Social vulnerability assessment to seismic risk using multicriteria analysis: the case study of Vila Franca do Campo (São Miguel Island, Azores, Portugal)

The increase in the frequency and magnitude of disasters triggered by earthquakes in different regions of the Earth is a major challenge to contemporary societies. The awareness that disasters and risk are processes structured on spatial–temporal interactions maintained at the social-ecological system between the natural hazards and the vulnerabilities of socioeconomic, political and physical nature becomes utterly important in the increase of social systems’ resilience. Thus, the assessment of social vulnerability plays a decisive role in understanding the factors that distinguishes individuals, households and communities, in terms of their ability to anticipate, cope with, resist to and recover from the impact of disasters triggered by natural hazards. This article presents a geographic information system (GIS)-based approach model to assess the social vulnerability to seismic risk using multicriteria analysis (MCA) techniques, in a group decision-making process. The methodology applied to the municipality of Vila Franca do Campo (Sao Miguel Island, Azores, Portugal) identified moderate social vulnerability values at the neighbourhood level and higher social vulnerability values for the built environment and demographic characteristics of the social groups. The social vulnerability patterns make a clear distinction between the older/historical urban cores and the new urban areas. In the first case, the presence of ancient buildings constructed with materials of low resistance to earthquakes coupled with a higher population density and the traits of demographic and socioeconomic frailties of the social groups, results in higher vulnerability values. This pattern is common in the historic centre of S. Miguel district, Ribeira das Tainhas, northern areas of Agua de Alto and western and eastern neighbourhoods of Ponta Garca. The new urban areas, mainly found in S. Pedro, central areas of Agua de Alto, S. Miguel and Ponta Garca districts, have lower values of social vulnerability due to changes in the built, demographic and socioeconomic environments. Results recommend the integration of social vulnerability indexes into seismic risk mitigation policies and emergency management planning.