SCALE OF EARTHQUAKE INTENSITIES WITH APPROXIMATELY CORRESPONDING MAGNITUDES
MERCALLI INTENSITY
DESCRIPTION
RICHTER MAGNITUDE
I.
INSTRUMENTAL: detected only by seismographs
3.5
II.
FEEBLE: noticed only by sensitive people
4.2
III.
SLIGHT: like the vibrations due to a passing train; felt by people at rest, especially on upper floors
4.3
IV.
MODERATE: felt by people while walking; rocking of loose objects, including standing houses
4.8
V.
RATHER STRONG: felt generally; most sleepers are awakened and bells ring
4.9 - 5.4
VI.
STRONG: trees sway and all suspended objects swing; damage by overturning and falling of loose objects
5.5 - 6.0
VII.
VERY STRONG: general alarm; walls crack; plaster falls
6.1
VIII.
DESTRUCTIVE: car drivers seriously disturbed; masonry fissured; chimneys fall; poorly constructed buildings damaged
6.2
IX
RUINOUS: some houses collapse where ground begins to crack, and pipes break open
6.9
X
DISASTROUS: ground cracks badly; many buildings destroyed and railway lines bent; landslides on steep slopes
7.0 - 7.3
XI
VERY DISASTROUS: few buildings remain standing; bridges destroyed; all services (railways, pipes and cables) out of action; great landslides and floods
7.4 - 8.1
XII
CATASTROPHIC: total destruction; objects thrown into air; ground rises and falls in waves
> 8.1