Mudflows are streams consisting of mud and stones that slide down the slopes of mountains and riverbeds, sweeping away any obstacle in their path. Such a natural phenomenon is one of the most dangerous for the life of people and the infrastructure of settlements.
The occurrence of mudflows
During the rapid melting of glaciers in the mountains, as well as after heavy rains, storms, hurricanes, water accumulates in front of a natural obstacle. In some places quite large lakes and reservoirs are formed. Such formations are called moraine lakes, it is they who, after some time, are transformed into landslides, mudflows, landslides and avalanches. Moraines consist of:
- Sand.
- Valunov.
- Ice and snow.
- Hardwood.
- Crushed stone.
- Clays.
At some point, a huge mass of mud, mixed with water and stones, breaks through the dams, rushing down in a swift stream. Developing tremendous speed, making a loud roar, the stream picks up more and more stones along the way.and trees, thereby increasing its destructive power.
Mudflows at the beginning of their movement reach no more than 10 meters in height. After a natural disaster breaks out of the gorge and rushes down the mountain, it will spread over a flat surface. Its movement speed and height will be greatly reduced. When it reaches an obstacle, it stops.
Consequences of the descent of rocks and water
In the event that a settlement is on the way of the mudflow, the consequences for its population can be catastrophic. A natural disaster is deadly, and often leads to large material losses. Especially a lot of destruction is brought by the descent of rocks and water in the villages where people live in poorly fortified frame houses.
The consequences of landslides, mudflows and landslides are catastrophic. So, a major disaster occurred in 1921 in the former capital of Kazakhstan - Alma-Ata. Late at night, a powerful mountain stream, about a million cubic meters in size, hit the sleeping city. As a result of an emergency, a strip of stones and mud 200 meters wide was formed right in the middle of the city. Buildings were destroyed, infrastructure was damaged, and people were killed.
In Russia, mudflows are also often formed in mountainous areas, especially in those places where it rains heavily, for example, in the Caucasus and the Far East. In Tajikistan, mudflows occur every year in the spring season. Especially often this phenomenon occurs in high mountains during the melting of snow.
Protection against mudflows
To protect the population and tourists from sudden rock falls in especially dangerous mountainous areas, where landslides, mudflows, landslides and avalanches periodically occur, it is necessary to monitor them from the air. Experts observe the formation of mountain lakes and can predict in advance about the danger of an emergency disaster. Engineers are also developing anti-mudflow artificial barriers and diversion channels, which are several hundred kilometers long.
In 1966, a protective dam was built from earth and large cobblestones near the city of Alma-Ata. The total weight of building materials amounted to about 2.5 million tons. After 7 years, the artificial structure saved the lives of many citizens, shielding the city from a mudflow of unprecedented power.
Despite the fact that in most cases mudflows fall from the mountains suddenly, scientists have learned to predict their approach by some signs, for example, by changing the color of the water in a mountain lake.
Emergency Survival
Tourists who often travel in the mountains should be aware of the danger of landslides, mudflows, landslides, life safety. Safety rules may save your life one day!
In order to properly prepare for a difficult and long hike in the mountains, you should find out the weather forecast before leaving. If it is raining heavily in the mountains, then the likelihood of mud flows increases significantly. For safety, it is better to keep to the inner part of the bend of the rivers, since the mudflow rises much higher on the outer side. Also, you should not spend the night near mountain lakes and rivers, andalso in narrow gorges.
What are landslides
A landslide is a downslope displacement of a formed mass of rocks. The reason for their occurrence is most often heavy rains, as a result of which rocks are washed away.
Landslides can occur at any time of the year, and differ from each other in the extent of destruction. A slight displacement of the rock leads to damage to the roads. Significant destruction and spalling of stones leads to the destruction of houses, as well as to human casu alties.
Separation of landslides into types
Landslides are divided into slow, medium and fast. The first move at a low speed (a few centimeters per year). Medium - a few meters per day. Such displacements do not lead to disasters, however, sometimes such natural phenomena lead to the destruction of houses and outbuildings.
Fast landslides are considered the most dangerous, because in this case, streams of water with stones break down from the mountains and move down at great speed.
All movements of rocks and masses of clay can be predicted by paying attention to the following signals:
- new cracks and crevices formed in the soil;
- falling stones from the mountains.
How to avoid destruction and casu alties
Against the backdrop of incessant downpours, the above signals should become harbingers of danger for the security services and the population. Timely detection of signsan impending landslide will help to take measures to rescue and evacuate the population.
As a preventive measure and protection against destruction, protective nets, artificial tunnels, and tree cover are being built near cities. Shore protection structures and slope stabilization with piles have also proven themselves well.
Where arise
Many are wondering where avalanches, landslides, mudflows and landslides most often occur. The displacement of rocks, huge masses of snow and water occurs in areas or slopes as a result of imbalance, which is caused by an increase in the steepness of the slope. This mainly happens for several reasons:
- Too much rain.
- Weathering or waterlogging of rock by groundwater.
- Earthquakes.
- Construction and human activities that do not take into account the geological conditions of the area.
Intensification of the landslide is facilitated by the slope of the earth towards the cliff, cracks on the top of the mountain, which are also directed towards the slope. In places where the soil is most moistened by rains, landslides take the form of a stream. Such natural disasters cause great damage to agricultural land, businesses and settlements.
In the highlands and northern regions of our country, the thickness of the soil is only a few centimeters, and therefore it is very easy to break. An example is the place in the Orlinaya Sopka area (Vladivostok city), where uncontrolled deforestation began in the early 2000s. As a resulthuman intervention on the hill disappeared vegetation. After each rainstorm, a stormy stream of mud pours onto the streets of the city, which was previously blocked by trees.
Landslides are often found in areas where slope erosion processes are actively taking place. They occur when masses of rocks lose their support as a result of an imbalance. A massive landslide occurs in places where there are:
- mountain slopes made up of alternating impervious and water-bearing rocks;
- man-made rock heaps near mines or quarries.
Landslides moving from the side of a mountain in the form of a pile of rubble are called rockfalls. If a huge block of stone slides along the surface, then such a natural phenomenon is called a collapse.
Instances of large landslides
To learn more about the largest convergences of landslides, mudflows, landslides, avalanches and the consequences for people, you should refer to the historical literature. Witnesses of terrible catastrophes often describe the descent of large masses of rock and snow avalanches from ancient times. Scientists believe that the world's largest descent of stones occurred at the beginning of our era near the Saidmarreh River in southern Iran. The total mass of the landslide was approximately 50 billion tons, and its volume was 20 cubic kilometers. The mass, consisting of stones and water, collapsed from Mount Kabir Bukh, whose height reached 900 meters. The landslide crossed the river 8 kilometers wide, then it crossed the ridge and stopped after 17 kilometers. ATAs a result of the blocking of the river, a large lake was formed, 180 meters deep and 65 kilometers wide.
In ancient Russian chronicles there is information about huge landslides. The most famous of them dates back to the 15th century in the region of Nizhny Novgorod. Then 150 yards were damaged, many people and farm animals were affected.
The scale of destruction and the consequences of landslides and mudflows depend on the density of buildings and the number of people living in the disaster area. The most destructive landslide occurred in Gansu Province (China) in 1920. More than 100 thousand people died then. Another powerful landslide that claimed the lives of 25 thousand people was registered in Peru (1970). As a result of the earthquake, a pile of stones and water fell into the valley at a speed of 250 kilometers per hour. During the disaster, the cities of Ranrahirca and Yungai were partially destroyed.
Landslide prediction
To predict landslides and mudflows, scientists are constantly conducting geological research and mapping dangerous areas.
Aerial photography is carried out to identify areas of accumulation of landslide material. The photographs clearly show the places where rock fragments are most likely to come off. Geologists also determine the lithological features of the rock, the volume and nature of the flow of groundwater, vibrations as a result of earthquakes, as well as slope angles.
Landslide protection
If the likelihood of landslides and mudflows is high, then special services take measures to protectpopulation and buildings from such a natural phenomenon, namely, they strengthen the slopes of the shores of the seas and rivers with a wall or beams. Soil slippage is prevented by driving piles in a checkerboard pattern, planting trees, and also carrying out artificial freezing of the earth. To prevent wet clay from coming off, it is dried by electroosmosis. The descent of landslides and mudflows can be prevented by pre-constructing drainage structures that can block the path to groundwater and surface water, thereby preventing soil erosion. Surface water can be diverted, canals can be pulled out, underground water can be drained with the help of wells. Such measures are quite expensive to implement, but such measures can prevent the destruction of buildings and avoid human casu alties.
Warning the public
The population is warned about the danger of earthquakes, landslides and mudflows in a few tens of minutes, at best, in a few hours. To notify a large populated area, an alarm is given using a siren, and announcers also announce the danger on TV and radio.
The main damaging factors in landslides and mudflows are mountain boulders that collide with each other during their movement from the mountains. The approach of rocks can be identified by the characteristic loud sound of rolling stones.
People living in a particularly dangerous mountainous area, where avalanches, mudflows and landslides are possible, should know from which side trouble can come, what will be the nature of the destruction. Residents should alsoknow the escape routes.
In such settlements, houses and territories on which they are built should be fortified. If the danger is known in advance, an urgent evacuation of the population, property and animals to safe areas is carried out. Before leaving home, you should take the most valuable things with you. The rest of the property, which cannot be taken with you, should be packed to protect it from dirt and water. Doors and windows should be closed. It is also necessary to close the ventilation hole. It is mandatory to turn off the water and gas, turn off the electricity. Poisonous and flammable substances must be taken out of the house, they are placed in pits remote from housing.
If the population was not warned in advance about landslides and mudflows, each resident must find shelter on their own. It is also necessary to help children and the elderly to hide.
After the end of the disaster, you should make sure that there is no danger, leave the shelter and start searching for the victims, if necessary, help them.
