Richter scale
From Longman Dictionary of Contemporary EnglishRichter scaleRich‧ter scale /ˈrɪktə ˌskeɪl, ˈrɪx- $ -tər-/ noun → the Richter scaleExamples from the CorpusRichter scale• According to official figures, the earthquake, measuring 7.6 on the Richter scale, left more than 20,000 homeless.• After all, it was only 5.7 on the Richter scale, not quite as big as the one six years ago.• The quake epicenter was southwest of Seattle with a magnitude on the Richter scale of 6.8.