We explain what the Richter scale is and who invented it. Also, what it can be used for and the formula it uses.
What is the Richter scale?
The Richter seismological scale, commonly known as the Richter scale or local magnitude (ML) scale, is a logarithmic scale for measuring the amount of energy released in the Earth's crust during an earthquake or earthquake, which It is named in honor of the American seismologist Charles Francis Richter (1900-1985), who was, together with the German Beno Gutenberg (1889-1960), its inventor.
The Richter scale is used worldwide to measure the intensity of earthquakes that range from values of 2.0 and 6.9 on the scale and that occur between 0 and 400 kilometers deep.
When the values of an earthquake are 7.0 points or higher, the Richter method is no longer used, but the seismological moment magnitude scale (Mw), more precise for extreme records and proposed by Thomas Hanks and Hiroo Kanamori in 1979. Therefore, There can be no earthquakes measuring more than 6.9 on the Richter scale.
This scale was conceived as a method of discrimination between minor and daily earthquakes, and major and sporadic ones. For this, a Wood-Anderson torsion seismograph was used and a particular area in southern California (USA) was initially evaluated.
Despite its proven usefulness and popularity, the Richter scale It has the disadvantage of being difficult to link with the physical properties of the origin of the earthquake. For magnitudes close to 8.3-8.5, it presents a saturation effect which makes it imprecise. Furthermore, since it is limited to the possibilities of the seismograph with which it was invented, it requires extensions and other additional scales.
That is why its use is common until earthquakes that register an intensity of 6.9 points, since from then on other coinciding scales but with greater precision and usefulness are used. This is unknown, however, and the media often gives erroneous information about it.
Richter scale formula
The scale proposed by Richter used logarithms, copying the logic of the stellar magnitude scale of astronomy. Its calculation formula was the following:
M = log A + 3log(8Δt) – 2.92 = log10 ((A.Δt3)/(1.62))
Where:
M = arbitrary but constant magnitude of earthquakes that release the same energy
A = amplitude of seismic waves in millimeters, as recorded by the seismogram
Δt = time in seconds from the beginning of the primary waves (P) to the secondary waves (S)
