What causes earthquakes to vary in magnitude?

Earthquake magnitude varies depending on the amount of energy released during the movement of tectonic plates. Factors such as the size of the fault area, the depth of the earthquake, and the amount of stress built up in the rocks influence its magnitude. Shallow earthquakes near the surface often cause more destruction, while deeper ones tend to dissipate their energy before reaching the surface. The Richter scale measures this energy, with higher numbers indicating stronger quakes.