The syllabus says
- Examine the relationships between the degree of risk posed by a hazard and the probability of a hazard event occurring, the predicted losses and a community’s preparedness for it.
- Explain the reasons why individuals and communities often underestimate the probability of hazard events occurring.
- Discuss the factors that determine an individual’s perception of the risk posed by hazards.
risk, probability, losses and preparedness
Remember: the risk of a hazard event means:
The vulnerability of a population means:
Part of an increased risk comes from a greater probability of the hazard event occurring. But this doesn't mean that the population is more vulnerable. This is because the population may have taken steps to reduce their vulnerability, such as by having early warning systems, or building codes that prevent poor quality construction. This is 'community preparedness'.
- "The probability of a hazard event causing harmful consequences (expected losses in terms of deaths, injuries, property damage, economy and environment)." (IB Geography Diploma Subject Guide, p30)
The vulnerability of a population means:
- "The susceptibility of a community to a hazard or to the impacts of a hazard event." (ibid.)
Part of an increased risk comes from a greater probability of the hazard event occurring. But this doesn't mean that the population is more vulnerable. This is because the population may have taken steps to reduce their vulnerability, such as by having early warning systems, or building codes that prevent poor quality construction. This is 'community preparedness'.
Examples of community preparedness to reduce predicted losses
Earthquakes in Japan
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Typhoons (tropical cyclones) in Hong Kong
- Hong Kong has the 'Hong Kong Observatory' which is the government's official meteorological station
- It produces typhoon warnings according to a scale that is easily understood by the public - T1, T2, T3, T8, T10 - in increasing order of severity
- Typhoon warnings are posted in all MTR (subway) stations and all major buildings including apartment blocks and shopping centres
- There are clear guidelines indicating who should be where during a typhoon. Employers automatically close offices and shops within a fixed time period
- Schools are automatically closed if a typhoon warning is given before school starts, and schools must comply with regulations about how to send students home if a warning is given during the day
hazard perception: the factors that affect our perception of hazards, and why we underestimate the probability of a hazard event occurring
The individual perception of hazards is dealt with in more detail in the page 'Vulnerability'.
Ultimately, perception of hazards is affected by internal (personal) factors and external (real-world) factors. Often, the personal experience of a hazard event is limited to those events which were not especially significant, either due to a short duration, low magnitude, or being in a different place. The result is that humans often underestimate that the hazard event will happen to them - while clearly understanding that it is likely to happen to someone.
Counter-intuitively, those who make the most efforts to reduce their vulnerability are often those who underestimate the seriousness of the potential hazard event.
Ultimately, perception of hazards is affected by internal (personal) factors and external (real-world) factors. Often, the personal experience of a hazard event is limited to those events which were not especially significant, either due to a short duration, low magnitude, or being in a different place. The result is that humans often underestimate that the hazard event will happen to them - while clearly understanding that it is likely to happen to someone.
Counter-intuitively, those who make the most efforts to reduce their vulnerability are often those who underestimate the seriousness of the potential hazard event.