Surface wave magnitude Surface wave magnitude The surface wave magnitude (formula_1) scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements in Rayleigh surface waves that travel primarily along the uppermost layers of the Earth. It is currently used in People's Republic of China as a national standard(GB 17740-1999) for categorising earthquakes. Surface wave magnitude was initially developed in the 1950s by the same researchers who developed the local magnitude scale M in order to improve resolution on larger earthquakes: Recorded magnitudes of earthquakes during that time, commonly attributed to Richter,
Magnitude (astronomy) been classified as "stars of the first magnitude". Magnitudes can also be calculated for objects far brighter than stars (such as the Sun and Moon), and for objects too faint for the human eye to see (such as Pluto). Often, only apparent magnitude is mentioned since it can be measured directly. Absolute magnitude can be calculated from apparent magnitude and distance from: This is known as the distance modulus, where is the distance to the star measured in parsecs, is the apparent magnitude, and is the absolute magnitude. If the line of sight between the object and observer is affected