What is the Richter Magnitude Scale?

What is the Richter Magnitude Scale?
When earthquakes occur, they can bring massive destruction and devastation. To better understand the size and force of earthquakes, scientists have developed different methods to try and quantify this power, such as the Richter Magnitude Scale. What is the Richter Magnitude Scale?

What is the Richter Magnitude Scale?

The Richter Magnitude Scale, also known as the Local Magnitude Scale, is a method for assigning a number to represent the magnitude, or size, of an earthquake. This value is determined using the logarithm of the amplitude (height) of the largest seismic wave, calibrated to a scale by a seismograph. Got all that that?

The Richter Magnitude Scale was one of the first useful ways to measure earthquakes. It was developed by geologist Charles Richter at the California Institute of Technology during the 1930s.

Over time, modern scientific practices would replace Richter’s scale with more accurate ones. Today, however, the Richter Magnitude Scale is still often mentioned in media coverage of earthquakes, albeit erroneously. In fact, the term Richter Scale has come to be a bit of a catch-all name for all logarithmic scales used to measure earthquakes.

How Does the Richter Magnitude Scale Work?

The Richter Magnitude Scale has no lower limit and no maximum limit. It is a logarithmic scale. What this means is that each one-point that is added to the scale is representative of an increase of 10-fold. Each increase of one unit also represents the release of about 32 times more energy than that represented by the previous whole number on the scale (so an earthquake measuring 4.0 has 32 times more energy than an earthquake measuring 3.0).

Below is a useful guide to better understand what Richter Magnitude Scale numbers mean:

Magnitude Category  Effects
1.0–1.9 Micro Typically not felt by people.
2.0–2.9 Micro Typically not felt by people.
3.0–3.9 Minor Felt by some people, but no damage.
4.0–4.9 Light Felt by most people, but with minimal damage.
5.0–5.9 Moderate   Felt by everyone, and some damage to weak structures.
6.0–6.9 Strong Felt in wider areas, with violent shaking at epicenter and moderate damage.
7.0–7.9 Major Felt across large distances, damages most buildings, and can bring loss of life.
8.0–8.9 Great Major, widespread damage, with loss of life over large areas.
9.0 and greater Great Near total destruction, potential changes to topography, and widespread loss of life.

What is it Used For?

The Richter Magnitude Scale is used simply to measure the strength of earthquakes. In the media, you might hear mention of a magnitude 5 earthquake happening somewhere in the world. This number was found using magnitude scales based on Richter’s original method. While there are other methods for measuring the strength of an earthquake, the Richter Magnitude Scale is popular because of its simplicity. As humans, we can easily grasp the concept of ranking earthquake size using what is essentially a 1-10 system. Low numbers mean small earthquakes, and higher numbers mean big earthquakes.

How Was the Richter Magnitude Scale Created?

The scale created by Richter was originally modeled on the stellar magnitude scale that is commonly used by astronomers. This uses the amount of light emitted by stars. The luminosity of a star is based on telescopic observations of how light it is. This is corrected for the magnification of the telescope and for the distance between the Earth and the star. Richter substituted this data for vibrations in the ground that were measured with a seismograph. Like the method used by astronomers, this would produce a simple number scale to measure the size of the quake itself.

The Richter Magnitude Scale provides us with an easy way to communicate the size of earthquakes that occur around the world. This allows for easier reporting, studying, and strategizing, as the scale helps get people on the same page. Overall, it makes understanding the severity of a quake more understandable to everyone, and this is important, because earthquakes can happen at just about any time and place.


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