Landslide formation, how to avoid landslides, external signs of a landslide slope. Landslides - What is it? Landslides and landslides, their consequences interesting facts

LANDSLIDE, detachment and sliding movement of the rock mass down the slope; the mass of displaced rock itself. O. are common in regions where weak plastic and impermeable rocks are overlain by relatively strong permeable ones. The weakening of the strength of rocks is caused by natural causes (increase in the steepness of the slope, washing away its foundations by waves and as a result of river erosion, waterlogging of soils with melt and rain waters, infiltration pressure in the rock mass caused by fluctuations in sea level, reservoir or water in the river, seismic tremors, etc. ) or human intervention (destruction of slopes by mountain and road cuts, overgrazing or irrigation, deforestation, improper agricultural practices on slope agricultural land, construction load on the edge or upper part of the slope, etc.). Occurrence and activation are facilitated by the technogenic rise in the level of groundwater on the banks of reservoirs. O. are displaced along the slope by several meters, often by tens and hundreds of meters. The volume of shifting rocks ranges from several tens of m 3 to 1 billion m 3 . Large lakes are formed on slopes with a steepness of St. 15° away from watersheds, often occur on the sides of valleys, high shores of seas, lakes and reservoirs. They retain a certain coherence and solidity inside the landslide body; their thickness reaches 10–20 m or more. Small lakes everywhere transform the sides of ravines. O. are often located on a slope in several tiers (for example, in the valley of the Moscow River).

In terms of plan, O. often have the shape of a crescent, forming a depression in the slope (the so-called landslide cirque). Shallow cirque-shaped dents on the steep slopes of valleys and gullies - wasps - appear as a result of surface displacements of highly moistened loamy masses, especially when snow slowly melts on shady slopes. After the separation and descent of the O., a bare surface or niche remains on a steep slope - a landslide ledge. Landslide breccia accumulates at the foot of the slope. A pressure landslide swell may occur in front of the front of the moving lake. O.'s tongue often protrudes into the water area of ​​a watercourse or body of water, changing the configuration of the coastline. The base of the landslide is the bottom of the slope or a separate flattened section of the slope, where the movement of landslide masses stops. Free sliding of the landslide body occurs if the shifting blocks are developed above the base of the landslide, in the case when the thickness of plastic rocks lies below, these rocks are squeezed out, accompanied by their movement against the general slope (O. extrusion I). O., which have not lost the natural composition of rocks in their blocks, are referred to as structural O. In "cutting x" O., the sliding surface cuts off different layers of rocks. When fine particles of fine earth are washed out from the base of an lake by spring waters, weakening the stability of the overlying rocks, it is classified as suffusion O. (widely distributed on slopes with a steepness of 10–18 °). Possible landslide-flows with a fluid consistency of the soil, their volume can reach millions of m 3. Small surface water-saturated lakes—slushes (up to several meters wide and 0.3 to 1.5 m deep) form under conditions of excessive moisture to a plastic (mud-like) or fluid state.

Slopes subject to landslide processes are characterized by pseudo-terraces (often with a reverse slope), mounds, swampy closed or poorly drained semi-closed depressions, and other forms of landslide relief, as well as a specific type of vegetation (for example, the so-called drunken forest). Gap cracks are observed in O.'s body. In the European part of Russia, lakes are distributed along the sides of the valleys of large rivers (especially the Volga and its tributaries), reservoirs, and along the Black Sea coast. Powerful landslide activity marked the coasts of the Black Sea - in the Crimea, near the city of Odessa (Ukraine) and in Adzharia (Georgia). A wide strip of ocean stretches for hundreds of kilometers along the coasts of the Mangyshlak Peninsula (Kazakhstan). Landslide danger is noted in most mountainous countries (the eastern periphery of Tibet, the Himalayas, etc.). O., descended from the sides of mountain valleys, often form temporary dams that dam the river, with the formation of a landslide lake. The catastrophic consequences of a flood wave that occurs when such a dam is destroyed are many times greater than the negative consequences of the displacement of the lake itself. lands, industrial enterprises, settlements, etc. To combat them, bank protection and drainage works, forest plantations, and slopes are being fixed with piles.

On relatively steeply sloping sections of the bottom of the oceans, seas, and deep lakes in seismically and volcanically active zones, as well as on the frontal slopes of underwater deltas (as a result of sharp differences in sedimentation rates), underwater lakes are found; one of the largest is the Sturegga landslide in the Norwegian Sea (length approx. 800 km, width 290 km). Submarine seas can cause submarine cables to break, which has happened more than once, in particular, at the bottom of the Atlantic Ocean.

Table. Catastrophic landslides*

*The table shows landslides that led to large-scale destruction (including on the seabed), or to numerous human casualties, or to a radical negative change in the natural landscape.

Mudflows are streams consisting of mud and stones that slide down the slopes of mountains and riverbeds, sweeping away any obstacle in their path. Such a natural phenomenon is one of the most dangerous for the life of people and the infrastructure of settlements.

The occurrence of mudflows

During the rapid melting of glaciers in the mountains, as well as after heavy rains, storms, hurricanes, water accumulates in front of a natural obstacle. In some places quite large lakes and reservoirs are formed. Such formations are called moraine lakes; after some time, they are transformed into landslides, mudflows, landslides and avalanches. The moraines are composed of:

1. Sand.
2. Boulders.
3. Ice and snow.
4. Hardwood.
5. gravel.
6. Clay.

At some point, a huge mass of mud, mixed with water and stones, breaks through the dams, rushing down in a swift stream. Developing tremendous speed, making a loud roar, the stream picks up more and more stones and trees along the way, thereby increasing its destructive power.

The mudflows at the beginning of their movement reach no more than 10 meters in height. After a natural disaster breaks out of the gorge and rushes down the mountain, it will spread over a flat surface. Its movement speed and height will be greatly reduced. When it reaches an obstacle, it stops.

The consequences of the descent of rocks and water

In the event that a settlement is on the way of the mudflow, the consequences for its population can be catastrophic. deadly, and often leads to large material losses. Especially a lot of destruction brings gathering rocks and water to settlements where people live in poorly fortified frame houses.

The consequences of landslides, mudflows and landslides are catastrophic. So, major disaster occurred in 1921 in the former capital of Kazakhstan - Alma-Ata. Late at night, a powerful mountain stream, about a million cubic meters in size, hit the sleeping city. As a result of an emergency, a strip of stones and mud 200 meters wide was formed right in the middle of the city. Buildings were destroyed, infrastructure was damaged, people were killed.

In Russia, mudflows are also often formed in highlands, especially in places where it rains heavily, for example in the Caucasus and Far East. In Tajikistan, mudflows occur every year in the spring season. Especially often this phenomenon occurs in high mountains during the melting of snow.

Mudflow protection

In order to protect the population and tourists from sudden rock falls in particularly dangerous mountainous areas where landslides, mudflows, landslides and avalanches periodically occur, it is necessary to monitor them from the air. Professionals oversee education mountain lakes and can tell in advance about the danger of an emergency disaster. Engineers are also developing anti-mudflow artificial barriers and diversion channels, which are several hundred kilometers long.

In 1966, a protective dam was built from earth and large cobblestones near the city of Alma-Ata. Total weight building materials amounted to about 2.5 million tons. After 7 years, it saved the lives of many citizens, shielding the city from unprecedented power.

Despite the fact that in most cases mudflows fall from the mountains suddenly, scientists have learned to predict their approach by some signs, for example, by changing the color of the water in a mountain lake.

Survival during an emergency

Tourists who often travel in the mountains should be aware of the danger of landslides, mudflows, landslides, life safety. Safety rules may one day save your life!

In order to properly prepare for a difficult and long hike in the mountains, you should find out the weather forecast before leaving. If it is raining heavily in the mountains, then the likelihood of mud flows increases significantly. For safety, it is better to keep to the inner part of the bend of the rivers, since the mudflow rises much higher on the outer side. Also, you should not spend the night near mountain lakes and rivers, as well as in narrow gorges.

What are landslides

A landslide is a downward movement of a formed mass of rocks. The reason for their occurrence is most often heavy rains, as a result of which rocks are washed away.

Landslides can take place at any time of the year, and differ from each other in the extent of destruction. A slight displacement of the rock leads to damage to the roads. Significant destruction and spalling of stones leads to the destruction of houses, as well as to human casualties.

Division of landslides into types

Landslides are divided into slow, medium and fast. The first move at a low speed (a few centimeters per year). Medium - a few meters per day. Such displacements do not lead to disasters, but sometimes such natural phenomena lead to the destruction of houses and outbuildings.

Rapid landslides are considered the most dangerous, because in this case, streams of water with stones break down from the mountains and move down at great speed.

All movements of rocks and masses of clay can be predicted by paying attention to the following signals:

• new cracks and crevices formed in the soil;
• falling stones from the mountains.

How to avoid destruction and casualties

Against the backdrop of incessant downpours, the above signals should become harbingers of danger for the security services and the population. Timely detection of signs of an impending landslide will help to take measures to rescue and evacuate the population.

As a preventive measure and protection against destruction, protective nets, artificial tunnels, and tree cover are being built near cities. Bank protection structures and fixing slopes with piles have also proven themselves well.

Where do

Many are wondering where avalanches, landslides, mudflows and landslides most often occur. The displacement of rocks, huge masses of snow and water occurs in areas or slopes as a result of imbalance, which is caused by an increase in the steepness of the slope. This mainly happens for several reasons:

1. Abundant rains.
2. Weathering or waterlogging of rock by groundwater.
3. Earthquakes.
4. Construction and economic activity human, which does not take into account the geological conditions of the area.

The intensification of the landslide is facilitated by the slope of the earth towards the cliff, cracks on the top of the mountain, which are also directed towards the slope. In places where the soil is most moistened by rains, landslides take the form of a stream. Such natural disasters cause great damage to agricultural land, businesses and settlements.

in mountainous areas and northern regions In our country, the thickness of the soil is only a few centimeters, and therefore it is very easy to break. An example is a place in the Orlinaya Sopka area (Vladivostok city), where uncontrolled deforestation began in the early 2000s. As a result of human intervention, vegetation disappeared on the hill. After each downpour, mud is poured onto the streets of the city, which was previously blocked by trees.

Landslides often occur in areas where slope erosion processes are actively taking place. They occur when masses of rocks lose their support as a result of an imbalance. A massive landslide occurs in places where there are:

• mountain slopes, composed of alternating water-resistant and water-bearing rocks;
• dumps of rocks artificially created by man near mines or quarries.

Landslides moving down a mountainside in the form of a pile of rubble are called rockfalls. If a huge block of stone slides along the surface, then such a natural phenomenon is called a collapse.

Cases of large landslides

To learn more about the largest convergences of landslides, mudflows, landslides, avalanches and the consequences for people, you should refer to historical literature. Witnesses terrible disasters often describe the descent of large masses of rock and snow avalanches from ancient times. Scientists believe that the world's largest descent of stones occurred at the beginning of our era near the Saidmarreh River in southern Iran. total weight landslide was approximately 50 billion tons, and its volume - 20 cubic kilometers. The mass, consisting of stones and water, collapsed from Mount Kabir Bukh, whose height reached 900 meters. The landslide crossed the river 8 kilometers wide, then it crossed the ridge and stopped after 17 kilometers. As a result of the blocking of the river, a large lake was formed with a depth of 180 meters and a width of 65 kilometers.

In ancient Russian chronicles there is information about huge landslides. The most famous of them dates back to the 15th century in the region of Nizhny Novgorod. Then 150 yards suffered, many people and farm animals suffered.

The scale of destruction and the consequences of landslides and mudflows depend on the density of buildings and the number of people living in the disaster area. The most destructive landslide occurred in Gansu Province (China) in 1920. More than 100 thousand people died then. Another powerful landslide that claimed the lives of 25 thousand people was registered in Peru (1970). As a result of the earthquake, a pile of stones and water fell into the valley at a speed of 250 kilometers per hour. During natural disaster the cities of Ranrahirka and Yungai were partially destroyed.

Landslide prediction

To predict the descent of landslides and mudflows, scientists are constantly conducting geological research and mapping dangerous areas.

To identify areas of accumulation of landslide material, aerial photography is carried out. The photographs clearly show the places where rock fragments are most likely to come off. Geologists also determine the lithological features of the rock, the volume and nature of the flow groundwater, vibrations due to earthquakes, as well as slope angles.

Landslide protection

If the probability of landslides and mudflows is high, then special services carry out measures to protect the population and buildings from such a natural phenomenon, namely, they strengthen the slopes of the shores of the seas and rivers with a wall or beams. Soil slippage is prevented by driving piles in a checkerboard pattern, planting trees, and also carrying out artificial freezing of the earth. To prevent wet clay from coming off, it is dried by electroosmosis. The descent of landslides and mudflows can be prevented by pre-constructing drainage structures that can block the path to groundwater and surface water, thereby preventing soil erosion. Surface waters can be diverted by tearing out canals, underground waters - with the help of wells. Such measures are quite expensive to implement, but such measures can prevent the destruction of buildings and avoid human casualties.

Population warning

The population is warned of the danger of earthquakes, landslides and mudflows several tens of minutes in advance, at best several hours in advance. To notify a large populated area, an alarm is given using a siren, and announcers also announce the danger on TV and radio.

The main damaging factors in landslides and mudflows are mountain boulders that collide with each other during their movement from the mountains. The approach of rocks can be determined by the characteristic loud sound of rolling stones.

The population living in a particularly dangerous mountainous area, where avalanches, mudflows and landslides are possible, should know from which side trouble can come, what the nature of the destruction will be. Residents should also be familiar with evacuation routes.

Such settlements the houses and territories on which they are erected must be fortified. If the danger is known in advance, an urgent evacuation of the population, property and animals to safe areas is carried out. Before leaving home, you should take the most valuable things with you. The rest of the property, which cannot be taken with you, should be packed to protect it from dirt and water. Doors and windows should be closed. It is also necessary to close the ventilation hole. AT without fail turn off the water and gas, turn off the electricity. Poisonous and flammable substances must be taken out of the house, they are placed in pits remote from housing.

If the population was not warned in advance about landslides and mudflows, each resident must find shelter on his own. It is also necessary to help children and the elderly to hide.

After the end of the natural disaster, you should make sure that there is no danger, leave the shelter and start searching for the victims, if necessary, help them.

Landslides.

Most of the earth's surface is slopes. Slopes include surface areas with slopes greater than 1 degree. They occupy at least 3/4 of the land area.

The steeper the slope, the greater the component of gravity, which tends to overcome the force of cohesion of rock particles and move them down. Gravity is helped or hindered by the structural features of slopes: the strength of rocks, the alternation of layers of different composition and their slope, groundwater, which weakens the cohesive forces between rock particles. The collapse of the slope can be caused by subsidence - separation from the slope of a large block of rock. Settling is typical of steep slopes composed of dense fractured rocks (eg limestones). Depending on the combination of these factors, slope processes take on a different form.

Landslides are the displacement of masses of rocks down a slope under the influence of gravity. They are formed in various rocks as a result of their imbalance and weakening of their strength and are caused by both natural and artificial causes. To natural causes include an increase in the steepness of slopes, erosion of their foundations by sea and river waters, seismic shocks, etc. Artificial, or anthropogenic, i.e. caused by human activity, the causes of landslides are the destruction of slopes by road cuts, excessive removal of soil, deforestation, etc. According to international statistics, up to 80% of modern landslides are associated with human activities.

At the site of the landslide cliff, a bowl-shaped depression remains with a ledge in the upper part - the wall of the fall. A sliding landslide covers the lower parts of the slope with either mounds or steps. A landslide can push loose rocks in front of it, from which a landslide swell is formed at the foot of the slope. Landslides can occur on all slopes with a slope of 20 degrees, and on clay soils - with a slope of 5-7 degrees. Landslides can come down from all slopes at any time of the year.

Landslides can be classified according to the type and condition of the material. Some of them are composed entirely of rock material, others are only soil layer material, and still others are a mixture of ice, stone and clay. Snow slides are called avalanches. For example, a landslide mass consists of stone material; stone material is granite, sandstone; it can be strong or fractured, fresh or weathered, etc. On the other hand, if the landslide mass is formed by fragments of rocks and minerals, that is, as they say, the material of the soil layer, then you can call it a landslide of the soil layer. It may consist of a very fine granular mass, that is, of clays, or of a coarser material: sand, gravel, etc.; all this mass can be dry or water-saturated, homogeneous or layered. Landslides can also be classified according to other criteria: according to the speed of movement of the landslide mass, the scale of the phenomenon, activity, and power.

From the point of view of the impact on people and on the conduct of construction work, the speed of development and movement of a landslide is its only important feature. It is difficult to find ways to protect against the rapid and usually unexpected movement of large masses of rocks, and this often causes harm to people and their property. If a landslide moves very slowly over months or years, it rarely causes accidents and preventive measures can be taken. In addition, the rate of development of the phenomenon usually determines the ability to predict this development, for example, it is possible to detect the precursors of a future landslide in the form of cracks that appear and expand over time. But on particularly unstable slopes, these first cracks may form so quickly, or in such inaccessible places, that they are not noticed, and a sharp displacement of a large mass of rocks occurs suddenly. In the case of slowly developing movements earth's surface even before a major shift, one can notice a change in the features of the relief and the distortion of buildings and engineering structures. In this case, it is possible to evacuate the population without waiting for the destruction.

As the statistics of landslides show, 80% of these phenomena are associated with human activities, and only 20% with natural phenomena.

Landslides

Rockfalls can form on any inclined surface of the earth, regardless of the steepness of the slope. The occurrence of landslides is influenced by river floods, washing away slopes, soil displacement from, road construction associated with excavation,.

Landslide statistics highlight the main causes of their formation - natural and artificial. Natural are produced by natural phenomena, artificial - by human activity.

Causes of the destruction of rocks

To understand , how landslides are born, it is necessary to consider the causes of their occurrence, which are divided into three groups:

• slope deformity a - can be caused by rain washouts, river floods, artificial excavation;
• change in rock structure that make up the slope. This is usually caused by groundwater dissolving the salt deposits that have bound the rock. The texture of the soil becomes looser, which increases the risk of its destruction;
• increase in ground pressure. Soil vibrations, artificial loads of man-made objects, as well as the pressure of groundwater, entraining particles along the way.

The influence of rains is associated with the physical destruction of the slope, an increase in soil friability and increased pressure on the slope.

Systematization of types of landslides

Exist different ways classification of natural phenomena. Landslides are divided according to the material: snow (avalanche) or stone. In the area, for example, a mountain landslide. According to the mechanism of the ongoing process. A landslide caused by heavy rain develops into a mudflow, and the resulting mudslide rapidly moves down the river, destroying everything in its path. According to the mechanism of occurrence, the following types of geomorphological phenomena are distinguished:

1. Compression landslides. They are formed when the soil is deformed under vertical pressure, and the layers are compressed. Top part the massif sags and forms a deflection, in which a crack appears under the influence of the resulting stress. Part of the rock breaks off and begins to move. Typical for clay soil.
2. Shear landslides. They occur during the accumulation of shear stresses, are formed on steep slopes, the rock slides, slides on the surface. Sometimes such phenomena are formed at the boundary of rocks, then significant massifs can “slide”, often the soil layer (sink) slips.
3. Liquefaction landslides associated with groundwater impact. Occur in rocks with a loosely bound structure under the action of hydrodynamic and hydrostatic water pressure. Depend on the level of groundwater and rainfall. The phenomenon is typical for clay and loamy soils, peat and soil structures.
4. Tensile landslides associated with separation, spalling of a part of the array under the action of tensile stresses. Rocky rocks begin to collapse when the allowable stress is exceeded. Sometimes ruptures occur along tectonic cracks.

There is also a division of landslides according to the scale of the ongoing process.

Landslides and mudflows

Landslides and landslides, as well as landslides and mudflows are very close in terms of origin. Crashes can form due to chemical reactions occurring in rock when water leaches rocks and destroys structural bonds, forming caves underground. At some point, the soil falls into this cave, forming a failure. Collapses are also associated with funnels, which are formed when the rock falls.

Mudflow formation pattern - heavy rains wash solid particles into the riverbed, which high speed are moving down.

The most dangerous regions

For the occurrence of a landslide, the presence of a slope with a slope of more than 1 o is sufficient. On the planet, ¾ of the surface meets these conditions. As the statistics of landslides show, more often such phenomena occur in mountainous areas with steep slopes. And also in places where fast flows deep rivers with steep banks. The mountainous seaside shores of resort areas are prone to landslides, on the slopes of which a large number of hotel complexes.

Areas of landslides are known in the North Caucasus. Dangers exist in the Urals and Eastern Siberia. There is a threat of landslides on the Kola Peninsula, Sakhalin Island, and the Kuril Islands.

In Ukraine, the last landslides occurred in Chornomorsk in February 2017. This is not the first case, since the Black Sea coast regularly "gives" such surprises. In Odessa, old-timers remember community work days for planting trees, in places where the soil is shifting. The existing development of the coast with high-rise buildings in the coastal zone is contrary to the norms and rules of construction in landslide areas.

The Ingulets River is one of the largest and most picturesque rivers in Ukraine. It has a great length, expands and narrows, washes the rocks. The risk of rock falls on the Ingulets River arises from the following points:

• the city of Krivoy Rog, where the course of the river comes into contact with rocks up to 28 meters high;
• the village of Snegirevka, where the natural monument "Nikolskoye Settlement of Serpents" is located downstream - a site with a very steep bank.

Modern realities

In April 2016, a landslide in Kyrgyzstan caused the death of a child. The occurrence of the collapse is associated with heavy rains that took place in the foothill areas. There are 411 places in the country where there is a danger of landslides.

Clay soil, almost 10 meters deep, retains moisture, which is well compensated by thick grass that evaporates excess liquid. But the human factor - regular mowing and the construction of roads between the hills violates this balance. As a result, frequent landslides destroy settlements, and sometimes lead to people.

The most tragic landslide in Kyrgyzstan occurred in 1994, when the number of victims reached 51 people. After that, the government decided to remove residents from dangerous areas. It was proposed to evacuate 1 thousand 373 families, plots were allocated for this and loans were issued. However, having received land and material assistance, 1,193 families remained to live in their places.

Landslide statistics show that the entire right bank of the Volga is a zone of regular landslides. Heavy rains and a rise in the level of unpaved rivers provoked a landslide in Ulyanovsk in April 2016. 100 meters of the roadbed collapsed, the landslide almost reached the railway embankment.

In September, collapses and landslides occurred in the Crimea in the village of Nikolaevka. Two people died, about 10 fell under the blockage. The proximity of the Black Sea is a factor in the formation of landslides for this region. Most vacationers prefer "wild" recreation in places prohibited for swimming, where there is a high risk of soil descent. does not stop the past landslide, they are located in dangerous areas, risking life and health.

The most destructive landslides on the planet

Landslides are not considered the most dangerous natural phenomena. So people don't take them seriously enough. Landslide statistics in the world:

This is not a complete statistics of landslides and their destructive effect in the world. The last landslides caused by rainstorms took place in Georgia in September 2016. Blockages formed on the road in Georgia. The Georgian military road was blocked.

Why are landslides dangerous?

At the first stage, the danger is represented by the collapsing masses of stones and soil. The damaging factors in the second stage are the destruction of roads and communications, damage. Landslides accompanied by downpours, blocking the riverbed, can cause. A landslide that brings soil into the river provokes a mudflow, which can intensify the destruction process, increasing its speed. The destruction of housing is another risk factor for people.

The elements in Chechnya in 2016 damaged 45 houses and destroyed 22 buildings. 284 people were left homeless.

How to behave in case of a threat of rock collapse

As landslide statistics show, most of happens to people who ignore the rules of behavior when the flow is coming down. They involve the following actions in case of landslides:

• disconnection of electricity, gas and water;
• collection of valuable things and documents;
• preparation for the evacuation of households;
• closing all windows and doors;
• evacuation to a safe place.

It is important to get up-to-date information about the speed of the landslide and its direction. The rules of conduct in mountainous areas contribute to adequate actions in case of danger. Among them is the possession of information at what speed of displacement of a landslide evacuation is recommended. This depends on the collection time.

The accumulated statistics of landslides recommends that at a speed of displacement of a mountain range exceeding 1 meter per day, evacuation to a safe place should be carried out according to plan. If the movement is slow (meters per month), you can leave, taking into account your capabilities. In areas where landslides are frequent, the population knows the safest places for landslides. Usually this:

• high areas located on the opposite side of the flow;
• mountain valleys and crevices;
• large stones or powerful trees behind which there is an opportunity to hide.

The warning system has come a long way in the last 5 years, modern facilities forecasting and warnings help to minimize human losses.

Landslide Prevention

The fight against landslides is aimed at preventing the event and measures to reduce losses from them, including measures that reduce the human impact on the formation of a landslide. To study the nature of landslides in a particular area, engineering and geological surveys are carried out. Based on the conclusions of experts, ways are being developed to reduce the risk factors for the formation of collapses. Work is carried out in two directions:

• a ban on human species that contribute to the formation of landslides (deforestation, excavation, soil weighting by the construction of buildings);
• carrying out protective engineering works, which include: strengthening the banks, diverting water, cutting off the active part of the landslide, reinforcing surfaces, retaining structures.

The devastating effects of landslides can sometimes be prevented. Professor from the UK, D. Loops has calculated the number of victims of landslides around the world over the past 10 years. The main damaging factors of landslides claimed the lives of 89,177 people during this time.

Potentially, landslides in Russia can occur almost everywhere where there is even a slight slope, but in some regions they occur regularly, and in others they are unexpected. In 2015, two displacements occurred in Chuvashia, which came as a surprise to the residents. The conducted studies have shown that over the past 5 years there has been a significant shift in the soil in the areas of elite development. To prevent collapses, studies and a number of protective works were carried out to strengthen the slopes.

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Mud flow - a mud or mud-stone stream, suddenly formed in the channels mountain rivers as a result of heavy rains, rapid melting of glaciers or seasonal snow cover. Moving at high speed, mudflows in their path often produce major destruction. In Peru in 1970, a mudflow destroyed several cities, more than 50 thousand people died, 800 thousand were left homeless. All movements of rocks and clay masses are preceded by various signals: the formation of new cracks and crevices in the soil; unexpected cracks in internal and external walls, water pipes, asphalt; falling stones; the occurrence of a strong rumble in the upper reaches of mudflow-prone watercourses, which overlaps other noises; a sharp drop in the water level in rivers; manifestation of a cloud of mud dust accompanying the "head" of the mudflow.

Mudflows - floods with a very high concentration of mineral particles, stones and rock fragments (from 10-15 to 75% of the flow volume), occurring in the basins of small mountain rivers and dry ravines and caused, as a rule, by heavy rainfall, less often by intense snowmelt, as well as a breakthrough of moraine and dammed lakes, a collapse, a landslide, an earthquake. The danger of mudflows is not only in their destructive power, but also in the suddenness of their appearance. Mudflows affect approximately 10% of the territory of our country. In total, about 6,000 mudflows have been registered, of which more than half are in Central Asia and Kazakhstan.

According to the composition of the transported solid material, mudflows can be mudflows (a mixture of water with fine earth at a low concentration of stones, bulk density y \u003d 1.5-2 t / m 3), mud and stone (a mixture of water, pebbles, gravel, small stones, y \u003d\u003d 2.1-2.5 t / m 3) and water stone (a mixture of water with predominantly large stones, y \u003d 1.1-1.5 t / m 3).

Many mountainous regions are characterized by the predominance of one or another type of mudflow in terms of the composition of the solid mass carried by it. So, in the Carpathians, water-stone mudflows of relatively small thickness are most often found, in the North Caucasus - mainly mud-stones, in Central Asia- mud streams. The mudflow flow velocity is usually 2.5-4.0 m/s, but when the blockage breaks, it can reach 8-10 m/s or more. The consequences of mudflows are catastrophic. So, on July 8, 1921, at 21:00, a mass of earth, silt, stones, snow, sand, driven by a mighty stream of water, fell on the city of Alma-Ata from the side of the mountains. This stream was demolished at the foot of the city buildings along with people, animals and orchards. A terrible stream broke into the city, turned its streets into raging rivers with steep banks of destroyed houses. The horror of the catastrophe was aggravated by the darkness of the night. There were cries for help that were almost impossible to say. Houses were torn off their foundations and carried along with the people by a stormy stream.

By the morning of the next day, the elements had calmed down. The material damage and loss of life were significant. Mudflow was caused by heavy rains in the upper part of the river basin. Small Almaty. The total volume of the mud stone mass was about 2 million m 3 . The stream cut the city with a 200-meter strip.

Ways to deal with mudflows are very diverse. This is the construction of various dams to delay solid runoff and pass a mixture of water and fine fractions of rocks, a cascade of dams to destroy the mudflow and free it from solid material, retaining walls to strengthen slopes, upland runoff intercepting and catchment ditches to divert runoff to the nearest watercourses, etc. Mudflow forecasting methods do not currently exist. At the same time, for some rural areas, certain criteria have been established to assess the likelihood of mudflows. So, for areas with a high probability of mudflows of storm origin, the critical amount of precipitation for 1-3 days is determined, mudflows of glacial origin (i.e., formed during outbursts of glacial lakes and intraglacial reservoirs) - the critical average air temperature for 10-15 days or a combination of these two criteria.

Landslide

Landslide - sliding and separation of masses of rocks down the slope under the influence of gravity.

Scientific interpretation of the term:

A landslide is a detached mass of loose rocks, slowly and gradually or abruptly sliding along an inclined plane of separation, while often retaining its coherence and solidity and not overturning.

Landslides occur on the slopes of valleys or river banks, in the mountains, on the shores of the seas, the most grandiose at the bottom of the seas. Landslides most often occur on slopes composed of alternating water-resistant and water-bearing rocks. The displacement of large masses of earth or rock along a slope or cliff is caused in most cases by wetting the soil with rainwater so that the mass of soil becomes heavy and more mobile. It can also be caused by earthquakes or the undermining work of the sea. The friction forces that ensure the adhesion of soils or rocks on the slopes are less than the force of gravity, and the entire mass of the soil (rock) begins to move. Landslides are classified as gravitational landforms.

underwater landslides

Underwater landslides remained unexplored for a long time. Only their consequences - tsunamis make themselves felt. They are formed when large masses of sedimentary rocks are sheared off at the edge of the shelf. For example, the volume of the Sturegg landslide on the slope of Norway has an area of ​​the whole country and is about 3900 km 3 , and the range of movement of material in it reaches 500 km. The volume of only one such landslide is more than 300 times the annual supply of sedimentary material to the World Ocean by all the rivers of the Earth. In Scotland, traces of the tsunami that followed the landslide were found at a distance of 80 km from the coast.

The reason for the formation of landslides is the imbalance between the shearing force of gravity and the holding forces. It is called:

an increase in the steepness of the slope as a result of washing with water;

weakening of the strength of rocks during weathering or waterlogging by precipitation and groundwater;

the impact of seismic shocks;

construction and business activities.

Characteristic

As a result of its activity, a landslide creates a "landslide body", which in plan is basically in the shape of a semicircle, forming a depression in the middle. As noted above, landslides occur on slopes composed of alternating water-resistant (argillaceous) and water-bearing rocks. Displacement of rock blocks with a volume of tens of cubic meters or more on steep slopes as a result of wetting of separation surfaces with groundwater.

Such natural disasters harm agricultural lands, enterprises, and settlements. To combat landslides, bank protection structures and planting of vegetation are used.

Classification

According to the power of the landslide process, i.e., the involvement of masses of rocks in the movement, landslides are divided into small - up to 10 thousand cubic meters, medium - 10-100 thousand cubic meters, large - 100-1000 thousand cubic meters , very large - over 1000 thousand cubic meters.

The surface along which the landslide breaks off and moves down is called the sliding or displacement surface; according to its steepness they distinguish:

b) gentle (5°-15°);

c) steep (15°-45°).

According to the depth of the sliding surface, landslides are distinguished: surface - no deeper than 1 m - mudslides, alloys; small - up to 5 m; deep - up to 20 m; very deep - deeper than 20 m.

Landslide classification (according to Savarinsky) according to the position of the displacement surface and the composition of the landslide body:

a) asequential (in some sources they indicate as sequet) - occur in homogeneous non-layered rock strata; the position of the curved sliding surface depends on friction and soil displacement;

b) consequential (sliding) - occur with a non-uniform slope; displacement occurs along the interface between layers or a crack;

c) incremental - also occur when the slope is inhomogeneous, but the displacement surface crosses layers of different composition; the landslide cuts into horizontal or sloping layers.

Security measures

Preventive measures

Study information about possible locations and approximate boundaries of landslides, remember the signals for warning of the threat of a landslide, as well as the procedure for issuing this signal. Signs of an impending landslide are jamming of doors and windows of buildings, seepage of water on landslide-prone slopes. If there are signs of an approaching landslide, report it to the nearest post of the landslide station, wait for information from there, and act according to the situation yourself.

How to deal with a landslide

When receiving signals of the threat of a landslide, turn off electrical appliances, gas appliances and water supply, prepare for immediate evacuation according to pre-developed plans. Depending on the landslide displacement speed detected by the landslide station, act according to the threat. With a low displacement rate (meters per month), act according to your capabilities (move buildings to a predetermined place, take out furniture, things, etc.). If the landslide displacement speed is more than 0.5-1.0 m per day, evacuate in accordance with a previously worked out plan. When evacuating, take documents, valuables with you, and, depending on the situation and instructions from the administration, warm clothes and food. Urgently evacuate to a safe place and, if necessary, help the rescuers in digging, extracting victims from the collapse and rendering assistance to them.

Actions after the displacement of the landslide

After the displacement of the landslide in the surviving buildings and structures, the condition of the walls, ceilings is checked, damage to the lines of electricity, gas, and water supply is revealed. If you are not injured, then, together with the rescuers, remove the injured from the rubble and provide first aid.