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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]
The first scale for measuring earthquake magnitudes, developed in 1935 by Charles F. Richter and popularly known as the "Richter" scale, is actually the local magnitude scale, label ML or M L. [11] Richter established two features now common to all magnitude scales.
This means that for a given frequency of magnitude 4.0 or larger events there will be 10 times as many magnitude 3.0 or larger quakes and 100 times as many magnitude 2.0 or larger quakes. There is some variation of b-values in the approximate range of 0.5 to 2 depending on the source environment of the region. [ 5 ]
The formula above made it much easier to estimate the energy-based magnitude M w , but it changed the fundamental nature of the scale into a moment magnitude scale. USGS seismologist Thomas C. Hanks noted that Kanamori's M w scale was very similar to a relationship between M L and M 0 that was reported by Thatcher & Hanks (1973)
In 1902, Italian seismologist Giuseppe Mercalli, created the Mercalli Scale, a new 12-grade scale. Significant improvements were achieved, mainly by Charles Francis Richter during the 1950s, when (1) a correlation was found between seismic intensity and the Peak ground acceleration (PGA; see the equation that Richter found for California).
In two most recent investigations using statistically stable samples for Italian earthquakes (approximately 100,000 events over the period 1981–2002 in the Richter local [M L ] magnitude range of 3.5–5.8) [5] and for Indian earthquakes exemplified by an aftershock sequence of 121 events with M s (surface wave magnitude) > 4.0 in 2001 in the Bhuj area of northwestern India, [4] the latest ...
Charles Francis Richter (/ ˈ r ɪ k t ər /; April 26, 1900 – September 30, 1985) was an American seismologist and physicist.He is the namesake and one of the creators of the Richter scale, which, until the development of the moment magnitude scale in 1979, was widely used to quantify the size of 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. [3]