Application of Social Vulnerability Index (SoVI) and delineation of natural risk zones in Greater Lisbon,Portugal

Social Vulnerability Index (SoVI) was applied to Greater Lisbon (Portugal). Based on the concepts used for the SoVI assessments in the US, 46 variables representing social vulnerability of the 149 civil parishes of Greater Lisbon were chosen. Thirty-eight variables were selected after application of correlation tests. They were standardized, and a Principal Component Analysis and a Varimax rotation were applied to them. Seven factors were extracted using the Kaiser criterion, which explain 79.5% of the variance, and the SoVI scores were then mapped using a standard deviation classification. Twelve of the 149 civil parishes of Greater Lisbon have a very high social vulnerability and 24 of them have a high social vulnerability. The map of SoVI was then integrated with susceptibility maps of earthquakes, floods, flash floods, landslides, tsunami, and coastal erosion, thus delineating risk zones. Twenty-two civil parishes of Greater Lisbon have a very high risk; among them, 17 belong to Lisbon Municipality, four belong to Loures Municipality, and one belongs to Vila Franca de Xira Municipality. Finally, exposed population was considered and combined with risk zones map in order to assess the number of people being potentially exposed to risk and their location.