Richter scale
The Richter scale is a logarithmic scale developed by seismologists Charles F. Richter and Beno Gutenberg to quantify the magnitude of seismic energy released by earthquakes, first introduced in the early 1930s. This scale assigns a numerical value to an earthquake based on data from seismographic stations, allowing for a comparative assessment of earthquake sizes, categorizing them as small, medium, or large. Each whole number increase on the scale indicates a tenfold increase in ground motion and approximately thirty-one times more energy release; for example, a 3.0 magnitude earthquake releases significantly more energy than a 2.0. The scale has no upper limit, though it is commonly understood that no earthquake has exceeded a magnitude of 10.0, while minor quakes typically range from 3.0 to 3.9, and an earthquake of 8.0 or higher is classified as a great quake. Prior to the Richter scale, other scales relied on subjective measures of intensity based on observed damage, making Richter's objective approach a significant advancement. Although more sophisticated methods for measuring earthquakes have since emerged, the Richter scale remains a widely recognized means of communicating earthquake size to the public and media.
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Richter scale
System that measures the magnitude of earthquakes and other seismic activity
Date Invented in 1935
The Richter scale provides a scientific measurement of earthquakes based on data collected from seismographs. Charles Francis Richter also introduced the word “magnitude” into seismology and gave meaning to the values so that the general public could understand that the higher the Richter scale number, the bigger the earthquake.
Richter, a professor of seismology at the California Institute of Technology in Pasadena, along with his colleague Beno Gutenberg, invented a scale to calculate the magnitude of seismic energy released by an earthquake. Using data from Southern California seismography stations, Richter and Gutenberg developed the mathematical scale to compare the size of earthquakes and classify them as small, medium, or large. The scale was used as early as 1933 for the Long Beach, California, earthquake and was formally described in a paper published in 1935.
The Richter scale expresses magnitude in whole numbers and decimal fractions. Each whole number increase in magnitude represents a tenfold increase in the ground motion, which is a release of about thirty-one times more energy than the previous whole number. In other words, a 3.0 earthquake is ten times larger and releases almost thirty-one times more energy than a 2.0 earthquake.
The scale has no upper limit, although ten is often assumed to be the ceiling because no recorded earthquake has ever exceeded that number. Zero is the smallest earthquake that can be measured by a seismograph, and minor earthquakes of 3.0 to 3.9 magnitude can be felt. A magnitude 5.0 earthquake is considered moderate, and 8.0 or higher is a great quake.
Impact
Earlier scales relied on intensity to quantify the earthquakes, but the method was partly subjective because it was based on the amount of damage caused to structures and how the earthquake was felt by people. The scale created by Richter and Gutenberg was used for years and greatly advanced the standardized measurement of earthquakes. The scale was the first to allow an accurate measurement of earthquakes based on ground motion. Although other, more accurate means of measuring earthquakes have been developed, Richter’s method formed the basis of them all and is usually how the media and general public refer to the size of any earthquake.
Bibliography
Green, Caroline. “The Man Who Loved Earthquakes.” The Geographical Magazine (December, 1995) 34-35.
Hough, Susan Elizabeth. Richter’s Scale: Measure of an Earthquake, Measure of a Man. Princeton, N.J.: Princeton University Press, 2007.