What is an avalanche and why is it dangerous? Snow avalanche: what is it, causes, dangerous periods, consequences, photos and videos Types of avalanches

According to the nature of the movement and depending on the structure of the avalanche focus, the following three types are distinguished:

- tray,
- wasp,
- jumping.

The trough moves along a specific drain channel or avalanche chute.

Osovaya is a snow landslide that does not have a specific runoff channel and slides across the entire width of the site.

The jumping one arises from the flumes where there are sheer walls or sections with a sharply increasing steepness in the drain channel. Having met a steep ledge, the avalanche breaks off the ground and continues to move through the air in the form of a huge jet. Their speed is especially great.

Depending on the properties of snow, avalanches can be:

- dry,
- wet
- wet.

Dry avalanches are usually caused by a low cohesive force between the recently fallen (or transferred) mass of snow and the underlying ice crust. The speed of dry avalanches is usually 20--70 m / s (up to 125 m / s, which is 450 km / h, some sources limit the speed of such avalanches to 200 km / h with a snow density of 0.02 to 0.3 g / cm. At such speeds, an avalanche from dry snow can be accompanied by the formation of a snow-air wave, producing significant destruction. The pressure of the shock wave can reach values of 800 kg / m². The most likely conditions for the occurrence of this type of avalanches are when the temperature is low.

Wet avalanches occur in spring as a result of an increase in the weight of the snow mass during warm winds (foehns) in the high-mountain zone, during drizzling rains in the upper reaches of snowy valleys, and also during snowfall at zero ambient temperature. Wet avalanches are distributed mainly in the high mountain zone.

Wet avalanches usually occur against the background of unstable weather conditions, the direct cause of their descent is the appearance of a water layer between layers of snow of different densities. Wet avalanches move much slower than dry ones, at a speed of 10–20 m/s (up to 40 m/s), but have a higher density of 0.3–0.4 g/cm3, sometimes up to 0.8 g/cm3] . A higher density causes a quick "grasping" of the snow mass after a stop, which makes it difficult to carry out rescue operations.

According to the nature of the sliding surface, the following types are distinguished:

- reservoir, when the movement is carried out on the surface of the underlying layer of snow;
- unpaved - the movement occurs directly on the surface of the soil.

According to the degree of impact on economic activity and natural environment avalanches are divided into:

- spontaneous (especially dangerous), when their descent causes significant material damage to settlements, sports and sanatorium complexes, railways and roads, power lines, pipelines, industrial and residential buildings,
- dangerous phenomena - avalanches that impede the activities of enterprises and organizations, sports facilities, as well as threatening the population and tourist groups.

According to the degree of repetition, they are divided into two classes

- systematic
- sporadic.

Systematic descend every year or once every 2-3 years. Sporadic - 1-2 times in 100 years. It is rather difficult to determine their place in advance. Many cases are known when, for example, in the Caucasus, villages that existed for 200 and 300 years suddenly found themselves buried under a thick layer of snow.

One of the most terrible avalanches in the history of mankind descended from Mount Huascaran (Peru) about half a century ago: after an earthquake, a huge mass of snow broke off its slopes and rushed down at a speed exceeding three hundred kilometers per hour. On the way, she broke off part of the underlying glacier, and also carried away sand, rubble, and blocks.

A lake also appeared on the path of the snow stream, the water from which, after a huge impact force, splashed out and, adding water to the rushing mass, formed a mudflow. The avalanche stopped only after it covered a distance of seventeen kilometers and completely demolished the village of Ranairka and the city of Yungai, killing about twenty thousand people: only a few hundred local residents managed to escape.

An avalanche is formed by snow, ice and rocks after they begin to slide down steep mountain slopes at an ever-increasing speed (from 20 to 1000 m/s), capturing new portions of snow and ice, increasing their volume. Given that the force of the impact of the elements is often estimated at tens of tons per square meter, an avalanche sweeps everything in its path. It stops only at the bottom, reaching the gentle sections of the slope or being at the bottom of the valley.

Avalanches form only in those parts of the mountain where forests do not grow, the trees of which could slow down and prevent the snow from gaining the required speed.

The snow cover begins to move after the thickness of freshly fallen snow begins to be at least thirty centimeters (or the old layer exceeds seventy), and the steepness of the mountain slope ranges from fifteen to forty-five degrees. If the layer of fresh snow is about half a meter, the probability of snow melting in 10-12 hours is incredibly high.

It is impossible not to mention the role of old snow in the formation of avalanches in the mountains. It forms an underlying surface, which allows freshly fallen precipitation to glide over it unhindered: old snow fills all the unevenness of the soil, bends bushes to the ground, forming a perfectly smooth surface (the larger its layer, the less rough obstacles that can stop snow from falling).

The most dangerous periods when snow falls are considered winter and spring (about 95% of cases are recorded at this time). Snowfall is possible at any time of the day, but more often this event occurs during the day. The occurrence of landslides and snow avalanches is primarily influenced by:

Snowfall or the concentration of a huge amount of snow on mountain slopes;

Weak cohesive force between new snow and underlying surface;

Warming and rain, resulting in a slippery layer between the snowfall and the underlying surface;

Earthquakes;

Sudden change in temperature regime (a sharp cold snap after an unexpected warming, which makes it possible for fresh snow to slide comfortably over the formed ice);

Acoustic, mechanical and wind effects (sometimes a scream or a pop is enough to set the snow in motion).

Sweeping everything out of the way

Freshly fallen snow precipitation is held on the slope due to the friction force, the magnitude of which depends primarily on the angle of the slope and the moisture content of the snow. The collapse begins after the pressure of the snow mass begins to exceed the force of friction, as a result of which the snow comes into a state of unstable equilibrium.

As soon as the avalanche begins its movement, an air pre-avalanche wave is formed, which clears the way for the avalanche, destroying buildings, filling up roads and paths.

Before the snow falls, a dull sound is heard high in the mountains, after which a huge cloud of snow rushes down from the top at high speed, taking with it everything that comes in its way. It rushes without stopping, gradually gaining momentum, and stops no sooner than it reaches the bottom of the valley. After that, a huge layer of snow dust rises high into the sky, forming a continuous fog. When the snow dust descends, dense piles of snow open before your eyes, in the middle of which you can see branches, the remains of trees, and stone blocks.

Why are avalanches dangerous?

According to statistics, it is snowfall that causes fifty percent of accidents in the mountains, and often causes the death of climbers, snowboarders, skiers. An avalanche going down can simply throw a person off the slope, because of which he can break during the fall, or fall asleep with such a thick layer of snow and cause death from cold and lack of oxygen.

A snow fall is dangerous because of its mass, often several hundred tons, and therefore, covering a person, often leads to his suffocation or death from pain shock caused by a broken bone. In order to warn people about the approaching danger, a special commission developed a system for classifying the risks of avalanches, the levels of which are indicated by flags and hung out at ski resorts and resorts:

The first level (minimum) - the snow is stable, so a collapse is possible only as a result of a strong impact on the snow masses on very steep slopes.

The second level (limited) - the snow on most slopes is stable, but in some places it is a little unstable, but, as in the first case, large avalanches will occur only due to a strong impact on the snow masses;

The third level (middle) - on steep slopes, the snow layer is weakly or moderately stable, and therefore an avalanche can form with a slight impact (sometimes an unexpected large snowfall is possible);

Fourth (high) - the snow is unstable on almost all slopes and the avalanche descends even with a very weak impact on the snow masses, while a large number of medium and large unexpected avalanches may occur.

Fifth level (very high) - the probability of a huge number of large collapses and snow avalanches, even on non-steep slopes, is extremely high.

Safety

In order to avoid death and not be buried under a thick layer of snow, every person who is going to the mountains to rest while there is snow there must learn the basic rules of behavior when a deadly stream descends.

If during your stay at the base an avalanche warning was announced, it is advisable to refrain from hiking in the mountains. If there was no warning, then before leaving the base and hitting the road, you need to take into account the forecast of the risk of the probability of snow melting, and also find out as much as possible about the mountains in which the risk of avalanches is maximum and avoid dangerous slopes (this simple rule of behavior is quite capable of saving a life).

If heavy snowfalls were recorded before going out into the mountains, it is better to postpone the trip for two or three days and wait for the snow to fall, and in the absence of avalanches, wait until it settles. It is also very important not to go to the mountains alone or together: it is advisable to stay in a group. This will always provide insurance for an avalanche, for example, if the group members are tied with an avalanche tape, this will make it possible to detect a satellite covered with snow.

Before going out into the mountains, it is advisable to take an avalanche transceiver with you, which will make it possible to find the person caught in the avalanche.

It is very important not to forget to take with you mobile phone(he has already saved the life of more than one person). It’s also a good idea to take special avalanche backpacks, which provide a system of inflatable pillows that make it possible for a person caught in an avalanche to “surface”.

In the mountains, you need to move only along the roads and paved paths of the valleys and along the ridges of the mountains, while it is very important to remember that you cannot go onto steep snow-covered slopes, cross them across or move in a zigzag. It is also forbidden to step on snow ledges, which are accumulations of dense snow in the form of a canopy on the leeward side of a sharp ridge (they may well suddenly collapse and cause an avalanche).

If it is not possible to get around a steep slope, before you overcome it, you need to make sure that the snow cover is stable. If he begins to sag under his feet and at the same time begins to make a hissing sound, you need to go back and look for another way: the likelihood of an avalanche is high.

Trapped in snow

If the avalanche breaks high and there is time to do something, it is very important to remember one of the basic rules of behavior when an avalanche rushes at you: to leave the path of the rushing stream to a safe place, you need to move not down, but horizontally. You can also hide behind a ledge, preferably in a cave, or climb onto a rise, a stable rock, or a sturdy tree.

In no case should you hide behind young trees, as the snow can break them.

If it so happened that you couldn’t get away from the avalanche, one of the rules of conduct says that you need to immediately get rid of all the things that will drag you into the rushing stream and hinder movement: from a backpack, skis, sticks, ice ax. It is necessary to immediately begin to sharply make your way to the edge of the stream, doing everything possible to stay at the top, and if possible, catch on a tree, stone, bush.

If the snow is still covered with the head, then the nose and mouth must be covered with a scarf or hat so that snow does not get there. Then you need to group: turning in the direction of the snow flow, take a horizontal position and pull your knees to your stomach. After that, with circular rotations of the head, do not forget to form as much free space as possible in front of the face.

As soon as the avalanche stops, you need to try to get out on your own or at least push your hand up so that the rescuers notice it. It is useless to scream, being under the snow cover, since the sound is transmitted very weakly, therefore, such efforts only weaken the forces (it is necessary to give sound signals only when the steps of the rescuers are heard).

It is important not to forget the rules of behavior under the snow: you need to remain calm and in no case panic (screams and senseless movements will deprive you of strength, heat and oxygen). Do not forget to move, otherwise a person sandwiched in the thickness of the snow will simply freeze, for the same reason you need to do everything not to fall asleep. The main thing is to believe: there are cases when living people were found under the snow cover even on the thirteenth day.

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

A brief excursion into history

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

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

What is an avalanche? Etymology of the word

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

What is an avalanche

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

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

Factors affecting the convergence of snow masses from the mountains

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

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

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

In general, more frequent snow avalanches indirectly or directly related to the violent economic activity a person who is not always intelligent. For example, forests that have been cut down today used to serve as natural protection against snow landslides.

Periodicity

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

Movement, the focus of a natural phenomenon

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

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

scale

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

snow properties

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

Volumes

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

Can avalanches be predicted?

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

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

All about avalanches: interesting facts

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

"It seemed that the cold inherent in the snow was supposed to inform him of the numbness of winter, and the whiteness of the stillness 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, a dull sound is heard somewhere above, and then the silent mountains seem to come to life. A huge cloud of snow rushes down the slope, sparkling with millions of snowflakes. Here it reached the bottom of the valley, spread over it, snow dust rose high, and everything disappeared like in a fog ... After a while, the snow dust subsided, but the bottom the valleys were covered with shapeless piles of snow, so dense that they looked like kuskilda with branches sticking out, fragments of tree trunks, stones. (3) Like all the elemental forces of the Earth, the sight is beautiful and terrible.

Two of the world's greatest "avalanche" disasters in our century occurred in Peru in the Santa Valley. January 10, 1962 at the top of Huascarana, a huge snow cornice, about 1 km wide and more than 30 m thick, broke off. "A mass of snow and ice with a volume of approximately 3 million m3 rushed down at a speed of 150 km / h, dragging blocks of stone, sand, rubble with it. A huge shaft grew with lightning speed, and within minutes a mass of at least 10 million m3 was moving along a steep valley, crushing everything in its path. After 7 minutes, the avalanche reached the town of Ranairka and swept its face of the Earth. Only after 16 km, descending 4 km and spreading along a wide valley for 1.5 km, it stopped, damming the river.

After 8 years, a similar event was repeated, but only on an even larger scale. May 31, 1970. Cordillera Blanca, where the top of Huascaran is located, there was a strong earthquake that blew off at least 5 million m3 of snow and ice from the slopes. Along the way, the avalanche brought down a small lake, which gave the whole mass even greater strength. A huge amount of snow, ice and rock was rushing along the valley at a speed of 320 km / h - 50 million m3! The avalanche overcame an obstacle 140 m high, again destroyed the newly built village of Ranairka and the city of Yungay, which in 1963 saved a low hill. Masses of snow, water and stones passed almost 17 km. The consequences were terrible: out of 20,000 inhabitants, only a few hundred people survived.

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

Avalanches interested a person only when they began to interfere with him, that is, when a person began to inhabit the mountains. At the same time, avalanches became interested in a person - the so-called unhealthy interest. to solitude and therefore met with hostility its violators: what else can you expect from a bear sleeping peacefully in a den, which people woke up with a whistle and hooting? (5)

Information about snow avalanches came from ancient times. In 218 BC. they caused a lot of trouble to the troops of the Carthaginian commander Hannibal, who was crossing the Alps. Then, under the avalanches, many people and animals died - every fifth foot warrior (60 thousand people), every second horseman (6 thousand), and 36 of the 37 elephants that participated in this transition.

In addition, the history of the crossing of the Alps by the army of Suvorov in 1799 is known. And here the 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 under avalanches - more than as a result of military operations. Only for one "black Thursday" on December 16, 1916, more than 6 thousand soldiers fell asleep in avalanches.

The losses of peacetime are immeasurably smaller, but they are palpable.

Nowadays, the Alps, "populated by people like bees" (5), are especially affected by avalanches. in the Swiss Alps, 1244 people died from avalanches. In total, there are 20 thousand avalanche sites in the Alps, of which more than 10 thousand are permanent descent sites, and 3 thousand of them threaten settlements, roads, power lines.

Avalanches are raging in both Americas, breaking down from the peaks of the Tien Shan, scandals in the Khibiny, Siberia, Kamchatka and in general in all mountainous regions. (5)

"Ina Kavkazelavins lie in wait for travelers and take many sacrifices," Strabo wrote in his "Geography" 2000 years ago. During the Great Patriotic War in the winter of 42/43, special units of military climbers caused avalanches artificially, thus destroying enemies.

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

An avalanche is an avalanche that has come into motion on a slope of a mass of snow. Avalanches are the most unpretentious creatures: in order to call them to life, you need only the snow of a dagor with suitable slopes. Snow for avalanches is manna from heaven, the only source of food. avalanche, at the very top, in order to then choose the right moment, rush with terrible speed along tray down and form at the place of descent avalanche cone sometimes with a power of several tens of meters. "(5).

The fluffy snow cover in the mountains only looks harmless from a distance. Austrian researcher Matthias Zdagarsky said about this: "Innocent-looking white snow is a non-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 down gradually, but on steeper slopes it does not linger. avalanche flume- a chute on a slope along which avalanches descend (as a rule, they descend along the same path).

The section of the mountain slope and bottom of the valley on which an avalanche forms, moves and stops is called avalanche collection.At the top is avalanche focus- the place of origin, and below - the channels outrigger 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 turbulent stream, sweeping away everything in its path. In the transit zone, it rushes down the slope, increasing its mass, breaking bushes and trees. In the deposition zone, snow cones with a thickness of 5 to 30 m, and sometimes more, are formed. In the winter of 1910/11 the avalanche of the Bzyken Caucasus ridge left the gorge of the river. A white dam 100 m thick. Snow has been melting in it for several years.

Most catastrophic avalanches occurred after many days of heavy snowfalls 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 unbound loose, like sand. Such snow easily generates avalanches. Avalanche danger increases many times over when snowfalls are accompanied by wind. With 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 break in the winter after a heavy snowfall without a thaw, when snow blows on ridges and steep slopes reach such a size that the shaking of the air from a blast of wind, a shot, even a loud cry The latter is greatly facilitated if fresh snow falls on a 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 snowfall, the snow gradually "ripens" to give rise to avalanches. Over time, the snow mass gradually settles, which leads to its compaction. The sources of avalanche danger are weakened layers in which loosely bound deep frost crystals form. It corrodes the lower layer of the snow cover, suspending the upper layer.

The state of the snow cover changes dramatically when water appears in it, which significantly weakens the strength of the snow. With a sharp melting or intense rain, the structure of the thickness is quickly destroyed, and then grandiose "wet" avalanches form. They descend in the spring over vast 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 comes into motion under the influence of gravity. For a long time, the forces of resistance to shear (the adhesion of snow to its lower layers or soil and the force of friction) hold the snow on the slope. In addition, the snow cover located below prevents the formation from moving and keeps the one that lies above. Snowfall or a snowstorm, recrystallization of the snow mass, the appearance of liquid water in the thickness leads to a redistribution of the forces acting on the snow.

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

For an avalanche to move from its place, it needs a first impulse. Such a trigger mechanism is heavy snowfalls or heavy snowstorms, warming, warm rain, snow cutting by skis, vibration from a sound or shock wave, earthquakes.

Avalanches start their movement either "from a point" (when stability of a very small volume of snow is disturbed), or "from a line" (when stability of a significant layer of snow is disturbed at once) (Fig. 2). The looser the snow, the less it needs to start an avalanche. The movement begins literally with a few particles. An avalanche from a snowboard begins with cracking of the snow cover. A narrow crack grows rapidly, side cracks are born from it, and soon the snow mass breaks off and rushes down.

For a long time, the avalanche was presented in the form of a snowball, which flies down the slope and increases due to the sticking of new portions of snow (this is how almost all ancient engravings depicted the avalanche). Sharomlavina was represented until the 19th century. The variety of snow avalanches and the many forms of their movement made it difficult to understand the physics of avalanches. An avalanche belongs to multicomponent flows, since it consists of snow, air and solid inclusions.

The forms of movement of an avalanche are diverse. Snow pellets can roll in it, snow clods 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, pass one into 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 ahead of the front from the impact of the avalanche. Thus, all new portions of snow are included in the avalanche, while in the tail part the speeds decrease. On the crests of waves that arise on the surface of a moving avalanche, stone fragments appear every now and then, which indicates strong turbulent mixing in the body of the avalanche.

As the slope of the body avalanche flattens out, its movement slows down. The body of the avalanche spreads over the surface of the cone. The snow that stops quickly hardens, but continues to move for some time under the pressure of the tail 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 chips. Concrete buildings do not withstand frontal impact either. If an avalanche cannot destroy a house, it will gouge out doors and windows and fill the ground floor with snow. Lavina spares nothing that she meets on her road. She 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) near Stevens Pass, an avalanche hit a passenger train and blew it to pieces. About 100 people died). She fills the roads with a layer of many meters of dense, like ice, snow. It demolishes many hectares of forest at once, and hundred-year-old trees cannot stand it. (fig.4)

Jumping avalanches have a particularly strong shock effect (if a cliff or a steep bend of a slope is in the way of a snow avalanche, the avalanche "jumps" from it and sweeps through the air for some time). Together with the landing of the avalanche, knockout pits appear. In the New Zealand Alps, in similar basins, 16 lakes with an area of 200 to 50 thousand m 2 were found. All of them are located at the base of steep avalanche flumes.

In order to properly design avalanche structures, it is necessary to measure the impact force. Back in the 30s, in our country, a railway car buffer with a powerful spring was used for this, which was fixed in the path of an avalanche. The magnitude of the compression of the spring upon impact was fixed by a metal rod. In Switzerland, on the way of avalanches, a shield was installed, on the reverse side of which there was a steel pointed rod, and an aluminum plate was fastened opposite it, into which the rod was hit by an avalanche. Data show that avalanche pressures typically range from 5 to 50, although one avalanche in Japan has hit over 300. In the table you can see what kind of destruction the impact of an avalanche of different strengths leads to:

To characterize the 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 covered almost 17 km. The longest range in the former USSR was recorded in the basin of the Kzylcha River in the Tien Shan, the avalanche traveled 6.5 km here. In most cases, in the mountains on the territory 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 with air of very low density, accompanied by a cloud of snow dust. They have great speed and great destructive power. With a slight change in motion in a dust avalanche, shock waves occur, creating a roar 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 by 20 m to the side and then threw them into a ravine.

Quite often, an avalanche of dry snow is accompanied not only by a snow-dust cloud, but also by an air wave, which produces destruction outside the zone of deposition of the main mass of avalanche snow. So, in the Swiss Alps, 1.5 km away from the stopping place of the avalanche, the air wave knocked out the window panes in the houses. And in another place, an air wave moved an 80 m railway car, and a 120-ton electric one threw it over the station building. A particularly tragic incident occurred in Switzerland in 1908. A small avalanche stopped a few meters in front of the hotel, nevertheless the building was destroyed, the roof was blown away from the opposite slope of the valley, and 12 people sitting at the table facing the avalanche were strangled by a sharp drop in air pressure.

Scientific research on avalanches began in the Alps. In 1881, the first book about avalanches by I. Koats "Avalanches of the Swiss Alps" was published. In 1932 The Avalanche Commission was formed in Switzerland to develop a research program for the study of snow and avalanches. This was necessary to protect against the avalanches of the growing network of railways that covered almost the entire Alps. A small research group led by Professor R. Hefeli began a comprehensive development of avalanche problems in the Weißflujoch region, located above Davos. on the site of a wooden hut on Weissflujoch at an altitude of 2700 m above sea level, the building of the Swiss Institute of Snow and Avalanches was built - now it is the world's leading center for avalanche science.

Then, in the 30s, great interest in avalanches was shown in the Caucasus, where the design of transcaucasian roads began, and in the Khibiny, where rich deposits of apatite began to be developed. A special anti-avalanche service was created at the Apatit plant. Uzhetogda issledovalistakie trudnyeproblemy, kakraschet ustoychivostisnega on a slope, dvizheniyalavin theoryruzheniy.V poslevoennyegody shirokieissledovaniyalavin nachalisv SredneyAzii mountains and the Caucasus, the Carpathians and Sibiri.Bolshoy vkladvnesli rabotyInstitutageofiziki ANGruzii and VysokvNalchike, Problemnoylaboratoriisnezhnyh avalanches landslides MGU.EkspeditsiiMGU izuchalilaviny on trassebuduschey BAMS 1946 to 1975

Currently, avalanche research is carried out mainly by the hydrometeorological service. Of particular importance are avalanche stations, whose tasks include meteorological observations, regular measurements of 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 are carried out, avalanche forecasts are given based on local signs and local links with meteorological indicators. Snow avalanche stations transmit avalanche hazard 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 acquaint with the violent nature of snow avalanches, teach the rules of behavior in avalanche-prone areas, and transfer experience in predicting and preventing snow avalanches.

The Avalanches newspaper is published in the USA. It publishes information about the avalanche situation, research on avalanches, experience in preventing and combating them, advertises new instruments and equipment, tells about avalanche operators and their work. It also reports on the classes of avalanche schools, of which there are about 20 in the USA and Canada, on seminars and symposiums on avalanche topics.

In Russia, scientific and practical seminars are also held for half of the provinces. However, regular avalanche schools have not yet been established.

The disappointing statistics of the catastrophic consequences of avalanches puts the task of preventing and protecting against avalanches in the first place. Back in the XV century. in the Alps, firearms were fired to cause snow to fall with the sound of a shot. Now the shelling of avalanche-prone slopes is the most common way to deal with avalanches. In many places, permanent "firing" positions are equipped. Field and anti-aircraft guns, mortars and howitzers are used. By means of artificial shelling, it is possible to cause smaller avalanches: "a cone of removal is piled up below, now a hundred thousand tons of avalanche snow no longer threatening anyone. On a kilometer-long slope, trays and couloirs are empty, the soil turns black, bare stones - all the snow is torn down: an ugly, but sweet heart of an avalanche, a picture. We have our own concepts of beauty: a bare slope - an avalanche cone and a pile this is truly frozen music!" (5)

Artillery systems for firing halves should be light 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 the projectiles fly to the opposite slope and up to 1% of the projectiles fired do not explode. All this limits the use of anti-avalanche artillery.

Sometimes shelling can play a fatal role in the gathering of catastrophic avalanches. This happened in the Swiss town of Zuoz 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 came down. She swept away the artillery position and 32 houses in the town.

The dangerous way of cutting the snow layer with skis is still practiced, but there are many cases when an avalanche dragged a skier along, not always leaving him alive. Sometimes mines are laid in advance in the zones of origin, blowing them up at the right time by radio. In Kyrgyzstan, a powerful charge was placed at the foot, so that the blast wave propagates up the slope and descends unstable snow. Recently, mass discharge of avalanches by shock waves, which are produced by low-flying supersonic aircraft, have begun to be used.

The snow cover on the slope can be fixed with the help of snow-retaining shields, fences, nets. In Switzerland, over the past hundred years, hundreds of kilometers of such structures have been installed. In snowstorm areas, high multi-row fences are installed that prevent the formation of dangerous accumulations of snow near snow eaves. The blowing wind blows them, forming blowing funnels around them. Such an uneven snow cover turns out to be much more durable. To prevent the movement of the snow layer, flexible metal meshes are pulled onto the slope.

In the middle part of the slope on the path of the avalanche, one has to build powerful structures: wedges, mounds, gouges. Their task is to reduce the speed of the avalanche, break it apart and slow it down. And to stop the avalanche, dams are built. They are located at the exit of the avalanche, when its energy is no longer enough to overcome the obstacle. Sometimes the dam is set so that it does not stop the avalanche, but deflects it, changing the path of the avalanche. To protect the mast of the power line towers, avalanche cutters are used - wedge-shaped structures that cut through the rushing snow, forcing it to flow around structures. There is a church in Davos, built back in the 16th century. In 1602, it was demolished by an avalanche, but, restored, it was no longer destroyed, although it was more than once covered with avalanche snow almost up to the roof. The shape of the back wall, built as a wedge in the direction of the avalanche log, helped out.

Roads in the mountains are laid so that they bypass avalanche-prone slopes as far as possible. Sometimes you have to build a road along a slope, protecting it with the help of an avalanche pass - a concrete tray that guides the avalanche over the road or with the help of a gallery that covers the road from the avalanche. (Fig. 5,6)

In the confrontation with avalanches, a huge role belongs to the forest. Where a continuous forest grows, consisting of different species of trees of unequal age, it does not allow avalanches to form. The snow cover in the forest creates a continuous layer, and if the snow begins to slide down the slope, its pressure is assumed by the trunks of the trees. They bend, but hold the snow, do not allow it to start a dangerous movement. The forest is absolutely reliable when its upper limit rises to the zone of avalanche separation. If it is destroyed by an avalanche, burnt down by a forest fire, cut down by people, it takes decades to restore it. 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 ramparts and dams, wooden and metal fences, poles and gouges. This is difficult and expensive, but still much cheaper than the construction of stationary anti-avalanche structures. Forest protection is natural, rational and reliable.

"An avalanche is safe only when it is dead, that is, down."(5) Avalanche danger lies in wait for a person on a variety of slopes. In the mountains, you need to carefully choose a route, bypass 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 breaking off, it makes a uterine sound: “boom! wow! wow! ", leaving you to think for a few stunningly fleeting seconds. If you find yourself on a slope alone, sprint to the side with all the speed you can ... "(5) The 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. “The Kogolavins really can’t stand it, because they are reckless people who forget about everything in the world at the sight of a snow-covered slope; however, apart from a good snowfall, they don’t like anyone at all” (5).

Once in an avalanche, a person has almost no chance to get out of it in the process of movement, and very soon finds himself buried in avalanche snow. An avalanche kills its prey with cold, shock, and suffocation. Most often, it is suffocation that occurs: during movement in an avalanche, snow dust clogs the nostrils and throat, and sometimes even penetrates into the lungs; after the avalanche stops, hardening snow compresses the chest and disturbs breathing; the dense avalanche blockage is almost not ventilated, and air for breathing very soon begins to lack; finally, even if the person in the blockage has some space, soon an icy crust appears on the inside of the snowy resting cavity, finally blocking the victim. Once in the snow, a person is deprived of the opportunity to announce himself by shouting. Sounds coming from the snow do not go up. The immured victim hears the sounds of the steps of the rescuers and everything that is done on the surface of the snow, but cannot tell anything about 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 explore a 1 hectare site in just half an hour. She easily finds a victim 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 polluted 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 managed to be brought back to life, in other cases it was too late.

The main thing in search of salvation is efficiency. During the first hour of being in an avalanche, a person retains a 50% chance of staying alive, and after three hours it does not exceed 10%. When there are no dogs, searches are carried out using an avalanche probe. The site of the dam in 1 hectare is examined by 20 rescuers in 4 hours. If sounding is not successful, and it is known that an avalanche buried people in this area, they begin to dig longitudinal trenches in the obstruction - one from the other at a distance of the length of the avalanche probe. This is laborious and inefficient work. Transmitting and receiving devices are used: if an avalanche person has a miniature transmitter, it is easy to find direction from the surface. They are strengthened in the handle of a ski pole, and when a person gets into an avalanche, they bloom and may end up on the surface of the blockage. Such a happy outcome is not always the case.

Today, the search for avalanche victims remains a serious problem, and therefore it is still important for early warning of an avalanche danger through all modern media.

In conclusion, I would like to cite two stories of famous avalanche pilots M. From water and M. Zdarsky, who themselves visited the avalanche, remaining alive after that.

M. Otwater, American avalanche operator: "... It was an avalanche of soft snow boards, and, consequently, the entire slope became unstable. I turned out to be a chip floating in a stream of snow ... I plunged knee-deep into boiling snow, then waist-deep, then neck-deep ...

Very quickly and suddenly, I was rolled forward twice, like a pair of trousers in a clothes-cleaning drum ... The avalanche took off my skis and thereby saved my life, refusing the lever with which she could twist me ...

I made all this way under the snow ... Instead of the radiance 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 millions of hands seemed to be fighting with me in it. I began to lose consciousness, darkness came from within.

Suddenly, Jasnova was on the surface, in the sun. After spitting the snow gag out of my mouth and taking a deep breath, I thought, "So that's why avalanche victims always have snow in their mouths!"

The next time I was thrown to the surface, I managed to take two breaths. So it was several times: up, take a breath, swim to the shore - and down, covered with snow, twisting into a ball. It seemed to drag on for a long time, and I again began to lose consciousness. Then I felt the snowfall slow down and become denser. Instinctively, or in a last glimpse of consciousness, I made a desperate effort and the avalanche spat me to 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; loudly shouting to his companions, who had taken refuge under a rocky wall:" Avalanche! Stay there!" - I ran to the edge of the avalanche ravine, but did not have time to make even three jumps, as something covered the sun: like a giant sling, about 60-100 meters across, a black-and-white spotted monster descended on me from the western wall. I was dragged into the abyss ... I felt as if my arms were missing like a mythical mermaid, and finally I felt a strong blow in the small of my back. like an avalanche cord. Only one desire I felt was to go to a better world as soon as possible. But the avalanche slowed down its course, the pressure continued to increase, my ribs cracked, my neck twisted to the side, and I already thought: "It's all over!" with you!" the avalanche spat me out."

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

Eleven years later, I started skiing again!

A little history of avalanches.

What are avalanches and what are they.

Causes of occurrence.

How she moves.

What can do.

Avalanche research.

Ways to deal with avalanches.

What is dangerous for a person.

ways to save people.

Two eyewitness accounts.

List of used literature:

Kotlyakov V.M. The world of snow and ice. Moscow: Nauka, 1994

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

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

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

SaninV. White Curse.

It is not difficult to say how avalanches arise: on steep mountain slopes, individual layers of snow or the entire snow cover lose their adhesion to the ground or the underlying layer. Due to the enormous weight of the snow, stress is generated inside the snow mass, leading to cracks; it spreads over them and slides down.

Of course, in reality, the science of avalanches is much more complicated, because snow is not a dead mass, having fallen to the ground from clouds, it is constantly changing. At first, it forms, depending on temperature and wind strength, a relatively light and loose cover. An avalanche can sometimes be set in motion by minor disturbances in the structure of the snow cover.

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

The four most dangerous types of avalanches are:

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

2. Of particular danger are glacial avalanches, which occur, in particular, when the tongue of a glacier breaks off. With their incredible weight, they develop a very high speed. Forces operate in them that can grind even ice, hard as a stone, into powder. Such avalanches have caused many devastating disasters.

3. The term "ground", "soil" and "surface" avalanche designate layers of snow cover that come into motion; soil and soil avalanches slide down the slope and cause its powerful erosion; after the snow melts, the blown material settles at the bottom of the valley. In contrast, surface avalanches slide into the valley on 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 PROVOTING AVALANCHES

It is not difficult to say how avalanches arise: on steep mountain slopes, individual layers of snow or the entire snow cover lose their adhesion to the ground or the underlying layer. Due to the monstrous weight of snow, stress is created inside the snow mass, leading to cracks; it spreads over them and slides down.

However, these days, avalanches are increasingly being triggered by reckless skiers and snowboarders. Thrill-seekers, despite the prohibitions, leave the safe track for unstable slopes, getting special pleasure from skiing on virgin snow untouched by skiing, and this endangers 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 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 ice 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 bakes more strongly with the base, the snow cover again acquires 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 watchers take drill samples in particularly dangerous places - mainly on steep slopes, ridges and slopes heavily indented by troughs and mounds - and carefully study individual layers. Thus, the uniformity and strength of the entire snow cover are determined. The weaker the individual layers are interconnected, the higher the risk of avalanches. The situation is assessed by three factors: the structure of the snow cover, weather conditions(according to the amount of fresh snow, wind strength and direction) and terrain (steepness, shape, underlying material, and which way the slope is facing).

Avalanche development

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

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

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

Dry avalanche

Dry avalanches are composed of loose snow and rush especially rapidly.

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

STONES THROWING DOWN

Avalanches also include rock masses falling down, that is, rockfall, collapse, mudflow.

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

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

The first victims of the avalanche were the military.

The first victims of the avalanche, which are mentioned in history, were warriors. When Hannibal and his army marched north across the Alps in 218 BC, the White Death claimed about 18,000 men, 2,000 horses, and several elephants.

The largest snow disaster of modern times is also related to the military. In December 1916, in the First world war on the Austrian-Italian front, in just two days, about 10,000 soldiers found death under avalanches. After a week of continuous snowfall, both belligerents began to fire artillery on the slopes located above the positions of the enemy. The shots caused a powerful avalanche, which 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 for three years in the highlands, suffering from lack of supplies, cold and snow. One of the soldiers recalled: “Nature was our most terrible enemy ... Entire platoons were knocked down, blown into the abyss, filled up without a trace.” The heaviest was December 1916, when 4 m of snow fell in 48 hours, which led to avalanches that killed about 10,000 who fought on both sides of the front.

In Peru, the May 31, 1979 earthquake and the resulting avalanche killed 66,000 people. The force of the shocks reached 7.7 on the Richter scale, the epicenter was located near the large port and industrial city of Chimbote, and the consequences were the most disastrous in the 20th century. A massive layer of soil and ice broke from Mount Huascaran, which demolished the village of Ranrairca, destroyed 5,000 inhabitants and filled up the mountain resort of Yungay. Nearly all of its 20,000 inhabitants perished here.

DECEIVELY IDYLL

After many days of heavy snowfalls, 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 enormous energy to the snow masses. Even massive defensive structures and large houses were demolished like toys.

A 300-meter avalanche with a roar broke off in 1999 from the top of Griskopf, bringing death with it.

In the Austrian Galtür on February 23, 1999, 31 people died in a few minutes, and thousands of guests and inhabitants of this skiing paradise were locked up for many days in the Paznau valley.

On the ruins of Galtür

At first, only local residents and their guests-athletes had to deal with rescue and assistance to the victims, since the valley turned out to be completely cut off from the outside world: the roads were covered with a ten-meter layer of snow. Mountain safety authorities have banned rescuers from making their way along the roads to the affected valley due to the high likelihood of new avalanches. Help to the disaster area arrived only the next day by helicopters of the Austrian Air Force.

Victims suffocate or get crushed

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

Most avalanche victims die very soon, as a snow wall rushing at a speed of 100 km / h and above creates a shock wave; it instantly clogs the lungs and airways of the victim with snow, and the person dies of suffocation. The survivors of this first onslaught are killed when they find themselves inside an avalanche that hurls them against rocks, trees, and other obstacles at great speed.

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

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

Therefore, rescuers advise in case 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 hold out for some time until rescuers arrive under a layer of snow.

People covered by an avalanche are searched for by probes. This must be done quickly, because after 20 minutes half of the victims die. The chance of rescue is increased if rescuers and victims carry “ ” 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. In a few seconds the ground shook and the valley was filled with deafening thunder. 600,000 tons of snow fell down the mountainside at a speed of 300 km/h.

In the middle of an avalanche-prone slope, a group of people is sitting in a massive bunker. All of them pinch their ears that hurt from the roar. The bunker is covered with a three-meter layer of hard, like concrete, snow. However, nothing happened to people - they are employees of a Swiss institute that studies snow and avalanches. They have 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 - for avalanches, which, despite the huge costs of protective and rescue measures, claim the lives of 150-200 people year after year in the mountains of Europe alone.

To prevent such catastrophes, Switzerland alone has spent over the past 50 years 1.5 billion francs on the construction of barriers against avalanches and another billion on the cultivation of forests that block the path of avalanches. And not without success: if in 1951 98 people died under snow masses, then at the end of the millennium “only” 17. And despite the fact that now the mountainous regions are more densely populated than before, and besides, many skiers come here .

This success is by no means accidental. For more than 70 years, the Alpine Republic has been systematically studying the dangers that snow brings with it. The Central Research Institute was founded near Davos on Mount Weisflujoch (altitude 2662 m). Scientists from various scientific fields are developing topics such as “Formation of snow cover”, “Snow mechanics and avalanche formation”.

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 the old snow layers.

The avalanche monitoring service operating in the countries of the Alpine region is installing more and more automatic weather stations, but an accurate forecast of avalanches is still not possible. As before, skiers should remember to take reasonable care in the mountains and avoid dangerous places.

NO ABSOLUTE PROTECTION

Despite all the successes of scientists, avalanches, as before, can suddenly come off the slope. They are born from time to time even in the most seemingly safe places. Sometimes even expensive defensive structures are not able to keep them. Until now, far from all the factors that lead to the fact that snow masses come into motion, crush everything that comes in their way, and drag what they have captured down, have not been studied.

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