Magnitude
|
Description
|
Earthquake Effects
|
Frequency
|
Less than 2.0
|
Micro
|
Micro earthquakes, not felt
|
About 8,000 per day
|
2.0-2.9
|
Minor
|
Generally not felt, but recorded
|
About 1,000 per day
|
3.0-3.9
|
Minor
|
Often felt, but rarely causes damage
|
49,000 per year
|
4.0-4.9
|
Light
|
Noticeable shaking of indoor items, rattling noises. Significant damage unlikely
|
6,200 per year
|
5.0-.5.9
|
Moderate
|
Can cause major damage in poorly constructed buildings over small regions. At most slight damage to well-designed buildings
|
800 per year
|
6.0-.6.9
|
Strong
|
Can be destructive in areas up to about 160km (100 miles) across in populated areas
|
120 per year
|
7.0-7.9
|
Major
|
Can cause serious damage over larger areas
|
18 per year
|
8.0-8.9
|
Great
|
Can cause serious damage in areas several hundred miles across
|
1 per year
|
9.0-9.9
|
Great
|
Devastating in areas several thousand miles across
|
1 per 20 years
|
10.0+
|
Massive
|
Never recorded, widespread devastation across very large areas
|
Extremely rare (unknown)
|