Earthquakes are measured based on what factor?

The measurement of earthquakes is fundamentally based on the energy released during the seismic event. This energy is produced by the sudden movement of tectonic plates along faults, which causes stress to accumulate until it is released in the form of seismic waves. The magnitude of an earthquake reflects this energy release, and scientists commonly use various scales, such as the Richter or moment magnitude scale, to quantify it.

The Richter scale, while often referenced in popular culture, primarily measures the amplitude of seismic waves, which is a consequence of the energy released, rather than measuring energy directly. The duration of shaking refers to the length of time that seismic waves are felt but does not provide a direct measure of the earthquake's strength. Similarly, the depth of focus relates to where the earthquake originates underground but does not indicate how much energy was released. Thus, focusing on energy released provides the clearest and most accurate measure of an earthquake's magnitude.