Movements of the Earth’s crust: volcanoes and earthquakes

Under the Earth’s internal forces some parts of the crust slowly rise and others sink – these are tectonic movements; they are very slow and take place over millions of years. In horizontal movement layers bend into folded mountains, valleys and depressions (the Fergana valley, the Tien Shan). Where the crust cracks, magma rises and flows onto the surface as lava; cooled lava builds volcanic mountains, and the vent is called the crater. Hot springs that spout from time to time are geysers. An earthquake is a sudden breaking or shifting of rock layers; the deep place where it begins is the focus (hypocentre), the point on the surface above it is the epicentre, where destruction is greatest. A seismograph records earthquakes; strength is measured on a 12-point scale (1–2 points are not felt, at 8 walls crack, 11–12 are catastrophic); magnitude, based on energy, is also used now. The eastern and southern mountain parts of Uzbekistan are seismic areas. During an earthquake: with an adult go under a sturdy table or by an inner wall and protect your head, keep away from windows, do not use a lift; when the shaking stops, go out to an open place.