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  2. Richter scale - Wikipedia

    en.wikipedia.org/wiki/Richter_scale

    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]

  3. Seismic magnitude scales - Wikipedia

    en.wikipedia.org/wiki/Seismic_magnitude_scales

    All magnitude scales retain the logarithmic scale as devised by Charles Richter, and are adjusted so the mid-range approximately correlates with the original "Richter" scale. [8] Most magnitude scales are based on measurements of only part of an earthquake's seismic wave-train, and therefore are incomplete.

  4. Gutenberg–Richter law - Wikipedia

    en.wikipedia.org/wiki/Gutenberg–Richter_law

    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 ]

  5. Moment magnitude scale - Wikipedia

    en.wikipedia.org/wiki/Moment_magnitude_scale

    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)

  6. Seismic intensity scales - Wikipedia

    en.wikipedia.org/wiki/Seismic_intensity_scales

    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).

  7. Earthquake duration magnitude - Wikipedia

    en.wikipedia.org/wiki/Earthquake_duration_magnitude

    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 ...

  8. Peak ground acceleration - Wikipedia

    en.wikipedia.org/wiki/Peak_ground_acceleration

    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 ...

  9. Surface-wave magnitude - Wikipedia

    en.wikipedia.org/wiki/Surface-wave_magnitude

    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]