It was first proposed in 2006, and explained in more detail in a peer-reviewed paper presented at a 2007 system sciences conference.
The scale can be tailored for use at any geographic level – city, county, state or continent.
Some scales are used before and/or during a crisis to predict the potential intensity and impact of an event and provide an understanding that is useful for preventative and recovery measures.
The Rohn Emergency Scale use two parameters that form the scope: percent of affected humans out of the entire population, and damages, or loss, as a percentage of a given gross national product (GNP).
The scale is a normalized function whose variables are scope (S), topography (T), and rate of change (D), expressed as These parameters are defined as follows: The model loosely assumes that a society whose majority of the population (70% in this model) is affected and half of its GNP is drained as a result of a calamity reaches a breaking point of disintegration.
comprise the rate of change that is of utmost importance to society and therefore incorporated in the model.