A Simplified Geometric Index for Territorial-Scale Seismic Risk Ranking of Masonry Churches

Aiming to contribute to the preservation of ancient masonry churches, this paper introduces a new simplified geometric-based seismic risk index to be employed for massive applications at territorial scale. A database of 46 masonry churches located in Southern Italy (Calabria) was considered. First, a screening of their seismic risk was performed using five simplified geometric-based indexes already proposed in the scientific literature. Given the high seismic hazard of the Calabrian territory, the indexes indicate that many of the churches composing the sample (about 75%) require additional investigation and allowed the definition of a list of priority for the subsequent analyses. The results were then used to calibrate a new index, here referred to as the “Volumetric Risk Index” (VRI). The VRI was designed to reproduce the same risk classification provided by the five indexes, while requiring significantly less effort. In addition, the VRI was validated through comparison with the results obtained from the first level of analysis introduced by the Italian code. The findings indicate that the new index can provide reliable information to carry out a preliminary screening of the seismic risk of a cluster of masonry churches, supporting the prioritization of subsequent in-depth investigations and, where necessary, interventions.