Pressure and Release Model

The Pressure and Release model (PAR), developed by Ben Wisner, Piers Blaikie, Terry Cannon, and Ian Davis in their book At Risk, is the foundational framework for analyzing disasters as socially produced rather than purely natural events. It conceptualizes a disaster as the intersection of two opposing forces: a natural hazard on one side and, on the other, a progression of vulnerability that builds from deep root causes through dynamic pressures into concrete unsafe conditions. The metaphor is a nutcracker or 'crunch': the hazard squeezes a population whose vulnerability has been progressively constructed by political, economic, and social processes. Risk is expressed as the product of hazard and vulnerability, and the model's hopeful corollary — the 'release' — is that reducing risk means tracing the chain backward and relieving the pressures, addressing unsafe conditions, dynamic pressures, and ultimately root causes.