A large-scale seismic risk approach accounting for local site effects and modelling of building exposure based on open-access datasets

This study proposes an enhanced macroseismic framework for regional seismic risk assessment that accounts for litho-stratigraphic site effects and refines building exposure modelling using open-access spatial datasets. The methodology is applied to the Campania region in southern Italy, combining official census data with high-resolution building height estimates to disaggregate structural typologies into three classes: low-rise (1-3 storeys), mid-rise (4-7 storeys), and high-rise (≥ 8 storeys), associated with distinct vibration period ranges. In addition, the year of construction and the conservation status of the buildings are considered to refine the vulnerability assessment. Seismic hazard is quantified through period-dependent spectral acceleration, which is then converted to macroseismic intensity. The results reveal significant spatial variability in damage scenarios and repair costs, driven by both structural typology and site conditions. Metropolitan areas exhibit the highest vulnerability and economic impact, with site amplification increasing estimated regional repair costs by over 60 %. The proposed GIS-compatible methodology offers a replicable and policy-relevant tool for supporting seismic risk mitigation, urban resilience planning, and targeted retrofitting strategies.