Risk, Hazard and Vulnerability
There are numerous environmental (natural) hazards to human life and well-being:
- Severe Storms (Tornados, Lightning, Hail)
- Cyclonic Storms (Hurricanes)
The amount of risk (the possibility that something undesirable will happen) is a function both of the likelihood of a hazard and the vulnerability (openness to harm or damage) of the people involved. This can be expressed as a pseudo-equation (Wisner, Blaikie, Cannon and Davis 2003):
Risk = Hazard * Vulnerability
Use of a truth table with that equation expresses the way in which risk is the confluence of hazard and vulnerability. Assigning the values of zero for low and one for high:
- Tornados are rare in the Pacific Northwest (hazard = 0). If you live in a a heavy steel-framed, tornado-resistant apartment building (vulnerability = 0), your risk of injury or property-loss from a tornado is low (0 * 0 = 0)
- Even if you live in a light wood-frame house (vulnerability = 1), in the Pacific Northwest (hazard = 0) your tornado risk will still be low (0 * 1 = 0)
- If you live in a tornado-prone area like Oklahoma (hazard = 1), but live in a heavy steel-framed apartment building (vulnerability = 0), your risk will also be low (1 * 0 = 0)
- But, manufactured (mobile) homes are lightly built (vulnerability = 1). Mobile home parks are often sited on flat, inexpensive land, which is prime tornado area in tornado-prone parts of the country (hazard = 1). Therefore, risk of injury or property loss in a mobile home park is often high (1 * 1 = 1)
The Social Construction of Risk
If a tornado occurs in an undeveloped, unpopulated rural area, the consequences to humans are minimal. However, if that tornado occurs in a densely-populated urban area, the consequences can be catastrophic.
This demonstrates how risk is socially-constructed, and how the term "natural disaster" can be considered a misnomer, something Smith (2006) expounds on in greater detail.
While hazards like earthquakes and floods are a function of environmental conditions beyond the control of individuals, vulnerability is a socially-constructed function of human factors like economics, politics, history and values.
For example: while a cyclone is an environmental hazard, the vulnerability of an individual to harm from that cyclone is affected by factors like:
- The ability to afford housing that can withstand high winds
- The ability to afford housing away from flood-prone areas
- The ability to afford transportation for evacuation
- The political will and economic ability of the government to build robust transportation and drainage infrastructure
- Familial and employment responsibilities to be in hazardous areas
In a broader sense, hazards can also be socially-constructed changes to "nature," calling into question where the boundary should be drawn between the human and the "natural:"
- Deforestation in Haiti has contributed to instability of mountain soils and a subsequent increase in mud slides and floods from runoff
- Flood and soil control measures on the Mississippi River have reduced silt flow to the Mississippi delta, resulting in shrinking marshlands that used to reduce the strength and flooding from hurricanes in New Orleans
- CO2 emissions from use of fossil fuels is contributing to atmospheric changes that result in more-severe storms, sea-level rise and associated flooding