Contrasting the Richter and Mercalli Scales

Plate Tectonic - Hazards (4)
Post Lab

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

[Dictionary]
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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