Richter magnitude Mercalli intensity (at epicentre) Experience of observers
1–2 I Felt by very few people, barely noticeable
2–3 II Felt by a few people, especially on upper floors
3–4 III Noticeable indoors, especially on upper floors, but may not be recognizable as an earthquake
4 IV Felt by many indoors, few outdoors
4–5 V Felt by almost everyone, some people awakened, small objects moved, trees and poles may shake
5–6 VI Felt by everyone, difficult to stand, some heavy furniture is moved, some plaster falls, chimneys may be slightly damaged
6 VII Well-built structures may have slight to moderate damage, poorly built structures may be badly damaged, some walls may collapse
6–7 VIII Little damage in specially built structures, considerable damage to ordinary buildings, severe damage to poorly built structures, some walls collapse
7 IX Considerable damage to specially built structures, buildings moved off foundations, large ground cracks, large-scale destruction, landslides
7–8 X Destruction of most structures and foundations, severe ground cracking, landslides, large-scale destruction
8 XI Total damage, few structures left standing, bridges destroyed, wide cracks in the ground, waves seen on the ground
8 or greater XII Total damage, waves seen on the ground, objects thrown up in the air.
From A Dictionary of Environment and Conservation in Oxford Reference.
Subjects: Environmental Science.