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Earth and Space > Mercalli Scale

The Mercalli scale is used to measure the intensity of earthquakes. The scale is commonly used in Japan and the former Soviet republics but is increasing in use across the world. The scale is similar to the Beaufort wind scale in that it uses human senses and observations to give an intensity reading.

Mercalli Number Description
1 Not felt except by a very few.
2 Felt only by a few persons at rest, delicately suspended objects may swing.
3 Felt quite noticeably by persons indoors, especially on the upper floors of buildings. Many do not recognize it as an earthquake. Standing cars may rock slightly.
4 Felt indoors by many. At night, some awakened. Standing cars rocked noticeably. Dishes and windows rattle.
5 Felt by nearly everyone; many awakened. Some dishes and windows broken. Unstable objects overturned. Clocks may stop.
6 Felt by all; many frightened and run outdoors, walk unsteadily. Windows, dishes, glassware broken; books off shelves; some heavy furniture moved or overturned. Damage slight.
7 Furniture broken; damage negligible in building of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.
8 Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture moved.
9 General panic; damage considerable in specially designed structures. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations. Damage to underground pipes.
10 Only strongest buildings survive. Rails bent. Ground badly cracked.
11 Few, if any masonry structures remain standing. Bridges destroyed. Rails bent greatly.
12 Total damage - Almost everything is destroyed. Lines of sight and level distorted. Objects thrown into the air. The ground moves in waves or ripples. Large amounts of rock may move.