Evaluating seismic risk in small and medium-sized cities with the modified vulnerability index method, a case study in Jiangyou City, China

The rapid urbanization of China generated not only dozens of megacities but also a great number of surrounding small and medium-sized cities. The utter lack of seismic risk assessments for small and medium-sized cities is emerging as a potential threat. A seismic risk evaluation of a medium-sized city, Jiangyou, is presented with the modified vulnerability index method (VIM), based on the investigation of 6369 buildings for a scenario corresponding to the destructive historical earthquake of May 12, 2008 (MW 7.9). The population-time-land (PTL) model is used to estimate the human deaths (MD) and resettlement population (MR). The direct economic loss from physical damage to buildings is calculated. The results show that the modified VIM not only can indicate that the distributions of building seismic vulnerability and direct economic loss are closely related with city plans, but reflect the seismic performance characteristics of buildings and the huge differences in seismic consequences under different time scenarios. Evaluating seismic risk in small and medium-sized cities will support accurate and comprehensive seismic risk mitigation strategies setting in similar rapid urbanization areas under earthquake threats.