Richter scale
RIK-ter
A logarithmic scale for measuring the magnitude of an earthquake — the amount of energy released at the source, as recorded by a seismograph. Each whole number increase represents roughly 32 times more energy. The scale is open-ended: no earthquake has exceeded 9.5 (Chile, 1960). The Richter scale measures what the earth did; the Mercalli scale measures what it did to us. The two are complementary — one is physics, the other is experience.
Etymology
Developed in 1935 by American seismologist Charles Richter and his colleague Beno Gutenberg at the California Institute of Technology. Largely superseded by the moment magnitude scale for scientific use, but "Richter scale" remains the term the public knows.
Notes
The moment magnitude scale (Mw), which replaced Richter for scientific measurement, uses similar numbers but is based on the physical properties of the fault rupture rather than seismograph readings.
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