Mercalli Scale

A measure of the intensity of an earthquake. This is a subjective value that varies depending on where the earthquake is observed. The ratings vary from I (felt only under especially favourable circumstances) to XII (total destruction).

IGenerally not felt.
IIFelt by a few people, suspended objects may swing.
IIIFelt by a few people, similar vibration levels to a passing truck.
IVFelt by most people indoors, but few outdoors. Windows, doors and dishes rattle.
VNearly everybody will feel it. People woken and small objects may topple.
VIFelt by everyone, heavy furniture moves, books fall from shelves, bushes and trees visibly shake.
VIIDifficult to stand. Some damage to poorly constructed buildings, tiles and loose bricks fall. Small landslides on slopes. Water becomes turbid.
VIIIDifficult to steer a car. Damage to good buildings, chimneys. Tree branches break and steep slopes crack.
IXExtensive building damage, underground pipes break.
XMost walls destroyed, large landslides, water thrown from rivers and lakes onto the banks.
XIMost masonry buildings destroyed, railroad tracks bent and most underground pipework destroyed.
XIIMore or less total destruction, objects thrown into the air.

Roman numerals (I-XII) to avoid confusion with magnitude estimates on the Richter scale.

The scale is named for the Italian geologist Giuseppe Mercalli (1850-1914), who devised the first version in 1902.

See also: Richter Scale, Seismic, Seismograph.

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Subjects: Geology Units