How do scientists compare earthquake depths and why does depth matter?

Earthquake depth is the distance from the surface down to the rupture origin inside the crust or upper mantle. Shallow quakes, generally less than about 70 kilometers deep, tend to produce stronger shaking near the surface and are more likely to damage buildings. Intermediate and deep earthquakes can occur within subducting plates, sometimes hundreds of kilometers below the surface. The deepest large earthquakes happen in subduction zones, such as beneath Japan and South America. Depth is crucial because it affects how much energy reaches communities above.