The intensity of earthquakes is a qualitative characteristic of the degree of destruction and other manifestations on the earth's surface, at a specific point on the earth's surface. A twelve-point scale is used for this.
Earthquake gradation by strength (intensity, seismic effect):
One point is the minimum fluctuation, it is not felt by people.
Two points (very weak) - slight fluctuations are noticeable on the upper floors of high-rise buildings. The reason may be man-made, from a loaded truck that passed under the windows.
Three points (weak) - chandeliers are swinging.
Four points (moderate) - there is a shaking inside the buildings.
Five points (strong) - fluctuations are felt both in the building and on the street.
Six points (strong) - furniture shifts and falls, dishes bounce, window panes burst. People run out of buildings into the street in fright.
Seven points (very strong) - it is difficult to stand on your feet, the walls of brick houses crack, staircases and ceilings of buildings fall, landslides and cracks appear on roads, in winter - ice cracks on rivers and reservoirs. There is an additional danger - fires, accidents, short circuits.
Eight points (devastating) - brick buildings are collapsing, underground utilities are being torn.
Nine points (devastating) - cracks form in the soil, there is a lot of excitement on rivers and in reservoirs.
Ten points (devastating) - asphalt on roads crumples and breaks, cracks in the ground - up to a meter wide, landslides and landslides.
Eleven points (catastrophic) - brick houses are almost all destroyed, roads are badly damaged.
Twelve points (catastrophic) - the earth's surface is changing; cracks in the earth's crust reach a width of up to 10-15 m, a depth of up to 10 m or more, closing or remaining open with the following shocks; the amplitude of vertical vibrations of the soil reaches half a meter; large areas settle and can be flooded, or rise - with an amplitude of up to several tens of meters or more; displacements occur along the faults.