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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]
Seismic magnitude scales are used to describe the overall strength or "size" of an earthquake. These are distinguished from seismic intensity scales that categorize the intensity or severity of ground shaking (quaking) caused by an earthquake at a given location. Magnitudes are usually determined from measurements of an earthquake's seismic ...
In seismology, the Gutenberg–Richter law[1] (GR law) expresses the relationship between the magnitude and total number of earthquakes in any given region and time period of at least that magnitude. or. where. is the number of events having a magnitude , and are constants, i.e. they are the same for all values of and .
The instrumental scales used to describe the size of an earthquake began with the Richter magnitude scale in the 1930s. It is a relatively simple measurement of an event's amplitude, and its use has become minimal in the 21st century. Seismic waves travel through the Earth's interior and can be recorded by seismometers at great distances.
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 ...
Earthquakes. The moment magnitude scale (MMS; denoted explicitly with M or Mw or Mwg, and generally implied with use of a single M for magnitude [1]) is a measure of an earthquake 's magnitude ("size" or strength) based on its seismic moment. Mw was defined in a 1979 paper by Thomas C. Hanks and Hiroo Kanamori.
A pie chart comparing the seismic moment release of the three largest earthquakes for the hundred-year period from 1906 to 2005 with that for all earthquakes of magnitudes <6, 6 to 7, 7 to 8, and >8 for the same period. The 2011 Japan quake would be roughly similar to Sumatra. Earthquakes of magnitude 8.0 and greater from 1900 to 2018.
v. t. e. The Modified Mercalli intensity scale (MM, MMI, or MCS) measures the effects of an earthquake at a given location. This is in contrast with the seismic magnitude usually reported for an earthquake. Magnitude scales measure the inherent force or strength of an earthquake – an event occurring at greater or lesser depth. (The " Mw ...