What Causes Landslides? The Most Important and Interesting Landslide Information
Important Landslide Information
Landslides and mudslides are moving masses of rock and mud with soil. Usually, it consists of loose soil, which is no longer able to withstand the load of its own weight, which causes it to shift. The debris flow definition states that this geological phenomenon is very dangerous because such rock masses can bury various objects and people under them. When huge masses of rocks topple down the slopes under the force of gravity, not everyone can escape. Especially a landslide and mudslide high up in the mountains, where huge quantities of sediment, diluted by river water, heavy rain, or melted snow, rush downhill at great speed.
The term “landslide” often refers to the process of displacement itself or the phenomenon, i.e., the result of displacement of ground masses (geological body, landslide accumulation, landslide body, etc.). Thus, information about landslides consists of two definitions: landslide (as a phenomenon) is a geological body represented by displaced rock masses and debris flows formed as a result of the development of a landslide process on the slope. Landslide (as a process) is the movement of the formed landslide body on the slope surface.
Occurrence of Landslides
Most often a landslide is formed on the banks of rivers, reservoirs, and on mountain slopes: 90% of the shifts are recorded at an altitude of one to two miles. At the same time, landslides are formed on slopes with an angle of nineteen degrees, and on clay soils with a strong moistening of rocks, landslides occur even at a slope of five degrees.
What Are the Causes of Landslides?
There are many reasons why this landslide disaster may occur. However, it should be understood that a landslide does not form in an even place. There must be suitable conditions for it to become possible. For example, to define debris flow, you should understand that landslides are often formed on various slopes, the banks of bodies of water, the bottom of the sea. Although they can also occur in other places. And they can form on their own, or they can be formed under external influence.
Let us discuss other reasons for landslides:
- Moistening and erosion of rocks by rainwater is the most common cause of landslide natural disasters. After all, as a result of this, the soil becomes heavier and more mobile. So it is displaced under the influence of its own weight.
- As well, landslides are caused by undermining of the banks of reservoirs is also often the cause of landslides. It is especially characteristic of rivers as the water moves at a high speed and it is hard to prevent landslides.
- Rocks can also be eroded from the inside. After all, geological sites are often composed of alternating water-bearing and water-resistant rocks. Because of this, groundwater can have a very strong influence on the ground.
- Information on landslides states that earthquakes are another cause of the phenomenon. By shifting the earth’s crust, earthquakes cause landslides, which is not at all surprising.
- Landslides are an example of shifts underwater as well. Similar shifts occur at the bottom of the seas or oceans. They are caused by the impact of water and various processes taking place in the body of water. Such landslides are the largest and strongest. They can cause the formation of tsunamis, which are extremely dangerous.
- Excessive load on the rocks can also cause them to move. In most cases, this occurs as a result of construction and economic activity. But in rare cases, even the weight of a small group of people can be the last straw that triggers a landslide. So you have to be very careful when traveling through such dangerous places.
Therefore, in spite of the fact that the causes of such land displacement are different, landslides are formed mainly because of erosion of rocks by water combined with weathering and over-wetting. A landslide can also be triggered by an earthquake or by sea or river water eroding the slopes.
A landslide caused by natural causes occurs mostly after heavy rains that wet the soil so much that it becomes mobile. At this point, the frictional force that binds it to the slopes is weaker than gravity, which sets the rocks in motion.
Some of the most dangerous and unexplored are submarine landslides, which form during the movement of sedimentary rocks at the edge of the shelf (the consequences are dangerous in that they raise tsunamis). According to statistics, about 80% of landslides are caused by human activities – road building on slopes, deforestation, unwise farming.
The Consequences of Landslides
A landslide is an example of a natural disaster where it is quite rare for people to become victims, as few people live under slopes. However, there are still settlements that are dangerously close to a possible landslide site. And sometimes such settlements are partially destroyed by the moving masses of rocks. But, as a rule, the movement of the ground is quite slow, so that often all the inhabitants can be saved.
Fortunately, the number of victims of landslides is not very high, but the economic damage caused by landslides is enormous and governments try to find any possible ways to prevent landslides. They cause the destruction of roads, buildings, communications, and various important objects. Also, serious damage is caused by this phenomenon to agricultural land. Therefore, in places exposed to the risk of landslides, some protective measures are taken. For example, trees are planted that can restrain the movement of loose soil.
What to Do during Landslides?
People living or staying in areas where landslides and mudslides are a frequent phenomenon should be well aware of the signs and features of these dangerous landslides. For example, one of the first signs of the approaching disaster is the seepage of water on slopes.
Therefore, as soon as there are the first signs of the dangers (despite the rapid nature of the elements, modern equipment makes it possible to register their appearance in time) usually the evacuation of the inhabitants of the region is carried out. Before leaving your home, you should tightly close all ventilation ducts, windows, and doorways, turn off electricity, gas and shut off the water.
If it happens that landslides appear suddenly and move so quickly that the population did not have time for preventing landslides and people received information a few minutes before the mudflow or even noticed it themselves, you must immediately run away to a safe place. Usually, these are hills or mountains that are away from the flow.
When the landslide has stopped, you should not return home immediately, but after a few hours, because there is a danger that a new landslide will occur. If there is no indication that the landslide may recur, you can return home and then immediately begin searching for and retrieving victims in the village, freeing vehicles blocked by mud.
How to Prevent Landslides?
In practice, special networks, gabion structures, and geogrids are often used for preventing landslides. Competent installation of protective engineering structures helps to protect the area from landslides for a long time. Experience shows that the most effective way is a complex of measures and the use of different protective materials against landslides. Thus, the effectiveness of gabions and geogrids significantly increases with the use of geotextile, which acts as an excellent reinforcing material and prevents the mutual penetration of technological layers.
There are also other ways to prevent landslides:
- soil stabilization. The technology consists of the use of meshes or geosynthetic grids. If you choose the first, it is enough to roll them out over the site and fix them with anchors. If you choose the latter, you will first have to fold them into modules and only then connect them to the surface;
- artificial lowering of groundwater level is an active method of landslide protection. By reducing groundwater also reduces its destructive effect on the soil. As a result, the risk of landslide formation is reduced;
- changing the relief of the slope helps prevent movement of the soil base. Measures are taken to terracing the area, forming slopes of the required steepness, and replacing weak soils.
Before performing any of the methods, it is important to conduct geological exploration, collect all the information about the site and analyze how one or another method of landslide protection will affect the environment.
In general, landslides cannot be called a very dangerous natural phenomenon. Yes, they cause serious damage, but the number of victims is small. And if you take the necessary precautions, you can easily avoid the danger. Stay with us!