A proposition of classification of the catastrophe systems based on complexity criteria

Abstract

Cet article est diffusé sur internet et ne figure pas dans un ouvrage : voir à l'adresse suivante http://www-lih.univ-lehavre.fr/~bertelle/epnacs2007-proceedings/provitolo4epnacs07.pdfInternational audienceA classification system of catastrophic events is a methodologyassembling all the catastrophes groups. It is possible to identify several catastrophesclassifications. The most widely known are classified into: nature, consequencesof the event, duration, affected territories and areas of the destroyedzone, and at last into the needed intervention measures. But these criteria ofclassification allow with difficulty to apprehend the complexity of the catastrophe.Thus we propose a classification based on the complex characteristicsof the risks and catastrophes. Within the scope of this paper, we focus firston the complexity of the organization and the emergence of the phenomenonwhich result from it, and then, on the complexities resulting to the spatialand temporal scales of the catastrophe. The organization is considered as acentral concept of the complexity. In the field of the catastrophe, the complexityof organization results essentially from the self-organization of the systems(the system develops its internal constitution and its behaviour thanks to theinteractions between its various components and not thanks to an externalstrength). Phenomena as different as mantels of snow, seismic hazards, behavioursof people and population have characteristics of self-organization allowingthe emergence of new events: snowslides, earthquakes, collective panic.A particular attention will be given to the emergence of this kind of panic insituation of disaster. There is indeed a double-way within two levels, a doubleaction of the crowd on the individual and the individual on the crowd,without leader. It means that we need to take into account the multi-scalesaspect in order to be able to study the behaviours. The complex systems ofcatastrophe have characteristics able to emerge at higher or lower levels ofscales. It allows us to apprehend the complexity of the disasters through thescales. The disasters belong to the multifarious temporal- and space scales.First, the disasters can not be classified in one single category of spatial scale.Some of them appear on the scale of a territory, a region, a country or theplanet. If we speak about a natural or technological disaster, none of them will be automatically associated with a spatial scale. Furthermore, a local disastercan have large-scale impacts. Various events (attacks of September 11th,2001 in New-York, the tsunami which ravaged the South of Asia in December2004, the hurricane Katrina who destroys New-Orleans in 2005) remind usthat the catastrophe is not always an event restricted at the affected area butcan have consequences outside this area. The increase of the complexity ofthe disaster can result from the movement between different spatial levels andfrom systemic relations between these levels. The complexity also results fromvarious temporal scales of the risks and the disasters. Three temporal phasescan be found. The first one is relative to the temporality of the potential riskI mean what takes place before the disaster. The second phase refers to thetemporality of the disaster I mean all what happens during the catastrophe.We show that during the disaster, the temporalities of the hazard, the vulnerabilityand the domino effects rarely happen together. The third and lastphase refers to the time after the disaster and to the experience feedback forthe risk management. These three temporal phases are based on two scales oftime: a short time, I mean a time - action, inherent to the functioning of anydynamic system (Ch.-P. P´eguy, 2001) and a long time. Thus, the catastrophemust be approached in various scales. And the study in each of the scalesgives several information of the disaster in its whole, or about some of itscomponents (hazard, vulnerability and domino effects)