Earthquake Magnitude Scale
The Richter-like magnitude scale measures earthquake energy release. Each whole number increase represents roughly 31.6 times more energy.
M1
Micro
Micro earthquakes, not felt by humans.
Felt: Not felt. Detected only by seismographs.
M2
Minor
Minor earthquakes. Felt by few people.
Felt: Felt by people at rest, on upper floors of tall buildings.
M3
Minor
Often felt, but rarely causes damage.
Felt: Felt by many indoors; hanging objects swing.
M4
Light
Noticeable shaking of indoor objects. Rarely causes significant damage.
Felt: Felt by most people; dishes rattle.
Damage: Light
M5
Moderate
Can cause major damage to poorly constructed buildings.
Felt: Causes damage to poorly built structures. Felt by everyone.
Damage: Moderate to significant
M6
Strong
Destructive in areas up to 160km from epicenter.
Felt: Destructive to a moderate radius.
Damage: Moderate to severe
M7
Major
Causes serious damage over large areas.
Felt: Can cause serious damage over wider areas.
Damage: Severe
M8
Great
Can cause severe damage in areas several hundred km wide.
Felt: Major damage to structures; felt at extreme distances.
Damage: Severe over large areas
M9
Extreme
Devastating over massive areas. Rare once-per-decade events.
Felt: Total destruction near epicenter; tsunamis generated.
Damage: Catastrophic