A numerical scale for expressing the magnitude of an earthquake on the basis of seismograph oscillations. The more destructive earthquakes typically have magnitudes between about 5.5 and 8.9; the scale is logarithmic and a difference of one represents an approximate thirtyfold difference in magnitude.
- ‘The earthquake had a magnitude of 7.2 on the Richter scale.’
- ‘Nine on the Richter scale indicates an earthquake of absolutely awesome destructive power.’
- ‘Seismographs and the Richter scale are just one type of graph that scientists use to measure the world.’
- ‘Each unit on the Richter scale represents a thirty-fold increase of energy.’
- ‘In the last hundred years, there have been about 20 earthquakes of 6 to 7.7 magnitude on the Richter scale under the sea.’
1930s: named after Charles F. Richter (1900–85), American geologist.