# Richter scale

Richter scale
a scale, ranging from 1 to 10, for indicating the intensity of an earthquake.
[1935-40; after Charles F. Richter (1900-85), U.S. seismologist]

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Widely used measure of the magnitude of an earthquake, introduced in 1935 by U.S. seismologists Beno Gutenberg (1889–1960) and Charles F. Richter (1900–1985).

The scale is logarithmic, so that each increase of one unit represents a 10-fold increase in magnitude (amplitude of seismic waves). The magnitude is then translated into energy released. Earthquakes that are fainter than the ones originally chosen to define magnitude zero are accommodated by using negative numbers. Though the scale has no theoretical upper limit, the most severe earthquakes have not exceeded a scale value of 9. The moment magnitude scale, in use since 1993, is more accurate for large earthquakes; it takes into account the amount of fault slippage, the size of the area ruptured, and the nature of the materials that faulted.

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Richter scale of earthquake magnitudewidely used quantitative measure of the magnitude of an earthquake, devised in 1935 by American seismologist Charles F. Richter (Richter, Charles F.). See table (Richter scale of earthquake magnitude).

The Richter scale was originally devised to measure the magnitude of local earthquakes in southern California as recorded by a specific kind of seismograph. Current scientific practice has replaced the original Richter scale with other scales, including the body-wave magnitude scale and the moment magnitude scale, which have no restrictions regarding distance and type of seismograph used. Nevertheless, the Richter scale is still commonly cited in news reports of earthquake severity.

On the original Richter scale the smallest earthquakes measurable at that time were assigned values close to zero. Since modern seismographs can detect seismic waves even smaller than those originally chosen for zero magnitude, the Richter scale now measures earthquakes having negative magnitudes. Each increase of one unit on the scale represents a 10-fold increase in the magnitude of an earthquake—in other words, numbers on the Richter scale are proportional to the common (base 10) logarithms of maximum wave amplitudes. In theory the scale has no upper limit, but in practice no earthquake has ever been registered above magnitude 9.

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Universalium. 2010.

### Look at other dictionaries:

• Richter scale — ☆ Richter scale [rik′tər ] n. [devised by C. Richter (1900 85), U.S. seismologist] a logarithmic scale for indicating the magnitude of earthquakes using data from a seismograph: each step represents a magnitude that is about 10 times greater than …   English World dictionary

• Richter scale — ► NOUN ▪ a logarithmic scale for expressing the magnitude of an earthquake on the basis of seismograph oscillations. ORIGIN named after the American geologist Charles F. Richter (1900 85) …   English terms dictionary

• Richter scale — 1938, devised by U.S. seismologist Charles Francis Richter (1900 1985) …   Etymology dictionary

• Richter scale —  for the standard measure of earthquake magnitudes. It is named for Charles Richter (1900–1985) of the California Institute of Technology, who invented it in the 1930s. The scale increases at a rate that is exponential rather than linear, making… …   Bryson’s dictionary for writers and editors

• Richter scale —    for the standard measure of earthquake magnitudes. It is named for Charles Richter of the California Institute of Technology, who invented it in the 1930s. The scale increases at a rate that is exponential rather than linear, making each level …   Dictionary of troublesome word

• Richter scale — Rich|ter scale [ˈrıktə ˌskeıl, ˈrıx US tər ] n the Richter scale a system of numbers used for measuring how powerful an ↑earthquake is ▪ a severe earthquake measuring 7.2 on the Richter scale …   Dictionary of contemporary English

• Richter scale — [[t]rɪ̱ktə(r) skeɪl[/t]] N SING: the N The Richter scale is a scale which is used for measuring how severe an earthquake is. An earthquake measuring 6.1 on the Richter Scale struck California yesterday …   English dictionary

• Richter scale — noun a) A logarithmic scale used to express the energy released by an earthquake, each increase of 1 representing a 32 fold increase in energy. The students also faced and experienced earthquakes at various Richter scales. b) …   Wiktionary

• Richter scale — /ˈrɪktə skeɪl / (say riktuh skayl) noun an open ended logarithmic scale used to express the magnitude or total energy of a seismic disturbance (as an earthquake). In this scale an increase of 1 indicates a tenfold increase in energy. Recorded… …   Australian-English dictionary

• Richter scale — Rich′ter scale n. gel a logarithmic scale for expressing the magnitude of an earthquake, a measurement under 5 considered minor and over 7 indicating major destruction • Etymology: 1935–40; after Charles F. Richter (1900–85), U.S. seismologist …   From formal English to slang