Optimal conditions for the occurrence of avalanches. Definition of an avalanche: varieties, safety. Consequences of snow avalanches

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, there is an avalanche danger. Freshly deposited snow is often loose and free-flowing like sand. Such snow easily generates avalanches. Avalanche danger increases many times when snowfalls are accompanied by wind. With a strong wind, a wind, or snow, board is formed on the surface of the snow - 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 down in winter after a heavy snowfall without a thaw, when the snow blows on the ridges and steep slopes reach such a size that the shaking of the air from a gust of wind, a shot, even a loud cry causes them to detach. The latter is greatly facilitated, if fresh snow falls on a smooth surface of old snow, frozen after a thaw, these avalanches fly down and at the same time fill the air with snow dust, forming a whole cloud.

In the absence of snowfall, the snow gradually "ripens" to generate avalanches. Over time, the snow mass gradually settles, which leads to its compaction. The sources of avalanche danger are weakened layers, in which weakly bound crystals of deep frost are formed. It is she who corrodes the lower layer of the snow cover, suspending the upper thickness.

The state of the snow cover changes dramatically when water appears in it, which significantly weakens the strength of the snow. With a sharp melt or intense rain, the structure of the stratum is quickly destroyed, and then grandiose "wet" avalanches are formed. They descend in the spring over vast areas, sometimes capturing all the snow that has accumulated over the winter. They are also called dirt, because they move right along the ground and rip off the soil layer, stones, pieces of turf, bushes and trees. These are very heavy avalanches.

Snow lying on a slope is set in motion by gravity. For the time being, shear resistance forces (the adhesion of snow to its lower layers or soil and the friction force) keep the snow on the slope. In addition, the displacement of the formation is prevented by the snow cover located below, and keeps the one that lies above. Snowfall or snowstorm, recrystallization of the snow mass, the appearance of liquid water in the mass leads to a redistribution of the forces acting on the snow.

Snowfall overloads the slopes with snow, and the forces holding the snow in place cannot keep up with the buildup of gravity 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 start moving, it needs a first impulse. Heavy snowfalls or strong snowstorms, warming, warm rain, snow cutting by skis, vibration from a sound or shock wave, earthquakes act as such a trigger mechanism.

Avalanches begin their movement either "from a point" (in case of violation of the stability of a very small volume of snow), or "from a line" (in case of violation of the stability of a significant layer of snow at once). The looser the snow, the less it is needed to start an avalanche. The movement begins literally with a few particles. A snowboard avalanche begins with the cracking of the snow cover. A narrow crack grows rapidly, lateral crevices 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 increases due to the sticking of new portions of snow (almost all ancient engravings depicted an avalanche in this way). An avalanche was represented by a ball until the 19th century. The variety of snow avalanches and the diversity of forms of its 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 physics of such flows is very complicated. Forms of avalanche movement are varied. 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 and dust cloud can rise into the air. Different types of movement complement each other, pass one into another in different parts of the same avalanche. The avalanche front moves faster than its main body due to the collapse of the snow cover in front of the front from the impact of the avalanche. So, all new portions of snow are included in the avalanche, while in the tail section the speeds are falling. 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 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 of the avalanche, until the avalanche finally calms down.

Recognizing an avalanche area is the first step in assessing avalanche risk. Many people caught in avalanches did not notice the danger until it was too late. The most common misconception is that avalanches only occur in large, well-defined pockets. Therefore, people do not pay attention to small relief traps. Another mistake is to assume that it is safe to travel along the bottom of a valley without considering the possibility of being caught by an avalanche from the overlying slopes. The following terrain features affect the occurrence of avalanches, so they will help you recognize an avalanche area.

The slope angle is an important variable that determines the likelihood of avalanches. Therefore, this factor plays an important role in the evaluation and development of the route.

Disturbance of stability and formation of avalanches is observed on slopes with a steepness of 15° to 60°, although it is not uncommon for avalanches to originate on more gentle slopes.

On steep slopes, snow does not hold well, most snowflakes roll down during a snowfall and large masses of snow are deposited relatively rarely. At a slope below 25 °, the load is not large enough for the occurrence of snow avalanches (exceptions are ultra-wet-hydro-pressure avalanches and water-snow flows, the descent of which is noted on slopes with a steepness< 15 °). Поэтому наиболее лавиноопасными считаются склоны крутизной от 25 до 50 ° (рис. 6).

Rice. 6.

The steepness of the slope is important because, simultaneously with its growth, the pressure on the snow mass and on all areas adjacent to the snow plate increases. It is important to remember that you can trigger an avalanche from below even when crossing a 15 degree slope if the top of the slope is at least 25° steep and there is instability.

On uneven slopes, additional compressive or tensile stresses arise due to the variability of the snow cover flow rates depending on the angle of inclination and the spatial heterogeneity of the snow height, density and viscosity.

On convex slopes, snow slabs are most often destroyed right at the bend, in the place where conditions are created for the occurrence of tensile forces. Concave slopes provide some support through compression at the base. As a result, snow density on concave slopes is often greater than on nearby smooth slopes and convex terrain. And along them, the line of avalanche separation can also pass, especially during the period of instability of the snow cover. On wide and smooth slopes, avalanches can come down anywhere. Boulders, sloped trees and landforms act as "anchors" and help hold the snow in place until it falls asleep. Such slopes are less prone to avalanches than open slopes, but such anchors must be located very close to each other so that they can be passed over without causing an avalanche. Moreover, such anchors can be areas of increased load, because the snow above them on the slope is held in place, and on the sides of them slides under the influence of gravity. Thus, the pressure on the thickness can be strongest near the anchors. As a result, they may turn out to be the initial points of avalanche separation.

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 the 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, as well as 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 a mobile phone with you (it 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.

Avalanches. Every year, many people die under them, either because they neglect the danger, or because little is known about avalanches.

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

Avalanches.

Potential Threats

An avalanche can move at a speed of 200 kilometers per hour. Such a force can smear you against trees and stones, grind you against rocks, make porridge from your insides and pierce you with your own skis or snowboard. About one third of all avalanche victims die due to injuries.

If you have not been injured by an avalanche, you will have to struggle with a mass of snow, the density of concrete, which squeezes your body. The avalanche, which began as snow dust, heats up as it moves downhill from friction on the slope, thaws a little and then freezes tightly around your body. All this mass is enough to squeeze all the air out of your lungs.

If you manage to create an air pocket around you before the snow settles, you have a good chance of surviving. If you and your friends have an avalanche transmitter and know how to use it, then the chances of survival are even greater. However, this is where the race against time begins. Most people are not able to survive under an avalanche for more than 30 minutes (Black Diamond AvaLung backpacks can increase this time to one hour), so it makes sense to buy and learn how to use avalanche transmitters. For lovers of winter freeride, a necessary thing. About 70% of avalanche victims die from suffocation.

The best defense against avalanches is, of course, knowledge of avalanche conditions and slopes, as well as avoiding dangerous situations.

Loose avalanches.

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

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

Plastic avalanches.

These avalanches are much more dangerous. Sheet avalanches form when a single layer of snow slides off the bottom layer and rushes down a slope. Most freeriders get into such avalanches.

They are caused by snowfalls and strong winds that deposit layers of snow that change over time. Some layers are deposited and held together, while others, on the contrary, are weakened. Weak layers are often granular or composed of very light snow (powder) so that other layers cannot adhere to them.

An avalanche occurs when the top layer, called the "board," is not sufficiently bonded to the underlying layer and is set in motion by some external agent, usually a skier or climber. Unlike unconsolidated avalanches, which start from a single point, sheet avalanches grow deeper and wider, usually along a break line at the top of a slope.

Avalanche release on Cheget:

Factors contributing to the descent of avalanches.

Locality.

Slope steepness: pay attention to the steepness of the slope when you ride or climb. Avalanches often occur on slopes steep in 30-45 degrees.

Slope side: in winter, the southern slopes are much more stable than the northern slopes, as the Sun heats and compacts the snow. Unstable layers of "deep frost", dry, icy snow that does not adhere to adjacent layers, are most often found on the northern slopes. So be careful when you see the tempting northern slope with excellent powder, for they are more dangerous than the southern slopes, since they do not receive enough solar heat to compact the snow over the winter. At the same time, in spring and summer, the southern slopes melt more strongly, which leads to dangerous wet avalanches. The warmer weather this time of year hardens the snow on the northern slopes, making them safer.

Terrain Threats: snow cover is most often not stable on convex slopes, rock ledges, boulders or trees where the snow cover is interrupted, lee slopes or under eaves. It is best to bypass bowls, circuses and pits, where snow can accumulate after an avalanche (avalanche discharges). Steep, narrow couloirs (or ravines) usually accumulate a lot of snow and pose a great danger to hikers and skiers caught in them. Often, there is no escape from such places, due to the steep side slopes, so that in the event of an avalanche, there is nowhere to run.

Weather

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

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

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

Deep frost ("sugar snow"), due to its similarity to granulated sugar, can be located at any depth or several depths of deep snow cover. Often a sharp increase in temperature leads to wet avalanches, especially in spring, so be careful when it gets warm in the mountains.

Snow cover

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

How to test a slope for avalanche risk:

Human factor

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

Common mistakes in decision making:

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

While in the upper layers of the snow cover the temperature drops to -10° and -20°, in the snow masses adjacent to the ground, temperatures remain close to 0° (approximately -2°). Thus, in a snow cover even 40-50 cm thick, there is a temperature difference between the upper layers of snow and the layers located near the earth's surface. Due to this temperature difference in the lower layers of snow, the movement of water vapor and the evaporation of snow begin. Gradually, the lower layer of snow loosens, loses its stability and turns into the thickness of an avalanche layer. Avalanches only occur when snow accumulates on steep slopes (15° and above) where the snow cannot hold. Slopes with a steepness of 30-35° are especially dangerous, on which snow slowly accumulates until its thickness reaches a significant thickness. Then the snow mass rolls down. The fall of the avalanche also occurs from overloading the slopes with snow during snowstorms or within two days after the end of the snowfall and during thaws. Avalanches carry a lot of rock fragments and form large bulk landforms in mountain valleys. Snow avalanches are a characteristic natural phenomenon in the mountainous and polar regions of the globe.

Signs of an avalanche danger

avalanche safety mountain avalanche

All visitors to the mountains are required to fill out the basic signs of avalanche danger in any mountainous area:

• 1. The height of the old snow: the old snow fills all the unevenness of the ground, bends the bush, forming a smooth, even surface on which the avalanche slides. The basic rule is that the greater the height of the old snow, the more likely an avalanche.
• 2. Condition of the underlying surface. The well-known delaying effect of dense shrubs, mountain forests, large-block scree. Small scree contributes to loosening the lower layers of snow and its adhesion to the ground. But on the surface of the glaciers, exceptionally favorable conditions are created for the separation of avalanches. If the surface has become rough due to the action of the wind, sastrugi hold new snow on the slopes and reduce the possibility of avalanches. After a thaw, a thin ice crust appears on the old snow, with which, as a rule, newly fallen snow has very weak adhesion.
• 3. The height of freshly fallen snow, that is, it has grown during snowfall, in the amount of 25-30 cm, in cases leads to avalanches.
• 4. The intensity of snowfalls is determined by the amount of snow falling per unit of time. An increase of about 50 cm of snow within 10-12 hours leads to avalanches.
• 5. Snow settling leads to stabilization of the snow cover. The speed of this process at 0 degrees is the greatest.
• 6. Wind with a speed of 7 - 8 meters per second is the main reason for the formation of avalanches from snow "boards".

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

Definition of an avalanche. This is a kind of landslide, when a large amount of snow and ice slides or falls down from steep mountain slopes. The speed depends on the steepness of the slope, the volume and severity of the snow. On average, this 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 snow melts, but also a 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. An avalanche is a natural process.

Avalanche: photo

They have always been and will be in the mountains. 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 skiing sports, climbers conquering peaks. Ski slopes are also at risk of avalanches. In these places, avalanches are provoked in advance and artificially with the help of special equipment to ensure safety.

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

The most common causes of avalanches include:

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

According to the nature of the movement, they are divided into:

• wasps - descend over the entire surface and are more reminiscent of a landslide
• Jumping - fall off ledges
• Tray - pass in the form of furrows along the zones of weathering of rocks, natural gutters

By movement they are divided into:

• Streaming
• Cloud
• Complex

Why is an avalanche dangerous?

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 are high risks of remaining disabled, even if they find him and dig him out from under the snow.

Even if the bones are intact, the snow can clog the airways. Or simply, under a huge layer of snow, a person simply does not have enough oxygen left, 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 frostbitten limbs are amputated for many.

The harbingers of an avalanche

The main harbinger is weather conditions. Heavy snowfall, rain, wind create dangerous conditions, so it is better not to go anywhere on this day. You can also look at the general condition of the area as a whole. Even small landslides of snow indicate that it is loose, the humidity is high. Better to be safe.

The most dangerous period of an avalanche is considered to be winter, in the moments after precipitation.

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

• cover your nose and mouth with gloves to keep snow out
• clear snow in front of the face, as well as in the chest area, so that you can breathe normally
• you can’t scream, because it takes strength, 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, ram it
• you can’t fall asleep to be alert and give a sign if the rescuers are close

How to survive an avalanche

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

Avalanche equipment

Today, many manufacturers of sports and outdoor products offer special avalanche equipment. It includes the following devices and equipment:

• Avalanche beacon- it must be turned on immediately, as soon as the athlete went 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 from the avalanche in order to dig out those who fell under it.

• avalanche probe. Such an adaptation is necessary in order to quickly find a person. With it, you can determine the exact depth of the snow under which a person is located in order to calculate the forces and dig it out.

• Avalung system from Black Diamond- a special device that takes the 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 more about avalanche equipment in our separate article.

Avalanche places in Russia

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

• Khibiny on the Kola Peninsula
• Kamchatka
• Caucasian mountains
• ridges and highlands of the Magadan region and Yakutia
• Ural mountains
• Sayans
• 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 is 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 the outside world for a long time, until rescuers came to their aid.

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

• 1980 France. The avalanche claimed the lives of about 280 tourists at the ski resort.

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

A lot of avalanches come down in Asia: in Pakistan, Nepal, China. But, there are no exact statistics on the dead and destruction.

We also suggest you watch the video of the largest snow avalanches:

Also interesting