A twelve-point scale for expressing the local intensity of an earthquake, ranging from I (virtually imperceptible) to XII (total destruction).
- ‘The Mercalli scale is based on observations at the site and therefore reflects the effects of soil conditions, distance from the epicenter, etc.’
- ‘There was no determination of the size of the earthquake on May 18, 1980, at Mount St. Helens on the Mercalli scale; because that scale depends of the type of destruction to such things as buildings, walls and roads; and there were few buildings, walls or roads around Mount St. Helens.’
- ‘Intensities on the Mercalli scale are usually shown in Roman numerals, a convention worth preserving because it helps to distinguish intensity ratings from magnitude ratings.’
- ‘The Mercalli scale measures the effect of an earthquake rather than its intensity.’
- ‘The Modified Mercalli scale is designed to describe the effects of an earthquake, at a given place, on natural features, on industrial installations and on human beings.’
1920s: named after Giuseppe Mercalli (1850–1914), Italian geologist.