Earthquake Magnitude Scale

Magnitude Earthquake Effects Estimated Number
Each 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