Explain the difference between hazard, risk, and vulnerability in tectonic hazards.

• A. Hazard is the probability of harm occurring.
• B. Risk is the probability of harm given exposure, and vulnerability is the susceptibility to damage; risk is often approximated as hazard × exposure × vulnerability.
• C. Hazard and vulnerability are the same concept.
• D. Exposure measures the likelihood that a site will experience a hazard.

Answer: (B)

Hazard is about the potential for a tectonic event to cause harm—the chance of an earthquake, tsunami, volcanic eruption, or landslide, and how strong or frequent it might be in a given area. Risk brings in what happens to people and property once that potential event occurs, combining how exposed they are to the hazard with how susceptible they are to damage. In practice, risk is often estimated as hazard multiplied by exposure multiplied by vulnerability, giving a sense of the expected harm or loss over a period of time. Exposure means the people, buildings, and assets in the hazard zone, while vulnerability covers how easily those people or structures can be damaged—factors like building design, construction quality, preparedness, and the ability to recover. So a region can have a high hazard but low risk if exposure is small or vulnerability is low, or high risk if there is large exposure and high vulnerability. The main idea is that hazard describes the event’s potential, exposure describes what is in the way of that event, and vulnerability describes how badly it would affect them; risk combines all three to reflect likely harm.