| Description | Richter Magnitudes | Earthquake Effects | Frequency of Occurrence |
|---|---|---|---|
| Micro | Less than 2.0 | Microearthquakes, not felt. | About 8,000 per day |
| Minor | 2.0-2.9 | Generally not felt, but recorded. | About 1,000 per day |
| Minor | 3.0-3.9 | Often felt, but rarely causes damage. | 49,000 per year (est.) |
| Light | 4.0-4.9 | Noticeable shaking of indoor items, rattling noises. Significant damage unlikely. | 6,200 per year (est.) |
| Moderate | 5.0-5.9 | Can cause major damage to poorly constructed buildings over small regions. At most slight damage to well-designed buildings. | 800 per year |
| Strong | 6.0-6.9 | Can be destructive in areas up to about 100 miles across in populated areas. | 120 per year |
| Major | 7.0-7.9 | Can cause serious damage over larger areas. | 18 per year |
| Great | 8.0-8.9 | Can cause serious damage in areas several hundred miles across. | 1 per year |
| Great | 9.0-9.9 | Devastating in areas several thousand miles across. | 1 per 20 years |
| Great | 10.0+ | Never recorded; see below for equivalent seismic energy yield. | Extremely rare (Unknown) |
(Based on U.S. Geological Survey documents.)[1] Source: Wikipedia.org