The Terza Torre Seismic Array in Bologna, Italy: A Monitoring Infrastructure for Soil-Structure Systems Analysis

Abstract Hybrid seismic arrays composed of collocated building-borehole sensors are essential for gaining better insight into the behavior of soil-structure systems using real data; however, they remain infrequent and are rarely supported by open, long-duration datasets. To help address this gap, we present a new long-term seismic monitoring installation and the associated seismic dataset. The network is installed on and around Terza Torre, a 20-story reinforced concrete building located in Bologna, Northern Italy. It comprises eight three-component stations deployed along the building’s height, including a basement reference station, and a nearby borehole station equipped with a surface and a downhole sensor at 50 m depth. The array was deployed in 2023 as part of a collaborative effort between the Emilia-Romagna Regional Government and the National Institute of Oceanography and Applied Geophysics to investigate the seismic response of a strategic building and possible soil-structure interaction (SSI) effects in urban environments typical of the Po Plain. The dataset includes recordings of 30 local and regional earthquakes (ML 3.0–4.8) and continuous ambient vibration. The quality of the dataset is analyzed in terms of signal-to-noise ratio, including possible applications and limitations. Three applications are exemplified, demonstrating its potential to estimate the building’s fundamental frequencies and the corresponding modes, and to assess the local site response. Should stronger seismic events be recorded in the future, SSI effects may be studied using earthquake recordings from the infrastructure. The dataset provides a rare opportunity to investigate the dynamic response of a tall building founded on soft soil and serves as a reference for validating numerical models and studying nonstationary structural behavior. Data and metadata of the first two years of the network operability are made publicly available under findable, accessible, interoperable, reusable principles within two years from publication.