On the morning of October 21, 1868, a massive quake struck the San Francisco Bay Area, home to 260,000 people. Nearly every dwelling and building in the town of Hayward—built directly on top of the Hayward Fault—was leveled by the quake, which claimed 30 lives across the region.
It wasn’t until the historic 1906 San Francisco earthquake that pioneering seismologist Andrew Lawson first mapped the San Andreas and other active fault lines, explaining why California was so prone to earthquakes.
Lawson taught at Berkeley, home to the first seismology laboratory in the country. But it was a rival “seismo lab” at Caltech in Los Angeles that hired a young physicist in the 1920s who became a household name in earthquake science: Charles Richter.
Richter Takes a Seismology Job
Born in rural Ohio in 1900, Richter’s original name was Charles Kinsinger. After his parent’s divorce (their second), he and his older sister took their mother’s maiden name. When Richter was nine, the family moved to Pasadena, California, outside of Los Angeles.
Richter’s first love was astronomy, then chemistry. But when he discovered he was too clumsy to handle dangerous chemicals, he settled on physics. After graduating from Stanford at 20, Richter suffered an emotional breakdown and landed back home in Pasadena. There, he worked odd jobs for a few years until he felt confident enough to enroll in a graduate physics program at the Throop Polytechnic Institute, later renamed the California Institute of Technology or Caltech.
Richter never planned to be a seismologist. In 1921, Harry Wood founded the Caltech Seismological Laboratory with money from the Carnegie Institution. Wood and his colleagues invented a smaller, lighter type of seismograph to measure local earthquakes in Southern California. As reams of data were collected from these seismographs, Wood needed someone to analyze it.
“Robert A. Millikan”—a Nobel-winning physicist and Caltech’s founding president—“knew of Richter and recommended him for the data analysis position,” says Susan Hough, a seismologist and author of Richter’s Scale: Measure of an Earthquake, Measure of a Man. “Richter considered it a stop gap, a temporary job until he could find a suitable position in modern physics.”
At least that was the plan. Richter stayed at the Caltech Seismo Lab for the next 43 years.
The Challenge: How to Compare Earthquakes?
As Richter began to work with the seismograph data, he ran into a challenge. Seismographs record how much the ground shakes at different locations, some of them far from the epicenter of the quake. Seismologists could report those various readings, but it was difficult to compare the total intensity of one earthquake event with another.
The only existing method of comparing earthquake intensity was created by a 19th-century Italian volcanologist and Catholic priest, Giuseppe Mercalli. The Mercalli Scale was based on human observation, not measurements. If shaking was barely perceptible, it was ranked a I or II in Roman numerals. An earthquake that rattled windows was a IV, that made it difficult to walk was a VI, and so on to the highest ranking of XII—total destruction.
Wood and Richter wanted a more objective, data-driven way of comparing earthquakes, but they kept running into a “scale” issue. The biggest earthquakes, like the 1868 and 1906 quakes that rocked San Francisco, were many, many times more powerful than the average California trembler. How do you design a scale that includes both extremes of the seismological spectrum?
Inventing the Magnitude Scale
It was Beno Gutenberg who had the answer. Gutenberg, an esteemed German-Jewish seismologist, came to Caltech in 1930. When Richter presented Gutenberg with his scale issue, Gutenberg suggested a logarithmic plot. A logarithmic plot is a way of condensing a wide range of data into a smaller, more manageable scale. Each number on a logarithmic plot represents an increase by a power of 10. One is 10, 2 is 100, 3 is 1000 and so on.
When Richter tried Gutenberg’s idea with his seismograph data, the result was remarkable. The seismograph numbers fit neatly into the logarithmic plot. The smallest blip on the seismograph corresponded with a 0 on Richter’s new scale and the largest conceivable quake registered as a 10 (or ten billion times bigger).
“The scale fell right out of my hands,” wrote Richter years later in a letter to Gutenberg’s son. “It was a much more powerful tool than we had any right to look for.”
Searching for a name for this new scale, Richter turned to his first love, astronomy. In astronomy, the brightness of a star is called its “magnitude,” which is calculated by measuring both the star’s luminosity and its distance from the observer. Richter wanted to do the same thing with earthquakes—turn multiple seismograph measurements into a single number. So he called it the magnitude scale.
Hough says that Richter’s real genius was in the way he “tuned” the magnitude scale to accurately describe the relative intensity of California earthquakes.
“The numbers don't mean anything,” says Hough. “What’s a magnitude 6? What’s a magnitude 8? There were never any units attached to that. Richter tuned the scale so that a magnitude 0 was the smallest earthquake that can be recorded at the surface under ordinary conditions. It was impressive, because even today with better equipment, zero is still the smallest you can record at the surface.”
The Richter Scale Controversy
Richter never named his invention “the Richter scale.” In 1935, he authored a paper titled “An instrumental earthquake magnitude scale.” In Richter’s mind, it was always called the magnitude scale.
But by the time Richter published his paper, he was already the best-known name in Southern California seismology. In 1933, Los Angeles was rocked by the Long Beach earthquake, which measured a 6.4 on Richter’s new magnitude scale and caused tens of millions of dollars in damage. Prior to the Long Beach earthquake, Richter was a number-crunching academic. In the wake of the earthquake’s destruction, Richter found a new role for himself.
“From that moment through the rest of his career, Richter was keenly interested in communicating with the public and talking with reporters,” says Hough.
Richter’s fame was cemented when Perry Byerly, a seismologist from Berkeley (Caltech’s rival), was asked by a reporter what they should call this new scale for measuring earthquakes. “Call it the Richter scale,” said Byerly.
Not all of Richter’s Caltech colleagues appreciated Richter’s newfound fame. Some accused him of being a publicity hound. Others felt that Gutenburg didn’t get enough credit for coming up with the idea of a logarithmic scale.
Over the years, there have been attempts to rename it the Gutenburg-Richter scale, with Gutenberg’s children leading the call. Richter never denied the roles of both Gutenberg and Wood in inventing the magnitude scale. In a private letter to Gutenberg’s son, Richter freely admitted his inferiority as a seismologist.
“Let me put the most important point very briefly,” wrote Richter in 1971. “Your father was a great man; I am not.”
Richter's Life and legacy
Even among seismologists, Richter had a hard time fitting in, a fact that he recognized early about himself and may have contributed to his breakdown in his 20s. After reading Richter’s personal papers (including poetry) at the Caltech archives, Hough believes that Richter had undiagnosed Asperger’s Syndrome, making it difficult for him to connect with colleagues and students.
Interestingly, somewhere that Richter and his wife, Lilian, found camaraderie was in the Los Angeles nudist community.
“On the weekends, the two of them would hang out at these camps without clothes on,” says Hough. “That became a big part of their social lives. Richter didn't have close friends in science, but within the nudist community, he did have a social circle.”
Today, seismologists don’t use the Richter scale anymore to measure quakes. At least, they don’t use the same exact calculations, because the instruments and measurements have changed. But they still use the word “magnitude” to describe the strength of earthquakes and measure them on a scale of 0 to 10.
“It’s not the Richter scale, but it kind of is,” says Hough, who thinks the units should be called “equivalent Richter magnitudes.”
To the public, a “magnitude 4” or “magnitude 8” earthquake will always be associated with Richter, an oddball scientist who became a household name.
