Hazard risk: hazard, vulnerability and capacity

Key terms

• Hazard: a natural event that threatens people and property (an earthquake, a tropical cyclone).
• Vulnerability: how likely people are to be harmed, linked to poverty, poor housing and lack of warning.
• Capacity to cope: the ability to prepare, respond and recover.

The risk equation

Risk = (Hazard x Vulnerability) / Capacity to cope.

Risk rises with the size of the hazard and with vulnerability, and falls as capacity rises.

Using it

Explain differences between places: a wealthier country with building codes, warnings and emergency services has higher capacity, so the same hazard often causes fewer deaths there.

Worked example

Two cities face the same earthquake. City A has strict building codes and trained emergency services. Which has lower risk?

1. Same hazard.
2. City A has higher capacity and lower vulnerability.

Answer: City A.

Check yourself

1. In the risk equation, which factor is on the bottom of the fraction?
   • Hazard
   • Vulnerability
   • Population density
   • Capacity to cope
   Show answer

   Capacity to cope. Higher capacity lowers risk.

2. Which increases vulnerability?
   • An early warning system
   • Poorly built housing
   • Emergency drills
   • Insurance and savings
   Show answer

   Poorly built housing. Weak buildings make harm more likely.

3. Which increases capacity to cope?
   • Rapid unplanned urban growth
   • Living on a floodplain
   • Lack of communication
   • Trained emergency services
   Show answer

   Trained emergency services. Emergency services help response and recovery.

4. Which is a hazard rather than a disaster?
   • A tropical cyclone over the open ocean
   • A cyclone that destroys 10,000 homes
   • An earthquake that kills 2,000 people
   • A flood that leaves 50,000 people homeless
   Show answer

   A tropical cyclone over the open ocean. A hazard becomes a disaster only when it seriously harms people.

5. If vulnerability doubles and nothing else changes, risk
   • halves
   • stays the same
   • doubles
   • falls to zero
   Show answer

   doubles. In the risk equation, vulnerability is on the top of the fraction, so (in this model) doubling it doubles risk.

Practise with instant feedback

Sources

• Pearson Information Manual 2026/2027: International A level

Last updated 7 November 2026. Spotted a mistake? Email alevel@lifereadysociety.com.