The Mercalli intensity scale is a scale used for measuring the intensity of an earthquake. A seismic scale is used to measure and compare the severity of Earthquakes (For a quick review see the table of seismic scales at the end of this article An earthquake is the result of a sudden release of energy in the Earth 's crust that creates Seismic waves Earthquakes are recorded with a Seismometer The scale quantifies the effects of an earthquake on the Earth's surface, humans, objects of nature, and man-made structures on a scale of I through XII, with I denoting a weak earthquake and XII one that causes almost complete destruction

Contents 1 Modified Mercalli 2 Correlations with Physical Quantities 3 See also 4 Bibliography

Modified Mercalli

The lower degrees of the MM scale generally deal with the manner in which the earthquake is felt by people. The higher numbers of the scale are based on observed structural damage. The table below is a rough guide to the degrees of the Modified Mercalli Scale. The colors and descriptive names shown here differ from those used on certain shake maps in other articles.

I. Instrumental	Not felt by many people unless in favorable conditions.
II. Feeble	Felt only by a few people at best, especially on the upper floors of buildings. Delicately suspended objects may swing.
III. Slight	Felt quite noticeably by people indoors, especially on the upper floors of buildings. Many do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated.
IV. Moderate	Felt indoors by many people, outdoors by few people during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably. Dishes and windows rattle alarmingly.
V. Rather Strong	Felt by nearly everyone; many awakened. Some dishes and windows broken. Unstable objects overturned. Clocks may stop.
VI. Strong	Felt by all; many frightened and run outdoors, walk unsteadily. Windows, dishes, glassware broken; books off shelves; some heavy furniture moved or overturned; a few instances of fallen plaster. Damage slight.
VII. Very Strong	Difficult to stand; 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. Noticed by people driving motor cars.
VIII. Destructive	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.
IX. Ruinous	General panic; damage considerable in specially designed structures, well designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations.
X. Disastrous	Some well built wooden structures destroyed; most masonry and frame structures destroyed with foundation. Rails bent.
XI. Very Disastrous	Few, if any masonry structures remain standing. Bridges destroyed. Rails bent greatly.
XII. Catastrophic	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 position.

Correlations with Physical Quantities

The Mercalli scale is not defined in terms of more rigorous, objectively quantifiable measurements such as shake amplitude, peak velocity, acceleration, or period. Information on these has been provided by the USGS Shakemap site. Note that perceived shaking (the basis for the Calligraph scale) is best correlated with acceleration for low-intensity events, and with velocity for high-intensity events.

See also

• Other seismic scales
• Hayward Fault Zone for seismic shake maps using the Mercalli scale

Bibliography

• The Severity of an earthquake pamphlet of the United States Geological Survey
• U.S. National Earthquake Information Center
• John N. Louie, Associate Professor of Seismology at the University of Nevada

Seismic scales view • talk • edit
Modern scales
Intensity scales
European Macroseismic Scale (EMS) | INQUA | Medvedev-Sponheuer-Karnik (MSK) | Modified Mercalli (MM) | Shindo
Magnitude scales
Local magnitude (Richter scale) | Moment magnitude
Historical scales
Mercalli-Cancani-Sieberg (MCS) | Mercalli-Wood-Neuman (MWN) | Omori | Rossi-Forel

A seismic scale is used to measure and compare the severity of Earthquakes (For a quick review see the table of seismic scales at the end of this article The Hayward Fault Zone is a Geologic fault zone capable of generating significantly destructive Earthquakes About 60 kilometers long it lies mainly along the A pamphlet is an unbound Booklet (that is without a hard cover or binding) The United States Geological Survey ( USGS) is a scientific agency of the United States government. The European Macroseismic Scale (EMS is the basis for evaluation of seismic intensity in European countries and moreover in use on most other continents The Medvedev-Sponheuer-Karnik scale, also known as the MSK or MSK-64, is a macroseismic intensity scale used to evaluate the severity of ground shaking on the basis The Japan Meteorological Agency seismic intensity scale is a measure used in Japan and Taiwan to indicate the strength of Earthquakes It is measured in units of. The Richter magnitude scale, or more correctly local magnitude M L scale assigns a single number to quantify the amount of seismic energy released TalkMoment magnitude scale#Real world examples please.--> The moment magnitude scale The Rossi-Forel scale was one of the first seismic scales to reflect earthquake intensities

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