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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]
First, the scale is logarithmic, so that each unit represents a ten-fold increase in the amplitude of the seismic waves. [12] As the energy of a wave is proportional to A 1.5, where A denotes the amplitude, each unit of magnitude represents a 10 1.5 ≈32-fold increase in the seismic energy (strength) of an earthquake. [13]
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).
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
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.
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 ...
The last tsunami warning in the San Francisco Bay Area followed a 9.1 earthquake in Tohoku, Japan that sparked a major nuclear accident at the Fukushima-Daiichi nuclear power plant in March 2011 ...
The Environmental Seismic Intensity scale (ESI 2007) [1] is a seismic scale used for measuring the intensity of an earthquake on the basis of the effects of the earthquake on the natural environment (Earthquake Environmental Effects).