RICHTER SCALE
Descriptor | Richter Magnitudes | Earthquake Effects | Average Annually |
---|---|---|---|
Micro | Less than 2.0 | Microearthquakes, not felt. | About 8,000 per day |
Very 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 (estimated) |
Light | 4.0-4.9 | Noticeable shaking of indoor items, rattling noises. Significant damage unlikely. | 6,200 (estimated) |
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 |
Strong | 6.0-6.9 | Can be destructive in areas up to about 100 miles across in populated areas. | 120 |
Major | 7.0-7.9 | Can cause serious damage over larger areas. | 18 |
Great | 8.0 or greater | Can cause serious damage in areas several hundred miles across. | 1 |
(Adapted from U.S. Geological Survey documents.)