Estimación holística del riesgo sísmico utilizando sistemas dinámicos complejos

Abstract

The present research commences with a revision of the concepts of hazard, vulnerability, and risk. This is a basic requirement for the construction of the theoretical framework herein developed. A revision of commonly used concepts is offered in order to identify gaps and fine-tune definitions that will help in the search to offer a coherent and integrated theoretical framework. Approaches developed in the natural, applied, and social sciences are discussed and a criticism of these is offered. It is argued that conceptual fragmentation and inconsistency have been two of the reasons why risk reduction has been in good part unsuccessful in a large number of countries. The lack of an adequate conceptual basis has impeded adequate interventions.<br/>Risk is understood in terms of potentially dangerous events and the vulnerability of exposed social elements. This type of analysis is linked into decision-making processes, and the difficulties associated with the implementation of risk reduction public policies are made explicit. Inherent uncertainty and reductionist approaches help explain this problem. Moreover, factors such as risk perception of decision-makers; legal contexts that impede preventive actions, and the general problem of levels of risk tolerance and acceptability also come into play.<br/>The traditional approach to evaluating urban seismic risk is revised. This involves a consideration of the physical effects and damage to be expected in exposed elements under determined seismic conditions. Modern techniques for seismic vulnerability estimates and knowledge in the area of loss and damage are summarized. And, the better approach to physical urban seismic risk evaluation from the perspective of the author is provided.<br/>A coherent and consistent conceptual risk model is provided based on complex non-lineal dynamic systems theory. This allows an explanation of the concept of crisis, instability and adaptability relating this to the concepts of disaster, vulnerability, risk and prevention. Urban centres are seen as complex dynamic systems. Two holistic urban seismic risk-modeling techniques are then proposed. The first methodology is based on relative indicators using hierarchical and pairwise analytical processes. The second methodology employs neural networks and fuzzy sets approaches. The two methodologies take into account the physical, economic, social and institutional variables, which allow a multidisciplinary approach to seismic risk assessment. The methods are subsequently employed in the estimation of seismic risk in the city of Bogotá, Colombia.<br/>Finally, a risk management strategy is proposed as a planning tool, and a global proposal is made for facing collective risk, which is a clearly significant contemporary technical and social problem. Recommendations are made, as regards needed future studies and research.