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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
Seismic moment is the basis of the moment magnitude scale introduced by Caltech's Thomas C. Hanks and Hiroo Kanamori, which is often used to compare the size of different earthquakes and is especially useful for comparing the sizes of large (great) earthquakes. The seismic moment is not restricted to earthquakes.
The original "body-wave magnitude" – mB or m B (uppercase "B") – was developed by Gutenberg 1945c and Gutenberg & Richter 1956 [25] to overcome the distance and magnitude limitations of the M L scale inherent in the use of surface waves. mB is based on the P and S waves, measured over a longer period, and does not saturate until around M 8.
Kanamori and American seismologist Thomas C. Hanks developed the moment magnitude scale which replaced the Richter scale as a measurement of the relative strength of earthquakes. [1] [2] [3] Kanamori invented the method for calculating slip distribution on the fault plane by teleseismic waveform with Masayuki Kikuchi. In addition, they studied ...
Magnitude scales measure the inherent force or strength of an earthquake – an event occurring at greater or lesser depth. (The "M w" scale is widely used.) The MM scale measures intensity of shaking, at any particular location, on the surface. It was developed from Giuseppe Mercalli's Mercalli intensity scale of 1902.
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.
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. Intensity scales are based on the observed effects of the shaking, such as the degree to which people or animals were alarmed, and the extent and severity of damage to ...
K is nominally the logarithm of seismic energy (in Joules) radiated by an earthquake, as expressed in the formula K = log E S. [2] Values of K in the range of 12 to 15 correspond approximately to the range of 4.5 to 6 in other magnitude scales; [3] a magnitude M w 6.0 quake will register between 13 and 14.5 on various K-class scales. [4]