Richter magnitude scale Richter correlation tables based on Richter standard seismic event (formula_26, formula_27, formula_28). Below, formula_29 is the epicentral distance (in kilometers unless otherwise specified). The Lillie empirical formula: Where formula_31 is the amplitude (maximum ground displacement) of the P-wave, in micrometers, measured at 0.8 Hz. For distances formula_32 less than 200 km, and for distances between 200 km and 600 km, where formula_31 is seismograph signal amplitude in mm and formula_32 is in km. The Bisztricsany (1958) empirical formula for epicentral distances between 4˚ to 160˚: Where formula_38 is the duration of the surface wave in seconds, and formula_39 is in
Absolute magnitude Absolute magnitude Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs (32.6 light-years), with no extinction (or dimming) of its light due to absorption by interstellar dust particles. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared on a magnitude scale. As with all astronomical magnitudes, the absolute magnitude can be specified