Seismic intensity scale "MSK-64"
1. Classification adopted in the scale
Types of structures:
Buildings erected without the necessary anti-seismic measures.
Type A - buildings made of even stone, rural buildings, houses made of raw bricks, adobe houses
Type B - ordinary brick houses, large-block and panel-type buildings, half-timbered buildings, buildings made of natural hewn stone.
Type B - frame reinforced concrete buildings, well-built wooden houses.
Quantitative characteristics:
some - about 5%
many - about 50%
most - about 75%
Damage classification:
1 degree. Light damage: fine cracks in plaster and small pieces of plaster.
2nd degree. Moderate damage: small cracks in the walls, chipping off rather large pieces of plaster, falling roof tiles, cracks in chimneys, falling parts of chimneys.
3 degree. Severe damage: large and deep cracks in the walls, falling chimneys.
4 degree. Destruction: through cracks and breaks in the walls, collapse of parts of buildings, collapse of internal walls and walls of the frame filling.
5th degree. Landfall: Complete destruction of buildings.
Scale signs grouping a
) People and their environment,
b) Structures,
c) Natural phenomena.
2. Intensity (in points)
I point. Imperceptible earthquake.
a) The intensity of vibrations lies below the limit of sensitivity of people; earth shaking is detected and recorded only by seismographs.
b) -
c) -
II points. A barely perceptible earthquake.
a) The vibrations are felt only by individuals at rest inside the premises, especially on the upper floors.
b) -
c) -
III points. Weak concussion.
a) Earthquakes are felt by a few people inside the premises; in the open air - only in favorable conditions. The vibrations are similar to the shock generated by a passing light truck. Attentive observers notice a slight swaying of hanging objects, somewhat more violent on the upper floors.
b) -
c) -
IV points. Noticeable concussion.
a) The earthquake is felt inside buildings by many people; in the open air - few. Sleepers wake up in some places, but no one is frightened. The vibrations are similar to the shock generated by a heavy-loaded truck passing by. Rattling of windows, doors, dishes. The creak of floors and walls. Furniture begins to shake. Hanging objects swing slightly. The liquid in open vessels fluctuates slightly. In cars standing still, the shock is noticeable.
b) -
c) -
V points. Awakening.
a) An earthquake is felt by all people indoors, outdoors - by many. Many sleeping people wake up. Few people run out of the premises. The animals are worried. Shaking the building as a whole. Hanging objects swing violently. Pictures budge. On rare occasions, the pendulum clock stops. Some unstable objects tip over or move. Unlocked doors and windows swing open and shut again. Liquid spills out in small amounts from filled open vessels. The vibrations felt are similar to vibrations created by dropping heavy objects inside a building.
b) Damage of the 1st degree is possible in separate buildings of type A.
c) In some cases, the flow rate of the sources changes.
VI points. Fright.
a) An earthquake is felt by most people both indoors and outdoors. Many people in buildings get scared and run out into the street. Few faces lose their balance. Pets run out of hiding places. In a few cases, dishes and other glass products may break; books are falling. The movement of heavy furniture is possible; small bells on the bell towers can be heard ringing.
b) Damage of 1 degree in certain buildings of type B and in many buildings of type A. In separate buildings of type A, damage of 2 degrees.
c) In few cases, in moist soils, cracks up to 1 cm wide are possible; in mountainous areas, isolated cases of landslides. Changes in the flow rate of sources and water level in wells are observed.
VII points. Damage to buildings.
a) Most people are scared and run out of the premises. Many people find it difficult to stay on their feet. Fluctuations are noted by persons driving the vehicles. Big bells are ringing.
b) In many buildings of type B, damage of the 1st degree; in many buildings of type B - damage of the 2nd degree. In many buildings of type A - damage of 3 degrees, in some buildings of this type - damage of 4 degrees. In some cases - landslides of carriageways on steep slopes and cracks on the roads. Violation of pipeline joints; cracks in stone fences.
c) Waves form on the surface of the water, the water becomes cloudy due to the rise of silt. The water level in the wells and the flow rate of the sources are changing. In a few cases, new water sources arise or existing water sources disappear. Isolated cases of landslides on sandy or gravelly river banks.
VIII points. Severe damage to buildings.
a) Fright and panic; even people driving cars are worried. In some places, tree branches break off. Heavy furniture moves and sometimes topples over. Some of the hanging lamps are damaged.
b) In many buildings of type B - damage of the 2nd degree, in some buildings of this group - damage of the 3rd degree. In many buildings of type B - damage of 3 degrees, in some - 4 degrees. In many buildings of type A, damage is of 4 degrees, in some - 5 degrees. Isolated cases of rupture of pipeline joints. Monuments and statues are shifting. Headstones are overturned. Stone fences are crumbling.
c) Small landslides on steep slopes of excavations and road embankments; cracks in the ground reach several centimeters. New reservoirs are emerging. Sometimes dry wells are filled with water or existing wells dry up. In many cases, the flow rate of the sources and the water level in the wells change.
IX points. General damage to buildings.
a) General panic; large damage to furniture. Animals rush and scream.
b) In many buildings of type B, damage is 3 degrees and in some - 4 degrees. In many buildings of type B - damage of 4 degrees and in some - 5 degrees. In many buildings of type A - damage of the 5th degree. Monuments and columns are overturned. Significant damage to artificial reservoirs; breaks in part of underground pipelines. In some cases - the curvature of the railroad tracks and damage to the carriageways.
c) On the flood plains, deposits of sand and silt are often noticeable. Cracks in the ground reach a width of 10 cm, and along the slopes and banks of rivers - over 10 cm; in addition, a large number of fine cracks in the ground. Rocks are collapsing; frequent landslides and soil crumbling. There are large waves on the surface of the water.
X points. General destruction of buildings.
b) In many buildings of type B - damage of 4 degrees, and in some - 5 degrees. In many buildings of type B there is damage of the 5th degree, in most buildings of type A there is damage of the 5th degree. Dangerous damage to dams and dams, serious damage to bridges. Light curvatures of the railroad tracks. Breaks or bends in underground pipelines. Road surfaces and asphalt form an undulating surface.
c) Cracks in soils with a width of several decimeters and, in some cases, up to 1 m. Wide gaps appear in parallel to the channels of water flows. Falling loose rocks from steep slopes. Large landslides are possible on river banks and steep sea coasts. Sandy and silty masses move in coastal areas; splashing water in canals, lakes, rivers, etc. e. New lakes appear.
XI points. Catastrophe.
b) Serious damage even to well-constructed buildings, bridges, dams and railways; highways fall into disrepair, destruction of underground pipelines.
c) Significant deformation of the soil in the form of wide cracks, breaks and displacements in the vertical and horizontal directions; numerous rock falls.
Determination of the intensity of the concussion (score) requires a special study.
XII points. Relief change.
b) Severe damage or destruction of almost all surface and underground structures.
c) Radical changes in the earth's surface. Significant cracks are observed in soils with extensive vertical and horizontal movements. Mountain falls and landslides of river banks in large areas. Lakes appear, waterfalls are formed; river beds change.
Determination of the intensity of the concussion (score) requires a special study.