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Progression of vulnerability and hazard

Progression of vulnerability

According to the UN Office for Disaster Risk Reduction, disaster risk is defined as:

The potential loss of life, injury or destroyed or damaged assets which could occur to a system, society or a community in a specific period of time, determined probabilistically as a function of hazard, exposure, and capacity.
(UNISDR 2017)
Alexander (2000: 13, cited in Wisner et al. 2004: 50) described a pseudo-equation to define risk as:
Risk = hazard x vulnerability
The impacts of disaster are influenced most significantly by the underlying conditions of the people exposed to hazards. Blaikie et al. (1994) introduced a model to explain how disasters happen, calling it the Pressure and Release (PAR) model. Watch the video at the top of this step to see how it can be applied.
PAR is a tool that shows that disasters occur when hazards affect vulnerable people. It seeks to explain how vulnerability is created (Blaikie et al. 1994). People’s vulnerability exists as a result of root causes (1) of wider social, economic and political conditions, which result in dynamic pressures (2) leaving many people not just exposed to hazards but living in unsafe conditions (3).
In the Pressure model, root causes (stage 1) are limited access to power, structure and resources, and ideologies such as political and economic systems. This leads to dynamic pressures (stage 2) consisting of lack of local institutions, training, appropriate skills, local investment, local markets, and ethical standards, and macro forces of rapid population change, rapid urbanisation, arms expenditure, debt repayment, deforestation and decline in productivity. This leads to unsafe conditions (stage 3) which may be physical such as dangerous locations, unprotected infrastructure, or low incomes, socioeconomic such as special groups being at risk, or institutional such as a lack of public preparedness or endemic diseases. Hazards which provide pressure in the model may be storm surges, flooding, sea level rise, heat, drought, geological disturbance, or biological pests and pathogens. The progression of vulnerability and the hazard apply pressure, leading to disaster. Risk equals hazard multiplied by vulnerability.Adapted from Wisner et al (2004). Click to expand.
Vulnerable groups live under pressure where their access to services such as education, healthcare and secure livelihood options are limited, which in turn means limited and unstable income, resulting in poverty, poor health and unsafe living conditions. In order to release these pressures, we must act to reduce the vulnerability component of risk.
Over the last 40 years, we have shifted from a hazard perspective, where we felt we could only respond to the impacts of the hazard, to a more vulnerability-focused view where disaster risk reduction initiatives seek to reduce the underlying causes and effects of vulnerability locally and limit potential impacts before they occur. However, the limited capacity of communities and governments means that residual risks are still present and disasters still occur. As a result, communities and agencies must prepare for impact and response.

Your task

Find some information about the conditions in Pakistan immediately prior to the 2010 floods. Use them to conduct a simple progression of vulnerability analysis using the pressure model.
Consider how the factors in Pakistan before the floods created root causes (1) that led to dynamic pressures (2) and ultimately unsafe conditions (3) meaning that some people were more significantly affected than others.


Alexander, D. (2000) Confronting Catastrophe: New Perspectives on Natural Disasters. New York: Oxford University Press

Blaikie, P., Cannon, T., Davies, I., Wisner, B. (1994) At Risk: Natural Hazards, People‘s Vulnerability & Disaster. London: Routledge

Wisner, B., Blaikie, P., Cannon, T., and Davis, I. (2004) At Risk: Natural Hazards, People‘s Vulnerability and Disasters. 2nd edn. London: Routledge

UNISDR (2017) UN Office for Disaster Risk Reduction – Terminology – UNISDR [online] available from [14 May 2020]

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Humanitarian Action, Response and Relief

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