The Geological Risk in the Historic Centers

Abstract

The objective of the present study concerned the determination of the geological risk of the historical center. Risk assessment is a complex issue that aims to assess different aspects of disaster damage. Traditionally, risk analysis is based on a series of historical and site data to verify the probability that an event occurs in a certain place with a certain intensity at a certain time (Orlando et al. 2005a, b). The main limitation of this method is the complexity of the mathematical models necessary to represent reality and therefore it is not always possible to make realistic assumptions about possible future scenarios. Furthermore, the interest is concentrated only on disaster scenarios deriving from a type of geological risk: either floods, or seismicity, etc. Therefore, a new approach is needed that takes into account all aspects of geological risk as a product of danger and vulnerability, and that will serve to define the response capacity of a territorial disaster system. A weighted combination of vulnerability and danger has finally allowed to determine the geological risk, whose planning applications urban planning and Civil Protection were examined in detail in the concluding chapters. The evaluation phase is carried out through the Analysis Hierarchy Process method. The aim of the research is to test procedures of analysis and techniques of geological risk assessment that take into account the complexity of the geological system and the state of the building heritage. In this work, completely independent of the vulnerability, we proceed to the definition of the danger as the sum of the geomorphological, hydraulic and seismic one. The result is a mapping of the areas studied (information base) elaborated in a GIS environment consisting of “layers of information layers of danger” interpolated with “layers of information layers on the structural history of the building”, descriptive of the state of the building heritage. The approach is tested in a case study estimating all geological risks in the Municipality of Polignano a Mare (Puglia, Italy). This contribution showed that the proposed method would allow the development of a methodology that ensures replicability applicable to the various centers in Puglia.