Landslide- a dangerous geological phenomenon, the displacement of the masses of rocks along the slope under the influence of its own weight and additional load due to erosion of the slope, waterlogging, seismic shocks and other processes. 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. Most often, landslides occur on slopes composed of alternating impermeable and aquifers. The displacement of large masses of land or rock along a slope or cliff is caused in most cases by wetting the soil with rainwater so that the mass of the soil becomes heavier and more mobile. It can also be caused by earthquakes or the destructive activity of the sea. The frictional forces that ensure the adhesion of soils or rocks on slopes are less than gravity, and the entire mass of rock is set in motion.
Causes
Landslides are caused by the imbalance between the shear force of gravity and the holding forces. It is called:
- an increase in the steepness of the slope as a result of water washout;
- weakening of the strength of rocks during weathering or waterlogging by precipitation and groundwater;
- the impact of seismic shocks;
- construction and economic activities.
Landslides usually occur on slopes composed of alternating water-resistant (clay) and aquifers. The displacement of rock blocks with a volume of tens of m³ and more on steep slopes occurs as a result of wetting of the separation surfaces by groundwater.
Such natural disasters harm agricultural land, businesses, and settlements. To combat landslides, bank protection structures and planting of vegetation are used.
Classification
According to the power of the landslide process, that is, the involvement of rock masses in the movement, landslides are divided into small - up to 10 thousand m³, medium - 10-100 thousand m³, large - 100-1000 thousand m³, very large - over 1000 thousand m³. m³.
The surface along which the landslide breaks off and moves downward is called the sliding or displacement surface; according to its steepness, they are distinguished:
By the depth of the sliding surface, landslides are distinguished:
- surface - not deeper than 1 m - mudslides, alloys;
- small - up to 5 m;
- deep - up to 20 m;
- very deep - deeper than 20 m.
Classification of landslides (according to Savarensky) according to the position of the displacement surface and the addition of the landslide body:
- Asequential(in some sources they are indicated as sequential) - occur in homogeneous non-layered rock strata; the position of the curved sliding surface depends on friction and soil displacement;
- Consequent(sliding) - occur when the slope is inhomogeneous; displacement occurs along the interface of layers or a crack;
- Insequent- also occur when the slope is inhomogeneous, but the displacement surface intersects layers of different composition; the landslide cuts into horizontal or inclined layers.
Underwater landslides
Underwater landslides remained unexplored for a long time. Only their consequences - tsunamis - make themselves felt. Formed during the breakdown of large masses of sedimentary rocks at the edge of the shelf. Underwater landslides are much larger than surface ones. For example, the Sturegga landslide on the slope of Norway has an area of about 3900 km², and the range of material movement in it reaches 500 km. The volume of only one such landslide is more than 300 times greater than the annual supply of sedimentary material to the World Ocean by all 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.
Security measures
Preventive measures
To warn you when you know about the possible locations and approximate boundaries of landslides, remember the warning signals about the threat of a landslide, and the order of action when this warning is given. Signs of an impending landslide are jamming of doors and windows of buildings on the lower floors, water seepage 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 yourself depending on the situation.
How to deal with a landslide
When receiving signals about the threat of a landslide, turn off electrical appliances, gas appliances and water supply network, prepare for immediate evacuation according to pre-developed plans. Depending on the rate of displacement of the landslide detected by the landslide station, act in accordance with the threat. With a low speed of displacement (meters per month), act according to your capabilities (transfer buildings to a pre-designated place, take out furniture, things, etc.). If the rate of displacement of the landslide 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 rescuers in digging, extracting victims from the collapse and providing assistance to them.
Actions after landslide displacement
After the displacement of the landslide in the surviving buildings and structures, the condition of the walls, ceilings is checked, and 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 blockage and provide first aid.
Largest landslides
The largest landslide in the Solar System is likely formed by Mount Euboea on Jupiter's moon Io. Its volume is estimated at about 25,000 km 3.
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Notes (edit)
Literature
- Landslides. Research and strengthening. M., 1981
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Excerpt from Landslide
- Only Countess Elena Vasilievna, considering for herself humiliating the company of some Bergs, could have the cruelty to refuse such an invitation. - Berg explained so clearly why he wanted to gather a small and good society, and why it would be pleasant for him, and why he spared money for cards and for something bad, but for a good society he was ready and incurred expenses that Pierre could not refuse and promised to be.- Only it's not too late, Count, if I dare to ask, then at ten minutes to eight, I dare to ask. We will make a party, our general will be. He is very kind to me. We'll have supper, Count. So do me a favor.
Contrary to his habit of being late, Pierre that day, instead of eight minutes to ten, arrived at the Bergam at eight at a quarter.
Bergie, having primed what was needed for the evening, were already ready to receive guests.
In a new, clean, light, decorated with busts and pictures and new furniture, Berg sat with his wife. Berg, in a brand new buttoned up uniform, was sitting next to his wife, explaining to her that it is always possible and necessary to have acquaintances from people who are superior to themselves, because then only there is a pleasantness from acquaintances. - “If you change something, you can ask for something. Look how I lived from the first ranks (Berg considered his life not years, but the highest awards). My comrades are nothing now, and I am at the vacancy of the regimental commander, I have the good fortune to be your husband (he got up and kissed Vera's hand, but on the way to her he turned back the corner of the rolled carpet). And how did I acquire all this? The main thing is the ability to choose your acquaintances. It goes without saying that one must be virtuous and orderly. "
Berg smiled with the consciousness of his superiority over a weak woman and fell silent, thinking that after all, this sweet wife of his is a weak woman who cannot comprehend all that constitutes a man's dignity - ein Mann zu sein [to be a man]. At the same time, Vera also smiled with the consciousness of her superiority over a virtuous, good husband, but who, like all men, according to Vera's concept, still mistakenly understood life. Berg, judging by his wife, considered all women weak and stupid. Vera, judging by her husband alone and spreading this remark, believed that all men ascribe reason only to themselves, and at the same time they do not understand anything, are proud and egoists.
Berg got up and, hugging his wife carefully so as not to wrinkle the lace cape he paid dearly for, kissed her in the middle of her lips.
“Only one thing so that we don’t have children so soon,” he said after his unconscious filiation of ideas.
“Yes,” Vera answered, “I don't want that at all. We must live for society.
“This is exactly what Princess Yusupova was wearing,” said Berg, with a happy and kind smile, pointing to the cape.
At this time, the arrival of Count Bezukhoi was reported. Both spouses looked at each other with a smug smile, each ascribing to himself the honor of this visit.
"This is what it means to be able to make acquaintances, thought Berg, this is what it means to be able to hold oneself!"
- Only please, when I entertain guests, - Vera said, - you don't interrupt me, because I know what to do with everyone, and in what society what to say.
Berg smiled too.
“It’s impossible: sometimes there should be a man’s conversation with men,” he said.
Pierre was received in a brand new living room, in which it was impossible to sit anywhere without breaking symmetry, cleanliness and order, and therefore it was quite understandable and not strange that Berg generously proposed to destroy the symmetry of an armchair or sofa for a dear guest, and apparently being in in this regard, in painful hesitation, he proposed a solution to this issue for the guest's choice. Pierre upset the symmetry by moving a chair for himself, and at once Berg and Vera began the evening, interrupting each other and engaging the guest.
Vera, having decided in her mind that Pierre should be kept busy with the conversation about the French embassy, immediately began this conversation. Berg, deciding that a man's conversation was also necessary, interrupted his wife's speech, touching on the question of the war with Austria and involuntarily jumped from the general conversation to personal considerations about the proposals that were made to him to participate in the Austrian campaign, and about the reasons why he did not accept them. Despite the fact that the conversation was very awkward, and that Vera was angry at the intervention of the masculine element, both spouses felt with pleasure that, despite the fact that there was only one guest, the evening was started very well, and that the evening was like two a drop of water is like every other evening with conversations, tea and lighted candles.
Boris, Berg's old comrade, arrived soon after. He treated Berg and Vera with a touch of superiority and patronage. A lady and a colonel came for Boris, then the general himself, then the Rostovs, and the evening was already quite, undoubtedly, like all evenings. Berg and Vera could not help smiling at the sight of this movement around the living room, at the sound of this incoherent talk, rustling of dresses and bows. Everything was like everyone else, the general was especially alike, praising the apartment, patting Berg on the shoulder, and with fatherly arbitrariness ordered the setting of the boston table. The general sat down with Count Ilya Andreich, as the most distinguished of the guests after himself. Old men with old men, young with young, the hostess at the tea table, on which there were exactly the same cookies in a silver basket that the Panins had at the evening, everything was exactly the same as at the others.
Pierre, as one of the most honored guests, was to sit in Boston with Ilya Andreich, general and colonel. At the Boston table, Pierre had to sit opposite Natasha, and the strange change that had taken place in her since the day of the ball struck him. Natasha was silent, and not only was she not as good as she was at the ball, but she would have been bad if she did not have such a meek and indifferent appearance to everything.
"What with her?" thought Pierre, looking at her. She was sitting beside her sister at the tea table and reluctantly, without looking at him, answered something to Boris who had sat down with her. Having departed a whole suit and took five bribes to the delight of his partner, Pierre, who heard the chant of greetings and the sound of someone's footsteps entering the room during the collection of bribes, looked at her again.
Landslide- These are large masses of dirt and rocks that slide down the slopes under the influence of gravity. Most often, landslides occur on the slopes of valleys or river banks, on the shores of the seas and in the mountains. The causes of a landslide can be different: the erosion of the slope by water, and the action of an earthquake, and human activity. A landslide that has come down can cause considerable damage to agriculture, enterprises and settlements. People struggle with landslides in the same way as with mudflows: they plant trees, build structures.
According to I.V. Popov, landslide is called the displacement of rock blocks with a volume of tens of cubic meters or more on steep slopes as a result of wetting of the separation surfaces by groundwater. It is the rock blocks that slide, while retaining (within the blocks) their original structure. Sliding rocks are usually loose or poorly cemented. A slumping block may contain separate interlayers or lenses of hard rock. When sliding, the rock is partially crushed, turning into a brecciated structureless mass. The accumulation of landslide masses at the foot of the slopes is called delapse.
Landslides occur when the stability of the slope is disturbed by natural processes or people. The forces of connectivity of soils or rocks are at some point less than the force of gravity, the whole mass starts to move, and a catastrophe may occur.
Earth masses can slide along slopes at a barely noticeable speed (such displacements are called slow, or creep). In other cases, the rate of displacement of weathering products turns out to be higher (for example, meters per day), sometimes large volumes of rocks collapse at a rate exceeding the speed of the express. All these are slope displacements - landslides. They differ not only in the rate of displacement, but also in the scale of the phenomenon. Geoscientists use a variety of scientific and technical terms to classify them.
The most commonly used name is "landslide". One of the world's most respected specialists on landslides, academician Quido Zaruba, defines a landslide as follows: “It is a sharp displacement of rocks, in which moving masses are separated from a monolithic base by a visible sliding surface”. He further points out that the landslide refers to both the process itself and the landforms resulting from this process.
Landslide Formation Conditions.
Slumping occurs in loose, poorly cemented rocks due to the fact that a steep and high slope, as it is cut by a river, a reservoir, or the sea, loses its stability, and significant rock masses begin to move down the slope in large blocks. Landslide movement is always associated with the presence of groundwater. Their abundance is a necessary condition for landslide. However, one must clearly understand that it is not the groundwater that is the cause of the landslide. Often we see that the steep slope of the valleys is prone to landslides, and next to it, upstream or downstream with the same geological structure, with the same water abundance of aquifers and the same height of the groundwater level, there are no landslides simply because the slope is slightly more sloping. Landslides are rarely observed on slopes less than 10-12 degrees steep. And with a slope of 15 degrees, landslides occur only under favorable geological and hydrogeological conditions. But a sufficient moisture content of the rocks, which ensures their plasticity, is always necessary. We can say that if a number of necessary conditions are met, landslides are a function of the slope steepness and height. But you can't say. That a landslide is a function of the presence of groundwater. For the occurrence of landslides, the most favorable geological conditions are when at the base of the landslide slope there are impermeable strata, and above there are aquifers. But even if the slope is composed only of aquifers, and there is no impervious layer, there will still be an unloading of groundwater, the level of which will gradually decrease from the interfluves towards the valley or the coast of the sea (lake). With sufficient steepness and height of the slopes, landslides will inevitably occur.
Landslides can be caused by various factors. The earth's surface consists mainly of slopes. Some of them are stable, others become unstable due to various conditions. This happens when the slope of the slope changes or if the slope is weighed down by loose material. Thus, the force of gravity is greater than the force of cohesion of the soil. The slope becomes unstable even with tremors. Therefore, each earthquake in mountainous terrain is accompanied by displacements along the slope. The formation of landslides is especially favored by such a bedding of rocks in which the fall of the roof of the waterproof rocks coincides with the direction of the slope of the surface. In this case, the water-resistant horizon serves as a sliding surface along which a more or less significant block of rock slides down the slope. The instability of the slope is also facilitated by an increase in the water content of soils, loose sediments or rocks. Water fills the pores and breaks the adhesion between soil particles. Interstitial water can act like a lubricant and facilitate sliding. The connectivity of rocks can be disrupted by freezing and weathering processes. The instability of the slopes can also be associated with a change in the type of plantations or the destruction of vegetation cover.
The matter is also serious when the rocky rocks on the slope are covered with loose material or soil. Loose deposits are easily separated from the underlying rocks, especially if the sliding plane is “smeared” with water. Unfavorable (from the point of view of the possibility of landslides) and those cases when the rocks are represented by layers of hard limestone or sandstone with underlying softer clay shale. As a result of weathering, a dividing plane is formed, and the strata slide down the slope. In this case, everything depends mainly on the orientation of the layers. When the direction of their fall and the slope are parallel to the slope, it is always dangerous. It is difficult to accurately determine the value of the slope angle, more than which the slope is not stable, and less than which is stable. Sometimes this critical angle is defined as 25 degrees. The steeper slopes seem to be no longer stable. The occurrence of landslides is most influenced by rainfall and shaking. Landslides always occur during strong earthquakes. As for rainfall, it depends on many conditions. For example, in the Alps, the amount of precipitation above 2500 mm is taken as the critical boundary. The fallout of such an amount of precipitation in a short period of time is an acute danger.
Classification:
Among the landslide phenomena, the following types can be identified:
1. Slumping of rock blocks (block or structural).
2. Slip of the cover of loose sediments (one-time and rapid) on the surface of rocky or frozen - landslides-slides.
3. Slumping of small blocks - sinking, covering the entire slope or a significant part of it.
4. Subsidence of slopes, displacement of blocks of rocky or semi-rocky rocks.
In accordance with this, it is possible to consider landslide slopes, slopes of sliding of the cover of loose sediments (slopes of landslides-slides), sliding slopes and slopes of subsidence.
Structural landslides are classified according to different criteria. A.P. Pavlov still in the last century divided landslides into detrusive and delapsive. The first landslides “push” plastic rocks in front of their lower end, deforming them. The second slide freely to the edge of the river, sea, lake.
In relation to the structure of rocks that compose the slopes, landslides are divided into the following types:
1.sequential, developed in homogeneous rocks;
2.Consequent, occurring along the planes of bedding rocks or along the planes of faults;
3.insequential, which are characterized by the intersection of creep planes of bedding surfaces or fault planes.
Landslides can occur on one high-level tier - single-tiered or on several - multi-tiered. Multi-tiered landslides are observed in the mountains and less often on the plains, mainly where the height of the slopes reaches 100-200 meters.
According to the time during which the sliding process takes place, landslides are distinguished, simultaneous, periodic and permanent. It is possible to distinguish between modern landslides, recent (occurring decades ago), old - sliding during historical time, that is, less than 3-5 thousand. years ago, and the ancients - geologically remote from us for long periods of time is an acute danger. All slope processes can be subdivided into three categories based on the displacement rate: slow, medium-speed displacements, and fast.
Landslide protection.
The most effective protection against landslides is their prevention. It would be ideal to avoid slopes altogether, but in our conditions this is not possible. Therefore, specialists in engineering geology, soil mechanics and construction equipment have developed comprehensive preventive measures. When the landslide has already begun, it is too late to carry out preventive work. To avoid slipping, it is not allowed to: 1) overload the upper part of the landslide; 2) undercutting of the base (by the river, reservoir, engineering measures); 3) additional moistening of the entire slope. It is known that water is the main cause of landslide. Therefore, the first stage of conservation work should be the collection and disposal of surface waters. In a landslide-prone area, it is recommended to drain the water from the wells. This is followed by dehumidification using underground drainage. The artificial transformation of the relief is also of great importance. In the separation zone, the load on the slope is reduced, thereby weakening the effect of gravity and increasing the adhesion forces of the rocks. There is a whole range of recommended technical operations, such as: anchorage of slopes, destruction of slip planes, injection of reinforcing mortars, anchorage of slopes with piles and construction of retaining walls. Both the degree of preparedness and the speed of action are important: at later stages, the fight against landslide processes will require much more effort.
Page 1LANDSLIDES.
Landslides are sliding displacements of rock masses down a slope under the influence of gravity. They occur on the slopes of mountains, ravines, hills, on the banks of rivers.
Landslides occur when the stability of the slope is disturbed by natural processes or people. The forces of binding of soils or rocks are at some point less than the force of gravity, the whole mass is set in motion and a catastrophe may occur.
Earth masses can slide along slopes at a barely noticeable speed (such displacements are called slow). In other cases, the rate of displacement of weathering products turns out to be higher (for example, meters per day), sometimes large volumes of rocks collapse at a rate exceeding the speed of the express. All these are slope displacements - landslides. They differ not only in the rate of displacement, but also in the scale of the phenomenon.
The consequences of landslides.
Landslides can destroy homes and endanger entire communities. They threaten agricultural land, destroy it and make it difficult to cultivate it, pose a threat to the exploitation of quarries and the extraction of minerals. Landslides damage communications, tunnels, pipelines, telephone and electrical networks; threaten water facilities, mainly dams. In addition, they can block the valley, form temporary lakes and contribute to floods, as well as generate disastrous waves in lakes and bays, and underwater landslides tear telephone cables. As a result of landslides, river beds, roads can overlap, and the landscape changes. Landslides threaten road and rail traffic safety. Destroy and damage bridge supports, rails, road surfaces, oil pipelines, hydroelectric power plants, mines and other industrial enterprises, mountain villages. Arable land below the landslide areas is often waterlogged. At the same time, there is a loss of yield and an intensive process of land retirement from agricultural use.
These phenomena can cause significant damage to the cultural and historical heritage of peoples, the state of mind of people inhabiting mountainous areas.
Landslides mainly occur in areas of living tectonics, where the processes of slow sliding of blocks of the earth's crust along faults and rapid movements in the foci of earthquakes interact and alternate.
Landslides on the territory of the Russian Federation take place in the mountainous regions of the North Caucasus, the Urals, Eastern Siberia, Primorye, about. Sakhalin, Kuril Islands, Kola Peninsula, as well as on the banks of large rivers.
Landslides often lead to large-scale disasters For example, the landslide of 1963 in Italy with a volume of 240 million cubic meters. meters covered 5 cities, while killing 3 thousand people. In 1989, landslides in Checheno-Ingushetia caused damage in 82 settlements of 2,518 houses, 44 schools, 4 kindergartens, 60 health care, culture and consumer services.
Occurrence and classification of landslides.
1. Natural causes of landslides.
Landslides can be caused by various factors. The entire earth's surface consists mainly of slopes. Some of them are stable, others, due to various conditions, become unstable. This happens when the slope angle changes or if the slope is burdened with loose materials. Thus, the force of gravity is greater than the force of cohesion of the soil. The slope becomes unstable even with tremors. Therefore, each earthquake in mountainous terrain is accompanied by displacements along the slope. The instability of the slope is also facilitated by an increase in the water content of soils, loose sediments or rocks. Water fills the pores and breaks the adhesion between soil particles. Interstitial water can act like a lubricant and facilitate sliding. The connectivity of rocks can be disrupted during freezing, and in the processes of weathering, leaching, and leaching. The instability of the slopes can also be associated with a change in the type of plantations or the destruction of vegetation cover.
The matter is also serious when the rocky rocks on the slope are covered with loose materials or soil. Loose deposits are easily separated from the underlying rocks,
especially if the sliding plane is "smeared with water".
Unfavorable (from the point of view of the possibility of
landslides) and those cases when rocks are presented
layers of hard limestone or sandstone with
underlying softer shales. As a result of weathering, a dividing plane is formed, and the strata slide down the slope. In this case, everything depends mainly on the orientation of the layers. When the direction of their fall and the slope are parallel to the slope, it is always dangerous. It is impossible to accurately determine the value of the slope angle, more than which the slope is unstable, and less than which is stable. Sometimes this critical angle is defined as 25 degrees. The steeper slopes appear to be already unstable, and landslides are most influenced by rainfall and tremors. Landslides always occur during strong earthquakes. Also, the occurrence of landslides is influenced by: the intersection of rocks by cracks, the arrangement of soil layers with an inclination towards the slope, the alternation of waterproof and aquifers, the presence of softened clays and floating sands in the soil, an increase in the steepness of the slope, as a result of erosion (on river banks).
2. Anthropogenic causes of landslides.
Landslides can be caused by deforestation of forests and shrubs on slopes, plowing of slopes, over-irrigation of slopes, plugging, and blockage of groundwater outlets.
The occurrence of landslides is influenced by the production of blasting operations, as a result of which cracks are formed, and this is also an artificial earthquake.
Landslides can form when slopes are destroyed by foundation pits, trenches and road cuts. Such landslides can occur during the construction of housing and other facilities on the slopes.
Landslide classification.
1. By material
rocks
B) soil layer
mixed landslides
are subdivided into:
extremely fast (3m / s)
B) very fast (Zdm / m)
fast (1.5 meters per day)
D) moderate (1.5 m per month)
They are not catastrophic. They are called dragging, creeping displacement of loose deposits, as well as sliding and slipping. This is really moving - sliding, because its speed does not exceed several tens of centimeters per year. Such displacement can be recognized by the curved trunks of trees growing on the slope, the bending of the seams and the surface, the so-called stripping, and with the help of sensitive instruments.
Solifluction and gelifluction are types of such slow displacements. Previously, solifluction was understood as displacement in soils and loose sediments saturated with water. Later, this term was extended to glacial conditions, where soils are displaced due to the alternation of freezing and thawing. Currently, it is recommended to use the term "gelifluction" to denote displacements caused by alternating freezing and thawing. The danger of these slow displacements is that they can gradually turn into rapid and then catastrophic displacement. Many large landslides began with loose material slumping or slow sliding of rock blocks. Average speed offset (fast).
Displacements that occur at a rate of meters per hour or meters per day. These include most of the typical landslides. The landslide area consists of a separation zone, a slip zone and a frontal zone. In the separation zone, the main separation crack and the slip plane along which the landslide body separated from the underlying rock can be distinguished.
Fast offsets.
Only rapid landslides can cause real disasters with hundreds of human lives. Such displacements include those whose speed is several tens of kilometers per hour (or much more), when escape is impossible (there is no time for a real evacuation).
There are different types of such disasters: "Rock collapse". Landslides - flows occur when solid material
mixes with water and flows at high speed. Landslides - streams can be mud (they include volcanic mud streams), stony or transitional. Avalanches, both snow and snow-stone, also belong to fast displacements.
3. By the scale, landslides are subdivided:
A) large
B) medium
C) small-scale.
Large landslides are usually caused by natural causes and form along the slopes for hundreds of meters. Their thickness reaches 10 -20 meters and more. The landslide body often retains its solidity.
Medium and small-scale landslides are smaller and are characteristic of anthropogenic processes.
4. The scale of landslides is characterized by the involvement in the process
area:
grandiose -400 hectares and more
B) very large - 200-400 hectares
large - 100-200 ha
D) medium - 50-100 hectares
D) small 5-50 hectares
5. By volume ( power)
A) small (10 thousand cubic meters)
B) medium (from 10 to 100 thousand cubic meters)
B) large (from 100 thousand to 1 million cubic meters)
D) very large (more than 1 million cubic meters)
6. By activity, landslides can be:
A) active
B) not active
Their activity is determined by the degree of capture of the bedrock of the slopes and the speed of movement, which can range from 0.06 m / year to 3 m / s
7.
Depending on the availability of water:
A) dry
B) slightly moist
B) very wet
8.
By the mechanism of the landslide process:
A) Shear landslides
B) extrusion
B) viscoplastic
D) hydrodynamic
D) sudden liquefaction
Landslides often show signs of a combined mechanism.
9. According to the place of formation, landslides are subdivided:
A) mountain
B) coastal
C) underwater, (B, C,) can cause tsunamis
D) snowy
E) landslides of artificial earth structures (canals,
pits ...)
The magnitude of the consequences is determined by:
the size of the population trapped in the landslide zone
the number of dead, injured, homeless
the number of settlements caught in the zone of natural
disasters
the number of objects of the national economy, medical
health and social and cultural institutions,
found destroyed and damaged
land
6) the number of dead farm animals.
Landslide protection measures.
The population living in landslide zones should know the foci, possible directions and characteristics of this dangerous phenomenon. Based on the forecast data, residents are informed in advance about the danger and measures regarding the identified landslide foci and possible zones of their action, as well as the procedure for signaling the threat of this dangerous phenomenon. Also, earlier informing people reduces the impact of stress and panic, which may arise later when transmitting emergency information about the imminent threat of a landslide.
The population of hazardous areas is also obliged to carry out measures to strengthen houses and territories on which they are built, as well as to participate in the construction of protective hydraulic engineering and other engineering structures. The population is alerted with the help of sirens, radio, television, as well as local warning systems.
In case of a landslide threat and if there is time, an early evacuation of the population, farm animals and property to safe areas is organized. Valuable property that cannot be taken with you should be protected from moisture and dirt. Doors and windows, ventilation and other openings are tightly closed. Electricity, gas, water supply are cut off. Flammable, poisonous and other hazardous substances are removed from the house and, as soon as possible, are buried in pits or cellars. In all other respects, citizens act in accordance with the procedure established for organized evacuation.
When there is a threat of a natural disaster, residents, taking care of the property, make an emergency independent exit to a safe place. At the same time, neighbors, all people on the way should be warned about the danger. For an emergency exit, it is necessary to know the paths of movement to the nearest safe places (mountain slopes, hills, not prone to landslide process).
In the case when people, buildings and other structures find themselves on the surface of a moving landslide area, leaving the room, move upward as much as possible, acting according to the situation, beware when braking the landslide of blocks, stones, debris, structures, earthen wall rolling down from its rear part , talus.
After the end of the landslide, people who hastily left the disaster zone and waited for it in a nearby safe place should, after making sure that there is no repeated threat, return to this zone in order to search for and provide assistance to the injured.
Landslide observation and forecasting.
Monitor unusual incidents, behavior
animals, for precipitation.
Analysis and forecasting of possible landslides.
A) rock mass analysis
B) analysis of the conditions of already known and existing landslides.
B) experience and special knowledge.
3. Carrying out complex protective engineering works.
They are active measures of protection against landslides.
1) Planning slopes, leveling bumps, filling cracks
Implementation of planned and strictly metered explosions
Construction of tunnels and sheltered fences, as well as protective walls
Reducing the steepness of a slope using technique or directional explosions
Construction of roads, flyovers, viaducts
Construction of retaining walls, construction of rows of piles
The device of the guiding walls
Interception of groundwater by the drainage system (system of special pipes), regulation of surface runoff with patches and ditches
Protection of slopes by sowing grasses, trees and shrubs
Relocation of power lines, oil and gas pipelines and
other objects in safe areas
Protection of slopes, road, road and railroad embankments by concreting and landscaping.
Education for people living, working and resting in hazardous areas
Compliance with the safe mode, building codes and regulations, as well as instructions and standards.
The tongues of mountain glaciers descend into the valleys, where sometimes they even come directly to settlements. In many alpine valleys of the glacier, you can, as they say, touch with your hand. Usually, the translational movement of glacial tongues occurs at a speed of several meters per year, while they melt and feed mountain rivers with water. However, it happens that for some reason the glacier loses its stability and suddenly moves tens or even hundreds of meters in a few days. By itself, this phenomenon does not yet represent a catastrophe, however, the situation is worse when, having lost its stability, the glacier breaks off and falls into the valley.
These are turbulent streams with mud and boulders. The main component of this mixture is water, it is it that determines the movement of the entire mass. The immediate causes of the onset of mudflows are heavy rainfall, washing of water bodies, intensive melting of snow and ice, earthquakes and volcanic eruptions, deforestation, rock explosions during road construction, improper organization of dumps.
Mudflows carry either small particles of solid material or coarse debris. In accordance with this, there are stone streams, mud - stone and mud streams.
Snow avalanches.
Avalanches are also referred to as landslides. Large avalanches are disasters that claim dozens of lives. Every year several people die under the avalanches in our mountains; on the scale of Europe and the whole world, the number of victims of avalanches is much higher.
From the point of view of mechanics, an avalanche occurs in the same way as other landslide displacements. The forces of snow displacement cross a certain boundary, and gravity causes the snow masses to shift along the slope. An avalanche is a mixture of snow and air crystals. Snow quickly changes its properties after falling out, that is, it undergoes metamorphism. Snow crystals grow, the porosity of the snow mass decreases. At a certain depth below the surface, recrystallization can lead to the formation of a sliding surface over which the snow layer will slide. The force of gravity determines the occurrence of tensile forces at the top of the slope. Disturbances of the snow layer in these places usually lead to the occurrence of an avalanche.
The critical angle in this case is 22 degrees. However, this does not mean that an avalanche cannot occur on less steep slopes. Large avalanches occur on the slopes of 25-60 degrees. Their occurrence depends not only on the absolute slope, but also on the profile of the slope. Concave slopes are less avalanche hazard than convex slopes. The bulge of the slope increases the stretching directions, although in winter it is not visible what is hidden under the snow, however, the so-called micro-relief largely determines the possibility of avalanches. Smooth grassy slopes are avalanche-prone. Shrubs, large rocks and other obstacles of this nature keep avalanches from occurring. In the forest, avalanches are very rare, but single trees on the slope do not prevent avalanches from occurring. The orientation of the slope is important: there are fewer avalanches on the southern slopes at the beginning of winter, but at the end of winter, the southern slopes become avalanche-prone, because as a result of melting, the snow cover loses its stability.
There are two main types of avalanches: dust and formation avalanches.
Dust avalanches are formed by a shapeless mixture of snow dust. There is no sliding plane between the shifting snow and the underlying snow. More and more snow is added from below, and the avalanche grows. Such avalanches often occur in one place or in a limited area. The formation avalanches are separated by a sliding plane from the base. They arise, like landslides, along the separation zone and slide in the form of a layer, both along the underlying older layers of snow and along the bedrock slope. Formation avalanches are more dangerous than dust ones.
According to their shape, avalanches are also divided into two types: trough avalanches, rolling down hollows and gorges, and flat wasps, moving along a flat surface.
The avalanche speed varies over a wide range. Dust avalanches are faster. Those with a lot of air can reach speeds of up to 120-130 km / h. Heavy dust avalanches move at a speed of 50-70 km / h. Formation avalanches are slower, their speed is 25-36 km / h.
In terms of size, avalanches are divided into large, medium, and small. The big ones destroy everything in their path. Mediums are dangerous only for people, small ones are practically not dangerous.
There are several indirect causes of avalanches: slope instability, snow recrystallization, formation of a slip plane, snow deposits with a larger slope angle than the slope. Concussion is often the direct cause. And a stone falling on a snowy field can cause an avalanche. Avalanches capture in their movement people who cross the snowy massif, prepared for separation. A lot of controversy raises the question of whether the avalanche can be caused by sound. The majority expresses doubt on this score.
Avalanche protection.
As with other landslide displacements, preventive measures are essential. Avalanche elephants are easy to recognize. Studies of previous avalanches are important, as most of them descend on the same slopes, although exceptions are possible.
For avalanche forecasting, both the wind direction and the amount of precipitation are important. When 25 mm of fresh snow falls, the occurrence of avalanches is possible, at 55 mm they are very likely, and at 100 mm one has to admit the possibility of their occurrence
In a few hours. The probability of avalanches is calculated from the rate of melting of the snow field.
Avalanche protection can be passive or active.
With passive protection, avalanche slopes are avoided or defensive shields are installed.
Active protection consists in shelling avalanche slopes. Thus, they cause the descent of small, harmless avalanches and prevent the accumulation of critical masses of snow.
Snow avalanches cause great damage and loss of life. So, on July 13, 1990, at Lenin Peak in the Pamirs, as a result of an earthquake, a large snow avalanche demolished the camp of climbers located at an altitude of 5300 m. 48 people died.
Bibliography.
Zdenek Kukal "Natural Disasters" Ed. 23nanie "Moscow 1985
Encyclopedia of Security, V.G. Ponamarev
Ed. 2Stalker "1997
E.P. Emelyanova "Basic laws of landslide processes"
Ed. "Nedra" Moscow 1972
Unfortunately, even today, people sometimes find themselves powerless in the face of natural disasters, destroying houses, destroying property, and sometimes claiming human lives.
One of these disasters is a landslide - a phenomenon that is quite frequent in mountainous areas or uplands that are subject to erosion.
What is a landslide?
Landslides are called displacements of large masses of loose soil, which are separated from the slopes and rush down, sliding down an inclined plane into the valley. The soil can be dry or wet, in the latter case it is called mudflow or mudflow.
The speed of movement of landslides is different: sometimes a huge mass collapses in a matter of minutes, but often they move almost imperceptibly, at a speed not exceeding a few centimeters per year. A slow landslide can accelerate at any time and turn into an unexpected and dangerous landslide.
The distance covered by a landslide depends on its mass and the height of the fall. Some of them cover an area of up to 400 hectares. The scale of the phenomenon is determined by the amount of sliding rock mass:
- up to 10,000 cubic meters m - small landslide;
- from 10,000 to 100,000 cubic meters m - medium landslide;
- from 100,000 to 1,000,000 cubic meters m - large landslide;
- more than a million cubic meters m - the largest landslide. 
Fortunately, major landslides are rare, but sometimes dire. Whole villages can be buried under the mass of rock if the movement of the rock is not detected in time and people are not resettled.
How and where do landslides form?
These phenomena are most frequent in mountainous areas with a predominance of loose rocks, i.e. in geologically old mountains, where erosion has led to soil loosening. Landfalls are also frequent on the steep banks of rivers, where they occur mainly due to the erosion of the coast by water.
A visor of sandy or clayey rock forms above the water, which once collapses or slides down under its own weight. If a river landslide is large enough, it can even slightly change the river bed, forming a new bend or an island in it.
As a rule, mountain landslides form on slopes, the steepness of which reaches 19 degrees, and the height ranges from one to two thousand meters. If the soil consists mainly of clay and is highly moistened, then a slope of only 5 degrees is enough for the rock to move downward.
As in the case of river banks, the main cause of mountain landslides is the erosion of rocks by sedimentary water flows or groundwater. Landslides usually occur after heavy or prolonged rains, when the soil becomes saturated with water, heavy and has lost its usual adhesion between solid particles. Water acts as a lubricant to facilitate downward movement by gravity.
Less often, but also quite often, landslides occur as a result of tremors. They are most dangerous under water, on the sea shelf. A breakaway large section of the seabed can cause a giant wave - a tsunami, dangerous both for the nearby coast and for ships encountered on its way. 
In recent decades, landslides resulting from human activities have become more frequent. Rock collapse can cause ground vibration if a road is built near the slope and heavy trucks are constantly driving. Explosive development of minerals can also provoke a downward movement of a loose formation.
Sometimes the "trigger" for a landslide is construction, during which workers drive piles into the ground, thereby spreading a shock wave in its thickness. Thoughtless deforestation of deserted mountain slopes is also often subject to landslides, as tree roots no longer hold soil particles together.
The consequences of landslides
The most dangerous are landslides that occur in populated areas. Even a small rock collapse can lead to the death of a person caught in his path. A man covered with several tons of rock dies in a matter of minutes from compression and lack of air. But it is much worse if, as a result, houses, cars, tourist camps or industrial enterprises are buried under a layer of soil. The number of victims in such cases turns out to be quite large.
One of the largest landslides in recent decades was the resulting rock collapse in Tajikistan. Then the death toll exceeded two hundred people: the breed covered about 50 houses in the village of Sharora. The width of the collapse was more than four hundred meters, and the wavelength was about four kilometers. 
In order to avoid such accidents, it is necessary to carefully inspect all slopes located in the immediate vicinity of housing, roads, enterprises, and record even the smallest ground movements. The slow movement of the landslide mass can at any moment turn into a destructive wave falling down on a defenseless village.
Landslides are often the reason for the destruction of houses for various purposes. Landslides are common in Crimea, Moldova, the Volga region, the Black Sea coast of the Caucasus and other places. Various types of landslides are capable of covering rather large territories, and the fight against the removal is carried out according to special projects and presents great difficulties and material costs.
Landslide reasons
A successful fight against landslides is carried out only on the basis of studying to the smallest details all the causes of landslides and making the right decisions to fix areas with landslides. The main reason for the occurrence of a landslide is the presence of soil layers with low strength properties in the landslide massif.
Picture 1. Landslide formation diagram
Landslide formation
As a result of moistening such fragile soil areas with ground or surface waters, landslide processes are activated. Landslide processes can intensify as a result of quarrying, cutting trees, waterlogging a landslide area with surface waters and other reasons.Depending on the composition and geological structure of landslide slopes and areas, the effect of water on the course of a landslide is manifested in different ways.
Homogeneous upper clayey soils located on steep slopes and saturated with water flow down as a viscous mass that forms alloys. Due to the increase in wet soil mass, homogeneous large soil masses can collapse down the resulting sliding surfaces.
In the presence of inclined massifs with a dense structure of impermeable rocks under the soil massif, water seeping and reaching a dense structure causes a loss of adhesion of the soil layers and the whole layer of soil slides along the so-called trajectory or sliding surface. Landslides on the banks of large reservoirs, rivers and seas often caused by erosion of steep banks.
Figure-2. The characteristic elements of the landslide area
Landslide areas
The landslide area is characterized by the following adopted elements:
1. Landslide area.
2. The edge of the main ledge.
3. Main ledge.
4. Top of the landslide.
5. Inner ledge of the landslide.
6. the body of the landslide.
7. Sliding surface of the landslide
8. Irregularities of the surface relief.
9. Transverse and longitudinal cracks in the soil massif
10. Landslide sole.
Sliding surface. This is the surface of the soil along which the landslide massif is displaced. The landslide sole is the exit line at the bottom of the sliding surface. Tear cracks are formed on the upper surface of the slope at the exit of the sliding surface before the landslide movement.
The stability coefficients of landslide massifs are not constant throughout the year. They change depending on the amount of ground and surface water, on the degree of moisture or drying out of the soil, which can change the weight of the soil and the shear resistance.
Landslides usually recur periodically. After the massif has moved from its place, a period of relative stabilization begins for several years. Since the massif has acquired a more stable position, no visible landslide processes are observed. But during such a period, under the influence of penetrating moisture, the hidden processes of accumulation of creep deformations intensify, and adhesion decreases. in the ground and internal stresses in the body of the landslide massif increase.
The stability coefficient decreases, and after a few years, a general shift occurs and a new period of landslide attenuation begins. The duration of a landslide cycle can be from five to twenty years. Therefore, landslide places can be detected visually, several successively displaced massifs can be seen in areas prone to landslides.
When moving below, at the bottom of the landslide, bulging mounds are formed. Signs of landslide areas are the terrain with characteristic traces of past landslides. Such traces can be in the form of various irregularities at the bottom of the slope, inclined trees, and others. Construction in such areas begins with the identification of landslide areas, as well as with a thorough analysis and identification of all causes that lead to landslides. If possible, landslide areas and karst areas should be bypassed.
Landslide types and their classification
Among the many ongoing landslide processes, the following types are determined:
1. Structural or block landslides, which are characterized by the sliding of entire blocks of rock.
2. Landslides slides. They are characterized by a rapid and one-time sliding of a cover of loose soil deposits on a rocky surface or on frozen ground.
3. Sliding of slopes - sliding of small blocks of soil, which can cover the entire slope or only a significant part of it.
4. Subsidence of slopes is a characteristic displacement of blocks consisting of rocky or semi-rocky rocks.
In accordance with these types, they are distinguished:
1.slide slopes,
2.splitting slopes,
3.slope slopes and
4. the slopes of landslides and slips (slumping of the cover of loose deposits).
A.P. Pavlov divided landslides into detrusive and delaptic. Detrusive landslides in front of their lower end push the most plastic rocks and deform them. Delaptic landslides slide down to the sea, river or lake. Depending on the structure of rocks, landslides composing the landslide slopes are divided into the following types:
1. Asequential, which develop in homogeneous soil rocks.
2. Consequent - occur along the planes of faults or along the planes of bedding rocks.
3. Insequential with characteristic signs of intersection of fault planes or bedding surfaces by sliding planes.
Landslides can occur and develop on one high-rise level (single-level) or on several (multi-level landslides). Most often, multi-tiered landslides are observed in mountainous areas and less often in flat areas (mainly where the slopes reach 100-200 meters). Depending on the rate of the landslide processes, the following types of landslides are distinguished:
1. Permanent landslides.
2. Periodic.
3. Simultaneous.
Also distinguish:
1. Modern landslides, which have been occurring for decades.
2. Long-standing landslides that formed less than 3-5 thousand years ago.
3. Ancient landslides formed many thousands of years ago.
All of these types of landslides pose a great danger to buildings and structures, as well as people living in such areas. Depending on the rate of displacement of the landslide, all landslide slope processes are divided into three categories:
1.slow (displacement occurs at a slow speed).
2. Medium (displacement occurs at an average speed).
3. Fast displacements (high speed up to several tens of kilometers per day)
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