Deformation and geometric change of GarisendaTower (2010‑2023): temporal variations and possible driving factors

The Garisenda Tower in Bologna, standing 48 meters high with a significant inclination (~4°), is under continuous observation due to alerts from its monitoring system. The tower’s structural health has been the focus of numerous studies aimed at its conservation. This article enhances the understanding of the tower’s deformation state through laser scanning measurements, employing a novel approach. Unlike previous analyses that focused on individual façades, this study evaluates deformation patterns and their evolution from 2010 to 2023, considering the entire structure. The proposed method selects the statistically most reliable height bands for point cloud alignment, ensuring optimal co‑registration into a common reference frame. Difference maps between multitemporal point clouds reveal overall displacements and deformations, suggesting torsion and bending effects along the entire structure. The south side of the tower appears to be the most affected, and the overall condition in 2023 seems worse than in 2012, possibly due to the Emilia‑Romagna earthquake. This new information could be valuable for planning and designing restoration interventions.