Dynamic characterization of the Tower of Palazzo dei Vicari in Scarperia (Italy) during and after the 2019 Mugello seismic sequence

The paper presents the first results of an experimental campaign conducted on the Tower of Palazzo dei Vicari, in Scarperia, Italy. The Tower is a slender medieval structure located at the corner of the main façade of Palazzo dei Vicari. Over the centuries, both Tower and Palace have undergone several severe earthquakes; therefore, they have been reinforced with steel tie rods. In 2019 the structure was hit by the Mugello seismic sequence, which occurred between 9th December 2019 and the first half of January 2020. The mainshock was registered as 4.5 ML, with an epicenter 5 km far from the city of Scarperia. The earthquake was felt in Toscana and Emilia Romagna Regions and caused some damage in the area's cities. During the seismic sequence, two seismometers were installed on the Tower to record earthquakes and natural vibrations and evaluate the behavior of the structure under seismic loads. A second monitoring experiment has been more recently performed, in June 2021. Eight seismic stations were deployed along the height of the Tower, to achieve a complete dynamic identification of the structure. The ambient vibration tests before and after the seismic sequence made it possible to exclude the presence of damage and to calibrate the numerical model of the Tower via model updating techniques.