How to escape from an avalanche? Snow avalanche The most dangerous period for snow avalanches is considered.

Called a tiger in the skin of a lamb by an innocent, at first glance, White snow Matthias Zdarsky is an Austrian researcher who studied the question of what an avalanche is. Softly falling snow fascinates even those who don’t like winter - too much Nice picture, similar to fairy tale. And the crystal stars smoothly falling to the ground create a deceptive impression of fragility and defenseless tenderness. However, excessively active snowfalls are fraught with danger, and a serious one. 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 exists as long as the steep slopes of mountains, and Polybius mentions the first large-scale snowfalls, causing 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, beloved by tourists and climbers, has a long history of disasters behind it. It is not for nothing that in the 20th century, in some areas, masses were celebrated in memory of those killed under snow rubble, because in this case an avalanche means pain and grief for the relatives and friends of those who suffered from it. It is also noteworthy that in one of the last winters of the First World War, more soldiers died from this on the Austro-Italian front 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 during the same time period and described his definition of what an avalanche means, noted that winter landslides are terrible, sudden and bring with them instant death.

Residents of Norway, Iceland, Bulgaria, the United States also suffered from the “white death”. Russian Federation, Canada, as well as Asian countries: Turkey, Nepal, Iran, Afghanistan, and in the latter, by and large, no records of the dead are kept. Tens of thousands of lives and counting snow avalanches, fell 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, the origins of which are the Latin root lab, meaning “instability”, although it came into the Russian language through German, since in ancient German there was a definition of Lavine. Xuan Zang poetically called them “white dragons,” and in Pushkin’s time avalanches were called landslides. In the Alps and the Caucasus, the names of individual mountains, gorges and valleys are already “speaking”. For example, Lansky Forest or Zeygalan Khokh (“the mountain from which avalanches always come down”). Sometimes the ability to read onomastics, although it won’t tell you everything about snow debris, can protect 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, falling lower and lower and capturing accompanying stones on its way, ice blocks, branches and uprooted trees, turning from boiling white snow into a dirty mass vaguely reminiscent of a mudflow. The flow can continue its “fascinating journey” until it stops in flat areas or at the bottom of the valley.

Factors influencing the descent of snow masses from the mountains

The reasons that cause avalanches largely depend on the old snow - its height and density, the condition of the surface underneath it, as well as on the increase in new masses of precipitation. The intensity of snowfall, subsidence and compaction of the cover, and air temperature also influence. In addition, a fairly long open slope (100-500 m) is optimal for the start of an avalanche path.

It is not for nothing that the main “architect” of this natural phenomenon is 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 the snow, although it arises quickly, passes no less actively (it either melts or an avalanche occurs). And when the low temperature is stable, the avalanche period increases.

Seismic vibrations can also activate snow melting, which is not uncommon in mountainous areas. In some cases, jet flights over dangerous zones are enough.

In general, the increasing frequency of snow avalanches is indirectly or directly related to stormy economic activity a person who is not always reasonable. For example, those cut down today forested areas used to serve as a natural defense against snow landslides.

Periodicity

Depending on the frequency of occurrence, a distinction is made between intra-annual convergence (for the winter and spring periods) and average long-term convergence, which includes, respectively, the overall frequency of avalanche formation. There are also systematic avalanches (annually or every 2-3 years) and sporadic ones, which occur at most twice per century, which makes them especially unpredictable.

Movement, source of natural phenomenon

The nature of the movement of snow masses and the structure of the source determine the following classification: flume snow avalanches, special and jumping. In the case of the former, the snow moves either along a tray or along a specific channel. Special avalanches cover the entire accessible area of ​​​​the terrain while moving. But with the jumping ones it’s already more interesting - they are degenerated from the flume, appearing in places where the drainage is uneven. The snow mass has to “bounce”, as it were, to overcome certain areas. The latter type is capable of developing the highest speed, therefore the danger is very significant.

Snow is treacherous and may well creep up unnoticed and silently, falling with an unexpected shock wave, destroying everything in its path. The peculiarities of the movement of these natural masses underlie another division into types. It distinguishes a layer avalanche - this is when the movement occurs tangent to the surface of the snow located below, as well as a ground avalanche - it slides directly along the ground.

Scale

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

Properties of snow

It is also important to note the classification associated with the properties of the snow itself, which is the basis of the avalanche. There are dry, wet and wet. The former are characterized by a high speed of convergence 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 decided to leave its cozy slopes at temperatures above zero. The speed of movement here is lower than in the previous ones, however, the density of the cover is 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 movement speed is 10-20 m/sec.

Volumes

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

Is it possible to predict the occurrence of avalanches?

It is extremely difficult to predict 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, and observation points for dangerous areas. Active actions consist of shelling areas of possible landslides from artillery and mortar installations in order to provoke the convergence of snow masses in small batches.

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

All about avalanches: interesting facts

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

It is not difficult to say how avalanches occur: on steep mountain slopes, individual layers of snow or the entire snow cover lose adhesion to the ground or underlying layer. Due to the enormous weight of the snow, stress occurs within the snow mass, leading to cracks; along them it blurs and slides down.

Of course, in reality the science of avalanches is much more complex, because snow is not a dead mass, falling to the ground from the clouds, it is constantly changing. At first it forms, depending on the temperature and wind strength, a relatively light and loose cover. Sometimes minor disturbances in the structure of the snow cover can set an avalanche into motion.

Even slight heating on a sunny afternoon can increase the tension between the upper and lower layers of snow so much that it will lead to the excavation of a snow shelf. This cause of avalanches is considered the most common.

The four most dangerous types of avalanches:

1. Dry avalanches consisting of loose snow are very dangerous. They rush into the valley at high speed and are accompanied by a monstrous shock wave that crushes even massive concrete barriers. They are formed according to the principle of a growing snowball.

2. Glacial avalanches, which occur, in particular, when the tongue of a glacier is torn off, are especially dangerous. Despite their incredible heaviness, they develop very high speeds. They have forces that can grind even rock-hard ice into powder. Such avalanches have caused many devastating disasters.

3. The term “soil”, “soil” and “surface” avalanche refers to layers of snow cover that begin to move; ground and soil avalanches slide down the slope and cause its powerful erosion; After the snow melts, the carried-away material settles on the valley floor. In contrast, surface avalanches slide into a valley over deep, very stable layers of snow.

4. Snow shelves break off along one long line and slide into the valley along their entire width directly along the ground or along an unstable snow layer.

FACTORS PROVOKING AN AVALANCHE

It is not difficult to say how avalanches occur: on steep mountain slopes, individual layers of snow or the entire snow cover lose adhesion to the ground or underlying layer. Due to the monstrous weight of the snow, tension arises within the snow mass, leading to cracks; along them it blurs and slides down.

However, these days, avalanches are increasingly caused by reckless skiers and snowboarders. Thrill-seekers, despite the prohibitions, leave the safe route for unstable slopes, getting special pleasure from skiing on virgin snow untouched by skiing, and thereby endangering not only their own lives, but also the lives of other people.

FORMATION OF CRYSTALS

During the daily rhythm with its temperature fluctuations individual snowflakes disintegrate and stick together into crystals.

The surface of the snow cover hardens, forming a crust. Under the weight of the snow, the lower layers are compressed more and more. From the rays of the sun and warm air currents, snowflakes melt and stick together into an icy layer.

If fresh snow falls after this, the danger of avalanches increases sharply for several days, since the new layer initially does not adhere well to the snow crust (which is called firn). Only when it settles and sinteres more firmly with the base does the snow cover again acquire greater stability.

The situation becomes especially dangerous in cases where a lot of snow falls or when the old layer of snow has not yet had time to harden. Therefore, avalanche watch services take drill samples especially dangerous places- mainly on steep slopes, ridges and slopes, heavily indented by gutters and mounds - and individual layers are carefully studied. Thus, the uniformity and strength of the entire snow cover is determined. The weaker the individual layers are connected to each other, the higher the risk of avalanches. The situation is assessed based on three factors: the structure of the snow cover, weather conditions (the amount of freshly fallen snow, the strength and direction of the wind) and the terrain (steepness, shape, underlying material, and the direction the slope faces).

Avalanche development

1. Loose snow slides over a layer of denser snow.

2. Having accelerated, the mass of snow can rise into the air.

3. The avalanche picks up speed, sometimes reaching 350 km/h.

Dry avalanche

Dry avalanches consist of loose snow and move especially rapidly.

They begin with small snow landslides, but due to ground shaking and the occurrence of a shock wave they quickly increase

STONES FALLING DOWN

Avalanches also include rock masses that fall down, that is, rockfall, landslide, mudflow.

During a rockfall, individual stones or blocks of stone fall out of a rock wall; with a more powerful collapse, a large mass of stone collapses or rolls down.

A mudflow is an avalanche consisting of a mixture of stones and liquid mud. Such liquid rock avalanches can be caused by precipitation or rapid changes occurring in the ice mass, and the consequences are often catastrophic. So, in 1938, 200 people died in Los Angeles when a mudslide hit the city.

The first victims of the avalanche were military personnel.

The first avalanche victims mentioned in history were warriors. When Hannibal and his army moved north across the Alps in 218 BC, White death took away approximately 18,000 people, 2,000 horses and several elephants.

The largest snow disaster of modern times is also related to the military. In December 1916, during the First world war On the Austrian-Italian front, about 10,000 soldiers died in avalanches in just two days. After a week of continuous snowfall, both warring sides began to fire from artillery pieces slopes located above enemy positions. The shots caused powerful avalanches that buried entire sections of the front along with the troops.

During the First World War, avalanches in the Tyrolean Alps claimed 60,000 lives. Italian and Austrian troops fought in the highlands for three years, suffering from lack of supplies, cold and snow. One of the soldiers recalled: “Our most terrible enemy was nature... Entire platoons were knocked off their feet, carried into abysses, and fell without a trace.” The worst was December 1916, when 4 m of snow fell in 48 hours, leading to avalanches that killed about 10,000 soldiers on both sides of the front.

In Peru, the May 31, 1979 earthquake and resulting avalanche killed 66,000 people. The force of the tremors reached 7.7 on the Richter scale, the epicenter was located near the large port-industrial city of Chimbote, and the consequences turned out to be the most disastrous in the 20th century. A massive layer of soil and ice fell from Mount Huascaran, demolishing the village of Ranrairca, killing 5,000 residents and burying the mountain resort of Yungay. Almost all of its 20,000 inhabitants died here.

A DECEPTIVE IDYLL

After days of heavy snowfall, the sun finally came out and warmed the western and southern slopes of the mountains. Fresh snow, not yet compacted, began to slide down faster and faster; Soon many small and large avalanches were rushing into the valley. According to experts, on steep slopes their speed reached 400 km/h, which gave the snow masses monstrous energy. Even massive defensive structures and large houses were demolished like toys.

A 300-meter avalanche crashed with a roar in 1999 from the top of Grieskopf, bringing death with it.

In the Austrian Galtür on February 23, 1999, 31 people died in a few minutes, and thousands of visitors and inhabitants of this ski paradise were trapped for many days in the Patznau valley.

At the ruins of Galtür

Rescue and assistance to the victims initially had to be done only local residents and their guests-athletes, since the valley was completely cut off from the outside world: the roads were covered with a ten-meter layer of snow. The services responsible for safety in the mountains prohibited rescuers from making their way along the roads into the affected valley due to the high likelihood of new avalanches. Help arrived in the disaster area only the next day by Austrian Air Force helicopters.

Victims are suffocated or crushed

An avalanche can carry up to a million tons of snow from a slope and drive an air force in front of it. shock wave, which, like a bomb explosion, destroys everything in its path. Whoever meets her on the road will be crushed.

Most avalanche victims die very quickly, as a wall of snow rushing at a speed of 100 km/h or more creates a shock wave; it instantly clogs the victim's lungs and airways with snow, and the person dies from suffocation. People who survive this first onslaught die, caught inside an avalanche, which throws them at great speed into rocks, trees and other obstacles.

The deeper a person is buried under an avalanche, the less chance of getting him out of there alive. After all, if a cubic meter of freshly fallen snow weighs only 60-70 kg, then the compacted snow mass of an avalanche presses on the body with the weight of more than a ton, does not allow breathing and simply flattens a person.

Many avalanche victims suffocate under a meter-long layer of snow, as fresh air does not reach them.

Therefore, rescuers advise that in the event of an accident, if possible, press your palms to your face in order to create at least a small space for air, and then the victim, if he is lucky, can hold out until the rescuers arrive. And also, the use of a special one will help the victim survive for some time under the thick snow until rescuers arrive.

People buried in an avalanche are being searched with probes. This must be done quickly, since after 20 minutes half of the victims die. The chance of rescue increases if rescuers and victims have “” with them, which send and receive signals.

STUDYING AVALANCHES

On February 25, 1999, the Sion Valley in the Swiss Alps shook with a terrible roar. A few seconds later the earth shook and the valley was filled with deafening thunderclaps. 600,000 tons of snow fell down the mountainside at a speed of 300 km/h.

In the middle of an avalanche slope, a group of people sits in a massive bunker. They all clutch their ears, which hurt from the roar. The bunker is covered with a three-meter layer of snow as hard as concrete. However, nothing happened to the people - these are employees of a Swiss institute that studies snow and avalanches. They had just caused an explosion to cause a dry avalanche, the largest in the world. Thus, they observe the most terrible danger that can only lie in wait in the mountains - avalanches, which, despite the enormous costs of protective and rescue measures, claim year after year the lives of 150-200 people in the mountains of Europe alone

To prevent such disasters, Switzerland alone has spent 1.5 billion francs over the past 50 years on building avalanche barriers and another billion on growing forests to block avalanches. And not without success: if in 1951 98 people died under the snow masses, then at the end of the millennium “only” 17. And this despite the fact that now the mountainous areas are more densely populated than before, and besides, many ski athletes come here .

This success is not at all accidental. In the Alpine Republic, a systematic study of the dangers posed by snow has been carried out for more than 70 years. The Central Research Institute is founded near Davos on Mount Weisflujoch (height 2662 m). Scientists from various scientific fields are developing such topics as “Formation of snow cover”, “Snow mechanics and the formation of avalanches”.

The purpose of the research, among other things, is to more accurately and timely predict avalanches and to develop effective protective structures that reduce the damage that avalanches cause to nature and buildings. In its forecasts, the institute works closely with meteorologists, because the danger increases significantly when a lot of fresh snow falls on old snow layers.

The avalanche watch service operating in the Alpine region is installing more and more automatic weather stations, but accurate forecast Avalanches are still impossible. As before, skiers should remember to use reasonable caution in the mountains and avoid dangerous places.

NO ABSOLUTE PROTECTION

Despite all the successes of scientists, avalanches, as before, can unexpectedly leave the slope. They are born from time to time even in the most seemingly safe places. Sometimes even expensive protective structures are unable to contain them. Until now, not all factors have been studied that lead to the fact that snow masses begin to move, crush everything that gets in their way, and drag what is captured down.

PHOTOS OF AVALANCHES IN DIFFERENT REGIONS OF THE WORLD or DEADLY BEAUTY:

Bezengi wall. Avalanche from Dzhangi-Tau. Photo-Baskakov Andrey

Avalanche between Western and Main Victory

An avalanche from the Bezengi wall that descended between the peaks of Dzhangi-Tau and Katyn. View from the Dzhangi-Kosh hut. Photo-Alexey Dremin

Bezengi, Dykh-Tau, 2009 (in 4x “zoom”) Photo: Tatyana Senchenko

Avalanche from Western Shkhara, Bezengi. Photo-Vladimir Chistikov

An avalanche from the Belukha massif flying onto the Mensu glacier. January 2003. Photo-Pavel Filatov

Avalanche from the Northern wall of the Mizhirgi - Dykh-Tau massif. Photo-Vladimir Kopylov

Avalanche from the northern slopes of Pobeda Peak. Photo-Vladimir Kopylov

An avalanche covering the right edge of the l. Small Tanymas. Photo-Georgy Salnikov

Avalanches from Pobeda Peak

Avalanches from the Northern wall of Dykh-Tau. Photo-Mikhail Golubev

Elbrus region. Winter avalanche from the Northern wall of Donguz-Orun. Photo: Innocent Maskilayson

Antarctica

Krasnaya Polyana. Caucasus

An avalanche from one of the five-thousanders in the Caucasus, Dzhangitau. Bezengi wall. Photo: Mikhail Baevsky

Avalanche on the railway in 1935 Canada

Avalanche is a rapid, sudden movement of snow and (or) ice down steep mountain slopes, posing a threat to the life and health of people, causing damage to economic facilities and environment. Avalanches form on treeless mountain slopes whose inclination angle is greater than 14°. This is a critical slope at which the snow constantly slides down. An avalanche begins when a layer of freshly fallen snow is 30 cm or when the thickness of 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, a snow avalanche is a mass of snow falling or sliding from steep mountain slopes and moving at an average speed of 20-30 m/s. The fall of a snow avalanche is accompanied by the formation of a pre-avalanche air wave, which produces the greatest destruction.

Formation of an avalanche layer

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

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

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

After heavy snowfalls in the mountains, there is a threat of avalanches. This is warned using special signs.

The impact force of an avalanche can reach from 5 to 50 tons per square meter. Avalanches can cause the destruction of buildings, engineering structures, and cover roads and mountain trails with snow. Residents of mountain villages, tourists, climbers, geologist and other people who find themselves in the mountains and caught in an avalanche may be injured and find themselves under thick snow.

Protecting the population from the consequences of avalanches

Prediction is of great importance for protecting the population from the consequences of avalanches. A special surveillance system is in place for this purpose.

Data received from the observation system is processed and presented in the form of forecasts.

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

In conditions of the threat of avalanches, they organize control over the accumulation of snow in avalanche-prone areas and cause artificial descent of developing avalanches during the period of their least danger.

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

Means for preventing avalanches

Rules of conduct for avalanche zones

Let's consider the recommendations of specialists from the Russian Ministry of Emergency Situations, 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; when in the mountains, monitor the weather changes; When going out into the mountains, know the places of possible avalanches in the area of ​​your route.

Rules of behavior in avalanche zones: 1 - if there is danger of an avalanche, listen to radio messages; 2 - if you find yourself in the mountains during an avalanche, try to run away 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 Ministry of Emergency Situations. And if you are going to be in an avalanche zone, report your intentions (register) to the search and rescue service of the Russian Ministry of Emergency Situations.

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

Remember

The most dangerous period for avalanches is spring and summer from 10 a.m. to sunset!

When an avalanche occurs, if there is a decent distance from you to it, you need to 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.

If it is impossible to escape from the avalanche, get rid of all things and take a horizontal position; cover your mouth and nose with a mitten or scarf to prevent suffocation; in the snow, move your arms and legs (pretend swimming) to stay on the surface; try to clear the layer of snow in front of you to make breathing easier.

When the avalanche has stopped, try to move up.

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

Test yourself

1. Where do avalanches form?
2. Name the reasons for avalanches.

After lessons

1. Ask parents or other adults if they were present when the avalanche occurred. Based on their story, prepare a report on the topic “Personal safety during an avalanche.”
2. Write down the main causes of avalanches in your safety diary. Give examples of these phenomena, descriptions of which you have come across in the literature, means mass 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 such a situation?

A snow avalanche is one of the most dangerous natural phenomena, which is typical for mountainous areas. From the name itself it is clear that snow is involved in this process.

Avalanche definition. This is a type of landslide when a large volume of snow and ice slides or falls down steep mountain slopes. The speed depends on the steepness of the slope, the volume and severity of the snow. On average this is 20–30 meters per second.

Avalanche in the mountains

Along the way, the weight of the snow mass increases because it captures new volumes. And the weight of some of them can reach tens, hundreds of tons. In rare cases, not only the snow melts, but also the glacier. Then the weight of the entire mass can reach tens and hundreds of thousands of tons.

Causes

In mountainous areas, especially if these are high peaks, there is almost always snow, including in summer. In winter, the layer of snow cover becomes larger. This increases the load, as a result of which, due to the steepness of the slope, a certain mass begins to roll down, gradually increasing. A snow avalanche is a natural process.

Avalanche: photo

They have always been and will be in mountainous areas. But if people live in these areas, the avalanche becomes dangerous. In the mountains they try to build houses in safe places where avalanches do not reach. Therefore, residential buildings and other structures rarely suffer from such natural phenomena, but such cases sometimes occur.

In most cases, the victims are people who, for one reason or another, ended up in this place. These are athletes involved in alpine skiing, climbers who conquer peaks. There are also risks of avalanches on ski slopes. In these places, avalanches are provoked in advance and artificially using special equipment to ensure safety.

In most cases the cause is natural. But an avalanche can also be triggered by people if they decide to go to the mountains when rescue workers have informed in advance that it is dangerous. Any slightest mechanical impact can be the beginning of snow melting.

The most common causes of avalanches include:

• heavy snowfalls, increasing the volume of snow mass on the slopes
• human factor (mechanical impact, loud sound, shot, etc.)
• an increase in air humidity, which also makes the snow heavier
• earthquakes (mountains are usually located in seismic zones)

According to the nature of movement they are divided into:

• Osovy — go down over the entire surface and look more like a landslide
• Jumping - fall from ledges
• Tray - pass in the form of furrows through rock weathering zones and natural gutters

According to movement they are divided into:

• Streaming
• Cloud
• Complex

How dangerous is an avalanche?

Large snowfalls can destroy entire settlements located at the foot of the mountains. Fortunately, this happens extremely rarely, because people try not to settle in dangerous areas. Mostly people suffer. There is very little chance of survival. The snow mass is very heavy and can immediately break bones, which deprives a person of the chance to get out. And then there is a high risk of remaining disabled, even if he is found and dug out from under the snow.

Even if the bones are intact, snow can clog the airways. Or simply, under a huge layer of snow, a person simply does not have a sufficient supply of oxygen, and he dies from suffocation. Some are lucky, and they manage to be saved. And it’s good if without negative consequences, because many have frostbitten limbs amputated.

Precursors of an avalanche

The main harbinger is weather. Heavy snowfall, rain, wind create hazardous conditions, so it’s better not to go anywhere on this day. You can also look at the whole general state terrain. Even small landslides of snow indicate that it is loose and the humidity is high. It's better to play it safe.

The most dangerous period for avalanches is considered to be winter, in the moments after precipitation falls.

If you notice an avalanche 200–300 meters away, there is a small chance of escaping from it. You need to run not down, but to the side. If this was not possible, you must perform the following steps:

• cover your nose and mouth with gloves to prevent snow from getting in there
• clear the snow in front of the face and also in the chest area so that you can breathe normally
• you can’t scream, because it takes energy, and anyway, due to the high sound-absorbing properties of snow, no one will hear anything
• you need to try to get out, trying to remove the snow on the way, compact it
• you should not fall asleep to be alert and give a sign if rescuers are close

How to escape an avalanche

Compliance with these rules increases the chances of survival in such an extreme situation.

Avalanche equipment

Today, many manufacturers of sports and tourism goods offer special avalanche equipment. This includes the following devices and equipment:

• Avalanche sensor- it must be turned on immediately as soon as the athlete goes to the mountains. In the event of an avalanche, other members of the group who managed to escape from it, as well as rescuers, will be able to record the signal from this sensor, quickly find and rescue the person.

• Shovel. It is more needed by those in the group who managed to escape the avalanche in order to dig out those who fell under it.

• Avalanche probe. This device is needed to quickly find a person. With its help, you can determine the exact depth of snow under which a person is located in order to calculate the forces and dig him out.

• Avalung system from Black Diamond- a special device that removes exhaled air to the back. This is necessary so that the exhaled warm air did not form a snow crust in front of the face, completely blocking the access of oxygen.

We talk in more detail about avalanche equipment in our separate article.

Avalanche areas in Russia

Avalanches in Russia are not uncommon. These are the mountainous regions of our country:

• Khibiny on the Kola Peninsula
• Kamchatka
• Caucasus Mountains
• ridges and highlands of the Magadan region and Yakutia
• Ural Mountains
• Sayan Mountains
• Altai Mountains
• ridges of the Baikal region

The most destructive avalanches in history

Destructive, terrible avalanches are mentioned in many ancient chronicles. In the 19th and 20th centuries, information about avalanches was already more detailed and reliable.

The most famous snow avalanches:

• 1951 Alps (Switzerland, Italy, Austria). This winter there was a whole series of avalanches due to heavy snowfalls and bad weather. 245 people died. Several villages were wiped off the face of the earth, and almost 50,000 people lost contact with outside world until rescuers came to their aid.

• 1954 Austria, village Blons. On January 11, 2 avalanches occurred at once, which claimed the lives of several hundred residents. More than 20 people are still missing.

• 1980 France. The avalanche killed about 280 tourists at the ski resort.

• 1910 USA, Washington state. A huge avalanche in an area where there had never been one before hit railway station and claimed more than 10 lives.

A lot of avalanches occur in Asia: in Pakistan, Nepal, China. But there are no accurate statistics about deaths and destruction.

We also invite you to watch a video of the largest snow avalanches:

Interesting too

Avalanches. 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 from 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.

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 managed to create air pocket around you before the snow settles, you'll have a good chance of surviving. 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.

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, go both in winter and in 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 represent 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 very light snow (powder) so that other layers cannot grip them.

An avalanche comes when upper layer, called a "board", 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. More warm weather at this time of year, it strengthens the snow on the northern slopes, making them safer.

Terrain hazards: Snow cover is most often unstable on convex slopes, rocky outcroppings, 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 number of snow that fell over short period 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 wind carries 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.”

Deep frost ("sugar snow"), due to its similarity to granulated sugar, 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 the 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, in 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 have an effect on you high pressure. “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 of avalanche danger when there is fresh, deep and untouched snow in front of you. Don't give in to temptation!
• “Others have passed!”: It is very easy to succumb to the “herd instinct” and go on 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.