Related to the amount of energy released during an earthquake. It is determined from parameters of the seismic waves recorded on seismographs e.g. amplitude, period, duration. A magnitude of 7.0 on the Richter Scale is a major earthquake. Each whole number on the scale represents an increase of about 10 times more energy released than the previous whole number represents. Therefore, an earthquake measuring 7.0 is about 100 times more powerful than one measuring 5.0.