Here is 10 Surprising Landslides Facts you must know.A landslide is a sliding displacement of rock masses down the slope under the influence of its own gravity, without loss of contact between moving and stationary rocks.
- by area: giant, very large, large, medium, small, very small (Table 5.3);
- according to the mechanism of displacement: sliding, squeezing, floating out, subsidence, landslides in rocks;
- by age: ancient, young, modern;
- by geological conditions: bedrock landslides, landslides of surface sediments.
Causes of landslide formation:
- an increase in the steepness of the slope as a result of water washing the base;
- weakening of the strength of the rocks during their weathering or overwetting;
- seismic activity;
- violation of mining technology;
- deforestation and destruction of vegetation on the slopes;
- improper agricultural practices using slopes and farmland.
Large landslides are usually caused by natural causes and are formed along the slopes for hundreds of meters. Their thickness reaches 10–20 m, and sometimes more. Medium and small landslides are smaller and characteristic of anthropogenic processes.
The landslide thickness is characterized by the volume of shifting rocks, which can range from 10 thousand (small) to several million cubic meters (very large).
The offset velocity of the landslide can also be different:
- exceptionally fast (3 m per second);
- very fast (3 dm per minute);
- fast (1.5 m per day);
- moderate (1.5 m per month);
- very slow (1.5 m per year);
- extremely slow (6 cm per year) .
Slow displacements are not catastrophic. Displacements with medium speed are dangerous, but they cause more economic damage, since the population is evacuated from the danger zone in time. Only fast, at speeds of up to tens of kilometers per hour, displacements can cause disasters with a large number of victims.
The magnitude of the effects of landslides are determined primarily by the number of people in the landslide zone; the number of dead, wounded, homeless; the number of localities caught in the disaster zone; the area of flooding and dumping of agricultural land.
Actions of the population in case of landslide threat
- The population living in landslide areas should know the sources, possible directions and characteristics of this dangerous phenomenon.
- Information about the danger and measures regarding the identified landslide foci and possible zones of their action, as well as the procedure for giving signals about the threat of this dangerous phenomenon, should be communicated to the residents in advance.
- The population is obliged to carry out activities to strengthen the houses and territories in which they are built, as well as to participate in the construction of protective hydraulic structures and other engineering structures.
- When a landslide is threatened, early evacuation of the population, farm animals and property to safe areas is organized.
- Valuable property that cannot be taken with you should be protected from moisture and dirt.
- Doors and windows, ventilation and other openings tightly closed.
- Electricity, gas, plumbing off. Flammable, poisonous and other hazardous substances are removed from the house and, at the earliest opportunity, are stored in pits or cellars.
- In case of the threat of a natural disaster, the residents produce an emergency independent exit to a safe place (mountain slopes, hills, not predisposed to the landslide process).
Public action in the event of a landslide
- In the case when people, buildings and other structures appear on the surface of a moving landslide plot, one should, having left the room, move upwards if possible, acting according to the situation.
- Beware when braking a landslide lumps, stones, debris, structures, earthen embankment, scree rolling down from the back of it.
- After the landslide is over, people who hastily left the disaster zone and have been outlining it in a nearby safe place should, making sure that there is no repeated threat, return to this zone in order to search for the victims and assist them.