Richter scale

Definition

Quantitative measure of earthquake-strength (magnitude) that indicates the seismic energy released by an earthquake at its epicenter (measured from a distance of 100 miles) on a 1 to 10 scale. It is a logarithmic scale: an increase of 1.0 in measurement corresponds to an increase of 10 times in the magnitude. The most powerful earthquakes recorded so far had a magnitude of 8.6, and occurred in 1920 in the Gansu province of China. Developed in 1935 by the US seismologist Charles F. Richter (1900-1985) of the California Institute of technology. Earthquake-intensity is measured on the Mercalli scale.