Compare hazard-based approaches with risk-based approaches in earthquake mitigation (e.g., HAZUS vs empirical damage curves).

• A. Hazard-based focuses on the probability of aftershocks; risk-based ignores exposure.
• B. Hazard-based uses historical losses only; risk-based uses engineering models only.
• C. Hazard-based relies on expert opinion; risk-based uses only simulations.
• D. Hazard-based focuses on the probability and intensity of ground shaking; risk-based includes exposure and vulnerability to estimate expected damage and losses; tools include HAZUS and empirical damage modeling.

Answer: (D)

Hazard-based approaches concentrate on the shaking hazard itself—the probability and expected intensity of ground motion at a location. They quantify how often a certain level of shaking might occur and how strong it could be, but they don’t by themselves translate that shaking into losses.

Risk-based approaches bring in what is in harm’s way and how it behaves when shaken. They combine the seismic hazard with exposure (the people, buildings, infrastructure present) and vulnerability (how those exposures respond to shaking) to estimate expected damage, casualties, and economic losses. This makes the assessment useful for planning and mitigation because it links the hazard to real-world impacts.

HAZUS is a tool that embodies this risk-based thinking by integrating seismic hazard, building inventories, and vulnerability relationships to produce loss estimates. Empirical damage curves, meanwhile, provide observed-based relationships between shaking intensity and damage for specific building types, and are used within risk-based assessments to translate ground shaking into expected damage.

The other statements either mix up what hazard-based versus risk-based focus on or imply limitations that aren’t accurate (for example, hazard-based isn’t solely about aftershocks, and risk-based isn’t limited to simulations or to using only one type of model).