In this paper a previously proposed damage localization algorithm, namely the Interpolation Damage Detection Method, is reviewed and its feasibility to estimate the magnitude of damage in a structure permanently monitored by a network of accelerometers is investigated. The investigation is carried out based on the numerically simulated responses obtained from the finite element model of a suspension bridge subjected to environmental excitation. The structure response both in the undamaged and in damaged configurations is computed. Damage is simulated through a reduction of the elastic modulus of the material in selected structural elements. Several damage severities are modeled and the correlation between the damage feature and the severity...