Types of avalanches. Definition of a snow avalanche: varieties, safety. Protection against snow drifts, blizzards, blizzards, avalanches

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“It would seem that the cold inherent in the snow should have given it the numbness of winter, and the whiteness the immobility of the shroud. However, this is refuted by the rapid movement. An avalanche is snow that has become a fiery furnace. It is icy, but it devours everything.” Victor Hugo

“An avalanche is an unforgettable sight. First, somewhere in the heights there is a dull sound, and then the silent mountains seem to come to life. A huge cloud of snow rushes down the slope, sparkling with millions of snowflakes. Then it reached the bottom of the valley, spread out across it, snow dust flew up high, and everything disappeared as if in a fog... After some time, the snow dust settled down, but the bottom the valleys were blocked by shapeless piles of snow, so dense that they looked like pieces of snow. Branches, fragments of tree trunks, and stones stuck out in them.” (3) Like all the elemental forces of the Earth, it is a beautiful and terrible sight.

After 8 years, a similar event repeated itself, but only on an even larger scale. May 31, 1970. In the Cordillera Blanca, where the peak of Huascaran is located, a strong earthquake occurred, which tore off at least 5 million m3 of snow and ice from the slopes. Along the way, the avalanche broke off a significant part of the underlying glacier and rushed, tearing off a thick layer of loose rock and carrying away huge stones. On the way, the avalanche lowered a small lake, which gave the entire mass even greater strength. A gigantic amount of snow, ice and mountain rock rushed through the valley at a speed of 320 km/h - 50 million m3! The avalanche overcame an obstacle 140 m high, again destroying the newly rebuilt village of Ranairka and the city of Yungai, which in 1963 saved the low hill. The mass of snow, water and stones covered almost 17 km. The consequences were terrible: out of 20 thousand inhabitants, only a few hundred people remained alive. Such terrible avalanches happen rarely, but avalanches of normal sizes are a formidable element of the mountains.

The ancient German word "lafina" comes from the Latin "labina", that is, sliding, landslide. Bishop Isidore of Seville (570-636 AD) mentioned “labines” and “avalanches” - this is the first literary source. In folklore, avalanches are called “white death”, “white dragons”, “white brides” and so on.

“Avalanches became of interest to man only when they began to disturb him, that is, when man began to inhabit the mountains. At the same time, avalanches became interested in man – the so-called unhealthy interest. Having arisen at a time when the Earth squeezed out mountain ranges from itself, and the first snow fell from the sky, avalanches took millions of years to get used to to solitude and therefore met its violators with hostility: why should one expect anything else from a bear sleeping peacefully in a den, which people woke up with whistling and hooting? (5)

Information about snow avalanches has come down from ancient times. In 218 BC. They caused a lot of harm to the troops of the Carthaginian commander Hannibal, who was crossing the Alps. Then many people and animals died under avalanches - every fifth foot soldier (60 thousand people), every second horseman (6 thousand), and 36 elephants out of 37 that took part in this transition.

In addition, the history of the crossing of the Alps by Suvorov’s army in 1799 is known. And here avalanches made it difficult for the army to operate on the dangerous St. Gotthard Pass.

During the First World War, when the Alps were in the sphere of military operations, about 60 thousand people died in avalanches - more than as a result of military actions. On just one “Black Thursday”, December 16, 1916, more than 6 thousand soldiers were buried in avalanches.

Peacetime losses are immeasurably smaller, but they are noticeable.

Nowadays, the Alps, “inhabited by people like bees and bees,” especially suffer from avalanches (5) From the beginning of this century to 1970. in the Swiss Alps, 1,244 people died from avalanches. In total, there are 20 thousand avalanche sites in the Alps, of which more than 10 thousand are permanent avalanche sites, and 3 thousand of them threaten populated areas, roads, and communication power lines..

“Avalanches are rampant in both Americas, they fall from the peaks of the Tien Shan, they create scandals in the Khibiny Mountains, in Siberia, in Kamchatka and in general in all mountainous regions.”(5)

“In the Caucasus, the lavains lie in wait for travelers and exact many victims,” writes Strabo in his “Geography” 2000 years ago. During the Great Patriotic War in the winter of 42/43, special units of military climbers artificially caused avalanches, thus destroying enemies.

Winter 1986/87 It was exceptionally snowy in the Caucasus - snow fell 2-3 times more than usual. In Svaneti it snowed non-stop for 46 days and gave rise to countless avalanches. Almost all the ancient houses in which people lived from the 10th to the 12th centuries were destroyed. Salvation from the “white death” could only be found in ancient towers 8-15 m high, where people once escaped from enemies.

An avalanche is a mass of snow that comes moving on a slope. "Avalanches are the most unpretentious creatures: in order to bring them to life, you only need snow and mountains with suitable slopes. Snow for avalanches is manna from heaven, the only source of food. During snowfall, it collects in avalanche collection, at the very top, in order to then choose the right moment to rush at terrible speed along tray down and form at the place of convergence avalanche cone sometimes with a thickness of several tens of meters."(5).

The fluffy blanket of snow in the mountains only looks harmless from a distance. Austrian researcher Matthias Zdagarsky said this: “Innocent-looking white snow is a wolf in sheep’s clothing, and a tiger in lamb’s clothing.” “Suitable” slopes for avalanches have a steepness of 15-45 degrees. On gentler slopes the snow flows gradually, but on steeper slopes it does not linger. Avalanche tray- a trench on a slope along which avalanches descend (as a rule, they descend along the same path).

The area of ​​the mountain slope and valley floor where an avalanche forms, moves and stops is called avalanche collection.At the top is avalanche source– place of origin, and below – channels avalanche cone.(Fig.1)

In the zone of origin, the avalanche gains strength, captures the first portions of snow from the slope and quickly turns into a stormy stream, sweeping away everything in its path. In the transit zone, it rushes down the slope, increasingly increasing its mass, breaking bushes and trees. Gradually, the movement slows down, masses of snow pile up in the form of an avalanche alluvial cone. Here, an avalanche deposition zone is formed. In the deposition zone, snow cones with a thickness of 5 to 30 m, and sometimes more, are formed. Winter 1910/11 the avalanche of the Bzyken Caucasus ridge left the river gorge. The white slope is 100 m thick. The snow melted in it for several years.

Most catastrophic avalanches occurred after days of heavy snowfall that overloaded the slopes. Already with a snowfall intensity of 2 cm/h, lasting up to 10 hours in a row, an avalanche danger arises. Freshly deposited snow is often loose, loose, like sand. Such snow easily gives rise to avalanches. Avalanche danger increases many times over when snowfalls are accompanied by wind. When there is a strong wind on the surface of the snow, a wind or snow board is formed - a layer of fine-grained snow of high density, which can reach a thickness of several tens of centimeters. Obruchev called such avalanches “dry”: “they occur in winter after heavy snowfall without thaw, when the blowing snow on the ridges and steep slopes reaches such a size that the shock of the air from the wind, a shot, Even a loud scream causes them to break out. The latter is greatly facilitated if fresh snow falls on the smooth surface of old snow, captured after a thaw and frost. These avalanches fly down and at the same time fill the air with snow dust, forming a whole cloud." (2) (Fig. 3)

In the absence of snowfalls, the snow gradually “ripens” to generate avalanches. Over time, the snow layer gradually settles, which leads to its compaction. Sources of avalanche danger are weakened layers in which loosely bound crystals of deep frost form. This is what eats away the lower layer of snow cover, suspending the upper layer.

The condition of the snow cover changes dramatically when water appears in it, which significantly weakens the strength of the snow. During sudden melting or intense rain, the structure of the thickness is quickly destroyed, and then enormous “wet” avalanches are formed. They fall in the spring over large areas, sometimes capturing all the snow that has accumulated over the winter. They are also called ground avalanches because they move straight along the ground and tear up the soil layer, stones, pieces of turf, bushes and trees. These are very heavy avalanches.

Snow lying on a slope moves under the influence of gravity. The supports keep the snow on the slope until the shear resistance forces (the adhesion of the snow to its lower layers or soil and the force of friction). In addition, the shift of the layer is prevented by the snow cover located below and held by the one that lies above. Snowfall or blizzard, recrystallization of the snow column, the appearance of liquid water in the thickness leads to a redistribution of forces acting on the snow.

Snowfall overloads the slopes with snow, and the forces holding the snow do not keep up with the increase in gravity tending to move it. Recrystallization weakens individual horizons, reducing the holding forces. Rapid melting of snow due to rising temperatures or wetting of snow by rain sharply weakens the bonds between snow grains, also reducing the effect of holding forces.

In order for an avalanche to move, it needs a first impulse. Such triggers include heavy snowfalls or heavy snowstorms, warming, warm rain, cutting snow with skis, vibration from a sound or shock wave, and earthquakes.

Avalanches begin to move either “from a point” (when the stability of a very small volume of snow is disrupted), or “from the line” (when the stability of a large layer of snow is disrupted at once) (Fig. 2). The looser the snow, the less it is needed to start an avalanche. The movement begins with just a few particles. An avalanche from a snow board begins with cracking of the snow cover. A narrow crack quickly grows, side cracks are born from it, and soon the snow mass breaks off and rushes down.

For a long time, an avalanche was represented in the form of a snowball that flies down the slope and grows due to the accumulation of new portions of snow (almost all ancient engravings depicted an avalanche this way). The ball avalanche was represented until the 19th century. The variety of snow avalanches and the many forms of its movement made it difficult to understand the physics of avalanches. An avalanche is a multicomponent flow, because it consists of snow, air and solid inclusions. The physics of such flows is very complex.

The forms of movement of an avalanche are varied. Snow pellets can roll in it, snow balls and fragments of a snow board can slide and rotate, a solid mass of snow can flow like water, or a snow-dust cloud can rise into the air. Different types of movement complement each other, transforming into one another in different sections of the same avalanche. The front of the avalanche moves faster than its main body due to the collapse of the snow cover in front of the front from the avalanche impact. Thus, more and more new portions of snow are included in the avalanche, while in the tail part the speeds drop. On the crests of waves that arise on the surface of a moving avalanche, stone fragments appear, which indicates strong turbulent mixing in the body of the avalanche.

As the slope flattens, the body of the avalanche slows down its movement. The body of the avalanche spreads over the surface of the cone. The stopping snow quickly hardens, but continues to move for some time under the pressure of the tail part of the avalanche, until the avalanche finally calms down.

The speed of avalanches varies from 115 to 180 km/h, sometimes reaching 400 km/h.

Avalanches have enormous impact force, easily smashing wooden houses into pieces. Even concrete buildings cannot withstand a frontal impact. If an avalanche fails to destroy a house, it pushes out doors and windows and fills the lower floor with snow. The avalanche does not spare anything that meets on its road. It twists metal power transmission masts, throws cars and tractors off the road, turns steam locomotives and diesel locomotives into a pile of scrap metal (in 1910, in the Cascade Mountains (USA) in the area of ​​​​Stevens Pass, an avalanche fell on a passenger train and smashed it into pieces. About 100 people died). She covers the roads with a layer of many meters of dense, ice-like snow. It destroys many hectares of forest at once; even hundred-year-old trees cannot withstand it. (Fig.4)

Jumping avalanches have a particularly strong impact effect (if there is a cliff or a sharp bend in the slope in the path of a snowfall, the avalanche “jumps” from it and sweeps through the air for some time). When an avalanche lands, knockout pits appear. In the New Zealand Alps, 16 lakes with an area of ​​200 to 50 thousand m2 were found in similar basins. All of them are located at the base of steep avalanche chutes.

To properly design avalanche structures, it is necessary to measure the force of the impact. Back in the 30s in our country, a railway car buffer with a powerful spring was used for this purpose, which was fixed in the path of the avalanche. The amount of compression of the spring upon impact was recorded with a metal rod. In Switzerland, along the path of an avalanche, a shield was installed, on the reverse side of which there was a pointed steel rod, and an aluminum plate was fastened opposite it, into which the rod entered under the impact of the avalanche. The greater the pressure, the stronger the dent. Nowadays, complex devices are used that make it possible to obtain not only the maximum snow pressure, but also its change during the impact. Data show that avalanche pressures typically range from 5 to 50, although the impact of avalanches in Japan exceeded 300. In the table you can see the destruction caused by an avalanche impact of varying strengths:

To characterize avalanche danger, it is very important to know the range of the avalanche, i.e. the maximum distance that an avalanche can travel in a given avalanche collection. The ejection range ranges from a few tens of meters to 10-20 km. The Huascaran avalanche in Peru traveled almost 17 km. The longest range in the former USSR was recorded in the Kzylcha river basin in the Tien Shan; the avalanche traveled 6.5 km here. In most cases in the mountains of our country, the range of avalanches is from 0.5 to 1.5 km.

Dust avalanches have special properties - a mixture of dry snow and air of very low density, accompanied by a cloud of snow dust. They have enormous speed and great destructive power. With a slight change in movement in a dust avalanche, shock waves arise, creating a rumble and roar that accompanies the avalanche. Such avalanches are capable of moving multi-ton objects. In the Rocky Mountains, a powerful dust avalanche carried a truck weighing more than 3 tons and an excavator bucket weighing more than 1 ton 20 m to the side and then dumped them into a ravine.

Often, avalanches of dry snow are accompanied not only by a snow-dust cloud, but also by an air wave that causes destruction outside the zone of deposition of the main mass of avalanche snow. So, in the Swiss Alps, 1.5 km from the avalanche stop site, an air wave knocked out the glass windows of houses. And in another place, an air wave moved a railway car 80 m away, and a 120-ton electric train lifted the station building. A particularly tragic incident occurred in Switzerland in 1908. A small avalanche stopped a few meters in front of the building, however, the building was destroyed, the roof was carried away to the opposite slope of the valley, and 12 people sitting at a table facing the avalanche were suffocated by a sharp change in air pressure.

Scientific research into avalanches began in the Alps. In 1881, the first book about avalanches by I. Koatz, “Avalanches of the Swiss Alps,” was published. In 1932 In Switzerland, the Avalanche Commission was created to develop a research program on snow and avalanches. This was necessary to protect against avalanches from the growing railway network that covered almost the entire Alps. A small research group led by Professor R. Hefeli began a comprehensive study of avalanche problems in the Weißflujoch area, located above Davos. In 1938, the professor’s book “Snow and Its Metamorphisms” was published, summing up the results of the first stage of work. On the site of a wooden hut on Weißflujoch, at an altitude of 2,700 m above sea level, the Swiss Snow and Avalanche Institute was built - now the world's leading center for avalanche research.

Then, in the 30s, great interest in avalanches was shown in the Caucasus, where the design of trans-Caucasian roads began, and in the Khibiny Mountains, where rich apatite deposits began to be developed in 1936. A special anti-avalanche service was created at the Apatit plant. Already then, such difficult problems as calculating the stability of snow on a slope, the theory of avalanche movement, and the design of avalanche structures were being studied. In the post-war years, extensive research on avalanches began in the mountains of Central Asia and the Caucasus, the Carpathians and Siberia. A great contribution was made by the work of the Institute of Geophysics of the Academy of Sciences of Georgia and the High Mountain Geophysical Institute in Nalchik, gentle avalanches of MSU mudflows. MSU expeditions studied avalanches on the route of the future BAM from 1946 to 1975.

Currently, avalanche research is carried out mainly by the hydrometeorological service. Snow avalanche stations are especially important, the tasks of which include meteorological observations, regular measurements of the thickness, density and physical and mechanical properties of snow, and recording of avalanches. At such stations, laboratory studies of snow are carried out, descriptions of avalanches on selected routes, and avalanche forecasts are given based on local signs and local connections with meteorological indicators. Snow avalanche stations transmit avalanche danger bulletins to all interested institutions every few days. Such stations now exist in almost all mountain ranges.

In recent years, avalanche schools have become increasingly popular. Their task is to introduce the violent nature of avalanches, teach the rules of behavior in avalanche-prone areas, and convey the experience of predicting and preventing avalanches.

The newspaper "Avalanches" is published in the USA. It publishes information about avalanche conditions, avalanche research, experience in preventing and combating them, advertises new devices and equipment, and talks about avalanche workers and their work. It also reports on classes at avalanche schools, of which there are about 20 in the USA and Canada, and on seminars and symposiums on avalanche topics.

In Russia, scientific and practical seminars are also held in half of the world. However, regularly operating avalanche schools have not yet been created.

The disappointing statistics of the catastrophic consequences of avalanches puts the task of avalanche prevention and protection in the first place. Back in the 15th century. in the Alps they shot from firearms in order to cause snow to fall with the sound of the shot. Now shelling avalanche-prone slopes is the most common way to combat avalanches. In many places, permanent “firing” positions have been established. They use field and anti-aircraft guns, mortars and howitzers. Through artificial shelling, it is possible to cause smaller avalanches: “a runaway cone is piled up below, now a hundred-thousand-ton mass of avalanche snow is no longer threatening to anyone. On a kilometer-long slope, the chutes and couloirs are empty, the soil turns black, bare stones - all the snow has been torn down: an ugly, but dear to the heart of an avalanche hunter. We have our own ideas about the beauty of a bare slope: and a pile of avalanche cone - This is truly frozen music! "(5)

Artillery systems for firing avalanches must be lightweight, mobile, provide high accuracy and have a range of 2-3 km, a powerful projectile with a small number of fragments, and special reliability. Unfortunately, there are cases when shells fly to the opposite slope and up to 1% of fired shells do not explode. All this limits the use of anti-avalanche artillery.

Sometimes shelling can play a fatal role in catastrophic avalanches. This happened in the Swiss town of Zuots in 1951. The slopes were overloaded with snow and a fatal decision was made - to shell the surrounding mountains. The first shots caused the snow to move, and soon a terrible avalanche descended. She swept away an artillery position and 32 houses in the town.

The dangerous method of cutting snow with skis is still practiced, but there are many known cases when an avalanche carried away a skier, not always leaving him alive. Sometimes mines are laid in advance in the nucleation zones, exploding them at the right moment by radio. In Kyrgyzstan, a powerful charge was placed at the foot, so that the blast wave spreads up the slope and releases unstable snow. Recently, mass avalanche discharges using shock waves produced by low-flying supersonic aircraft have begun to be used.

Snow cover on a slope can be secured using snow-retaining shields, fences, and nets. In Switzerland, over the last hundred years, hundreds of kilometers of such structures have been installed. In blizzard-covered areas, high multi-row fences are installed that prevent the formation of dangerous accumulations of snow near snow cornices. In avalanche hotspots, special snow-blowing shields are placed - kolktofeli (two shields placed perpendicular to each other). The blowing wind blows them, forming blowing funnels around them. Such uneven snow cover seems much more durable. To prevent movement of the snow layer, flexible metal meshes are stretched over the slope.

In the middle part of the slope on the path of an avalanche it is necessary to build powerful structures: wedges, mounds, and over-cuts. Their task is to reduce the speed of the avalanche, break it into pieces and slow it down. And to stop the avalanche, dams are built. They are placed at the exit of an avalanche, when its energy is no longer enough to overcome an obstacle. Sometimes a dam is placed so that it does not stop the avalanche, but deflects it, changing the path of the avalanche. To protect the mast of power line supports, avalanche cutters are used - wedge-shaped structures that cut through the rushing snow, forcing it to flow around structures. In Davos there is a church built back in the 16th century. In 1602, it was demolished by an avalanche, but, having been restored, it was no longer destroyed, although it was not covered almost to the roof by avalanche snow. The shape of the back wall, built like a wedge towards the avalanche ravine, helped.

Roads in the mountains are laid so that they avoid avalanche-dangerous slopes whenever possible. Sometimes it is necessary to pave a road along a slope, protecting it with the help of an avalanche pass - a concrete chute that directs the avalanche over the road or with the help of a gallery that covers the road from the avalanche. (Fig. 5, 6)

Forests play a huge role in preventing avalanches. Where a continuous forest grows, consisting of different types of trees of unequal age, it prevents avalanches from forming. The snow cover in the forest creates a continuous layer, and if the snow begins to slide down the slope, its pressure is absorbed by the tree trunks. They bend, but hold onto the snow and do not allow it to begin dangerous movement. The forest is absolutely reliable when its upper boundary rises to the avalanche zone. If it is destroyed by an avalanche, burned by a forest fire, or cut down by people, it takes decades to restore it. And during this period, there are many snowy winters, and then avalanches go where the forests previously did not allow them. Forestation in the mountains is extremely difficult. Avalanches often occur in treeless areas, and seedlings must be protected in order to grow, protecting plantings with earthen banks and dams, wooden and metal fences, poles and overdoubles. This is difficult and expensive, but still much cheaper than the construction of stationary avalanche structures. Forest protection is natural, rational and reliable.

“An avalanche is safe only when it is dead, that is, lowered down.” (5) Avalanche danger awaits a person on a variety of slopes. In the mountains, you need to carefully choose a route, avoid known dangerous slopes. In an avalanche zone, you need to be attentive to all extraneous sounds and movements: “an avalanche behaves honestly for the only time in its life: before it breaks, it makes a guttural sound: “thump!” wow! ", leaving a few stunningly fleeting seconds for reflection. If you find yourself on the slope alone, scramble to the side with all the speed available to you..." (5) Sad events associated with avalanches usually arise from the fact that people forget or ignore the simplest rules of behavior in the mountains, naively believing that nothing bad can happen to them. “What avalanches really can’t stand are reckless people who forget about everything in the world at the sight of a snow-covered slope; however, except for good snowfall, they love no one and nothing at all” (5).

Once in an avalanche, a person has almost no chance of getting out of it while moving, and very soon finds himself buried in avalanche snow. An avalanche kills its victim using cold, shock, and suffocation. Most often, suffocation occurs: while moving in an avalanche, snow dust clogs the nostrils and throat, and sometimes even penetrates the lungs; after the avalanche stops, the hardening snow compresses the chest and impairs breathing; a dense avalanche rubble is almost not ventilated, and there is very soon a lack of air for breathing; finally, even if a person in the rubble has some space, soon an icy crust appears on the inside of the snow resting cavity, finally clogging the victim. Finding himself in the snow, a person is deprived of the opportunity to announce himself by shouting. The sounds coming from the snow do not come up. The immured victim hears the sounds of the rescuers’ steps and everything that is happening on the surface of the snow, but cannot communicate anything to himself.

Starting from the 13th century, dogs began to be used in searches, even a special breed of St. Bernards was bred, trained to work in the rubble of avalanche snow. A well-trained dog can examine a 1-hectare area of ​​rubble in just half an hour. It easily finds prey at a depth of 2-3 m, and under favorable conditions even at a depth of 5-6 m. The use of dogs is very difficult in wet and contaminated snow, in severe frost and strong winds. In the Alps, avalanche dogs are trained in special schools. They participated in 305 rescue operations and found 269 people, but only 45 of them were able to be brought back to life, in other cases it was too late.

The main thing in search and rescue is efficiency. During the first hour of being in an avalanche, a person retains a 50% chance of surviving, and after three hours it does not exceed 10%. When there are no dogs, searches are carried out using an avalanche probe. A 1-hectare area of ​​the dam is inspected by 20 rescuers in 4 hours. If sounding is not successful, and it is known that the avalanche buried people in this area, they begin to dig longitudinal trenches in the rubble - one from the other at a distance of the length of the avalanche probe. This is labor-intensive and ineffective work. Receiving and transmitting devices are used: if someone caught in an avalanche has a miniature transmitter, it can be easily found from the surface. The long-standing traditional method of marking those in trouble is avalanche cords 30-40 m long, painted in bright colors. They are attached to the handle of a ski pole, and when a person falls into an avalanche, they unravel and may end up on the surface of the avalanche. Such a happy outcome does not always happen.

Today, the search for avalanche victims remains a serious problem, and therefore it is still important to provide advance warning of avalanche danger using all modern media.

In conclusion, I would like to cite two stories of famous avalanche climbers M. Otwater and M. Zdarsky, who themselves were in an avalanche and remained alive after that.

M. Otwater, American avalanche expert: “... It was an avalanche made of a soft snow board, and, consequently, the entire slope became unstable. I found myself as a sliver of wood floating in a stream of snow... I was immersed knee-deep in boiling snow, then waist-deep, then neck-deep...

Very quickly and suddenly, I was flipped forward twice, like a pair of trousers in a clothes dryer... The avalanche took my skis off and thereby saved my life, giving up the lever with which it could have twisted me...

I traveled all this way under the snow... Instead of the shine of the sun and snow, which are never as bright as immediately after a snowfall, there was complete darkness in the avalanche - foaming, twisting, and in it it was as if millions of hands were fighting with me. I began to lose consciousness, the darkness came from within.

Suddenly I found myself on the surface, in the rays of the sun. Having spat out a snow gag from my mouth and taking a deep breath, I thought: “This is why those killed in an avalanche always have their mouths full of snow!” You fight like the devil, your mouth is wide open to take in more air, and the avalanche fills it with snow.

When I was next thrown to the surface, I managed to take two breaths. So it happened several times: up, take breaths, swim to the shore - and down, covered in snow, spinning into a ball. It seemed to drag on for a long time, and I began to lose consciousness again. Then I felt that the snowfall was slowing down and becoming more dense. Instinctively or in the last flicker of consciousness, I made a desperate effort and the avalanche spat me out onto the surface like a cherry pit."

Matthias Zdarsky once fell into an avalanche. Here is the description he left: “At that moment... the roar of an avalanche was heard; shouting loudly to his companions, who had taken refuge under a rocky wall: “Avalanche! Stay there!" - I ran to the edge of the avalanche lair, but before I could make three jumps, something blocked the sun: like a giant sling, about 60-100 meters across, a black and white spotted monster was descending on me from the western wall. I was dragged into the abyss... It seemed to me that I was deprived of arms and legs, like a mythical mermaid; finally, I felt a strong blow to the lower back. The snow pressed on me more and more, my mouth was filled with ice, my eyes seemed to be coming out of their sockets, blood threatened to spurt out of my pores. It felt like my insides were being pulled out. like an avalanche cord. I had only one desire - to quickly go to a better world. But the avalanche slowed down, the pressure continued to increase, my ribs cracked, my neck turned to the side, and I already thought: “It’s all over!” But another avalanche suddenly fell and broke it into pieces with a distinct “Damn.” with you!" the avalanche spat me out."

Zdarsky had eighty fractures - he not only survived, but also

eleven years later I started skiing again!

A little history of avalanches.

What are avalanches and what types of them are there?

Causes of occurrence.

The way she moves.

What can it do?

Avalanche Research.

Methods of combating avalanches.

Why is it dangerous for humans?

Ways to save people.

Two eyewitness accounts.

List of used literature:

Kotlyakov V.M. World of snow and ice. M.: Nauka, 1994

Obruchev V.A. Entertaining geology M.: publishing house of the USSR Academy of Sciences, 1961

Encyclopedia for children: GEOGRAPHY. M.: Avanta+, 1997

Encyclopedia for children: GEOLOGY.M.: Avanta+, 1995

SaninV. White curse.

A slope of 15-20 degrees can be considered avalanche dangerous, with a snow thickness of about 40 cm. There are cases of avalanches from flatter slopes of 10-15 degrees.
The greatest danger of avalanches occurs when the snow thickness is 50-70 cm and the slope steepness is 25-50 degrees.

According to the shape of the start of movement Avalanches can be divided into two types:
1. Avalanches from the point - dry and wet.
2. Avalanches from the line are “snow boards”.
Dry Avalanches usually occur due to little adhesion between recently fallen or transported snow and the dense icy crust covering the slope. Most often, dry avalanches occur in conditions low temperatures when the density of freshly fallen snow is less than 100 kg/sq.m. and more. In this case, the density of the snow mass can reach 150 kg/cub.m.

Wet Avalanches occur in unstable weather against the backdrop of thaws and rains. The cause of wet avalanches is the appearance of a layer of water between layers of snow with different densities. Wet avalanches are significantly inferior in speed to dry ones, not exceeding 50 km/h, but in terms of the density of the snow mass, sometimes reaching 800 kg/cub.m., they are ahead of other types of avalanches. Distinctive feature Wet type avalanches have a rapid setting when stopping, which often makes rescue efforts difficult to carry out.

"Snow boards"- These are avalanches, the mechanism of which originates when particles of the surface layer of snow freeze. Under the influence of the sun, wind and heat, an ice crust forms, under which the snow recrystallizes. Over the resulting loose mass, reminiscent of cereals, a denser and heavier layer easily slides down when the layer is separated from the mass, it carries with it more and more snow mass: The speed of “snow boards” can reach 200 km/h, just like dry avalanches .

The possibility of “snow boards” falling off is characterized by the multi-layered nature of the snow mass - alternating dense and loose layers. The likelihood of their disappearance increases with a sharp cold snap accompanied by snowfall. A slight layer of snow is enough for separation to occur. The cold causes additional stress in the upper layer and, together with the weight of the fallen snow, tears off the “snow board”. At the point of separation, snow boards can be from 10-15 cm to 2 meters or more in height.

During their movement, avalanches can change from one type to another or form a combination of different types of avalanches, due to different densities, humidity and temperatures of the oncoming snow masses.

By nature of movement Avalanches are divided into:

Osovy- snow slides descending over the entire surface of the slope.
Jumping- avalanches falling from ledges and shelves.
Tray- avalanches passing through chutes, couloirs and weathering zones of rocks in the form of furrows.

Degree of danger Snow depth Characteristics of avalanche danger

I 15-30 cm Danger appears on the slope of St. 30°

II 30-50 cm Significant danger

III 50-70 cm High avalanche danger

IV 70-100 cm Very large already on the slope of St. 20°

V 120 cm Catastrophic position

Types of avalanches

Osov- snow that has slid along a wide front outside a strictly fixed channel.
When the fall occurs, snow masses detach and slide down the slope, but the underlying snow retards the movement of the sliding masses and they stop before reaching the bottom of the valley.
Typically, the height of snow sliding during snow fall is several times less than the width of its front and sometimes reaches several tens of meters; the speed of snow movement is low.
It is believed that such movement of snow does not pose a particular danger. This doesn't hit the mark once in a while. For example, the famous mountain guide Sepp Kurz died on February 10, 1951 near his home in a snow slide, the length and width of which were 6 and 4 meters, and the thickness of the snow cover was only 24 centimeters.

Trough avalanche

In the case of concentration of moving snow in drainage channels (along strictly fixed channels), the speed of movement increases significantly. The movement of snow takes the form of a current. An avalanche cone forms at the foot of the slope.

Jumping avalanche.

If the drainage channel along which the snow moves has steep sections, then the movement of snow masses during free fall acquires enormous speed. Avalanches of loose fluffy fresh snow that falls in frosty weather can reach speeds of up to 250-300 km/h. Most often, they arise from loose fluffy snow directly during a snowfall or immediately after it.
Even more dangerous are the air waves that arise from the movement of jumping avalanches. Soon after the start of movement, avalanches appear as a cloud of tiny snow dust. Such avalanches do not leave avalanche cones.
If someone falls into such an avalanche at the initial stage, then it does not pose a danger to him, because the snow flows lightly around your feet. But in the middle and further parts there is a threat not only of suffocation by snow dust, but also of being thrown down.
The direct front of the shock wave breaks everything and throws it down. Such avalanches have great destructive power; the pressure can reach 9000 kg/m2. This is enough to break pine trunks like matches.
As an example, I will give a description of the consequences of an avalanche at st. Dallas (Austria) in 1954. An air wave from an avalanche of dry snow threw a railway car weighing 42 tons through the air, and lifted a 120-ton electric locomotive off the rails and hit it into the station building.

Snow board- During the day, in the sun, the top layer of snow heats up and melts, and at night it freezes, turning into a dense, hard crust. The lower layers, compacted under their own weight, sag, and an air cavity is created between it and the crust. The dense crust, not fastened to the bottom layer of snow and as if hanging in the air, is a snow board.
It is very fragile, sometimes a slight external influence is enough for it to break off and an avalanche to begin.
Avalanches from snow boards usually occur during periods of sharp cold weather, hairdryers, and snowfalls, when the latter significantly overload the slope.

Signs of avalanche danger

The surest sign of avalanche danger is the presence of avalanche cones. Most avalanches occur year after year in the same places, and if you see a cone, the avalanche has passed and will pass here more than once.
During their movement, avalanches destroy all vegetation, so dense Pine forest on a slope is a sure sign of the absence of avalanche danger, and vice versa, vertical clearings in forests are a sure sign of an avalanche. Only slopes on which stones or rock outcrops protrude from under the snow, and below there are thickets of bushes that prevent sliding until the snowfall completely covers them, can be considered relatively safe.
A sure sign is heavy snowfall. The degree of avalanche danger gradually decreases during the day after a snowfall, depending on the thickness of the fallen snow cover.
The weakest point of the snow cover on the slope is in its upper part, so spontaneous avalanches begin from here.
Leeward slopes where large masses of snow have accumulated.
Valleys shaped like gorges are very dangerous. Deep ravines filled with snow.
When approaching the highlands, the choice of movement depends on the nature of the valley.
When moving along wide trough-shaped glacial valleys, you should stick to the middle (but avalanches and exposure to air waves are possible from the slopes)

Precautionary measures.

After a snowfall, you should wait a day for the snow to settle
The safest slopes are irregularly shaped or covered with forest.
The sun's heat, which causes snow to melt, can cause an avalanche, so you should walk in shaded areas before noon, avoiding sunlit areas.
In the afternoon, stick to slopes that have previously been exposed to the sun and avoid areas that are new to the sun's rays.
Avoid small ravines, ravines and valleys with steep slopes.
Walk along mountain ridges and hills above avalanche paths. In this case, however, the likelihood that you will provoke an avalanche increases, but in this case there is a good chance of remaining on the surface of the snow masses or not being carried down by them at all. Always be aware of the possibility of an avalanche, even if you have never witnessed one yourself. Try to determine where the avalanches started, their direction, and how long ago they occurred. This will indicate the places where you can expect them to converge.
By choosing a path at the very top of an avalanche slope (above the line of maximum stress of the snow layer), you can trigger an avalanche of loose snow. However, given the small size of the snow masses located above and the fact that the avalanche will gain its strength only on the section of the slope located below, such an avalanche will not pose a serious danger.
If closer to the lower part, when moving on the snow, its natural support is destroyed (the slope is cut), then first some minor (10-15 cm) movements of the snow occur, instantly setting the higher-lying masses of snow into motion.
Slopes with snow board. The crust can be so strong that there are almost no traces left on it, not only from boots but also from the edges of skis, and when moving on it there is no movement of snow. But, if the crust is damaged in the upper part of the board (in the tension zone), this can instantly lead to the formation of longitudinal cracks in the overstressed layer and the formation of an avalanche. The same thing will happen if you overload the board with your weight. In the lower part of the board (compression zone), the same actions do not lead to the formation of avalanches.
In an avalanche zone, the ascent must take place along prominent relief forms. Under no circumstances should you climb up depressions (gullies, couloirs). If there is no other way, climbing through snow should be done head-on, regardless of snow conditions. If there are rocky outcrops on the slope or large forms of ice protruding from under the snow, movement is carried out under their protection. On a ski trip, the track along an avalanche-prone slope is laid at a slope of 8-12 degrees.

Rules for overcoming avalanche areas.
Firstly think over and choose the safest route through avalanche-prone areas.
Secondly– prepare for the worst, put on a sweater and a windbreaker, cover your face with a scarf or windproof mask, raise the hood, fasten the collars and cuffs of your windbreaker tightly, put on mittens. The straps of the backpack must be moved so that it can be quickly thrown off the shoulders. Ski bindings loosen or unfasten, the hands are removed from the lanyards of the ski poles.
Third. If there are people in the movement area, take and tie an avalanche cord.

When an avalanche begins to move
Try to escape, leave, if this cannot be done (in case of small avalanches), you can take the avalanche upon yourself if you are near the separation zone. Sticking an ice ax, ski poles or removed skis deep into the dense snow, secure yourself in place to let the moving stream pass.
Caught in an avalanche
Immediately get rid of ski poles, backpack, skis, because all these objects will play the role of a kind of anchor and pull you upside down into the snow.
Once caught in an avalanche, you need to try with all your might to stay on the surface and try to rake to its edge, where the snow moves much slower. Swimming movements along the flow of snow flow to a certain extent prevent a person from being sucked into an avalanche.
If you can’t get out, then you need to group yourself, pulling your knees to your stomach and protecting your face from the snow with clenched fists, while simultaneously creating a void near your face, allowing you to breathe freely.
When stopping an avalanche, determine your position (where is up and where is down) Collect saliva and let it flow out of your mouth, this will allow you to find out where is down, and begin to move in the opposite direction if possible.. Keep your spirit and air calm.
Do not consider your situation hopeless, do not lose confidence in your position, under no circumstances should you sleep. You must fight sleep with all your might.
A person caught in an avalanche can only scream when he hears the voices and footsteps of the search participants above him. Since the sound from the depths of the snow layer is heard only in the immediate vicinity of the source
With all types of avalanches made of dry snow, and especially with avalanches made of fluffy snow, snow dust gets into the mouth, nose, eyes, ears and suffocates a person, even if the snow that covers him is only 15-20 cm thick (the importance of protecting the mouth and nose scarf). Warm clothes protect against freezing.
When stopping an avalanche, immediately try to gain as much space as possible from the snow. To do this, try to move your arms, head, and legs. Push the snow, then determine where is up and where is down
For an avalanche to move, the snow becomes very hot and freezes very quickly when it stops, so don’t waste time, catch your breath and start getting out without wasting time. It is not at all necessary that you will be covered with many meters of snow; it is possible that you are very close to the surface, but it will be impossible to break through the frozen snow.
When caught in an avalanche of wet and wet snow, it is very important to maintain a snow-free space in front of your face.
Wet snow is a gigantic load of 800 kg/m3. At the moment the avalanche stops in its cone, due to the high pressure of the snow masses, the temperature rises. Formed melt water fill the gaps between the fused snow particles and soon freeze. The resulting “snow cement” cannot be shoveled and is difficult to break with an ice ax.
When caught in an air wave- throw yourself face down into the snow, trying to bury yourself deeper into it and at the same time be sure to close your nose, mouth and ears from the penetration of snow dust. You can hide behind a large rock; trees cannot serve as protection.
Don’t despair, there are known cases where the living were dug up after a few days. However, only a few survived

"Mountaineering Federation Nizhny Novgorod region" Nizhny Novgorod

A snow avalanche is one of the most dangerous natural phenomena that 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 noise, 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 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 there are no negative consequences, because many have frostbitten limbs amputated.

Precursors of an avalanche

The main harbinger is weather conditions. 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.

Most dangerous period An avalanche is considered to occur in 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 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 does not form a snow crust in front of the face, completely blocking the access of oxygen.

We talk in more detail about avalanche control 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

Many dangers await climbers, snowboarders and ski lovers. alpine skiing. But the most inexorable and unpredictable of them are avalanches. What are they? Below is a detailed classification of avalanches.

According to Tushinsky

Back in 1949, Professor Georgy Tushinsky proposed a typology of snow avalanches based on differences in the specifics of movement paths.

The geographer divided the types of snow masses descending from the mountains into:

1. Tray. They move along a strictly fixed vector from glacial trenches, as well as from craters formed as a result of the destruction of rocks.
2. Basics. When a gap forms in a layer of snow and part of the mass slides down a flat slope, on which there are no erosion cuts or furrows.
3. Jumping. On the path of the site there are steep cliffs from which snow slides into free fall.

By the nature of movement and structure of mass

A dust avalanche is formed from dry snow. During the movement, the structure of the mass is destroyed and creates a cloud of snow dust. Avalanche speed of this type can reach 250 km/h. It is the most dangerous and destructive.

The same classification of avalanches established the presence of so-called “snow slabs”. They are formed from a layer of fine-grained dry snow with a density of up to 400 kg per cubic meter, under which there is a less dense snow mass. Hollow areas form under the slabs, which destroy the top layer and provoke its subsidence.

When the imbalance reaches a critical point, a stepped separation line is formed, perpendicular to the surface of the mass, and a collapse occurs over a large area, the speed of which can reach 200 km/h.

There is also an “avalanche from a point”. It is formed from wet snow in the form of a huge drop coming off a rocky outcrop. This occurs due to the heating of the rocks, as a result of which the lower layer of the mass is fed with moisture, becomes heavier and begins to shift. Most snow avalanches of this type can be observed in spring. Their speed does not exceed 120 km/h.

IN summer season Hydropressure avalanches often occur, in which masses move that resemble mudflows in composition: they contain a mixture of stones, water, soil and snow.

Due to the occurrence

Based on this criterion, in 1984 V. Akkuratova proposed the following typology:

• Blizzard avalanches

They are formed from the redistribution of the upper layer due to the transfer of masses during a snowstorm. Wind-blown accumulations of snow grains are deposited in relief depressions. The rate of formation of a snowstorm layer depends on the structure of the relief, as well as on the speed of the snowstorm.

• Advection

They are formed as a result of water seeping into a layer of snow, which causes its structure to be destroyed and the lower layer to thaw and the connections between dense clusters of snowflakes to break.

• Avalanches of dry “young” snow

During intense snowfall, a fresh layer is formed on the surface of the mass, consisting of crystals with a density of no more than 200 kg per 1 cubic meter.

The stability of this structure depends on the strength of adhesion, as well as on the area of ​​contact with the “old” layer and on the rate of accumulation of dry crystals.

• Avalanches caused by metamorphism

Due to the deformation of the structure of ice particles and the connections between them, snow recrystallization occurs, as a result of which loosened layers appear in the upper cover. This leads to an avalanche.

• Insolation

Snow absorbs solar energy, under the influence of which it begins to move. The movement speed is relatively low.

• Mixed

The movement of snow masses occurs due to an increase in air temperature with the simultaneous accumulation of solar energy in the snow.

• Avalanches triggered by snow compression

They are formed as a result of overvoltages arising from an increase in the density of snow masses caused by a strong decrease in air temperature.

Classifications by strength and level of danger

Based on the volume and approximate weight of the moving layer, avalanches can be divided into five types:

1. A disaster that could destroy locality or have a destructive impact on a large forest area (more than 4,000 km²);
2. Sliding of minor accumulations of snow that are not capable of causing harm to humans;
3. An avalanche, which can destroy a forest area of ​​up to 4,000 km² and also cause damage to buildings, vehicles and technology;
4. A slight shift in the snow mass that can harm a person;
5. A medium-sized avalanche capable of breaking trees and damaging cars and buildings.

If we talk directly about the danger of an avalanche for humans, then it is usually assessed on a 5-point scale:

The danger is negligible. There is a minimal chance of snow melting, but in general the surface is dense and stable. The conditions are quite reliable for holding events.

The formation of an avalanche is possible only in critical areas of the relief, subject to additional pressure on the slope by the movement of several athletes along it. In quiet areas, you can load slopes with a steepness of up to 50 degrees. It is advisable not to lay routes through problem areas with an inclination angle of more than 45 degrees.

Medium level of danger. At some points on the slope there is a decrease in density and slight destabilization. On steep terrain there is an increased risk of an avalanche. Spontaneous shift of snow masses is unlikely.

Events are permitted if the organizers take into account the structure of the terrain and the specific conditions at the sites. It is allowed to strain normal slopes with an angle of up to 40 degrees. In areas with problematic terrain, loads at an angle of up to 35 degrees are permissible.

Increased danger. On most slopes, the snow masses are unstable and have a loose structure. The probability of an avalanche is high. The most dangerous points are steep slopes. Several avalanches are expected to occur spontaneously medium strength and single snowfalls of large volumes of snow. Events are allowed, but only if their participants are only experienced athletes who have sufficient knowledge of avalanche science, are familiar with the geography of the region, and do not plan to go to the zones increased danger. Groups of athletes are prohibited on most routes. The permissible load is on slopes forming an angle of up to 35° in normal areas and up to 30° in dangerous areas.

The snow cover is not compacted and unstable in the vast majority of areas. The probability of an avalanche is high even with a slight load on the slope surface. Movement of groups of athletes is prohibited. Only single events are allowed.

Only professional athletes who are well acquainted with the geography of the area, have impeccable knowledge of avalanche science and good intuition, and are ready to return to base at the slightest suspicion, are allowed to enter the route. Loading in normal and potentially hazardous areas is permitted on slopes up to 25° and 20°, respectively.

Catastrophic danger. Snow masses are mobile and unpredictable. Events are strictly prohibited. Large volume avalanches are occurring on all slopes, regardless of the degree of inclination.

Mountains are undoubtedly one of the most beautiful and mesmerizing panoramas on Earth. Many strive to conquer the majestic peaks, not fully realizing how severe such beauty is. That is why, when deciding to take such a courageous step, extreme people face difficulties in all their manifestations.

Mountains represent a rather dangerous and complex terrain, in the vastness of which there is a constant mechanism of gravity, so destroyed rocks move and form plains. Thus, mountains eventually turn into small hills.

There can always be danger in the mountains, so you need to undergo special training and be able to act.

Avalanche detection

Snow avalanches are one of the most devastating and dangerous destructive phenomena of nature.

A snow avalanche is a rapid, sudden, minute-long process of moving snow and ice, occurring under the influence of gravity, the water cycle and many other atmospheric and natural factors. This phenomenon most often occurs in the winter/spring period, much less often in summer/autumn, mainly at high altitudes.

It is always worth remembering that the harbinger of a gathering snow avalanche First of all are weather conditions. Hiking in the mountains in bad weather: snowfall, rain, strong wind- quite dangerous.

Most often, a snow avalanche occurs lasting about a minute, while covering a distance of about 200–300 meters. It is extremely rare to be able to hide or run away from an avalanche and only if it has become known at least 200–300 meters away.

The avalanche mechanism consists of the sloping slope, the avalanche body and gravity.

Sloping slope

The level of slope and the roughness of its surface greatly influence the avalanche danger.

A slope of 45–60° usually does not pose a danger, since during snowfalls it is gradually unloaded. Despite this, such places under certain weather conditions can create avalanche accumulations.

Snow will almost always fall from a slope of 60–65°; in addition, this snow can linger on convex areas, creating dangerous blows.

Slope 90° - the collapse is a real snow avalanche.

Avalanche body

Formed from accumulations of snow during an avalanche, it can crumble, roll, fly, or flow. The type of movement directly depends on the roughness of the lower surface, the type of snow accumulation, and swiftness.

The types of avalanches based on the movement of snow accumulations are divided:

• to streaming;
• cloudy;
• complex.

Gravity

Acts on a body on the surface of the Earth, directed vertically downwards, being the main moving force that promotes the movement of snow accumulations along the slope to the foot.

Factors influencing the occurrence of an avalanche:

• type of matter composition - snow, ice, snow+ice;
• connectivity - loose, monolithic, layered;
• density - dense, medium density, low density;
• temperature - low, medium, high;
• thickness - thin layer, medium, thick.

General classification of avalanches

Avalanches of powdery, dry recent snow

Such an avalanche usually occurs during heavy snowfall or immediately after it.

Powder snow is fresh, light, fluffy snow, consisting of tiny snow flakes and crystals. The strength of snow is determined by the rate of increase in its height, the strength of its connection with the ground or previously fallen snow. It has quite high fluidity, which makes it possible to easily flow around various obstacles. IN different cases can reach speeds of 100–300 km/h.

Avalanches caused by snowstorms

This convergence is the result of snow being transported by a blizzard. Thus, snow is transferred to mountain slopes and negative landforms.

Avalanches of dense dry powder snow

They arise from snow a week or more old, which during this time is compressed and becomes much denser than freshly fallen snow. Such an avalanche moves more slowly, partially turning into a cloud.

Avalanches

They grow after the collapse of snow cornice blocks, which sets a large volume of snow in motion.

Dust avalanches

An avalanche is characterized by a huge cloud or a thick coating of snow on trees and rocks. It is created when dry, powdery recent snow melts. The dust avalanche sometimes reaches speeds of 400 km/h. Risk factors are: snow dust, strong shock wave.

Avalanches are layered

They arise through the melting of sheet snow and reach speeds of 200 km/h. Of all snow avalanches, they are the most dangerous.

Avalanches of hard stratified snow

The flow is formed by the descent of solid layers of snow over a weak, loose layer of snow. They consist predominantly of flat snow blocks resulting from the destruction of dense formations.

Soft formation avalanches

A snow flow is formed by the descent of a soft layer of snow along the underlying surface. This type of avalanche is created from wet, settled dense or moderately bound snow.

Avalanches of monolithic ice and ice-snow formations

At the end of winter, snow deposits remain, which, under the influence external factors become much heavier, turning into firn, which eventually turns into ice.

Firn is snow cemented by frozen water. Formed by changes or temperature fluctuations.

Complex avalanches

Consist of several parts:

• flying cloud of dry snow;
• a dense flow of layered, loose snow.

They occur after a thaw or a sharp cold snap, which is the result of snow accumulation and its separation, thereby forming a complex avalanche. This type of avalanche has catastrophic consequences and can destroy a mountain settlement.

Avalanches are wet

Formed from snow accumulations with the presence bound water. Occur during the period of accumulation of moisture in snow masses, which occurs during precipitation and thaw.

Avalanches are wet

They arise due to the presence of unbound water in snow accumulations. Appear during a thaw with rain and warm wind. They can also occur by sliding of a wet snow layer over the surface of old snow.

Mudflow-like avalanches

They arise from snow formations with a large amount of moisture, the driving mass of which floats in a large volume of unbound water. They are the result of long thaws or rains, as a result of which the snow cover has a large excess of water.

The types of avalanches presented are quite dangerous, rapid flows, so you should not think that some are safer than others. Basic safety rules must always be followed.

Avalanche safety

The term avalanche safety refers to a set of actions aimed at protecting and eliminating the tragic consequences of avalanches.

As practice shows, in most accidents, extreme sports enthusiasts themselves are to blame, who, without calculating their own strengths, themselves violate the integrity and stability of the slopes. Unfortunately, fatalities occur every year.

The main rule for safely crossing mountain ranges is complete knowledge of the territory being traversed, with all the dangers and obstacles, so that in an extreme situation you can calmly and carefully leave the dangerous section of the route.

People going to the mountains need to follow basic avalanche safety rules and know how to use avalanche equipment, otherwise the likelihood of getting caught in a snowfall and dying is very high. The main equipment is avalanche shovels, beepers, avalanche probes, a float backpack, maps, and medical equipment.

Before going to the mountains, it will be useful to take courses on rescue work in case of a collapse, first aid, and making the right decisions to save life. Also an important step is mental training and ways to overcome stress. You can learn this in courses to practice techniques for saving people or yourself.

If a person is a beginner, it will be useful to read books about avalanche safety, which describe different situations, moments, and stages of overcoming them. For a better understanding of avalanches, the best option is personal experience gained in mountain conditions in the presence of an experienced teacher.

Avalanche Safety Basics:

• psychological attitude and preparation;
• mandatory visit to the doctor;
• listening to instructions on avalanche safety;
• taking with you a sufficient amount of food, small in volume, a spare pair of clothes, shoes;
• thorough study of the route and upcoming weather conditions;
• taking a first aid kit, flashlight, compass, equipment on a hike;
• going to the mountains with an experienced leader;
• studying information about avalanches in order to have an idea of ​​the degrees of avalanche safety in case of a landslide.

A list of avalanche equipment that you need to be able to work with confidently, quickly, for your own safety and to save victims:

• tools for searching for victims: transmitter, avalanche ball, beeper, radar, avalanche shovel, avalanche probe, other necessary equipment;
• tools for checking snow flooring: saw, thermometer, snow density meter and others;
• tools for rescuing victims: backpacks with inflatable cushions, avalanche breathing apparatus;
• tools for transporting victims, as well as medical equipment: bags, stretchers, backpacks.

Avalanche slopes: precautions

To avoid getting caught in an avalanche or if there is a high probability of an avalanche situation, you need to know a few important rules on avalanche safety and ways of prevention.

• move on safe slopes;
• do not go into the mountains without a compass, know the basics of wind direction;
• move along elevated places, ridges, which are more stable;
• avoid slopes with snow cornices hanging above them;
• return along the same road that they walked forward;
• monitor the top layer of the slope;
• do tests for the strength of snow cover;
• fasten the belay well and reliably on the slope, otherwise an avalanche can drag a person with it;
• take spare batteries for your phone and flashlight on the road, and also have the numbers of all nearby rescue services in your mobile phone’s memory.

If a group or a certain number of people still find themselves under an avalanche, you need to call rescuers, immediately starting the search yourself. In such a situation, the most necessary tools will be an avalanche probe, beeper, and shovel.

Every person who goes to the mountains should have an avalanche probe. This tool performs the function of probing snow during search work. It is a disassembled rod, two to three meters long. During safety courses, a mandatory item is the assembly of an avalanche probe, so that if an extreme situation arises, it can be assembled in the shortest possible time.

An avalanche shovel is indispensable when searching for victims and is necessary for digging out snow. It is more effective when combined with an avalanche probe.

A beeper is a radio transmitter that can be used to track a person covered in snow.

Only with coordinated, quick actions can a comrade be saved. After thorough avalanche safety instruction, a person will be mentally and physically ready to help others.

In conclusion, I would like to emphasize that hiking in the mountains should not be carried out in bad weather, in the evening or at night; when crossing a dangerous area, you must use rope belay, and be sure to have beepers, flashlights, avalanche shovels and avalanche probes in your arsenal. Some of these tools must necessarily be 3–4 m in length.

By observing all the rules and following the instructions, a person will protect himself from harmful consequences and return home safely.

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Materials from the website www.snowway.ru and other open sources were used.