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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]
Much of an earthquake's total energy as measured by M w is dissipated as friction (resulting in heating of the crust). [52] An earthquake's potential to cause strong ground shaking depends on the comparatively small fraction of energy radiated as seismic waves, and is better measured on the energy magnitude scale, M e. [53]
That is, many low-magnitude earthquakes are not catalogued because fewer stations detect and record them due to decreasing instrumental signal to noise levels. Some modern models of earthquake dynamics, however, predict a physical roll-off in the earthquake size distribution. [13] The a-value represents the total seismicity rate of the region ...
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 ...
For example, the 1984 Nagano earthquake, which caused a lot of damage but was only rated as a 4 in terms of seismic intensity, and the 1946 Nankai earthquake, a huge earthquake that was rated as a 5, would have been given lower ratings if there weren't any monitoring stations near their origin points before 1995. After the increase in ...
Most of the earthquake's energy is used to power the earthquake fracture growth or is converted into heat generated by friction. Therefore, earthquakes lower the Earth's available elastic potential energy and raise its temperature, though these changes are negligible compared to the conductive and convective flow of heat out from the Earth's ...
For example, an eastern magnitude 4.0 earthquake typically can be felt at many locations as far as 100 km (60 mi) from where it occurred, and it might or might not cause damage near its source. An eastern magnitude 5.5 earthquake usually can be felt out to 500 km (300 mi) in most directions and can cause damage out to 40 km (25 miles). [3]
The recurrence interval for a series of large earthquakes starting in 1899 (including the 5.9 1937 Terwilliger Valley earthquake) was 18, 5, 14, 5, 12, 14, and 19 years, yet there has not been a strong earthquake for 37 years (since the 1987 Superstition Hills and Elmore Ranch sequence).