The most grandiose landslides in the world. The biggest collapse in the history of the earth. Consequences of mudflows and landslides

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 the 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 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 (width up to several meters, depth from 0.3 to 1.5 m) 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 arising from the destruction of such a dam 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 repeatedly happened, in particular, at the bottom of the Atlantic Ocean.

Table. Catastrophic landslides*

	Location (the current geographical location is indicated)	Event characteristic	Volume of solid removals, m3	Devastating consequences and loss of life
980 BC e.			No data	Destruction. The death of "a huge number of people"
373–372 BC e.	Greece, Sev. coast of the Peloponnese	Seismogenic landslide		The disaster led to the immersion of the ancient city of Helios and a kilometer-long stretch of coast into the waters of the Gulf of Corinth
Start n. e.	Iran. River valley Saidmarreh	The largest landslide from Mount Kabir Bukh crossed a valley 8 km wide and crossed the ridge high. 450 m		When the river was blocked by a landslide body, a dammed lake 65 km long and up to 180 m deep was formed.
	Jordan. City of Jarash	Natural-anthropogenic mudflow-landslide disaster	Over 100,000	Burial under landslide masses and mudflow proluvium b. part of the large ancient city of Geras
	Russia. City of Nizhny Novgorod	Catastrophic landslide after heavy rainfall	No data	150 households were buried. More than 600 people died.
		Seismogenic (?) landslide	No data	The village of Khanko is buried under a landslide mass. 2000 people died.
	Russia. South coast of Crimea. Village of Opolznevoe	The largest in the South coast of Crimea in the historical seismogenic Kuchuk-Koysky landslide and stone stream		Village destroyed. A large stream disappeared into the hole. The tongue of the landslide moved into the Black Sea by 100–160 m
	China. Gansu Province. Center. part of the Loess Plateau.	7 seismogenic landslides of large volumes of loess strata moving in whole hills, cutting off mountain slopes	No data	Numerous people are buried. inhabited caves in loess, farms and villages. St. died. 200 thousand people
	Canada. Atlantic coast	The descent of underwater landslides provoked an underwater turbidity stream 330 km wide and (a consequence of an earthquake on the Great Newfoundland Bank at a depth of 800 m)		7 submarine cables were torn and 3 were buried at a distance of up to 1000 km from the epicenter. There was a wave that hit the south. the coast of Newfoundland. Several villages were destroyed. 33 people died.
	China. Sichuan Province	Seismogenic landslide Deihi		Break of the dam on the river. Min. In the city of Deihi, 577 people died.
	Japan. Honshu Island, Kobe city area	Landslide caused by heavy rains	No data	100,000 houses were destroyed in the city. 600 people died.
	Japan. Kyushu, Kure city area		No data	2,000 residential buildings were badly damaged or destroyed. 1154 people died.
		Cerro Condor-Senkas Landslide		Destroyed 100-meter dam on the river. Rio Montara (with subsequent flooding)
	Tajikistan. The junction of the Zeravshan and Alay ranges	Landslide caused by Khait earthquake		On the right bank of the river Surkhob, the village of Surkhob was buried, the village of Yarkhich was destroyed, and nearby villages were destroyed. The villages of Khait and Khisorak were flooded. 7200 people died.
	China. Tibet - Himalayas, near the border of India with China	Numerous seismogenic collapses and landslides of loose rocks saturated with monsoon rains		Colossal changes in terrain near the epicenter
	Japan. Honshu island. Wakayama prefecture	The landslide, caused by heavy rains that destroyed a series of dams, turned into a mudflow along the river. Arida	No data	1046 people died.
	Japan. Honshu island. Kyoto prefecture	Minamiyashiro landslide caused by heavy rains	No data	5122 houses destroyed. 336 people died.
	Russia. City of Ulyanovsk	Large landslide on the right bank of the Volga		Deformed drainage gallery
	Japan. Honshu island. Shizuoka Prefecture	Kanogawa landslide caused by heavy rains	No data	19,754 houses destroyed or badly damaged. 1094 people died.
	USA. State of Montana	Landslide caused by Hebgen earthquake		The landslide blocked the river. Madison, creating a dammed lake. 28 people died.
	Italy. Province of Belluno. Vajont Reservoir	As a result of the washing of the shore into the lake, the Vayont landslide rapidly descended		Waves arose. 260 m and 100 m. Destroyed villages in the valley of the river. Piave. The city of Longarone suffered greatly. 3000 people died.
	USA. State of Alaska. City of Anchorage	Seismogenic landslides and landslides		The wave generated by the displacement of landslide masses flooded the port facilities. 106 people died.
	China. Yunnan Province	Seismogenic (?) landslide		4 villages destroyed. 444 people died.
	Great Britain. Wales. City of Aberfan	Technogenic landslide as a result of the collapse of the top of the waste heap	No data	144 people died.
	Brazil. City of Rio de Janeiro	A landslide caused by heavy rains, which turned into an earthen avalanche and a mudflow	No data	Died ok. 1000 people
	Brazil. Vost. slopes of the Brazilian plateau. Serra das Araras	Landslide in Ribeirão da Floresta Valley caused by heavy rains	No data	A section of the highway was demolished, the camp of road builders was flooded with a landslide mass, and that means. part of the nearest village
	USA. State of Virginia	Flooding caused by Hurricane Camille contributed to large landslides	No data	More than 100 people died.
	Canada. Quebec. City of Saint-Jean-Vioni	Liquefied clay of water-glacial origin flowed along the valley of the river. Petit Bra at a distance of 2.8 km and disappeared into the river. Seguenay	More than 7 million	The embankment on the river was destroyed. Petit Bra. More than 40 houses were destroyed. 34 people died.
	Uzbekistan. Pos. Brichmulla	Technogenically provoked activation of the Mingchukur landslide during the filling of the Charvak reservoir	25–30 million	Partial filling of the reservoir bowl with landslide mass
	USA. State of the West Virginia. Buffalo Creek Township	The collapse of three coal heaps (as a result of heavy rains) caused a landslide that advanced 2–4 km	No data	4000 people were left homeless. 125 people died.
	Peru. River valley Mantaro	The giant Maunmark landslide blocked the riverbed		Village destroyed. Mountmark. A dammed lake 31 km long (up to 170 m deep) was formed. 450 people died.
	Abkhazia. River basin Tskhenis-Tskali	Lashadur tectonic-seismogenic landslide
	Guatemala	Seismogenic landslide	No data	200 people died.
	Sweden. Gothenburg area	A landslide caused by heavy rains covered a distance of 100 to 175 m	3-4 million	67 houses destroyed. 600 people were left homeless. Destroyed 1 km of the road. 60 people were injured. 9 people died.
	Abkhazia. River basin Kelasuri	Kelasuri tectonic-seismogenic landslide		Revival of Holocene landslide movements, creating the danger of a large-scale collapse
	Uzbekistan. Tashkent region.	Technogenically provoked (as a result of siltation of the Pskem river canyon) activation of the Bashkaragach landslide on board the bowl of the Charvak reservoir		Sharp partial filling of the reservoir bowl and the formation of a high wave
	France. City of Nice	An underwater landslide that has transformed into a turbid stream		Part of the river delta is involved in the landslide. Var and the railway. High Wave 3 m spread over 120 km of coastline, causing damage to communications and harbors. 2 submarine cables were broken at a distance of 120 km from the city of Nice. Several people died.
	Uzbekistan. Tashkent region	Zagasan-Atchinsky landslide, technogenically provoked by the mining of a coal deposit and underground gasification of coal on the side of the river valley. Angren (on a slope of 600 m). The displacement plane is located at a depth of 130 m.		Forced transfer of more than 2,000 houses to the opposite bank of the river. Backfilling of 50 million m3 of soil to stabilize the landslide
	China. Hubei province.	Landslide (earth avalanche Yanchikhe), technogenically provoked by the development of a phosphorite deposit		284 people died.
	USA. California State. Hall area. San Francisco	Storm and catastrophic floods caused several large landslides	No data	Damaged or completely destroyed 6500 residential buildings, 1000 prom. enterprises and institutions. 30 people died.
	USA. Utah	Landslide caused by melting snow and heavy rainfall		Landslide on record in US history ($600 million)
	China. Gansu Province.	Saleshan landslide caused by heavy rains		4 villages destroyed. 237 people died.
		Chuncha landslide caused by torrential rains and violent snowmelt in the Andean highlands		150 people died.
	Puerto Rico. Center. part of the island. City of Mameyes	A landslide caused by heavy rains.		129 people died.
		Earthquake Reventador provoked a landslide of the same name	75–110 million	1000 people died.
	Brazil	Petropolis landslide caused by heavy rains		300 people died.
	Tajikistan. Hissar Valley	Several seismogenic landslides (as a result of the Gissar earthquake), the largest of them - 3700 m long, 600 m wide, up to 28 m thick		The liquefaction of the landslide mass led to the formation of a mudflow that advanced several kilometers, causing destruction and loss of life.
	China. Sichuan Province	Hiksu landslide caused by heavy rains	No data	221 people died.
	China. Yunnan Province	Touzahi landslide caused by heavy rains		216 people died.
	Colombia. Department of Cauca	Seismogenic landslide Paez, caused by one. earthquake	No data	Area covered. 250 km2. 1700 people went missing. 272 people died.
	India. Himalayas. Malpa	Landslide caused by heavy rain	No data	221 people died.
	Papua New Guinea. Northwest coast.	Powerful seismogenic underwater landslide	No data	A wave arose, the victims of which were 2000 people.
		Seismogenic landslide by Ju Feng-er-shan	No data	At least 119 people died.
	China. Tibet.	Yangong landslide triggered by rapid melting of snow and ice.		500,000 people were left homeless. 109 people died.
	Salvador. Suburb of San Salvador Las Colinas	Seismogenic landslide (Epicenter in the Pacific)	No data	4692 houses were destroyed. More than 1000 people went missing. 585 people died.
	Russia. Saratov region City of Volsk. Vost. slopes of the Volga Upland	Natural-technogenic landslide in the center. parts of the city		321 families relocated from 237 houses
	Sri Lanka	Landslide and mudflow caused by heavy rains	No data	24,000 buildings destroyed. 260 people died.
	Pakistan, India (Kashmir, outskirts of Muzaffarabad)	Seismogenic landslides and rock falls	80 million (Hattian Bala debris avalanche)	The avalanche blocked the channels of two tributaries of the river. Jelam, a village was buried (1000 victims). In total, 25.5 thousand people died.
	Philippines. Luzon Island. Albay Province	Landslides and earth avalanches caused by heavy rains (Typhoon Durian)		1100 people died.
	China. Sichuan. Around Chengdu	Seismogenic landslides, debris avalanches and mudflows	No data	20 thousand people died.
	Egypt. Vost. (upland) part of Cairo	Technogenic landslide Al-Duwayki as a result construction works in the edge part of the plateau	No data	107 people died.
	Afghanistan. Baghlan Province	Seismogenic landslide	No data	More than 20 houses were buried. 80 people died.
	Uganda. District of the national Mount Elgon Park (near the border with Kenya)	Landslide caused by heavy rains	No data	18 people died.
	Japan. Honshu island. Hiroshima	Landslide caused by heavy rains (204 mm of precipitation in 3 hours)	No data	Destruction in the city. Several people died.
	Georgia. City of Tbilisi	Landslide caused by heavy rains	No data	He blocked the gorge of the Vera River and caused flooding in Tbilisi. Mass death of animals in the Tbilisi Zoo. 19–22 people died.
	Kyrgyzstan. Almalyk south of Osh	Catastrophic landslide		No data
	Sri Lanka	Landslide caused by heavy rains	No data	180 people were left homeless. 7 people died.

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

In the mountains, 27 tourist bases and 49 registered tourist groups were cut off, consisting of more than 500 people, including 133 foreigners -. After a mudflow in the Elbrus region of Kabardino-Balkaria, three cars fell into the Baksan River, in which two people were rescued, three more are being searched for by rescuers.

August 18, 2017 showers and thunderstorms with hail (Crimea). A mudflow with mud flooded households, vehicles, communications in the village of Krasnokamenka (Kizil-Tash) in the Sudak region, and the elements also damaged vineyards near Sudak. Mudflow damaged about 42 hectares of vineyards, 15 of which were completely washed away.

On the night of June 22, 2016, a rock after heavy rains leading to the Shatoi and Itum-Kalinsky regions of Chechnya, blocking the passage of vehicles. 27 mountain settlements with a population of about 16 thousand people were cut off from the outside world. The landslide blocked a section of the road about 50 meters long and up to six meters wide.

On June 9, 2016, as a result of rainstorms that took place in Chechnya and Dagestan, 65 residential buildings were flooded or damaged by mudflows. 125 people were relocated to a temporary accommodation facility. Water of the automobile bridge in the Shali district of Chechnya. Mudflows blocked road communication with seven settlements in the Shatoisky district of the republic.

October 15, 2015 about 350 cubic meters mud-stone mass descended, according to updated data, to railway track between Dagomys and Sochi, that. On railway tracks from the side of the slope, the soil reached a level of more than one meter. From the side of the sea, the movement of trains was hindered by trees felled during the descent of the ground. 122 people and 15 units of equipment were involved in the elimination of the consequences of the incident.

On July 20, 2014, in the Adler region, a mudflow descended on the road in Krasnaya Polyana near the technological tunnel behind the Rosa Khutor ski resort. Twenty cars, in which there were more than a hundred people, 50 people were evacuated by rescuers, another 40 people wished to stay near their cars. It took about two days for the road services to eliminate the consequences of the mudflow. On July 27, the second mudflow in a week came down on the road in Krasnaya Polyana. Several cars .

On June 28, 2014, heavy rains occurred in the Tunkinsky district of Buryatia. To the village of Arshan, where almost 3 thousand people live, from the mountains along the bed of the river Kyngarga. Five streets were flooded. One person died. According to the republican authorities, a total of 112 houses fell into the emergency zone, 15 of which were completely destroyed. The damage amounted to hundreds of millions of rubles.

On the night of October 10, 2012, as a result of past heavy rains that caused mudflows in Derbent (Dagestan), they were flooded. . In total, 1.12 thousand people fell into the flood zone.

On August 29, 2009, after three days of rain in the vicinity of Karamken, Magadan Region, a mudflow, which serves as a diversion channel for the storage of waste rock (tailings) of the former gold mining plant. The mud flow blocked the channel of the Tumanny, water poured into the Khasyn River, the level of which began to rise rapidly, after which the dam of the Karamken GOK broke through. As a result, the water flow demolished 11 prefabricated houses in Karamken, one person died, one woman went missing.

On June 15, 2008, a mudflow descended onto a road near the village of Zagardon in the Alagir district of North Ossetia, completely in the Kurtatinsky gorge, about 50 cars, in which there were about 150 people. In the evening of the same day, the track was completely unblocked, the road service equipment broke a track, along which cars could leave the gorge.

On the night of 17 houses were damaged as a result of a mudflow in the upper part of the village of Bulungu in the Chegemsky district of Kabardino-Balkaria, eight of which were completely destroyed. Mudflow also demolished outbuildings, transport and livestock. Of the 11 missing villagers, ten were found.

In June 2007, a landslide came down in the Valley of Geysers in Kamchatka, as a result of which seven geysers were under the rubble, and about a dozen were flooded by a dammed lake. Subsequently, most of the geysers resumed their work, new outlets of hot springs formed. In September 2013, the flooded geysers Skalisty and Artifact flooded again. In January 2014, a mudflow of clay, water and snow again transformed the Valley of Geysers in Kamchatka. A stream of clay, water and snow washed away the observation deck near the geyser Schel. The mode of operation of the largest geyser in the Kronotsky Reserve, Velikan, has temporarily changed.

The material was prepared on the basis of information from RIA Novosti

The largest known landslide is in the Hart Mountains in Wyoming (USA). It covers an area of ​​two thousand square kilometers and, judging by the remaining traces, in places it spread at a speed of one hundred kilometers per hour. This catastrophe happened in a very distant past - about thirty million years ago.

In Europe, the first place belongs to the Flim landslide, which happened in the Alps. Scientists suggest that it happened before the Ice Age and before the appearance of man here (about a million years ago).

Twelve cubic kilometers of loose material was displaced into the Rhine valley. This happened on the territory of present-day Switzerland near the city of Chur - where the village of Flim (Canton of Graubünden) is now located. The landslide fell into the Rhine, the river valley fell to a height of about six hundred meters. First, a lake was formed two hundred meters deep, but it did not last long. The Rhine found another way for itself, and the lake was drained.

And the largest landslide of historical time is the event that took place on February 18, 1911 in the Pamirs. The landslide was caused by a strong earthquake, after which a fantastic amount of loose material - 2.2 billion cubic meters - slid down from the slopes of the Muzkolsky Range, from a height of five thousand meters above sea level. The village of Usoy was littered with all its inhabitants, their property and livestock. Rocky rocks blocked the valley of the Mughrab River. For four years, a huge shaft-dam with a diameter of four to five kilometers and a height of more than seven hundred meters stopped the flow of the river. A new Pamir lake appeared - Sarez, which began to grow rapidly and, in turn, flooded the villages of Sarez, Nisor-Dasht and Irkht.

In 1913, the length of Lake Sarez reached 28 kilometers, and its depth was almost 130 meters. Then the waters of Mughrab made their way through the stone blockage, but the lake still continued to grow. Nowadays, its length is already 75 kilometers, and the depth is about five hundred meters.

The impact force of the mass of earth and stones that fell from a great height was so great that it generated a powerful seismic wave. She was registered by seismic stations around the world, as she ran around the globe several times.

The mystery of the Usoy landslide is its exclusively big sizes. Until now, scientists cannot say for sure whether there has ever been a similar landslide on the globe (in historical time). No traces of a larger one have yet been found.

The roar of crumbling rocks (some scientists attribute this landslide to landslides) was heard by residents of Tajik villages located twenty kilometers from the village of Usoy. People called this place "Valley of Death" and walked around it for a long time.

And the most tragic in terms of the number of victims was a landslide that occurred in the Chinese province of Gansu in 1920. Most of the territory of this province is occupied by a loess plateau, which suffered a terrible earthquake. A fatal role was played here not only by the force of the earthquake, but also by the specific conditions of the soil of Central China. The affected area was located in the center of the "country of loess" - fertile dust, brought by winds from the Gobi desert at the beginning of the Quaternary period. The fertility of the soil was the main reason that this area was densely populated.

Loess is very porous, but at the same time it has a fairly significant strength. Therefore, canyons and valleys with steep slopes are formed in loess areas. When the loess was broken by an earthquake, the slopes became unstable. Loess strata moved literally in whole hills. It was these hills that buried tens of thousands of people who lived in caves dug in the loess. In one cave lived the Muslim prophet Ma the Blessed with his community, which consisted of three hundred of his followers. They were cut off from the whole world and doomed to a slow and painful death. For a whole month, the relatives and co-religionists of the dead dug up the loess cover that closed over their cave, but they could not find anything.

The tragedy was aggravated by the fact that it happened on a winter night. The ensuing darkness and cold forced almost the entire population to take refuge in their dwellings. At 7:30 p.m., a dull noise was heard from the north, “as if heavily laden huge cars were racing at breakneck speed along a bad pavement.”

One missionary, miraculously surviving, later said:

“When I heard the noise, I thought it was an earthquake and ran outside. But as soon as I found myself on the street, I felt as if something had hit me in the back with terrible force.

With my legs wide apart, like a drunkard trying to stay on his feet, I felt a strong rotational movement of the earth under me ...

This first and longest push lasted two minutes. It was followed by five or six others, and so quickly that it was almost impossible to separate them one from the other ...

The aftershocks followed one after another at intervals of a few seconds and merged with the deafening roar of collapsing houses, the screams of people and the roar of animals that came from under the rubble of buildings.

The resulting landslides reached grandiose proportions. Seven of the most gigantic of them cut the slopes of the mountains, and thousands of cubic meters of loess filled up the valleys, covered cities and villages. One of the houses captured by the loess was carried on a moving mass of rocks and miraculously remained on the surface. In this house there were a man and a child, but in pitch darkness and a deafening roar, they did not even really understand what had happened. In the morning, a truly apocalyptic picture opened before them - “mountains moved”, and they did not even recognize their native places.

The section of road that was moving along with their house (about four hundred meters long) moved down one and a half kilometers. Having stopped, it subsequently almost retained its former appearance, and the tall poplars on both sides of the road continued, as before, to sway their branches. The house traveled almost a kilometer long, and then two other landslides forced the avalanche to change direction.

This place is also called the "Valley of Death" because 200,000 people were buried here.

Landslides in the Nizhny Novgorod region very often occur in our country. This was reported even in ancient chronicles. So, for example, in the 15th century, a landslide came down from Gremyachaya Mountain, which destroyed a large settlement. Here is how this event is recorded in the annals: “And by God’s will, sin for our sake, a mountain slid down from above over the settlement, and one hundred and fifty households with people and with all cattle fell asleep in the settlement.”

A large landslide also occurred on the night of June 17, 1839, near the village of Fedorovka on the left bank of the Volga between Saratov and Ulyanovsk. The earth walked underfoot, the houses cracked and shook, there was noise and roar in the air.

Nobody understood what had happened. People did not know where to run and how to save their lives. Women and children were screaming and crying loudly. Dawn came, but it did not bring calm - everything around remained the same, and the earth even began to tremble even more. In places it swelled, and in place of the lowlands, hills grew, and in the place of the hills gaps and cracks gaped.

The fluctuations of the earth's surface (sometimes strong, sometimes weak) lasted for three whole days. And all this time the population was in constant anxiety and excitement. And when everything calmed down, it turned out (to the great amazement of the inhabitants!) that the village of Fedorovka "moved out" closer to the Volga by several tens of meters.

Landslides- this is a sliding displacement of rock masses down the slope under the influence of gravity.

They are formed in various rocks as a result of a violation of their balance or a weakening of strength. Caused by both natural and artificial (anthropogenic) causes. The natural ones include: an increase in the steepness of the slopes, washing away their foundations with sea and river waters, seismic shocks. Artificial are the destruction of slopes by road cuts, excessive removal of soil, deforestation, unreasonable management Agriculture on the slopes. According to international statistics, up to 80% of modern landslides are associated with human activities. A significant number of landslides occur in the mountains at an altitude of 1000 to 1700 m (90%).

Landslides can occur on all slopes, starting from a steepness of 19°. However, on clay soils, they also occur with a slope of 5-7 °. For this, excessive moisture of the rocks is sufficient. They descend at any time of the year, but mostly in the spring and summer.

Landslide classification

Landslides are classified: by the scale of the phenomenon, the speed of movement and activity, the mechanism of the process, the power and place of formation.

By scale landslides are classified into large, medium and small scale.

Large ones are caused, as a rule, by natural causes and are formed along the slopes for hundreds of meters. Their thickness reaches 10-20 or more meters. The landslide body often retains its solidity.

Medium and small scale are smaller and are characteristic of anthropogenic processes.

The scale is often characterized by the area involved in the process. In this case, they are subdivided into grandiose - 400 hectares or more, very large - 200-400 hectares, large - 100-200 hectares, medium - 50-100 hectares, small - 5-50 hectares and very small - up to 5 hectares.

By movement speed very different, as can be seen from Table. 2.3.

By activity landslides are divided into active and inactive. The main factors here are the rocks of the slopes and the presence of moisture. Depending on the amount of moisture, they are divided into dry, slightly wet, wet and very wet. For example, very wet ones contain such an amount of water that creates conditions for liquid flow.

According to the mechanism of the process subdivided: into shear landslides, extrusion, viscoplastic, hydrodynamic removal, sudden liquefaction. Often have signs of a combined mechanism.

By process power landslides are divided into small - up to 10 thousand m 3, medium - from 11 to 100 thousand m 3, large - from 101 to 1000 thousand m 3, very large - more than 1000 thousand m - mass of rocks involved in the process.

By place of education they are subdivided into mountainous, underwater, adjacent and artificial earthworks (pits, canals, rock dumps).

Landslides cause significant damage to the national economy. They threaten train traffic road transport, residential buildings and other buildings. During landslides, the process of land withdrawal from agricultural circulation is intensively going on.

Table 2.3. Characteristics of landslides but speed of movement

Speed	Motion estimation
	Exceptionally fast
	Very fast
1.5 m/day
1.5 m/month	Moderate
	very slow
	Exceptionally slow

Often they lead to human victims. So, on January 23, 1984, as a result of an earthquake in the Gissar region of Tajikistan, a landslide 400 m wide and 4.5 km long occurred. Huge masses of earth covered the village of Sharora. 50 houses were buried, 207 people died.

In 1989, landslides in Ingushetia caused destruction in 82 settlements. 2518 houses, 44 schools, 4 kindergartens, 60 healthcare facilities, culture, trade and consumer services were damaged.

A variety of landslides are snow avalanches. They are a mixture of snow and air crystals. Large avalanches occur on slopes of 26-60°. They are capable of causing great damage, with loss of life. So, on July 13, 1990, on Lenin Peak in the Pamirs, as a result of an earthquake, a large snow avalanche demolished the climbers' camp, located at an altitude of 5300 m. 40 people died. It was the biggest tragedy of domestic mountaineering.

Mudflow

Mudflow (mudflow)- a turbulent mud or mud-stone stream, consisting of a mixture of water and rock fragments, suddenly arising in the basins of small mountain rivers.

It is characterized by a sharp rise in the water level, wave movement, short duration of action (on average from one to six hours), a significant erosive-accumulative destructive effect.

Mudflows pose a threat to settlements, railways and roads and other structures located on their way.

The immediate causes of mudflows are downpours, intensive snowmelt, breakthrough of reservoirs, less often earthquakes, volcanic eruptions.

Mudflow classification

All if according to the mechanism of origin are divided into three types: erosion, breakthrough And landslide.

In the case of erosion, at first the flow is saturated with clastic material due to flushing and erosion of the adjacent soil, and then a mudflow wave is already formed.

Breakthrough is characterized by an intensive process of water accumulation, at the same time rocks are eroded, a limit is reached and a reservoir (lake, intraglacial reservoir, reservoir) breaks through. Mudflow mass rushes down the slope or river bed.

During a landslide, a mass of water-saturated rocks (including snow and ice) is shed. The saturation of the flow in this case is close to the maximum.

Each mountain region has its own causes of mudflows. For example, in the Caucasus, they occur mainly as a result of rains and showers (85%).

IN last years to the natural causes of the formation of mudflows were added technogenic factors, violation of the rules and norms of the work of mining enterprises, explosions during the laying of roads and the construction of other structures, felling of forests, improper conduct of agricultural work and violation of the soil and vegetation cover.

When moving, mudflow is a continuous stream of mud, stones and water. The steep leading front of the mudflow wave with a height of 5 to 15 m forms the “head” of the mudflow. The maximum height of the shaft of the water-mud flow sometimes reaches 25 m.

The classification of mudflows based on the causes of occurrence is given in Table. 2.4.

In Russia, up to 20% of the territory is located in mudflow zones. Mudflows are especially active in Kabardino-Balkaria, North Ossetia, Dagestan, in the region of Novorossiysk, the Sayano-Baikal region, the area of ​​the Baikal-Amur Mainline, in Kamchatka within the Stanovoy and Verkhoyansk ridges. They also occur in some areas of Primorye, the Kola Peninsula and the Urals. Back in 1966, more than 5,000 mudflow basins were registered on the territory of the USSR. Currently, their number has increased.

Table 2.4. Classification of mudflows based on the root causes of occurrence

	root causes	Distribution and origin
1. Rain	Downpours, heavy rains	The most massive type of mudflows on Earth is formed as a result of slope erosion and landslides.
2.Snowy	Intensive snowmelt	Occurs in the mountains of the Subarctic. Associated with the breakdown and waterlogging of snow masses
3. Glacial	Intensive melting of snow and ice	In the highlands. The origin is associated with a breakthrough of melted glacial waters
4. Volcanogenic	Volcanic eruptions	In areas of active volcanoes. The largest. Due to rapid snowmelt and outburst of crater lakes
5. Seismogenic	Strong earthquakes	In areas of high seismicity. Disruption of soil masses from the slopes
b. limnogenic	Formation of lake dams	In the highlands. Dam failure
7. Anthropogenic direct impact	Accumulation of technogenic rocks. Poor quality earth dams	In areas where dumps are stored. Erosion and sliding of technogenic rocks. Dam failure
8. Anthropogenic indirect impact	Land cover disturbance	In areas of deforestation, meadows. Erosion of slopes and channels

Based on the main factors of occurrence mudflows are classified as follows: zonal manifestation - the main factor in the formation are climatic conditions(precipitation). They are zonal. The descent occurs systematically. The paths of movement are relatively constant; regional manifestation (the main factor of formation is geological processes). The descent occurs episodically, and the paths of movement are inconsistent; anthropogenic - is the result of human activities. Occur where the greatest load on the mountain landscape. New mudflow basins are being formed. The gathering is episodic.

Classification by power (according to the transferred solid mass):

1. Powerful (strong power), with the removal of more than 100 thousand m 3 of materials. They happen once every 5-10 years.
2. Medium capacity, with removal from 10 to 100 thousand m 3 of materials. They happen once every 2-3 years.
3. Weak power (low power), with the removal of less than 10 thousand m 3 of materials. Happen every year, sometimes several times a year.

The classification of mudflow basins according to the frequency of mudflows characterizes the intensity of development or its mudflow activity. According to the frequency of mudflows, three groups of mudflow basins can be distinguished:

• high mudflow activity (with a frequency of once every 3-5 years and more often);
• average mudflow activity (with a frequency of once every 6-15 years);
• low mudflow activity (with a frequency of once every 16 years or less).

Mudflows are also classified according to their impact on structures:

• Low-power - small washouts, partial clogging of openings of culverts.
• Medium-power - strong erosion, complete clogging of holes, damage and demolition of non-foundation buildings.
• Powerful - great destructive force, demolition of bridge trusses, destruction of bridge supports, stone buildings, roads.
• Catastrophic - complete destruction of buildings, road sections along with the canvas and structures, burial of structures under sediment.

Sometimes a classification of basins according to the height of the sources of mudflows is used:

• alpine. The sources lie above 2500 m, the volume of removals from 1 km 2 is 15-25 thousand m 3 per mudflow;
• mid-mountain. The sources lie in the range of 1000-2500 m, the volume of removal from 1 km 2 is 5-15 thousand m 3 per one mudflow;
• low mountain. The sources lie below 1000 m, the volume of removals from 1 km 2 is less than 5 thousand m 3 for one mudflow.

Falls (mountain collapse)- detachment and catastrophic fall of large masses of rocks, their overturning, crushing and rolling on steep and steep slopes.

Landslides of natural origin are observed in the mountains, on the seashores and cliffs of river valleys. They occur as a result of the weakening of the coherence of rocks under the influence of the processes of weathering, washing, dissolution and the action of gravity. The formation of landslides is facilitated by: the geological structure of the area, the presence of cracks and zones of crushing of rocks on the slopes. Most often (up to 80%), modern landslides are associated with the anthropogenic factor. They are formed mainly during improper work, during construction and mining.

The landslides are characterized by the power of the landslide process (volume of fall of rock masses) and the scale of manifestation (involvement of the area in the process).

According to the power of the landslide process, landslides are divided into large (rock separation 10 million m 3), medium (up to 10 million m 3) and small (rock separation less than 10 million m 3).

According to the scale of manifestation, landslides are divided into huge (100-200 ha), medium (50-100 ha), small (5-50 ha) and small (less than 5 ha).

In addition, landslides can be characterized by the type of collapse, which are determined by the steepness of the slope of the landslide masses.

Landslides, mudflows, landslides cause great damage to the national economy, the natural environment, and lead to human casualties.

The main damaging factors of landslides, mudflows and landslides are the impacts of moving masses of rocks, as well as the collapse and flooding of previously free space by these masses. As a result, buildings and other structures are destroyed, settlements, economic facilities, agricultural and forest lands are hidden by rock masses, river beds and overpasses are blocked, people and animals die, and landscape changes.

Landslides, mudflows and landslides on the territory of the Russian Federation take place in the mountainous regions of the North Caucasus, the Urals, Eastern Siberia, Primorye, Sakhalin Island, the Kuril Islands, the Kola Peninsula, as well as along the banks of large rivers.

Landslides often lead to large-scale catastrophic consequences. Thus, a landslide in Italy in 1963 with a volume of 240 million m 3 covered 5 cities, killing 3 thousand people.

In 1982, a mudflow with a length of 6 km and a width of up to 200 m hit the villages of Shiveya and Arend in the Chita region. As a result, houses, road bridges, 28 farmsteads were destroyed, 500 hectares of cultivated land were washed away and covered, and people and farm animals died. The economic damage from this mudflow amounted to about 250 thousand rubles.

In 1989, landslides in Checheno-Ingushetia caused damage in 82 settlements of 2518 houses, 44 schools, 4 kindergartens, 60 health, cultural and consumer services facilities.

Consequences of mudflows and landslides

sel- this is a temporary stream of oxen suddenly formed in the beds of mountain rivers with a high content of stones, sand and other solid materials. Mudflows are caused by intense and prolonged downpours, rapid melting of snow or glaciers. Mudflow can also be formed from the collapse of a large amount of loose soil in riverbeds.

Unlike ordinary streams, mudflow usually moves not continuously, but in separate waves. At the same time, hundreds of tons, and sometimes millions of cubic meters of viscous mass, are carried out. The size of individual boulders and debris reaches 3-4 m in diameter. When meeting obstacles, mudflow passes through them, continuing to build up its energy.

Having a large mass and high speed of movement, up to 15 km / h, mudflows destroy buildings, roads, hydraulic and other structures, disable communication and power lines, destroy gardens, flood arable land, and lead to the death of people and animals. All this lasts 1-3 hours. The time from the occurrence of a mudflow in the mountains to the moment it reaches the foothills is often estimated at 20-30 minutes.

To combat mudflows, they fix the surface of the earth by planting forests, expand the vegetation cover on mountain slopes, especially in the places where mudflows occur, periodically let water from mountain reservoirs, arrange anti-mudflow dams, dams and other protective structures.

Active snowmelt is reduced by arranging smoke screens with the help of smoke bombs. In 15-20 minutes after smoke, the temperature of the surface air layer decreases, and the water runoff is reduced by half.

The level of water accumulated in moraines (mountain lakes) and mudflow reservoirs is reduced with the help of pumping units. In addition, in the fight against mudflows, such simple structures as wadding, ditches and terraces with a wide base are widely used. Protective and retaining walls, semi-dams and dams are built along the riverbeds.

In order to take timely action, organizations reliable protection population, a well-organized warning and warning system is of paramount importance. In areas threatened by mudflow, an anti-mudflow service is being created. Its tasks include mudflow forecasting and informing the population about the time of its occurrence. At the same time, a route is foreseen in advance along which the population is evacuated to higher places. There, if time permits, cattle are driven away and equipment is brought out.

In case of capture of a person by a moving stream of mudflow, it is necessary to help him by all available means. Such means can be poles, ropes or ropes. It is necessary to take the rescued people out of the stream in the direction of the stream with a gradual approach to its edge.

Landslide- sliding mixing of earthen masses under the action of its own weight - occurs most often along the banks of rivers and reservoirs and on mountain slopes. The volume of rocks displaced during landslides ranges from several hundred to many millions and even billions of cubic meters. Landslides are caused by various reasons: washing away rocks with water, weakening their strength due to weathering or waterlogging by precipitation and groundwater, unreasonable human activities, etc.

Landslides can destroy settlements, destroy agricultural land, pose a danger to the operation of quarries and mining, damage communications, tunnels, pipelines, telephone and electrical networks, water facilities, mainly dams. In addition, they can block the dam, form a dammed lake and contribute to floods. Thus, the economic damage they cause can be significant.

The most effective protection against landslides is their prevention. A landslide usually does not start suddenly. First, cracks appear in the ground, breaks in roads and coastal fortifications, buildings, structures, telegraph poles are displaced, underground communications. At the same time, it is very important to notice these first signs in time and make a correct forecast about further development landslide. It should also be taken into account that landslides move with maximum speed only in the initial period, then it gradually decreases.

In landslide areas, constant monitoring of the movement of soils, the water level in wells, drainage structures, and drainage systems is organized Wastewater, boreholes, rivers, reservoirs, for precipitation and runoff. Such observation is especially carefully organized in the spring-autumn periods, when the most precipitation falls.

In the event of a landslide, it is necessary, firstly, to warn the population, and secondly, as the situation worsens, organize the evacuation of the population to safe areas.

In the event of the destruction of buildings and structures as a result of a mudflow or landslide, rescue work is carried out, the victims are removed from the rubble, and people are helped to get out of the danger zone.

Protection of the population in the event of a threat and during landslides, mudflows and landslides

The population living in landslide-, mudflow- and landslide-prone zones should know the centers, possible directions and characteristics of these hazards. Based on the forecast data, residents and enterprises are informed in advance about the danger regarding the identified landslide, mudflow, landslide centers and possible zones of their action, about the periods of mudflows, as well as about the procedure for signaling the threat of these phenomena. Such early informing of people about possible sources of natural disaster reduces the impact of stress and panic that can arise later when emergency information about the immediate threat of these events is transmitted.

The population of these dangerous mountainous regions is obliged to carry out measures to strengthen the houses and the territory on which they are built, as well as to participate in the construction of protective hydraulic and other engineering structures that protect against landslides and mudflows.

Primary information about the threat of landslides, mudflows and collapses comes from landslide and mudflow stations, parties and posts of the hydrometeorological service. It is important that this information be brought to the destination in a timely manner. The notification of the population about these natural disasters is carried out in accordance with the established procedure through sirens, radio and television, as well as through local warning systems that directly connect the units of the hydrometeorological service with settlements located in threatened zoggs.

If there is a threat of a landslide, mudflow or collapse and if there is time, an early evacuation of the population, farm animals and property from threatening areas to safe places is organized.

Before leaving the house or apartment for early evacuation, they are brought into a state that contributes to the weakening of the damaging factors of a natural disaster, prevents the occurrence of secondary factors and facilitates subsequent excavation and restoration. Therefore, the transferred property from the yard or balcony must be removed into the house, the most valuable property that cannot be taken with you, sheltered from moisture and dirt. Doors, windows, ventilation and other openings are tightly closed. Electricity, gas, water are turned off. Flammable and poisonous substances are removed from the house and, if possible, buried in remote pits or separate cellars. In all other respects, citizens act in accordance with the procedure established for organized evacuation.

If there was no advance warning of the danger and the residents were warned about the threat immediately before the onset of a natural disaster or noticed its approach themselves, each of them, not caring about property, makes an emergency independent exit to a safe place. At the same time, relatives, neighbors, all people met along the way should be warned about the danger. For an emergency exit, you need to know the directions of movement to the nearest safe places. These paths are determined and communicated to the population on the basis of the forecast of the most probable directions of the arrival of a landslide (mudflow) to a given settlement (object). Natural safe measures for an emergency exit are the slopes of mountains and hills that are not prone to a landslide process or between which a mudflow-prone direction occurs. When climbing safe slopes, valleys, gorges and cuts should not be used, since side channels of the main mudflow may form in them. On the way, help should be provided to the sick, the elderly, the disabled, children, and the weakened. Whenever possible, personal transport, mobile agricultural machinery, riding and pack animals are used for movement.

In the case when people, buildings and other structures find themselves on the surface of a moving landslide area, one should, after leaving the premises, move as far as possible upwards and, acting in the situation, beware of blocks, stones, fragments of structures rolling down from its rear part, earthen shaft, scree. It can also take over the overthrust of immovable rocks. At high speed, a strong push is possible when the landslide stops. Everything poses a great danger to people on the landslide.

After the end of a landslide, mudflow or landslide, people who previously hastily left the disaster area and waited it out in a nearby safe place, making sure that there is no second threat, should return to this area in order to search for and provide assistance to the victims.

Landslides most commonly occur when the bedrock, composed of limestone or other carbonate rock, is "eaten" by acidic groundwater, sags after heavy rainfall, or is damaged by burst pipes. Such sudden collapses are especially dangerous, for obvious reasons, in cities where entire houses can suddenly go underground. Below you will find photos from the sites of the largest collapses of the earth's surface in recent decades:

In May 1981, this giant hole formed in the city of Winter Park (Florida). The local authorities decided, having strengthened the edges, to turn the resulting pit into a picturesque city lake.

In this hole (18 m deep, 60 m long and 45 m wide) in 1995, two houses of the fashionable district of San Francisco failed.

In 1998, after unusually heavy rains and a rupture of a sewer pipe in San Diego, a giant crack formed. Its length is about 250 meters, width - 12 meters and depth - more than 20 meters.

In 2003, rescuers had to pull this bus out with a crane after it suddenly fell into the ground on a street in Lisbon (Portugal).

This hole swallowed up in February 2007 several houses in the capital of Guatemala. Three people are missing.

Bird's eye view.

In March 2007, in the Italian city of Gallipoli, a road collapsed into a network of underground caves underneath.

In September 2008, a car driving along a street in the Chinese province of Guangdong suddenly found itself in a hole 5 meters deep and 15 meters wide.

This giant crater formed in May 2010 in Guatemala City after Tropical Storm Agatha swept through it.

The same funnel from a closer distance.

In May 2012, due to a collapse of the soil on the roadway in the Chinese province of Shaanxi, this hole appeared 15 meters long, 10 meters wide and 6 meters deep.

And another collapse in Shaanxi (6 meters deep and 10 meters wide) damaged three gas pipes and one water pipe in December 2012.

This gigantic sinkhole was formed one of the December nights of 2012 in southern Poland. Its depth is about 10 meters, width is about 50 meters.

In January 2013, part of a rice field in the Chinese province of Hainan fell into the ground. There have been about 20 such incidents in the county in the previous four months.

The most catastrophic collapses in America

A selection of photographs from the sites of the largest collapses of the earth's surface in recent decades in America.