Natural and Man-Made Disasters,
Historical Natural Disasters

Richter and Mercalli
Earthquake Scales

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The Richter scale was created in 1935 by the American seismologist Charles F. Richter. It measures how much the ground shakes 60 miles from the earthquakes epicenter. Richter magnitudes increase logarithmically, meaning the energy increases 10 times for each magnitude number.

Mercalli intensity is based upon observations of the resulting earthquake damage and not actually measured on instruments. Invented by Italian seismologist Giuseppe Mercalli.

Richter Magnitude Mercalli Intensity Description
2 I Usually not felt, but detected by instruments.
II Felt by very few people.
3 III Felt by many, often mistaken for a passing vehicle.
IV Felt by many indoors, dishes and doors disturbed.
4 V Felt by nearly everyone. People awakened. Cracked walls, trees disturbed.
5 VI Felt by all. Many run outdoors. Furniture moves. Slight damage occurs.
VII Everyone runs outdoors. Poorly built buildings suffer severe damage. Slight damage every where else.
6 VIII Everyone runs outdoors. Moderate to major damage. Minor damage to specially designed buildings. Chimneys and walls collapse.
7 IX All buildings suffer major damage. Ground cracks, pipes break, foundations shift.
X Major damage. Structures destroyed. Ground is badly cracked. Landslides occur.
8 XI Almost all structures fall. Bridges wrecked. Very wide cracks in ground.
XII Total destruction. Ground surface waves seen. Objects thrown into the air. All construction destroyed.

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