Richter v.s. Mercalli

Richter and the Mercalli scale are two different ways to measure earthquake eruptions.


The Richter scale, the “Scale of Magnitude” was invented by Charles Richter in 1932. He developed his own scale based on the amount of energy. Every magnitude the earthquake goes up it is times ten. For example, if the waves were at five, and if went up to six, it would be ten times higher. The Richter uses regular numbers for its scale.

Earthquake Magnitude Scale
Magnitude
Earthquake Effects
Estimated NumberEach Year
2.5 or less
Usually not felt, but can be recorded by seismograph.
900,000
2.5 to 5.4
Often felt, but only causes minor damage.
30,000
5.5 to 6.0
Slight damage to buildings and other structures.
500
6.1 to 6.9
May cause a lot of damage in very populated areas.
100
7.0 to 7.9
Major earthquake. Serious damage.
20
8.0 or greater
Great earthquake. Can totally destroy communities near the epicenter.
One every 5 to 10 years
Earthquake Magnitude Classes
Earthquakes are also classified in categories ranging from minor to great, depending on their magnitude.
Class
Magnitude
Great
8 or more
Major
7 - 7.9
Strong
6 - 6.9
Moderate
5 - 5.9
Light
4 - 4.9
Minor
3 -3.9


The Mercalli scale, the “Scale of Intensity” is a modified scale. This Was Invented by Giuseppe Mercalli in 1902. In my opinion this is an easier to read and work with. This scale doesn’t use numbers they use numeral numbers.

Modified Mercalli Intensity Scale
Mercalli Intensity
Equivalent Richter Magnitude
Witness Observations
I
1.0 to 2.0
Felt by very few people; barely noticeable.
II
2.0 to 3.0
Felt by a few people, especially on upper floors.
III
3.0 to 4.0
Noticeable indoors, especially on upper floors, but may not be recognized as an earthquake.
IV
4.0
Felt by many indoors, few outdoors. May feel like heavy truck passing by.
V
4.0 to 5.0
Felt by almost everyone, some people awakened. Small objects moved. Trees and poles may shake.
VI
5.0 to 6.0
Felt by everyone. Difficult to stand. Some heavy furniture moved, some plaster falls. Chimneys may be slightly damaged.
VII
6.0
Slight to moderate damage in well built, ordinary structures. Considerable damage to poorly built structures. Some walls may fall.
VIII
6.0 to 7.0
Little damage in specially built structures. Considerable damage to ordinary buildings, severe damage to poorly built structures. Some walls collapse.
IX
7.0
Considerable damage to specially built structures, buildings shifted off foundations. Ground cracked noticeably. Wholesale destruction. Landslides.
X
7.0 to 8.0
Most masonry and frame structures and their foundations destroyed. Ground badly cracked. Landslides. Wholesale destruction.
XI
8.0
Total damage. Few, if any, structures standing. Bridges destroyed. Wide cracks in ground. Waves seen on ground.
XII
8.0 or greater
Total damage. Waves seen on ground. Objects thrown up into air.

DJB 3
http://www.geo.mtu.edu/UPSeis/intensity.html