houses into ruins, crushes rocks, demolishes cable cars, uproots trees and destroys all life around.
Avalanches can come from any mountains. The main thing is that they are covered with snow cover. If there have been no avalanches in a certain area for 100 years, then there is always the possibility that they can occur at any time.
Approximately from 40 thousand to 80 thousand people lost their lives during the First World War, they remained buried under avalanches in the Alps. The data is approximate.
In America (California), people surrounded Mount St. Gabriel with deep ditches. Their sizes are equal to football fields. Avalanches descending from the mountain linger in these ditches and do not roll into settlements.
This destructive natural phenomenon is called differently by different peoples. The Austrians use the word "schneelaanen", which means "snow stream", the Italians say "valanga", the French - "avalanche". We call this phenomenon an avalanche.

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

Signs of an avalanche area:

Avalanches rarely descend from slopes with a steepness of less than 25 degrees.
From slopes with a steepness of 25 to 35 degrees, avalanches sometimes descend, especially when the cutting action of the skis contributes to this.
The most dangerous slopes are steeper than 35*. In such places, avalanches are likely with every big snowfall.
Steep, narrow ravines are natural avalanche paths.
Combing in the forest, especially narrowing upwards, can be avalanche paths.
In the dense forest, avalanches rarely come down.
Slopes with isolated trees are no safer than no forest at all.
Leeward slopes are favorable for the accumulation of excess amounts of loose snow and the formation of snow boards. The protrusion of the snow cornice is directed towards the leeward slope. The snowdrifts are elongated perpendicular to the wind direction, with the leeward slope being steeper.
In logs located perpendicular to the wind, the accumulation of loose snow or the formation of snow boards occurs mainly on the leeward slope.
On windward slopes, the snow cover is usually strongly wind-compacted and safe.
The slopes facing south are favorable for the formation of wet avalanches in spring and especially from fresh snow under the influence of sunlight.

HOW TO ACT IF YOU ARE IN AVALANCHE ZONE

Observe basic rules of conduct in avalanche areas:

do not go to the mountains in snowfall and bad weather;
being in the mountains, watch the weather change;
when going out into the mountains, know in the area of \u200b\u200byour path or walk the places of possible avalanches.

Avoid areas where avalanches may occur. They most often descend from slopes with a steepness of more than 30°, if the slope is without shrubs and trees - with a steepness of more than 20°. With a steepness of more than 45 °, avalanches come down almost every snowfall.

Remember that during the avalanche period in the mountains rescue teams are created.

Avoid avalanche danger by:

Choose your route carefully. Learn known avalanche paths, prevailing winds, and data from the latest blizzard. A good source of information is the nearest avalanche operator or ski patrol leader.
Avoid known dangerous slopes. Cross the questionable slope one person at a time and as far up the slope as possible or as far away as possible from the place of a possible avalanche. It is safe to walk along the crest of the ridge, but do not walk on the ledge of the cornice.
Be careful. As you move, constantly monitor the condition of the snow. Before you go on a big slope, try a small one with the same steepness and orientation in relation to the sun. If you see an avalanche trail from a snowboard, be aware that the same avalanche may be waiting for you nearby. Watch your shadow. When it is directed to the slope, the effect of the sun is strongest. Seek protection in dense forest, on windward slopes, and behind natural barriers. Watch the weather: any sudden change is dangerous.
Make good use of your time. Sit out a strong storm and for some time after it, until avalanches come down or until the snow settles. Control your every step. In the very first hours of the snowstorm, movement is possible. Use this time to get out of the avalanche area. In spring, the period between ten o'clock in the morning and sunset is the most prone to avalanches. Early morning hours before sunrise are the safest.
Resort to self-defense. If you still need to cross a very dangerous place, have one person on skis check the slope. This person must be secured with a climbing rope and an avalanche cord. Don't be satisfied with one test. Avalanches have a treacherous habit of picking the third skier in the chain.

HOW TO ACT IN THE EVENT OF AVALANCHE

If the avalanche breaks high enough, quickly move or run out of the path 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 get away from the avalanche, get rid of things, take a horizontal position, pulling your knees to your stomach and orienting your body in the direction of the avalanche.

HOW TO ACT IF YOU HAVE AVALANCHED

Cover your nose and mouth with a mitten, scarf, collar; moving in an avalanche, try to keep on the surface of the avalanche with swimming movements of the hands, moving to the edge, where the speed is lower.
When the avalanche has stopped, try to create space around your face and chest to help you breathe.
If possible, move towards the top (the top can be determined with the help of saliva, letting it flow out of the mouth).
Once in an avalanche, do not scream - the snow completely absorbs sounds, and screams and senseless movements only deprive you of strength, oxygen and heat.
Do not lose your temper, do not let yourself fall asleep, remember that you are being looked for (there are cases when people were rescued from under an avalanche on the fifth and even thirteenth day).

HOW TO ACT AFTER THE AVALANCHE

If you find yourself outside the avalanche zone, report the incident to the administration of the nearest settlement by any means and proceed to search and rescue the victims.
Having got out from under the snow on your own or with the help of rescuers, examine your body and, if necessary, help yourself.
When you reach the nearest settlement, report the incident to the local administration.
Go to the first-aid post or see a doctor, even if you think you are healthy. Then proceed as directed by the doctor or the leader of the rescue team.

Let your family and friends know about your condition and whereabouts.