Landslides in the last 5 years. Landslides are the greatest catastrophes on planet earth. The biggest landslide in the history of Italy

The biggest collapse in the history of the earth

Most landslides in the mountains occur in the spring. This is no coincidence. Autumn rains moisten the rocks, water collects in their cracks. In winter, it freezes and at the same time expands, presses on the walls, pushes the cracks apart. So, acting repeatedly, the ice "wedges" loosen the blocks, split them into pieces. Finally, the moment comes when individual parts break off from the parent rock and fall down.

Quite often, flowing waters actively help the force of ice, which acts like a sly. Washing the slope of the valley, they gradually undermine the ice, and at some point, under the influence of their own gravity, the washed rocks collapse down and fill up the river valley. In these places there are mountain lakes. An example is such pearls among lakes as Ritsa, Lake Sarez and many others.

Of all the landslides that have occurred in historical time, the largest was the Usoi; it took place in the Central Pamirs in the area of the former village of Usoy. Here, on the night of February 17-18, 1911, from the slopes of the Muzkolsky Range, from a height of about 5000 meters above sea level, a fantastic amount of earth and rock fragments fell into the valley of the Murghab River.

In the same area, a strong earthquake was observed simultaneously with the collapse.

When scientists made a thorough survey of the area where everything happened, and made the necessary calculations, it turned out that, firstly, the epicenter of the earthquake coincided with the collapse site and, secondly, the energy of the earthquake and collapse are equal. So the collapse was the cause of the earthquake.

But the question of its phenomenally large size remained a mystery of the Usoi collapse for a long time. Until now, no one knows whether there has ever been a similar collapse on the globe in historical times.

Only after many years of research did geologists reveal the secrets of the Usoi collapse. It turned out that the layers that make up the slopes of the mountains are inclined towards the valley of the Murghab River. The mass of the blockage consisted of stronger rocks than those that underlay them. The Murgab River has washed away the steep right-hand slopes of the valley over the course of millennia, and thus their connection with the base was weakened.

The force of the impact of the earth and stones that fell from a great height was so great that it generated a powerful seismic wave that circled around the globe several times. It was registered by all seismic stations of the world.

Record landslides

Unlike landslides, landslides come off less steep slopes. Their movement occurs smoothly, calmly for hours, days and even months.

Treacherous acts river water seeping into the depths earth's crust. It impregnates layers of loose sediments, moistens clays. Often such a moistened layer plays the role of a lubricant between the layers of the earth, and the upper layer, as if on a sled, begins to slide and float down. Small landslides are called - mudslides, mudslides.

THE HIGHEST NUMBER OF LANDSLIDE VICTIMS

On December 16, 1920, an earthquake triggered a landslide on a mountain in Gansu Province (China), killing 180,000 people under it.

LARGE LANDSLIDES IN RECENT YEARS

Several hundred people died on March 29, 1994, when heavy rains near the city of Cuenca in Ecuador triggered a landslide that buried the mining village.

In June 1997, in the Chinese province of Yanan, two landslides in gold mines killed 227 miners.

In September 2002, in the Karmadon Gorge (North Ossetia), as a result of a huge glacier and a landslide, more than a hundred people died, including the film crew of S. Bodrov Jr.

LANDSLIDE THAT SWALLOWED THE CITY

The city of Sainte Jeanne-Viannie in the Canadian province of Quebec was completely abandoned after a landslide in May 1971. The city was built in the 17th century by the first settlers - in a secluded depression on the edge of a giant slope. Its inhabitants lived without any natural disasters for several hundred years. And on May 4, 1971, the first sign of an impending threat followed, when livestock refused to enter the fields on the edge of the city: most likely, the animals felt slight ground vibrations. That same night, a huge landslide moved in. Roads, vehicles and houses were swallowed up by a huge wave of mud 15 meters high, which spread over 15 kilometers within three hours. As a result, 31 people died, and the city is still empty due to the strong movements of the layers of clay lying under it.

THE BIGGEST LANDSLIDE IN THE HISTORY OF ITALY

The Piave River Valley is located in northern Italy and thanks to E. Hemingway's novel "Farewell to Arms!" familiar to millions of people. During the First World War, the Italian army was located here, acting against the Austrians after their defeat at Caporetto. On October 9, 1963, at 11:15 p.m., a terrible natural disaster occurred - the entire Piave river valley was flooded. There were reports that the 260 meter high Walmoth dam collapsed under the onslaught of a massive landslide formed as a result of the earthquake.

The world's tallest dam, more than 20 meters thick, withstood the earthquake. It collapsed a bit later. As the surviving witnesses of the disaster recall, the roar that was heard before the huge water shaft hit the valley had a different origin. It came from the cracked mountains on either side of the dam. There is evidence from Captain Fred Mickelson, a US military helicopter pilot who evacuated the residents of Casso village. The village stood above the dam and was in danger of residual landslides. He described the event as follows: “Behind the dam there was a lake about two kilometers long, but now it is no more. The rock tops on either side of the dam fell into the lake and literally filled it.”

The water displaced from the lake rushed through the dam, destroying it, and in a giant waterfall 450 meters high at a right angle poured into the valley of the Piave River.

Longaron, a village located on the path of a water stream, disappeared instantly. 3,700 out of 4,000 inhabitants died. Only the bell tower, the cemetery chapel and one house survived in Pigaro. Until now, no one lives in the village.

THE MOST TERRIBLE LANDSLIDE IN EUROPE

For centuries, mountains of waste rock have grown in the vicinity of mining towns, such as Aberfan, in Wales (England), being an integral attribute of mines. Due to their composition, such mountains are very unstable and mobile. In Aberfan, a stream flowed under the mountain, which, by washing away the base, further reduced its stability. A few days before the disaster, local residents noticed some movement on the mountain and notified the authorities.

On the morning of October 21, 1966, a representative of the municipal government went up the mountain to check the information received. While he was inspecting the mountain, suddenly two million tons of rock started to move and fell on the city. The roar was heard several kilometers from the town. Rescue work was immediately started, the miners rose to the surface and, together with the townspeople, began excavations. 43 people died - mostly children who were at the school at that moment.

RIVERS

"Smoke that thunders", or the largest waterfalls

This is how the locals have long called the famous African Victoria Falls. The first European to see him was the Englishman D. Livingston in 1855. The traveler sailed in a small boat on the Zambezi. The calm river suddenly changed: the water accelerated its run, became agitated, and somewhere beyond the forest a frightening roar was growing. Barely having time to moor to a small island, Livingston was struck by the picture that opened up: a wide river broke off, falling into the abyss.

How does such a natural phenomenon arise? Rivers carve their way between different rocks. Some of them are easily and quickly washed away by water, while others are difficult. And it happens like this: somewhere in one place, the river suddenly falls down, falling off steep, sheer ledges made of very strong rocky rocks.

Gradually, the water washes away the rocky ledge, the waterfall recedes up the river and becomes smaller. Over time, only thresholds remain - large pitfalls. Rivers with waterfalls are mostly young. The age of rapids rivers is already more solid; and the rivers that have erased all stone barriers in their path are old rivers.

For a long time, geographers believed that the Zambezi waterfall was the largest in the world. Then, in one of the most remote and inaccessible places on our planet, on the Churun River in Venezuela, the highest waterfall in the world, Angel Falls, was opened. Masses of water break here from a sheer stone wall about a kilometer high! It was discovered in the South American jungle by pilot D. Angel (Angel) in 1935. in the same South America, on the border of Brazil, Argentina and Paraguay, there is another waterfall - Iguazu; its width exceeds three kilometers. In fact, this is not one waterfall, but many. There are 275 of them here! It is impossible to capture the whole fairy-tale picture with a glance. More than 12,000 tons of water are thrown down every second. Two large cascades stand out, falling from a height of seventy - eighty meters. The mass of water generates an air wave that throws up light aircraft if they descend over the waterfall.

In North America, on the border between the United States and Canada, is the well-known Niagara Falls. The river falls in two wide streams into a hole fifty meters deep. Businessmen use this majestic waterfall for profit. All sorts of spectacles are organized in Niagara, which are stared at by crowds of tourists. In the 19th century, an unemployed American announced that he would swim across the lower rapids of the falls for a fee. In the presence of numerous spectators, he threw himself into the seething water, appeared for a moment in the middle of the river and disappeared forever among the foam and darkness. The unwitting hero turned out to be a seven-year-old boy, Roger Wood. In 1962, he and his uncle and older sister were boating in Niagara. The current overturned the boat, and all three found themselves in a seething rapid. They managed to snatch my sister out of the water, and the river threw the uncle and nephew into a fifty-meter abyss. The adult crashed, and the child, unexpectedly for everyone, remained alive.

And another interesting story. On March 29, 1848, Niagara Falls…disappeared! Every second, six to seven thousand tons of water fall into the abyss here. And suddenly everything stopped. Only small streams flowed from above. The rocks were exposed. More than a day passed, and the water came again. What happened? On the morning of March 29, 1848, a violent storm swept over Lake Erie, from which the Niagara flows. She broke the ice that covered the lake, and large blocks of ice blocked the flow of water from the lake to the river bed ...

Russia also has waterfalls. They are found in the Far East, Siberia, Karelia and the Caucasus. The championship in height is held by Ilya Muromets in the Kuril Islands - 141 meters. “The waterfall,” writes Yu. Efremov, “bursts out of the hollow, as if from a drainpipe, almost horizontally, bends in the air and falls freely. It turns out a vertical column of collapsing water, several meters away from the plumb wall ... The wind either stronger or weaker deflects the falling stream, and it bends to the right, then to the left, as if alive ... "In the Sayans (Eastern Siberia)," dancing water "attracts attention - Grandiose waterfall, two hundred meters high. It flows in cascades from the ice grotto.

In Central Asia, in the western Tien Shan, the Arstanbap waterfall is known, in translation - the Lion's Gate. It falls in three cascades straight from sky-high heights - from a four-kilometer mountain!

Beautiful, poetic names are given by the peoples of the world to "dancing water". In Sweden there is a waterfall Hare's Jump, in Korea - Seven Dragons, in Kyrgyzstan - a Pigeon Watering Place, and in the Caucasus - Maiden's Hair and Water Throat. The highest waterfall in India (252 meters) - Wonderland... Are all the waterfalls already open? Probably not. Here is one of the newspaper reports from the end of the last century:

“A new waterfall was discovered from an airplane in the tropical jungle at a distance of 250 kilometers from the capital of Guiana. It is four times the height of Niagara and twice the height of Victoria Falls. The newly discovered waterfall falls from a height of about two hundred meters. They named him Caleter.

The most unusual rivers

THE RIVERS PLAY HIDE AND SEEK

The Kara-Balta River flows from the Kyrgyz Range, giving its waters to wheat fields, sugar beet plantations, orchards. Examining its channel, scientists found that even before entering the valley, the river loses about a third of its flow. When they drilled a well, it turned out that this river is two-story! Seeping through the pebbles and sand, part of its water formed, as it were, a second, underground, stream.

In 1981, hydrogeologists found that the Volga runs parallel to the territory of the Mari ASSR, and in some places even adjoins the channel of a large underground river. It also happens that part of its path a river or river passes on the surface, part - underground.

AT Perm region, not far from the village of Kyn, such a trick is performed by the tributaries of the Chusovaya River: they seem to dive underground and then reappear on the surface. The place where they disappear, the locals call dives, and where they come out again - dives. The local river Kumysh has cut such a channel for itself that for six kilometers it is almost invisible, and only then it breaks out from under the rock and again becomes an ordinary river. In the Urals, about fifteen rivers, large, small and very small, are distinguished by such inconstancy - sometimes they are visible, sometimes they are not, they hid. The right tributary of the Kosva - Gubeshka - is not visible for ten kilometers, the Vezha River is hidden for eight kilometers.

One place on the South Ural River Sim is unusually beautiful, where, meeting a rock on its way, it disappears under it, its noisy run is heard again somewhere below, in dense thickets of bushes.

A rare sight is a key on the right bank of the same river Sim, one and a half kilometers below the mouth of another river - Berda. It hits directly from the cliff, but it is interesting that the water pours out in jolts: for three minutes it is strong, and then just as calmly.

In Yugoslavia there is a river that first carries its waters in a narrow gorge, and then completely disappears into huge caves. After going a long way through the underground galleries, she disappears into a deep crack. Exactly - it disappears, because no one knows where it goes. They tried to find out with the help of dyes, but colored water was found in many springs around Trieste and even in the city water supply ...

THE RIVER MAKES A CIRCLE

There is a river in the Gorky region with a curious name - Pyana, a tributary of the Sura. And the river is interesting in that it has both a source and a mouth very close. After running in a circle for more than four hundred kilometers, it reappears almost at the place of its birth, and then only flows into Sura. “Almost” is three dozen kilometers. And “running in a circle” is not quite accurate. Wandering somewhere hundreds of kilometers, it makes so many zigzags, unexpected turns, that it's time to talk not about a circle, but about some other figure.

"NOVGOROD MIRACLE"

It happened a long time ago, in those days when Novgorod was an independent feudal republic and was referred to only as Lord Veliky Novgorod. This event did not go unnoticed by the chronicler. Still would! After all, it concerned a person who occupied a prominent place in the church hierarchy - the bishop. In addition, this bishop, named John, was at the head of the city council. What happened to him?

That year turned out to be difficult for the Novgorodians: first, the drought burned the fields, and then its eternal companion, hunger, fell upon the city. The bishop was accused of everything - a lover of the female sex: for his sins, they say, God sent misfortune. At first they wanted to drown him, but changed their minds and decided to simply expel him from the city. They put together a raft, put a fornicating bishop on it and took it to the middle of the Volkhov - let it go with the flow! But the raft… did not want to go with the flow, but swam against it! One can imagine what was happening on the shore with the God-fearing Novgorodians. The chronicler (and they, as we know, were mostly monks) naturally interpreted what happened in the sense that God in this way condemned the little people who raised their hand against his servant.

However, it is doubtful that such a phenomenon as the reversal of the river was an isolated fact. It is even more doubtful that no one in the city knew the cause of this phenomenon. After all, in order to establish it, you just need ordinary observation, since cases when rivers and rivers temporarily change the direction of flow are not so rare. This happens (and then, of course, it happened), for example, on some lowland rivers during spring floods: a large river “locks” the tributaries, and then they either stop and overflow, or even flow back for a while.

Well, in Novgorod everything is explained even more simply. Volkhov, in essence, is a natural, miraculous canal connecting two large lakes - Ilmen and Ladoga. The river is full-flowing, with a slight natural slope. In the year of the "Novgorod miracle" there was a dry summer in the upper reaches of the Volkhov, the level of Lake Ilmen dropped. It was enough in the lower reaches, that is, over Ladoga, to have heavy rainfall for the Volkhov to slow down or even turn back for a while.

By the way: the Greek river Avor changes the direction of flow regularly, in the rhythm of fluctuations in the level of the Aegean Sea, caused by ebbs and flows.

THE FUNNIEST TITLE

The funniest name, of course, is a small river in the Vologda region - the Kuku River. “Shouldn’t we go fishing - on the Kuku River?” You can also wash nearby - in the river Portomoyka.

The largest ravine on earth

If we ignore everyday life, from our petty worries and passions, then we can say that on the edge of the Grand Canyon of Colorado you clearly feel the breath of Eternity. And you realize the insignificance of the piece of life allotted to us. And you feel like a speck of dust in the grandiose temple of the Universe.

The Grand Canyon is a huge ravine 350 kilometers long, dug by the Colorado River in the layered sedimentary rocks of the plateau of the same name. Its width in the upper part is 8-30 kilometers, at the water's edge in the river - less than 1 kilometer (in some areas - up to 120 m). Depth in some places up to 1800 meters. Steep, in some places strongly dissected slopes are replete with bizarre ledges in the form of bastions, columns and pyramids. The river cuts through horizontally lying rock layers: from Archean crystalline to Upper Paleozoic sedimentary - limestone, sandstone, shale, etc., having a different color. The canyon was formed in the Cenozoic as a result of river erosion, intensified by the gradual uplift of the plateau. The Colorado River in the Canyon has an average drop of 1.5 m per 1 km and flows at speeds up to 25 km/h.

In high water, the river can transfer about two million tons of silt per day - it colors its waters, and 20 percent of pebbles and gravel must also be added to this huge amount of abrasive material. Therefore, it is not surprising that over millions of years the river completely demolished the top 12 of the 25 layers of sandstone, limestone, shale and other sedimentary rocks on its way, and deeply cut through the remaining layers. 225-280 million years ago there was an ocean in this place, but over the past geological epochs it has repeatedly been replaced by a desert. Layers of multi-colored ocean and wind-blown sediments are cut in places by lava flows from ancient volcanoes. On this thickness of stone pages, you can read the entire geological history of the continent, draw conclusions about climate change.

The surface of the plateau, once the floor of an ancient ocean, was the topmost of many layers of sandstone, shale, and limestone that formed during the Paleozoic era, 600–250 million years ago. These rocks were deposited on top of even older Precambrian schists 2 billion years ago.

According to various estimates, the laying of this giant gorge took the river from 1.7 to 9 million years. If you take the average figures, it turns out that annually Colorado carried 2.5 billion cubic meters of rock into the ocean, and the rate of erosion was a meter deep per thousand years.

People have settled in the Grand Canyon at least 4,000 years ago. In 1930, rock carvings (petroglyphs) of the most ancient inhabitants were discovered here; The subjects were mostly animals. Before 500 B.C. e. in the Canyon lived in small groups semi-nomadic Indians of one of the desert cultures, characterized by the manufacture of baskets. Their dwellings were carved into the rock or made of clay. Then the territory was occupied by Indians belonging to the Anasazi archaeological culture. They hunted deer and cougars and grew corn, pumpkins and beans in the side branches of the canyon. And at the end of the 10th - beginning of the 11th century A.D. e. Pueblo Indians lived here and built stone houses. A century and a half later, they were replaced by the ancestors of the current local tribes.

Around 1540, the Spanish conquistadors led by Francisco de Coronado came here in search of gold, but, standing on the edge, bypassed the inhospitable gorge. Apparently, they gave the name to this unique geological formation (canyon - translated from Spanish as “chimney”). In 1776, the Spanish missionary Pater Garces entered the canyon to convert the Havasupai Indians to Christianity. They did not accept Christianity, but Father Garces left his mark here: he gave the river the name Colorado, which in Spanish means “colored” or “colored”.

In 1848, after a successful war with Mexico, the American government claimed these lands as their own. Lieutenant Ives, who commanded a group of military topographers who studied the area in 1858, wrote in his report: “We were the first and probably the last group of white people who ever visited this completely useless barren area. Apparently, nature is destined for the Colorado River to flow in undisturbed peace for most of its lonely and proud path.

The first person to cross the Grand Canyon on the Colorado River and survive was John Wesley Powell. This significant event took place in 1869. Powell was the first to study and describe the remains of the Canyon Indian civilizations. After this expedition, which took place in 1869, the interest of Americans in a unique monument of nature and history grew. However, this attention turned into a drama for the local tribes. After deposits of lead, zinc, asbestos and copper were found here in the 1870s, the Indians were forcibly relocated to reservations.

Later, despite the economic benefits of mining the Canyon, preference was still given to the development of tourism. The first tourist groups visited the valley as early as 1883; By the beginning of the 20th century, a railway was built here. In 1919, Senator Harrison introduced the Grand Canyon National Park; then US President Wilson supported the proposal. Since then, the status of the Canyon has not changed. Its area is almost 500 thousand hectares.

After 1919, about a hundred million tourists visited the Grand Canyon. In 1979, the canyon was included in the list of "objects of world importance" compiled by UNESCO.

Athletes from all over the world come here to raft through over a hundred rapids in canoes, kayaks, kayaks, rubber boats or rafts. Classical music concerts are held in natural caves, which are located in the walls of the gorge - the acoustics are excellent here.

To the untrained eye, these harsh places may seem lifeless, but the Grand Canyon is full of plants and animals. At the bottom, where it is dry and hot, you can find various inhabitants of the desert, such as spotted skunk, yellow scorpion and whip-tailed lizard. Purple ferrocactus and mesquite trees grow beautifully here. The bushy-eared kaibab squirrel is found only on the north side, while the Abert squirrel prefers the warmer south. The cool slopes of the canyon are home to Arizona gray foxes and rocky chipmunks. Mountain lions also roam the rocks, but there are very few of them left, just like the people who once lived here. Tourists who are taken by helicopter to Havasu Canyon to see the remaining Havasupai Indians see the last indigenous inhabitants of these places.

In the place where the Colorado, breaking out of the Grand Canyon on the border of Arizona and Nevada, forms the 115-mile Lake Mead, is the Hoover Dam - the largest dam in the world. It was built in 1931-1936 and named after former President Hoover in 1947. The dam was being built at about the same time as the first stage of the famous Soviet Dneproges (1927–1932). Its height is 220 meters, and the thickness at the base is 180 meters (the height of the Dneproges is 60 m). The Hoover Dam is far from the only one built on the Colorado River along its entire length, but it is the largest.

Its plant has a capacity of 1.25 million kilowatts and irrigates vast expanses of Northern California, Arizona, Nevada and New Mexico. It is also a source of energy and water for the entire region. That's exactly what it was designed for - multi-functional. During the construction of this hydrotechnical miracle, the latest technologies were used. The dam, begun during the Great Depression, provided jobs for tens of thousands of unemployed Americans. And although the work on the dam was fraught with great risk, and in five years more than a thousand people died on its construction, the influx of labor did not diminish.

In total, along its length of 2333 kilometers, the Colorado River rotates the turbines of 30 power plants. Dams hold back the flow of the river, silt and other abrasive materials settle at the bottom of the reservoirs, and further deepening of the Canyon has practically stopped. However, the river can wait: what is two or three centuries, during which the dams can stand, compared to millions of years?

Based on the materials of Yu. Ryazantsev

SCIENTISTS DISCOVERED THE ORIGIN OF THE GRAND CANYON?

The rocks in which the Colorado River cut the Canyon are composed of sandstone that hardened about 150 to 300 million years ago. Where so much sand came from in these places remained a mystery.

According to research conducted by Bill Dickinson and George Gerels of the University of Arizona at Tucson, at least half of the hardened sand of the Grand Canyon was once part of the Appalachians, which stretch along the east coast of the United States and are located at a distance of several thousand kilometers from the Grand Canyon. According to scientists, sand got to the west along with powerful river flows. Then he settled in the territory of modern Wyoming, after which, together with the winds, he was carried away to the south, where he turned into dunes.

In their study, the scientists used the uranium-lead dating method. Sand rocks contain particles of zircon, a mineral containing uranium. As soon as zircon crystallizes from liquid magma, uranium begins to decay, and uranium naturally turns into lead. The amount of lead in zircon particles makes it possible to determine the age of the zircon. The age of zircon particles from one mountain range can then be compared with the age of zircon from other mountains.

Half of the zircon samples taken in the Grand Canyon formed either 1.2 billion years ago or about 500 million years ago. This age coincides with the age of granite in the Appalachians. Only a quarter of the zircon particles match the age of the Rocky Mountains. Also, a small part of the sand came to the western United States, most likely from Canada.

This method has proved its effectiveness in determining the route of movement of tectonic layers on the Earth's surface. By comparing the age of zircon in the sandstone of one continent with that of the mountain ranges of another, one can obtain reliable evidence that both continents were once a single entity.

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 bases with sea and river waters, seismic tremors. Artificial are the destruction of slopes by road cuts, excessive removal of soil, deforestation, unreasonable farming 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 national economy. They threaten the movement of trains, 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.

With erosion, saturation occurs first stream of water 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 water body (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 recent years, natural causes of mudflow formation have been supplemented 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 is climatic conditions (precipitation). They are zonal. The descent occurs systematically. The paths of movement are relatively constant; regional manifestation (the main factor in the 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):

Powerful (strong power), with the removal of more than 100 thousand m 3 of materials. They happen once every 5-10 years.
Medium capacity, with removal from 10 to 100 thousand m 3 of materials. They happen once every 2-3 years.
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: geological structure terrain, 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, riverbeds 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 mountainous areas 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 estates were destroyed, 500 hectares of sown areas were washed out 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 places where mudflows occur, periodically let water from mountain reservoirs pass, 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.

For the timely adoption of measures, the organization of reliable protection of the 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, create a danger in 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, and underground communications are destroyed. At the same time, it is very important to notice these first signs in time and make a correct forecast about the further development of the landslide. It should also be taken into account that landslides move at a maximum speed only in the initial period, then it gradually decreases.

On landslide sites, constant monitoring of the movement of soils, the water level in wells, drainage structures, sewage disposal systems, boreholes, rivers, reservoirs, precipitation and runoff is organized. 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 zones should know the sources, possible directions and characteristics of these hazardous phenomena. 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 hydrometeorological service units 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 had previously hurriedly left the disaster zone and waited it out in a nearby safe place, making sure that there is no second threat, should return to this zone in order to search for and provide assistance to the victims.

Everything that surrounds us is filled with movement, grandiose movements of substances both inside the planet and on its surface. The processes that will be discussed in this article can occur almost imperceptibly. Only at the moments of cataclysms (earthquakes, stone or snow avalanches, etc.) can they quite strongly declare themselves.

general information

Many natural disasters have threatened the inhabitants of the planet since the dawn of civilization, and it is impossible to find a completely safe place on Earth.

Natural disasters that can cause enormous damage include floods, volcanic eruptions, earthquakes, snow drifts, hurricanes, droughts, mudflows, avalanches, storms, landslides and rock falls. In some cases, fires (peat and forest) can be attributed to them.

A collapse, an avalanche, a landslide are natural processes of enormous destructive power that accompany the evolution of the Earth. They happen now, they will arise in the future, until in billions of years everything will solidify in the form of a single stone ball.

Crashes: Definition

What is a collapse? The meaning of the word "collapse": separation and rapid fall from the steep, steep slopes of the mountains of huge volumes of rocks due to the loss of their adhesion to the parent base. It can be both fragments of rocks and snow blocks that have fallen from the mountains. During collapses, ice, snow cornices and bridges can be torn off.

The collapse is a natural process that begins gradually, with the appearance of cracks on the slopes. It is very important to detect its first signs in time for the correct prediction of events and the implementation of appropriate preventive measures.

Preventive measures include constant monitoring of hazardous areas. When mining rocks, technologies that provoke the formation of collapses should not be used.

Types and causes of collapses

Falls are of three types:

small - with the volume of detached blocks up to several tens of cubic meters;
medium - with a mass of collapsed rocks of more than several hundred cubic meters;
large - with a weight of blocks more than 10 million cubic meters. meters.

weakening of the cohesion of rocks, which occurs under the influence of washing,
dissolution,
weathering,
tectonic events.

It all depends on the geological structure of the area, the presence of cracks on the slopes, as well as the crushing of rocks.

Education process

A collapse is a process that mostly occurs in the mountains in the spring, which is not at all accidental. How does this happen? Under the influence of autumn rains, the rocks get wet, and the existing cracks are filled with water. AT winter time the liquid freezes, due to which it expands and presses on the walls, thereby pushing the cracks apart. Such a process occurs repeatedly, as a result of which the ice "wedges" undermine the blocks, gradually splitting them into different parts.

As a result, there comes a moment when separate pieces break off from the main parent rock and fall in huge masses down the slopes.

Often the thickness of the ice is supplemented with the help of flowing waters, which, washing the slopes of the valleys, slowly undermine the soil base. The washed rocks collapse under their own gravity and fill up the river valley. This is how mountain lakes are formed. Vivid examples are such natural reservoirs as Lake Sarez (presented below), Ritsa, etc.

Landslide

Unlike collapses, landslides are the displacement of huge volumes of rocks along a steep slope under the influence of their own gravity.

The main causes of landslides:

Washing the base of the slope with water, increasing its steepness;

Weathering or excessive moisture, weakening the strength of rocks;

Seismic processes;

Development of rocks with violation of technological processes;

Destruction of the vegetation landscape and cutting down trees on the slopes;

Irrational use of agricultural technology when plowing slopes for agricultural land.

Landslides form in a variety of rocks. This is due to the weakening of their strength or imbalance of balance. Provocateurs of landslides are natural phenomena (seismic tremors, steepness of slopes, rock erosion) and artificial factors (deforestation, soil erosion, irrational agricultural work).

According to international statistics, approximately 80% of landslides of our time are associated with human activity. A large number of such natural phenomena occur in the mountains (at an altitude of 1.0-1.7 thousand meters).

Landslides occur throughout the year, but the largest volumes move during the spring and summer periods.

The collapse is a natural phenomenon that can destroy highways, create natural dams with the formation of lakes in the future. As a result of this phenomenon, overflows of huge volumes of water from reservoirs are even possible.

A collapse is a natural disaster that can change a lot in nature. Below is one of the worst (known) collapses in the world.

The most catastrophic collapse in the world

The largest collapse is the Usoi, which happened in 1911 in the winter in the Central Pamirs (on the territory of the former village of Usoi). From the slopes of the Muzkolsky ridge, located at an altitude of 5 thousand meters above sea level, a unimaginable amount fragments of rocks and soil masses. During the ongoing collapse, an earthquake was observed in this area.

The volume of the collapsed mass amounted to 2.2 billion cubic meters. The consequence of the destructive process was the emergence of a huge natural dam that blocked the Murgab River and, as a result, the formation of Lake Sarez 75 kilometers long and up to 3.4 km wide. Its maximum depth is 505 meters.

After a thorough study of the area and the calculations made by the experts, the following conclusions were made: the epicenter of the earthquake was located in the same place where the collapse occurred, and the energy of both cataclysms turned out to be equal. It turns out that the collapse was the cause of the earthquake.

Until now, no one knows whether there have ever been similar, phenomenal volumes of collapses on the globe.

After many years of geological research, the secrets of the famous Usoy catastrophe were revealed. The layers extending on the slopes of the mountains have a slope in the direction of the river valley. Murgab. The strongest and most durable rocks were located above the soft underlying ones. For many millennia, the Murgab River washed away the steep slopes of the valley, which caused the weakening of the connection between the rocks and the parent base.

The stones fell with force, which led to the generation of a powerful seismic wave, which ran around the Earth several times and was recorded by all seismic stations in the world.

On measures to prevent disasters

Active measures to prevent mudflows, landslides and collapses are the creation of hydraulic and engineering structures: retaining walls, counter-banquets, pile rows, etc.

There are also quite simple ways that do not require significant expenditures of building materials. These include the following activities:

frequent cutting of masses of earth from the upper part and their subsequent placement at the foot of the slopes in order to reduce the threatening state;
arrangement of drainage systems for the removal of groundwater located above the level of a possible landslide;
sowing grasses, planting plantings (trees and shrubs) to protect slopes,
importation of sand and pebbles in order to strengthen the shores of natural reservoirs.

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

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

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

On relatively steeply sloping sections of the bottom of the oceans, seas, and deep lakes in seismically and volcanically active zones, as well as on the frontal slopes of underwater deltas (as a result of sharp differences in sedimentation rates), underwater lakes are found; one of the largest is the Sturegga landslide in the Norwegian Sea (length approx. 800 km, width 290 km). Submarine seas can cause submarine cables to break, which has 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.			There is 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	There is no data	150 households were buried. More than 600 people died.
		Seismogenic (?) landslide	There is 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. Centre. part of the Loess Plateau.	7 seismogenic landslides of large volumes of loess strata moving in whole hills, cutting off mountain slopes	There is 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	There is no data	100,000 houses were destroyed in the city. 600 people died.
	Japan. Kyushu, Kure city area		There is 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	There is no data	1046 people died.
	Japan. Honshu island. Kyoto prefecture	Minamiyashiro landslide caused by heavy rains	There is 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	There is 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.
	United Kingdom. Wales. City of Aberfan	Technogenic landslide as a result of the collapse of the top of the waste heap	There is 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	There is 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	There is 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	There is 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	There is 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	There is 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 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 (Yanchihe earth avalanche), 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	There is 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. Centre. 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	There is 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	There is no data	Area covered. 250 km2. 1700 people went missing. 272 people died.
	India. Himalayas. Malpa	Landslide caused by heavy rain	There is no data	221 people died.
	Papua New Guinea. Northwest coast.	Powerful seismogenic underwater landslide	There is no data	A wave arose, the victims of which were 2000 people.
		Seismogenic landslide by Ju Feng-er-shan	There is 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)	There is 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	There is 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	There is no data	20 thousand people died.
	Egypt. Vost. (upland) part of Cairo	Technogenic landslide Al-Duwayki as a result of construction work in the near-edge part of the plateau	There is no data	107 people died.
	Afghanistan. Baghlan Province	Seismogenic landslide	There is 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	There is no data	18 people died.
	Japan. Honshu island. Hiroshima	Landslide caused by heavy rains (204 mm of precipitation in 3 hours)	There is no data	Destruction in the city. Several people died.
	Georgia. City of Tbilisi	Landslide caused by heavy rains	There is 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	There is no data	180 people were left homeless. 7 people died.

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

Most often collapses earth's surface 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 (pictured above).

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 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 landslide 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.