How Do We Model Vulnerability?

Structural vulnerability

We model structural vulnerability through the use of curves that describe a probable damage severity or economic loss for a particular type of infrastructure when it is subjected to some level of hazard.

An example may be a residential building with brick walls and a tile roof that is subjected to a particular level of ground motion due to an earthquake. Our models define the probability that the building will be in one of five damage states. Each of those damage states has a reparation cost associated with it and likely level of habitability. It should be noted that overall outcomes predicted for the buildings are not necessarily correct for each specific building, but should be representative of the overall population.

These models can be developed in a number of ways including:

  • Expert opinion
  • empirical models: these are based on post-event damage surveys and are limited to the infrastructure exposed and the hazard to which it was subjected. A number of houses all subjected to the same wind speed would only provide one point on a damage curve
  • engineering models: These are based on our knowledge of the structure and its components and how they will behave when loaded. This type of model is difficult to develop however it permits an assessment of what contributes most to the vulnerability, and the cost-effectiveness of various mitigation strategies to be assessed.

Community vulnerability

We model community vulnerability using community assessments. Community assessments aim to identify people in the community who are most likely to suffer loss or injury during a hazard event. They are based on demographic data mainly sourced from the Australian Bureau of Statistics but supplemented with other data sources.

Individuals who are particularly at risk - such as the elderly, the disabled and those on low incomes - are identified and mapped to highlight the areas most at risk.

Topic contact: Last updated: July 15, 2013