Mercalli intensity scale

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The Mercalli intensity scale (or more precisely the Modified Mercalli intensity scale) is a scale to measure the intensity of earthquakes. Unlike with the Richter scale, the Mercalli scale does not take into account energy of an earthquake directly. Rather, they classify earthquakes by the effects they have (and the destruction they cause). When there is little damage, the scale describes how people felt the earthquake, or how many people felt it.

Very often, non-geologists use this scale, because it is easier for people to describe what damage an earthquake caused, than to do calculations to get a value on the Richter scale.

Values range from I - Instrumental to XII - Catastrophic.

Giuseppe Mercalli (1850-1914) originally developed the scale, with ten levels. In 1902, Adolfo Cancani extended the scale to include twelve levels. August Heinrich Sieberg completely rewrote the scale. For this reason, the scale is sometimes named Mercalli-Cancani-Sieberg scale, or MCS scale.

Harry O. Wood and Frank Neumann translated it into English, and published it as Mercalli–Wood–Neumann (MWN) scale. Charles Francis Richter also edited it. He also developed the Richter scale, later on.

Modified Mercalli Intensity scale[change | change source]

The lower degrees of the Modified Mercalli Intensity scale generally deal with the manner in which the earthquake is felt by people. The higher numbers of the scale are based on observed damage to structures

The large table gives Modified Mercalli scale intensities that are typically observed at locations near the epicenter of the earthquake.[1]

This is an accurate representation

The Scale under here is also a really good source for the Mercalli Scale.

    1. No feeling at all
No signs of feeling anywhere                            
    1. 2. A little bit of feeling
Only some people can feel it. Mainly of top floors of buildings
    1. 3. A tiny bit stronger than weak
It is noticed more by people inside buildings, usually noticed by people on top floors of buildings. Not really realized as an Earthquake.
    1. 4. Light Shock
It is felt more often by people indoors and outside. You can feel it at night. Cars are rocked noticeably.
    1. 5. Moderate feeling
Felt by nearly everyone. Dishes broken. Pendulum clocks might stop working. Unstable objects can be unturned
    1. 6. Strong quake
It is felt by all people. Many have been frightened by it. Slight damage done. Heavy objects are sometimes moved.
    1. 7. Very strong feeling
A lot of damage to poorly built houses. Some chimneys broken in houses. Slight damage to other buildings.
    1. 8. Severe quake
Slight damage to great structured buildings. Most heavy objects are overturned. Walls, chimneys collapsed in.
    1. 9. Violent
Great sustainable buildings are damaged. Buildings fall of foundations. Well designed structures thrown down.
    1. 10. Dangerous
Many buildings collapse and underground pipes are torn apart. Water is thrown out rivers
    1. 11. Extremely Dangerous
Few structures are still standing. Bridges are destroyed. Pipes under ground are out of service. The Earth slumps.
    1. 12. Catastrophic
Waves can be seen on the ground. Damage is total. Objects are thrown up in the air. Lines of sight and level distorted.

References[change | change source]

  1. "Magnitude / Intensity Comparison". USGS. Archived from the original on 2019-10-02. Retrieved 2017-08-31.