What is earthquake magnitude a measure of?

Earthquake magnitude specifically quantifies the amount of ground shaking and the energy released during an earthquake. This measurement provides a standardized way to compare the sizes of different earthquakes, regardless of their location or the depth at which they occur. The magnitude is typically determined using data from seismic waves recorded by seismographs, which capture the vibrations transmitted through the Earth.

Magnitude scales such as the Richter scale or the moment magnitude scale are designed to reflect the energy released at the seismic source. As a result, a higher magnitude indicates a more powerful earthquake that generates significant shaking and has the potential to cause greater destruction and impact.

In contrast to other options, measuring the intensity of sound produced, the depth of the earthquake, or the frequency of seismic waves does not capture the overall energy release and ground motion, which are central to understanding an earthquake's magnitude.