the Richter scale
From Longman Dictionary of Contemporary Englishthe Richter scalethe Richter scalea system of numbers used for measuring how powerful an earthquake is a severe earthquake measuring 7.2 on the Richter scale → Richter scaleExamples from the Corpusmeasuring ... on the Richter scale• According to official figures, the earthquake, measuring 7.6 on the Richter scale, left more than 20,000 homeless.