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The velocity of mudflows is on average 2-4 m / s, sometimes 4-6 m / s, which leads to their great destructive effect. On their way, streams lay deep channels, which are normally dry or contain small streams. The mudflow material is deposited on the foothill plains.

Mudflows are characterized by the advancement of its frontal part in the form of a shaft of water and sediment, or more often by the presence of a series of successively shifting shafts. The passage of mudflow is accompanied by significant changes in the channel .

The mud flows as a result of intense and prolonged downpours, violent melting of glaciers or seasonal snow cover, and also as a result of the collapse of large amounts of friable material into the riverbed (with slopes of at least 0.07-0.10). The decisive factor of occurrence can be deforestation in the mountains - the roots of the trees hold the upper part of the soil, which prevents the occurrence of mudflow.

Sometimes mudflows occur in basins of small mountain rivers and dry dens with significant (at least 0.10) thalweg slopes and in the presence of large accumulations of weathering products.

By the mechanism of nucleation, erosive, breakthrough, and landslide landslides are distinguished.

Potential mudflow center - a section of the mudflow channel or mudflow basin, having a significant amount of loose soil or conditions for its accumulation, where mudflow occurs under certain irrigation conditions. Mudflows are divided into mudflow incisions, potholes and foci of dispersed mudflow formation.

• Mudflow pothole is a linear morphological formation that cuts through rocky, soddy or forested slopes, usually composed of a small weathering crust . Mudflows are characterized by a small length (rarely exceed 500 ... 600 m) and depth (rarely more than 10 m). The bottom angle of the potholes is usually more than 15 °.

• Mudflow insert is a powerful morphological formation developed in the thickness of ancient moraine deposits and most often associated with sharp bends of the slope. In addition to ancient moraine formations, mudflow incisions can form on the accumulative, volcanic, landslide, landslide relief. Mudflow incisions are significantly larger in size than mudflow potholes, and their longitudinal profiles are smoother than mudflow potholes. The maximum depths of mudflows reach 100 m and more; catchment areas of mudflow incisions can reach more than 60km². The volume of soil carried out from mudflow for one mudflow can reach 6 million m³.

• By the center of dispersed mudflow formation is understood a section of steep (35 ... 55 °) outcrops, heavily destroyed rocks, having a dense and branched network of furrows, in which the products of weathering of rocks accumulate intensively and the formation of microsels occurs, which then combine in a single mudflow channel. They are usually associated with active tectonic faults , and their appearance is due to large earthquakes. The areas of mudflow centers reach 0.7 km² and rarely more.

Seismicelli

As a result of earthquakes, breakaway fragments of glaciers or rocks can block the path of rivers, forming very unstable dam dams. When such a dam breaks through, water from it is not released gradually, but instantly, which contributes to the accumulation of unimaginable kinetic energy by a stream.

Lahari

Lahars are mudflows of volcanic origin. As a result of the outpouring of lava, precipitation of hot ash or the disappearance of pyroclastic flows, snow and glaciers quickly melt on the slopes of the volcano, and the resulting water mixes with ash and rocks ^[2] . During the eruption of Vesuvius in '79 , under the ashes of which Pompeii was buried, the city of Herculaneum was inundated with a three-meter layer of mud-stone mass brought by the Lahar. During excavations, it was found that the mudflow shell of Herculaneum is much more dense than the ash layer of Pompeii.

Connected

The mud-stone flows , in which water practically does not separate from the solid part, are referred to as connected. They have a large bulk density (up to 1.5-2.0 t / m³) and a large destructive force. To disconnected carry water flows. Water carries debris material and, as the speed decreases, it deposits it in the channel or in the region of the removal cone on the foothill plain. Volumetric weight of mudflows.

In the mudflow basin, the following zones are distinguished:

1. Zone of origin (nutrition),
2. Transit zone
3. Accumulation zone.

By the degree of saturation of sediments and their fractional composition

• Mud mudflows - a mixture of water with fine earth at a low concentration of stones, bulk density y = 1.5—2 t / m³
• Mud-stone mudflows - a mixture of water, pebbles, gravel, small stones, y = 2.1—2.5 t / m³
• Water-stone (nano-water) mudflows - a mixture of water with predominantly large stones, y = 1.1-1.5 t / m³

Mudflows can produce huge damage. The fight against mudflows is carried out mainly by fixing the soil and vegetation cover, the construction of special hydraulic structures.

To combat mudflows, preventive measures and the construction of engineering structures are carried out.

The use of certain methods of control is determined by the mudflow zones. Preventive measures are taken to prevent the occurrence of mudflow or weaken its action at the very beginning of the process. The most radical means is afforestation on mudflow hazardous mountain slopes. The forest regulates runoff, reduces the mass of water, cuts flows into separate weakened streams. In the catchment area it is impossible to cut down the forest and disturb the turf. It is also advisable to increase the stability of the slopes by terracing , to intercept and divert water by upland ditches , earthen ramparts.

In mudflow channels, dams give the greatest effect. These structures made of stone and concrete, installed across the channel, delay the mudflow and take away part of the solid material from it. Semi-dams push the stream to the shore, which is less prone to rupture. Screening machines are used in the form of pits and pools laid on the path of flow; shore-supporting retaining walls are built to prevent the erosion of the banks of the riverbed and protect buildings from the impact force of mudflows. Effective guide dams and storehouses. Dams direct the flow in the right direction and weaken its effect.

In sections of settlements and individual structures located in the zone of deposition of the river , diversion canals are arranged that guide dams, the riverbed is taken to high stone banks, limiting the spreading of the mudflow. To protect road structures, the most rational are mudflows in the form of reinforced concrete and stone trays, allowing mudflows to pass above or below structures.

• Tsunami
• Hydrology
• Omaira Sanchez

• Fleishman S.M. Mudflows. - M .: Geografgiz , 1951. - 96 p. - (Natural phenomena). - 30,000 copies.
• Chernomorets S. S. Mudflows before and after disasters. - M.: Scientific World, 2005. - 184 p.
• Chernomorets S.S., Seinova I.B. Mudflows on volcanoes . - Moscow: Publishing House UC DO, 2010. - 72 p. ISBN 978-5-88800-341-1
• Seinova I. B., Chernomorets S. S., Tutubalina O. V., Barinov A. Yu., Sokolov I.A. Conditions for the formation of mudflows in areas of active volcanism (for example, volcanoes Klyuchevskoy and Shiveluch, Kamchatka) . Part 1. Cryosphere of the Earth, 2010, vol. XIV, No. 2, p. 29–45
• Seinova I.B., Chernomorets S.S., Tutubalina, A.F. Kovalsky, O.V., Barinov A.Yu., Sokolov I.A. Conditions for the formation of mudflows in areas of active volcanism (for example, volcanoes Klyuchevskoy and Shiveluch, Kamchatka) . Part 2. Cryosphere of the Earth, 2010, vol. XIV, No. 3, p. 29–36

• Mudflow Formation