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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.
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]
Similar to the local magnitude/Richter scale (M L ) defined by Charles Francis Richter in 1935, it uses a logarithmic scale; small earthquakes have approximately the same magnitudes on both scales. Despite the difference, news media often use the term "Richter scale" when referring to the moment magnitude scale.
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 JMA intensity scale differs from magnitude measurements like the moment magnitude (Mw) and the earlier Richter scales, which represent how much energy an earthquake releases. Similar to the Mercalli scale, the JMA scale measures the intensities of ground shaking at various observation points within the affected area.
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).
This page was last edited on 31 August 2023, at 11:46 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may ...
Unlike the Richter and moment magnitude scales, it is not a measure of the total energy (magnitude, or size) of an earthquake, but rather of how much the earth shakes at a given geographic point. The Mercalli intensity scale uses personal reports and observations to measure earthquake intensity but PGA is measured by instruments, such as ...