Edexcel Specification focus:
‘Definitions of natural hazard and disaster, the importance of vulnerability and a community’s threshold for resilience; the hazard risk equation.’
A natural hazard becomes a disaster when people are vulnerable and exposed to it. Resilience, vulnerability and risk are essential ideas in understanding tectonic hazards.
Natural Hazards and Natural Disasters
What Is a Natural Hazard?
Natural hazards are naturally occurring physical events that have the potential to cause loss of life, damage to property and the environment, and disruption to human activities.
Natural Hazard: A naturally occurring physical event (e.g. earthquake, volcanic eruption, tsunami) that poses risk to people or the environment.
Not all natural hazards become disasters. A hazard becomes a disaster only when it affects people, their livelihoods, or the economy significantly.
From Hazard to Disaster
A natural disaster is the realisation of a natural hazard that results in significant impacts, such as fatalities, economic losses or social disruption.
Natural Disaster: A major hazard event that causes widespread disruption to a community or region, including significant loss of life, property damage, or economic hardship.
Whether a hazard becomes a disaster depends not just on the physical event but also on human vulnerability and capacity to cope.
Vulnerability and Resilience
Understanding Vulnerability
Vulnerability refers to the degree to which a population or individual is susceptible to harm from a hazard. Vulnerability is influenced by a range of social, economic and physical factors, including:
Poverty – limits access to safe housing and healthcare.
Location – proximity to plate boundaries or steep slopes.
Education and awareness – knowledge of risks and how to respond.
Population density – more people in high-risk zones can increase impact.
Governance and planning – poor planning and weak institutions increase vulnerability.
Vulnerability: The degree to which a population, system or asset is likely to experience harm due to exposure to a hazard.
A community with high vulnerability is more likely to experience severe consequences from the same hazard compared to one with lower vulnerability.
What Is Resilience?
Resilience is the ability of a community or system to anticipate, cope with, resist and recover from the effects of a hazard. It involves:
Preparedness – effective early warning systems and planning.
Response capability – access to emergency services and support.
Recovery speed – how quickly infrastructure and services can be restored.
Adaptability – learning from past events to improve future responses.
Resilience: The capacity of a community or society to resist, absorb and recover from the effects of a hazard efficiently.
A high level of resilience reduces the severity of a disaster’s impacts.
Diagram illustrating that Risk emerges from the convergence of Hazard, Vulnerability, and Exposure, with Adaptive Capacity (labelled as resilience) acting to lower overall risk. The inclusion of exposure provides context, though the syllabus focuses on coping capacity as the key resilience factor. Source
The Hazard Risk Equation
The hazard risk equation summarises how the potential risk from a natural hazard is influenced by different variables:
Risk (R) = Hazard (H) × Vulnerability (V) / Capacity to Cope (C)
R = Overall risk level
H = Frequency and magnitude of the hazard
V = Population and infrastructure vulnerability
C = Coping capacity of the community or region
This equation illustrates that even a low-magnitude hazard can lead to a high-risk situation if vulnerability is high and coping capacity is low. Conversely, strong coping strategies and low vulnerability reduce overall risk, even in high-hazard zones.
Factors Affecting Disaster Severity
Disasters occur at the intersection of natural systems and human society.
The severity of a disaster is shaped by:
Magnitude of the hazard – more intense earthquakes or larger tsunamis cause more damage.
Duration and areal extent – prolonged events or widespread impacts intensify outcomes.
Population exposure – high population density increases potential casualties and disruption.
Quality of infrastructure – poorly built structures collapse more easily.
Emergency planning – effective evacuation and relief systems save lives.
Social inequality – marginalised groups often have fewer resources to prepare or recover.
A hazard’s impact is therefore not solely a function of its physical force, but also of how human systems prepare, respond, and rebuild.
Threshold of Resilience
Every community has a threshold of resilience — the point beyond which the social, economic or environmental systems can no longer cope without significant external support.
A community with strong infrastructure and well-funded emergency services has a higher threshold, enabling better absorption of impacts.
Poorer communities may reach their threshold quickly, triggering major crises.
Once this threshold is crossed, the impacts can include:
Long-term displacement
Economic collapse
Public health crises
Erosion of social cohesion
In tectonic hazard zones, managing this threshold is vital through investment in education, emergency planning, structural engineering, and international cooperation.
Linking Hazard, Vulnerability and Risk
In summary, tectonic disasters are not just “natural” — they are shaped by human choices. Understanding the interconnectedness between hazard characteristics, population vulnerability, and resilience allows geographers and planners to:
Identify at-risk populations
Design effective risk reduction strategies
Develop more sustainable communities
FAQ
Vulnerability can be physical, social, economic or environmental. Each type increases risk in different ways:
Physical: Living near fault lines, in poorly built structures, or on unstable slopes.
Social: Limited access to healthcare, education or early warning systems.
Economic: Poverty reduces the ability to prepare, respond or recover.
Environmental: Deforested areas or degraded land can worsen hazard impacts.
Communities often experience a combination of these, increasing overall exposure and reducing their ability to cope.
High population density means more people and infrastructure are exposed to a hazard in a given area.
This can:
Increase casualty rates during earthquakes or tsunamis.
Make evacuation and emergency response more difficult.
Strain healthcare and rescue services during the aftermath.
In urban areas, dense housing and informal settlements are often less resistant to hazards, leading to higher losses.
The resilience threshold varies based on development, governance and access to resources.
High-income countries often have better infrastructure, emergency services and recovery systems.
Low-income countries may lack the capacity to rebuild quickly or manage crises effectively.
Political stability and good governance also strengthen resilience through planning, legislation and coordination.
These factors determine how much disruption a society can absorb before it reaches a crisis point.
Yes. Even a moderate hazard can become a disaster if vulnerability is high and coping capacity is low.
For example:
A shallow earthquake of magnitude 5.5 can be deadly in poorly constructed urban areas.
A small volcanic eruption may cause severe disruption if emergency plans are weak or the population is unprepared.
This shows that the context of the hazard often determines the disaster outcome, not just the hazard's size.
Governance influences how well a country prepares for, responds to and recovers from hazards.
Key roles include:
Enforcing building codes and land-use planning to limit exposure.
Investing in education, early warning systems and emergency services.
Coordinating disaster response and recovery through clear institutional frameworks.
Effective governance reduces vulnerability and increases resilience, making disasters less likely or less severe.
Practice Questions
Question 1 (3 marks)
Define the term natural disaster and explain how it differs from a natural hazard.
Mark Scheme:
1 mark for correct definition of natural disaster:
A major hazard event causing widespread disruption, including loss of life, property damage, or economic hardship.1 mark for correct definition of natural hazard:
A naturally occurring physical event that poses risk to people or the environment.
1 mark for clear explanation of the difference:
A hazard becomes a disaster when it affects people significantly, turning potential risk into actual impact.
Question 2 (6 marks)
Explain how vulnerability and resilience influence whether a natural hazard becomes a disaster.
Mark Scheme:
1–2 marks: Basic explanation of either vulnerability or resilience with limited development or examples.
3–4 marks: Developed explanation of both vulnerability and resilience with some link to disaster outcomes. May include one clear example or relevant factor (e.g. poverty, infrastructure).
5–6 marks: Detailed explanation with clear understanding of how both vulnerability and resilience interact to influence disaster severity.
Stronger answers will include:Vulnerability factors (e.g. poverty, population density, poor governance).
Resilience aspects (e.g. emergency planning, recovery capacity).
Clear reasoning of how low resilience/high vulnerability leads to greater disaster impact.
May include real-world understanding (though not required for full marks if explanation is strong).
No marks awarded for generic or irrelevant responses.
