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Mercalli Scale, Richter Scale and Magnitude Scale are the three major scales used to measure earthquakes.
The Mercalli scale measures the intensity of an earthquake using the data (observations) collected from individuals that experienced the earthquake. The scale was developed in 1902 by Giuseppe Mercalli. The Richter Scale is a logarithmic scale and is the most common method used. It determines the magnitude of earthquake by using the amplitude of the largest wave calibrated to a scale by a seismograph. The scale was invented in 1934 by Charles F. Richter. The Magnitude Scale measures the intensity of earthquakes of various sizes accurately and it is the most preferred method.