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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]
Even for distant earthquakes, measuring the duration of the shaking (as well as the amplitude) provides a better measure of the earthquake's total energy. Measurement of duration is incorporated in some modern scales, such as M wpd and mB c . [66] M c scales usually measure the duration or amplitude of a part of the seismic wave, the coda. [67]
This scale is also known as the Richter scale, but news media sometimes use that term indiscriminately to refer to other similar scales.) The local magnitude scale was developed on the basis of shallow (~15 km (9 mi) deep), moderate-sized earthquakes at a distance of approximately 100 to 600 km (62 to 373 mi), conditions where the surface waves ...
That is, many low-magnitude earthquakes are not catalogued because fewer stations detect and record them due to decreasing instrumental signal to noise levels. Some modern models of earthquake dynamics, however, predict a physical roll-off in the earthquake size distribution. [13] The a-value represents the total seismicity rate of the region ...
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.
Although the Richter scale was used historically to measure earthquake magnitude (although, notably, not earthquake damage), it was found in the 1970s that it does not reliably represent the magnitude of large earthquakes. It has therefore been largely replaced by the moment magnitude scale, [245] although very small earthquakes are still ...
Seismic moment is the basis of the moment magnitude scale introduced by Caltech's Thomas C. Hanks and Hiroo Kanamori, which is often used to compare the size of different earthquakes and is especially useful for comparing the sizes of large (great) earthquakes. The seismic moment is not restricted to earthquakes.
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.