Happy Birthday Mr. Richter

It’s the birthday of the geophysicist and seismologist Charles Richter, born in Overpeck, Ohio (1900). Richter devised the earthquake grading scale that bears his name.

He began as a research assistant to the scientist Beno Gutenberg at Caltech in the early 1930s. At the time, scientists in Southern California wanted to begin producing regular earthquake reports, which required a reliable way to talk about the phenomena. The existing “Mercalli scale” ranked earthquakes by public fear response and building damage — both of which were highly subjective. Richter and Gutenberg developed an absolute measure of earthquake intensity by recording real motion during a seismic event. The Richter scale is logarithmic, meaning that each number of magnitude is 10 times stronger than the last. These more precise measurements were important in preventing future deaths.

Richter became so engrossed in his work that he kept a seismograph machine in his living room and made himself available to answer earthquake questions 24/7. He also helped to develop new building codes for earthquake-prone neighborhoods. In the latter half of the 20th century, the Richter scale was replaced by the moment magnitude scale, which measures the size of earthquakes in terms of the energy released. Still, to the public, the Richter scale remains the most recognizable measurement.

There are around 500,000 earthquakes across the world every year, only 100 of which cause damage. Tectonic movement of just seven to eight inches is enough for a major earthquake. The largest recorded earthquake in the world happened in 1960 in Chile, a magnitude of 9.5 on the Richter scale.
- Writer's Almanac