Earthquakes are called tremors which are caused by generally natural processes, but can have also artificial reasons. Weak earthquakes sometimes are not perceived by feelings of the person, and strong are capable to cause huge destructions.
Instruction
1. The most part of earthquakes occurs under the influence of natural processes. One of the most common causes of earthquakes – shifts and movements of tectonic plates. Earth crust consists of a set of plates which constantly are in the movement and move relatively each other. When two plates face among themselves, they form folds, shifts, dumpings and other formations, and quite often it is followed by tremors.
2. Sometimes huge layers of the earth approach at each other, sometimes between them the collapse is formed. The centers of such earthquakes – that is areas in which they arise – are deeply. As a rule, tectonic earthquakes the most destructive, their force can reach seven points on the Richter scale. The Richter scale – the most popular method of measurement of force of earthquakes which is based on determination of magnitude.
3. Some earthquakes arise because of activity of volcanoes. In a muzzle of active volcanoes there can be various processes leading to pushes: a vypiraniye of a lava stopper from a muzzle, failures of emptiness after outpouring of a lava, sharp depression of gases. Eruptions of volcanoes lead to strong earthquakes too. The center of volcanic earthquakes is superficially, but destructions from them can be too serious as such pushes proceed for a long time, sometimes months.
4. Failure earthquakes often not such destructive, they are created because roofs of the emptiness created in breeds of the earth by underground waters collapse. Also lead collapses and landslides to earthquakes, but they have no big force and do not extend to long distances.
5. Some earthquakes are caused by human activity, at the same time they can be both intended, and accidental. Artificial earthquakes are created by means of explosions. For example, there is such concept as underground nuclear explosion – the nuclear bomb is put in action underground to create an earthquake. It is called tectonic weapon.
6. To accidental it is possible to carry such technogenic earthquakes which are caused by construction of large reservoirs or oil and gas production at big depths. In the first case in one place too much water which begins to press on rocks that causes tremors accumulates. In the second strong breeds begin to take the place of the rolled-out oil, and these shifts cause small earthquakes.