Keywords: holistic approach, risk evaluation, seismic risk, socio-economic vulnerability.

Risk has been defined, for management purposes, as the potential economic, social and environmental consequences of hazardous events that may occur in a specified period of time. From the perspective of this paper, risk requires a multidisciplinary evaluation that takes into account not only the expected physical damage, the number and type of casualties or economic losses, but also the conditions related to social fragility and lack of resilience conditions, which favour the second order effects when a hazard event strike an urban centre. The proposed general method of urban risk evaluation is holistic, that is, an integrated and comprehensive approach to guide decision-making and uses fuzzy set theory in order to manage qualitative concepts.

The first step of this method is the evaluation of the potential physical damage as the convolution of hazard and physical vulnerability of buildings and infrastructure. Subsequently, a set of social context conditions that aggravate the physical effects are also considered. In the method here proposed, the holistic risk evaluation is based on urban risk indicators. Accordingly, a physical risk index is obtained, for each area unit of analysis, starting from existing loss scenarios, whereas the total risk index is obtained by factoring the former index by an aggravating coefficient, based on variables associated with the socio-economic conditions of each unit of analysis (Moncho's equation). The indicators describing the seismic risk and the aggravating conditions are defined, in each case, by using membership functions corresponding to the linguistic qualifications of the risk and aggravation levels. In some cases, cities do not have the complete information necessary for this type of evaluation, especially that required by the aggravating conditions. In such cases, the methodology is flexible and expert opinions can be used in order to complement the information necessary to perform the holistic risk evaluation. Finally, the method is applied in its single hazard version to the holistic seismic risk evaluation for the cities of Barcelona (Spain) and Bogotá (Colombia).

This new model for holistic evaluation of risk facilitates the integrated risk management by the different stakeholders involved in risk reduction decision-making. It permits the follow-up of the risk situation and the effectiveness of the prevention and mitigation measures can be easily achieved. Results can be verified and the mitigation priorities can be established as regards the prevention and planning actions to modify those conditions having a greater influence on risk in the city. Once the results have been expressed in graphs for each locality or district, it is easy to identify the most relevant aspects of the total risk index, with no need for further analysis and interpretation of results.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £78 +P&P)