Earthquakes ofof the Earthquake - underground blows (pushes) and fluctuations of the Earth`s surface caused by processes of release of energy in it (mainly tectonic). On the destructive consequences earthquakes have not equal among natural disasters. All surface of the globe is divided into several huge parts of crust which are called tectonic plates. It: North American, Euroasian, African, it is southern - the American, Pacific and Atlantic plates. Tectonic plates are in the continuous movement (can be moved apart, move or slide one concerning another), and it makes several centimeters a year. Earthquakes are result of collision of these plates and are followed by changes of the Earth`s surface in the form of folds, cracks, etc. which can stretch for long distance. The areas located near borders of tectonic plates are most subject to earthquakes. Sometimes there are earthquakes in internal parts of plates - so-called vnutriplitovy earthquakes.
Earthquakes can arise also for other reasons. One of such reasons is volcanic activity (in places where tectonic plates are moved apart). The collapse of a roof of mines or underground emptiness with formation of elastic waves is other reason. The earthquakes arising at development of large landslides call landslide. Besides, earthquakes can be caused also by engineering activity of the person (filling of reservoirs, pumping water in wells).
Dangerous consequences of earthquakes are divided into natural hazards and connected with activity of the person. Treat natural: soil concussion, soil violation (cracks and shifts), landslides, avalanches, mudflows, fluidifying of soil, subsidence, tsunami, seiches.
Treat the consequences of earthquakes connected with activity of the person: destruction or building collapse, bridges and other constructions; floods at breaks of dams and water supply systems; the fires at damages of oil storages and ruptures of gas pipelines; damage of vehicles, communications, lines of power and water supply, and also sewer pipes; radioactive leaks at damage of nuclear reactors.
One of the main characteristics of an earthquake is the energy radiated at a seismic push in the form of elastic waves. Energy of seismic waves or magnitude can make up to hundreds of thousands millions KW/hour
Besides natural earthquakes, occur and there can be destructive earthquakes caused by human activity. An example of such activity is filling deep (more than 100 m) reservoirs, formation of underground cavities owing to mining. Destructive ability of an earthquake depends on its magnitude and on depth of the center and is characterized in conditional points of intensity. In Russia it is accepted 12 - a ball International seismic scale of intensity of MSK-64 (Merkalli`s scale) describing result of an earthquake in its epicenter, and for destructive (6-9 points) earthquakes - additional own scale of 1973.