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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 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 "M w" scale is ...
With an isoseismal map of the observed intensities (see illustration) an earthquake's magnitude can be estimated from both the maximum intensity observed (usually but not always near the epicenter), and from the extent of the area where the earthquake was felt. [2] The intensity of local ground-shaking depends on several factors besides the ...
Magnitude has replaced it, expressed as "a 4.0 magnitude earthquake." What are earthquake intensity scales? Earthquake intensity is a slightly different number that measures people's on-the-ground ...
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 ]
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.
PGA is an important parameter (also known as an intensity measure) for earthquake engineering, The design basis earthquake ground motion (DBEGM) [2] is often defined in terms of PGA. 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 ...
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