Often in the news there are reports of landslides that occurred in various regions of the country or the world. We also often hear about avalanches that descended in mountainous regions. What are landslides and avalanches? What damage can they cause and is there a way to protect themselves from these natural phenomena?
Landslides
The sudden separation of rocks from the bulk is called a collapse. It can occur in the mountains, on the steep banks of the seas, along river banks and in valleys. Why is the land lying on the slope suddenly collapsing?
Most often, collapses occur for the following reasons:
- thanks to water washing, the steepness of the slope increased,
- with excessive waterlogging or weathering, the strength of the rocks decreases,
- under the influence of earthquakes,
- thanks to human activities.
Not only soft soil rocks fall off. There are frequent cases when a single moving stone in the mountains, falling down the slope, carries away hundreds of others, this is called a mountain collapse. Large landslides mainly occur as a result of tremors. Happened near settlements, such incidents can escalate into a real disaster. The most significant of them can even change the topography of the area. What are landslides, you can clearly see by visiting Lake Sarez. It was it that was formed due to the severe collapse of 1911, in which 2.2 billion cubic meters of rocks were involved. A huge mass fell into the river, blocking it. This is how the lake was formed.
Kinds
Now it’s clear what the collapses are. But it turns out they come in many forms. If less than 5 cubic meters of rock are involved in the collapse, this is considered to be a very small collapse. Small - up to 50 cubic meters. Medium - from 50 cubic meters to a ton. Large includes more than a ton of rocks.
According to statistics, of all the collapses, the majority are small. They occur about 70% of the total number. Medium - in second place: about 15%. Well, large ones happen quite rarely - less than 5% of the total. It is extremely rare - with a frequency of 0.05% - that gigantic or even catastrophic landslides occur. In such incidents, a huge number of rocks are involved - millions and billions of cubic meters.
Effects
Most countries around the world know what landslides are. And everyone knows that the scale is sometimes very impressive. In addition, the consequences of collapses are catastrophic. Such incidents can cause collapse of railway embankments, large blockages, destruction of dwellings and forests. There are frequent cases when gigantic landslides were the cause of severe flooding and loss of life. Collapses of this kind most often occur as a result of strong earthquakes - from 7 points.
Stop
There are ways to deal with collapses, but they are not able to protect everywhere, and it will not work with any collapse. For example, a railway runs from Tuapse to Sukhumi along the Black Sea. On the one hand, the canvas is threatened by strong sea waves, from which it was decided to protect the road with reinforced concrete structures. On the other hand - steep cliffs. Stone walls protect the falling stones from collapses. Similarly, they protect mountain roads. Unfortunately, these methods minimize the consequences of collapses only in cases of minor collapses.
Where rocky overhangs significantly, there is only one way to save people and buildings from disaster - on their own, without waiting for the disaster, to destroy the rocks. Strengthening the slopes is much less common, then they are surrounded by steel hoops, the cracks appear are poured with cement, etc. If there is a danger of collapse near settlements, the inhabitants have to be evacuated, and the village must be moved to another place.
Avalanches
Not only rocks can fall off. In the mountains covered with snow, snowfalls often occur - the masses of snow that fall from the mountain slopes often have a strong destructive effect. Why do avalanches happen? The fact is that the snow on the slopes is not uniform. Different layers of it have different coupling stiffness. And when the adhesion between the layers is weak, the top layer simply slides.
Avalanches distinguish superficial when one or several upper layers descend, and full-depth ones, taking away all covering of a mountain slope, exposing the earth. Also, an avalanche can be wet or dry, depending on the water content. A snowfall can begin from one point, but it can also break off as a whole layer, leaving behind a separation line. Almost any gathering of snow that is capable of knocking down a person by its own motion is considered an avalanche.
In order to assess the likelihood of an avalanche, many factors are taken into account. The most important is the weather. However, the evolution of the snow cover is no less important, but it directly depends on the weather. And since a skier or climber is able to analyze both of these indicators, he should not forget about any of them.
Consequences of avalanches
Currently, avalanches are mostly dangerous for athletes and tourists traveling to the mountains. Most often they fall in love with snowmobile riders in the mountains, climbers and skiers. Strong avalanches can cover settlements, sweeping away everything living and nonliving on its way. Sometimes mountain roads are in the way of the elements. Then the movement on them stops until the entire width of the avalanche is removed from the path.
Prevention
In traditional places of winter recreation, it has long been common practice to artificially cause a collapse. The avalanche in this case will be small, its descent will not cause harm.
So, it is customary to commit forced snow caving using artillery guns, mortars, and other methods. In addition, on the path of the possible movement of the avalanche, structures are installed that can stop the progress of snow or slow down its movement. To achieve better results, you must use the full range of measures currently known. Only using active, passive and engineering methods can save people from falling into a snowfall.
An avalanche is dangerous not only directly at the moment of descent. During movement, the snow is able to heat up to positive temperature. And at the time of stopping, he forms a very hard crust, which is not easy to pierce even for an ordinary person - with intact organs and in a calm mental state. To a person who has fallen into an avalanche, received various injuries, and is frightened, it is almost impossible to do so.