Typology of risks

Later on, risk will be referred as the conjunction of a single hazard and the corresponding stakes; that is to say as a potential damage resulting from the possibility of occurrence of a dangerous phenomenon. Several typologies are consequently possible.

A typology is a classification of objects or phenomena with common characteristics in different groups. Establishing a class or a group is thus the result of a work of generalization. The level of general information is determined by the properties or characteristics that are chosen to define one or more classes (Cuny and Lejeune, 2003).

There is neither standard typology nor one unanimously acknowledged today. Basic and seldom exhaustive classifications are often offered by various sources, and several approaches are possible.

A typology of risks could naturally be build up when risks could be gathered according to their probable occurrence, the nature of the source phenomenon (hazard), the importance of damages they can be the cause of, the capability to deal with those damage, etc.

The following propositions have been made by Perihlon (2003) within the scope of the MADS model (Analysis’ Methodology of Systems Dysfunctions) :
- a typology of systems considered as sources of danger (mechanical, chemical, electric, biological, environmental, economic and social sources; fire and radiations sources);
- a typology of target systems resulting from these dangers (individuals, population, ecosystems, material or symbolic systems) ;
- a typology of events (flow of matter, of energy, of information ; punctual or diffuse flow ; chronic flow or flow with limited effects) ;
- a typology of fields of danger (physical, chemical, natural or artificial, psychological, economic, sociological, political, legal-statutory, cultural, organizational fields).

We have chosen the most traditional presentation, although it is often criticized (Dauphiné, 2001, supplemented). It classifies risks according to the origin of the phenomena. Risks from natural and technological origin shall be distinguished.

The weak point of this typology is due to the difficulty of considering a single source of a risk. It is for instance difficult to classify a landslide (natural risk) which would bring an hazardous materials’ transport crash about (technological risk).