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Magnitude

Description

Mercalli intensity

Average earthquake effects

Less than 2.0

Micro

I

Micro- earthquakes, not felt, or felt rarely by sensitive people. Recorded by seismographs.

2.02.9

Minor

I to II

Felt slightly by some people. No damage to buildings.

3.03.9

Minor

II to IV

Often felt by people, but very rarely causes damage. Shaking of indoor objects can be noticeable.

4.04.9

Light

IV to VI

Noticeable shaking of indoor objects and rattling noises. Felt by most people in the affected area. Slightly felt outside. Generally causes none to minimal damage. Moderate to significant damage very unlikely. Some objects may fall off shelves or be knocked over.

5.05.9

Moderate

VI to VIII

Can cause damage of varying severity to poorly constructed buildings. At most, none to slight damage to all other buildings. Felt by everyone.

6.06.9

Strong

VII to X

Damage to a moderate number of well-built structures in populated areas. Earthquake-resistant structures survive with slight to moderate damage. Poorly designed structures receive moderate to severe damage. Felt in wider areas; up to hundreds of miles/kilometres from the epicentre. Strong to violent shaking in epicentre area.

7.07.9

Major

VIII or greater

Causes damage to most buildings, some to partially or completely collapse or receive severe damage. Well-designed structures are likely to receive damage. Felt across great distances with major damage mostly limited to 250 km from epicentre.

8.08.9

Great

VIII or greater

Major damage to buildings, structures likely to be destroyed. Will cause moderate to heavy damage to sturdy or earthquake-resistant buildings. Damaging in large areas. Felt in extremely large regions.

9.0 and greater

Great

VIII or greater

Near or at total destruction - severe damage or collapse to all buildings. Heavy damage and shaking extends to distant locations. Permanent changes in ground topography.