From physics to seismology

Richter graduated from Stanford in 1920 and earned a Caltech physics doctorate in 1928. He joined the Seismological Laboratory in 1927, later collaborating with Beno Gutenberg and others on local and worldwide earthquake observations.

References: [1] [3]

Comparing amplitude and distance

Local magnitude was designed for Southern California earthquakes, using amplitudes recorded by a particular instrument and corrections for distance. A one-unit increase represents a tenfold increase in the compared recording amplitude. Magnitude differs from the shaking intensity experienced at a specific place.

References: [2]

The scale’s range

Local magnitude saturates for very large earthquakes and requires attention to regional propagation differences. Later moment magnitude uses physical properties of the earthquake source and is better suited to large events. A reported magnitude is therefore not necessarily an original Richter local magnitude.

References: [2]