In the last chapter, we argued that disasters occur as the result of the impact of hazards on vulnerable people. We suggest two frameworks for explaining this relationship between natural events and the social processes that generate unsafe conditions. The first is the Pressure and Release (PAR) model, which shows in diagrammatic terms how the causes of vulnerability can be traced back from unsafe conditions, through economic and social ('dynamic') pressures, to underlying root causes. PAR is an organising framework outlining a hierarchy of causal factors that together constitute the pre-conditions for a disaster. We can also describe this as a pathway, 'progression of vulnerability' or 'chain of causation'. It is a sequence of factors and processes that leads us from the disaster event and its proximate causes back to ever more distant factors and processes that initially may seem to have little to do with causing the disaster. The 'Release' aspect arises from the realisation that to release the pressure that causes disasters, the entire chain of causation needs to be addressed right back to the root causes, and not just the proximate causes or triggers of the hazard itself or the unsafe conditions of vulnerability.
But the PAR model does not provide a detailed and theoretically informed analysis of the precise interactions of environment and society at the 'pressure point', at the point where and when the disaster starts to unfold. Firstly, any analysis of a disaster must explain differential vulnerability to, and the impacts of, a disaster-why wealthier people often suffer less, and why women and children may face different (and sometimes more damaging) outcomes than men and adults. Particular groups, defined by ethnicity, class, occupation, location of work or domicile may suffer differentially from others. In these senses, the Access model focuses on the precise detail of what happens at the pressure point between the natural event and longer-term social processes, and, to signify this in visual terms, a magnifying glass is drawn on the PAR model (Figure 2.1).
Secondly, the PAR framework is essentially static, and without a series of iterations through the trajectory of a disaster, it cannot suggest nor account