Holistic evaluation of the seismic risk in urban centers

Abstract

In the past, the concept of risk has been defined in a fragmentary way in many cases, according to each scientific discipline involved in its appraisal. At nowadays, the risk is 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 article, 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 favors the second order effects when a hazard event strike a urban centre. The urban seismic risk evaluation is proposed from a holistic point of view; that is an integrated and comprehensive approach to guide decision-making. Evaluation of the potential physical damage is the first step of this method. 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. According to this procedure, a physical risk index is obtained, for each unit of analysis, from existing loss scenarios, whereas the total risk index is obtained by factoring the former index by an impact factor, based on variables associated with the socio-economic conditions of each unit of analysis. Finally, examples of the model application are given for two urban centers: Bogotá and Barcelona.