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The Richter scale [1] (/ ˈ r ɪ k t ər /), also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale, [2] is a measure of the strength of earthquakes, developed by Charles Richter in collaboration with Beno Gutenberg, and presented in Richter's landmark 1935 paper, where he called it the "magnitude scale". [3]
First, the scale is logarithmic, so that each unit represents a ten-fold increase in the amplitude of the seismic waves. [12] As the energy of a wave is proportional to A 1.5, where A denotes the amplitude, each unit of magnitude represents a 10 1.5 ≈32-fold increase in the seismic energy (strength) of an earthquake. [13]
This magnitude scale is related to the local magnitude scale proposed by Charles Francis Richter in 1935, with modifications from both Richter and Beno Gutenberg throughout the 1940s and 1950s. [ 1 ] [ 2 ] It is currently used in People's Republic of China as a national standard ( GB 17740-1999 ) for categorising earthquakes.
Thus, a magnitude zero microearthquake has a seismic moment of approximately 1.1 × 10 9 N⋅m, while the Great Chilean earthquake of 1960, with an estimated moment magnitude of 9.4–9.6, had a seismic moment between 1.4 × 10 23 N⋅m and 2.8 × 10 23 N⋅m. Seismic moment magnitude (M wg or Das Magnitude Scale ) and moment magnitude (M w) scales
Seismic intensity scales categorize the intensity or severity of ground shaking (quaking) at a given location, such as resulting from an earthquake.They are distinguished from seismic magnitude scales, which measure the magnitude or overall strength of an earthquake, which may, or perhaps may not, cause perceptible shaking.
Moment magnitude scale, based on seismic moment, supersedes the Richter scale; Richter magnitude scale, the energy of an earthquake, superseded by Moment scale; Surface-wave magnitude, based on Rayleigh surface wave measurement through heat conduction; Seismic intensity scales, the local severity of a quake
Magnitude scales measure the inherent force or strength of an earthquake – an event occurring at greater or lesser depth. (The "M w" scale is widely used.) The MM scale measures intensity of shaking, at any particular location, on the surface. It was developed from Giuseppe Mercalli's Mercalli intensity scale of 1902.
The original "body-wave magnitude" – mB or m B (uppercase "B") – was developed by Gutenberg (1945b, 1945c) and Gutenberg & Richter (1956) [2] to overcome the distance and magnitude limitations of the M L scale inherent in the use of surface waves. mB is based on the P- and S-waves, measured over a longer period, and does not saturate until ...