Assessment of physical vulnerability of buildings and analysis of landslide risk at the municipal scale: application to the Loures municipality, Portugal

摘要

This study offers a semi-quantitative assessmentof the physical vulnerability of buildings to landslides in aPortuguese municipality (Loures), as well as the quantitativelandslide risk analysis computed as the product of thelandslide hazard by the vulnerability and the economic valueof the buildings. The hazard was assessed by combining thespatiotemporal probability and the frequency–magnitude relationshipof the landslides. The physical vulnerability assessmentwas based on an inquiry of a pool of European landslideexperts and a sub-pool of landslide experts who knowthe study area, and the answers’ variability was assessed withstandard deviation. The average vulnerability of the basic geographicentities was compared by changing the map unitand applying the vulnerability to all the buildings of a testsite, the inventory of which was listed on the field. The economicvalue was calculated using an adaptation of the PortugueseTax Services approach, and the risk was computedfor different landslide magnitudes and different spatiotemporalprobabilities. As a rule, the vulnerability values given bythe sub-pool of experts who know the study area are higherthan those given by the European experts, namely for thehigh-magnitude landslides. The obtained vulnerabilities varyfrom 0.2 to 1 as a function of the structural building types andthe landslide magnitude, and are maximal for 10 and 20mlandslide depths. However, the highest risk was found for thelandslides that are 3m deep, because these landslides combinea relatively high frequency in the Loures municipalitywith a substantial potential damage.