What is the name of the earthquake magnitude scale now preferred for comparing very large earthquakes?

The moment magnitude scale is now preferred for comparing very large earthquakes.

It measures an earthquake’s size from seismic moment, which incorporates the area of the fault that ruptured, the amount of slip, and the strength of the rocks involved. These physical properties allow the scale to describe earthquakes more consistently than the older local-magnitude, commonly called Richter, scale.

The scale is logarithmic: an increase of one whole magnitude represents ten times greater measured wave amplitude and roughly 31.6 times more energy release. Because the moment magnitude method does not saturate in the same way for giant earthquakes, scientists use it for major global events.

Earthquake magnitude and intensity are different. Magnitude describes the earthquake’s overall source size, while intensity describes shaking and damage at a particular location. The Modified Mercalli scale is used for intensity and can vary from place to place during one earthquake. In news reports, “Richter scale” is still common shorthand, but technical earthquake catalogs generally use moment magnitude.