# What is the Richter scale?

## What Does Richter scale Mean

We explain what the Richter scale is and who invented it. Also, what can it 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 scale (ML), is a logarithmic scale for measuring the amount of energy released into the earth's crust during an earthquake or earthquake , named after the American seismologist Charles Francis Richter (1900-1985), who was its inventor together with the German Beno Gutenberg (1889-1960).

The Richter scale is used worldwide to measure the intensity of earthquakes ranging from values of 2.0 to 6.9 on the scale and occurring 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 scale of magnitude of the moment (Mw), more precise for extreme records and proposed by Thomas Hanks and Hiroo Kanamori in 1979. Therefore, there can be no earthquakes greater than 6.9 on the Richter scale .

This scale was conceived as a method of discrimination between minor and everyday earthquakes, and those major and sporadic. For this, a Wood-Anderson torsion seismograph was used and a particular area of southern California (USA) was initially evaluated.

Despite its proven usefulness and popularity, the Richter scale 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 has a saturation effect that makes it inaccurate. In addition, being limited to the possibilities of the seismograph with which it was invented, it requires extensions and other additional scales.

For this reason, its use is common even to earthquakes that register an intensity of 6.9 points, since from then on other matching scales are used, but with greater precision and utility. This, however, is unknown and the media often give information erroneous respect.

### 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 releasing the same energy

A = amplitude of the seismic waves in millimeters, as recorded by the seismogram

Δt = time in seconds from the start of the primary waves (P) to the secondary waves (S)

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