What determines the potential number of affected structures during an earthquake?

The magnitude of an earthquake is a critical factor in determining the potential number of affected structures. Magnitude is a measure of the energy released at the source of the earthquake, commonly quantified using the Richter scale or the moment magnitude scale. Higher magnitude earthquakes indicate a greater release of energy, which typically results in more intense shaking and a larger area being affected. This increased shaking intensity can lead to structural damage or failure in buildings, infrastructure, and other facilities within the vicinity of the epicenter and beyond.

In contrast, while the scale of the earthquake, its depth, and location can influence the specifics of the damage and the immediate impact zone, it is the magnitude that directly correlates with the severity of shaking experienced over a broader area. The greater the magnitude, the more likely that numerous structures will experience varying levels of damage, thus affecting an increased number of buildings throughout the impacted region.