Magnitude is 1) the large size or great importance; 2) a measure of the brightness of a star as it appears from earth; 3) used to describe the overall strength or size of an earthquake (Seismic Magnitude Scale. The energy released in the earthquake but the energy goes up with magnitude faster than the ground velocity, by a factor of 32. Thus, a magnitude 7 earthquake has 32 times more energy than a magnitude 6 and almost 1,000 times more energy than a magnitude 5 earthquake).
Reference Definition by Earthquake.usgs.gov: The Magnitude is a number that characterizes the relative size of an earthquake. Magnitude is based on measurement of the maximum motion recorded by a seismograph. Several scales have been defined, but the most commonly used are (1) local magnitude (ML), commonly referred to as “Richter magnitude”, (2) surface-wave magnitude (Ms), (3) body-wave magnitude (Mb), and (4) moment magnitude (Mw). Scales 1-3 have limited range and applicability and do not satisfactorily measure the size of the largest earthquakes. The moment magnitude (Mw) scale, based on the concept of seismic moment, is uniformly applicable to all sizes of earthquakes but is more difficult to compute than the other types.
Related Definitions in the Project: Property and Unit; Science Definitions
