Skip to main content Skip to Search Box

Definition: Richter Scale from Environmental History and Global Change: A Dictionary of Environmental History

Developed in 1935 by Charles F. Richter, California Institute of Technology, to measure the severity of earthquakes. Ranging from 1 to 9.9, an increase from one whole number to the next on the scale represents a tenfold rise in earthquake severity. An earthquake recording 7.0 on the scale would be considered a major one and 9.0 an unusually severe one. See earthquakes.

Summary Article: Richter scale
From The Columbia Encyclopedia

(rĭk'tӘr), measure of the magnitude of seismic waves from an earthquake. Devised in 1935 by the American seismologist Charles F. Richter (1900–1985) and technically known as the local magnitude scale, it has been superseded by the moment magnitude scale, which was developed in the 1970s. The Richter scale is logarithmic; that is, the amplitude of the waves increases by powers of 10 in relation to the Richter magnitude numbers. The energy released in an earthquake can easily be approximated by an equation that includes this magnitude and the distance from the seismograph to the earthquake's epicenter. Numbers for the Richter scale range from 0 to 9, though no real upper limit exists. An earthquake whose magnitude is greater than 4.5 on this scale can cause damage to buildings and other structures; severe earthquakes have magnitudes greater than 7. Like ripples formed when a pebble is dropped into water, earthquake waves travel outward in all directions, gradually losing energy, with the intensity of earth movement and ground damage generally decreasing at greater distances from the earthquake focus. In addition, the nature of the underlying rock or soil affects ground movements. In order to give a rating to the effects of an earthquake in a particular place, the modified Mercalli scale, based on a scale developed by the Italian seismologist Giuseppe Mercalli, is often used. It measures an earthquake's intensity, the severity of an earthquake in terms of its effects on the inhabitants of an area, e.g., how much damage it causes to buildings.

The Columbia Encyclopedia, © Columbia University Press 2018

Related Articles

Full text Article Richter scale
Brewer's Dictionary of Modern Phrase and Fable

The numerical scale for expressing the magnitude of an earthquake on the basis of seismograph oscillations takes its name from the US...

Full text Article seismology
Encyclopedia of Earthquakes and Volcanoes

The scientific study of earthquakes. Earthquakes generate several kinds of waves. These are sometimes classified in two categories: surface waves an

Full text Article magnitude (seismology)
Encyclopedia of Earthquakes and Volcanoes

A measure of the energy released in an earthquake. The magnitude is determined by analyzing the amplitude of the seismic waves (vibrations) that arr

See more from Credo