Spectroscopy of Urban Vulnerability

Despite the considerable work carried out in risk management, vulnerability indexes and aggregative assessments remain a serious issue. The main challenges facing vulnerability assessment are the collection, integration, and synthesis of large quantities of heterogeneous data to provide reliable estimations. This situation has led to the neglect of all significant interactions between the considered indicators, despite their being essential to vulnerability analysis. The scope of the article is to show that most obstacles to vulnerability assessment can be overcome by shifting the focus from absolute vulnerability assessment (i.e., the attempt to quantify an absolute level of weakness or resilience) to relative vulnerability assessment (i.e., the attempt to find out which populations and places are vulnerable and why). We propose a first attempt to assess relative vulnerability. The spectroscopy of urban vulnerability reveals the heterogeneity of vulnerability by focusing on the locally convergent specific characteristics and processes reinforcing (or reducing) vulnerability to inform the implementation of more targeted mitigation policies. This is a two-step approach, first focusing on the vulnerability underlying factors and establishing vulnerability profiles; the second step is to focus on their spatial distribution to confront each vulnerability profile to its multithreat exposure. The Lyon, France, and Bucharest, Romania, case studies reveal the risk transfers induced by some risk management policies and they highlight that vulnerability is a multidimensional phenomenon almost impossible to assess by using a single index. The two case studies also permit local multithreat comparisons as well as international comparisons.