GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Synthesis of writen, architecture, and geology informaton sources improving the understanding of seismic sequences in the Ferrara area M. Stefani 1 1 Università di Ferrara (Italy) This contributon is aimed at delving deeper into the impact of historic seismic events on the town of Ferrara and surrounding areas. The paper is based on the integraton of the published palaeosismological research with the reconstructon of the architectural history of ancient buildings, and with the results of recent geological and microzonaton investgatons. The short artcle is not intended to provide a comprehensive seismological history, but to the interpretatons of some signifcant seismic sequences, ofen characterized by the migraton of the epicentre areas. Given the nature and size of the contributon, provide an exhaustve list of references and historic sources is impossible. The reader is therefore referred to the important contributons of Guidoboni 1984, Locat et al. 2016, Guidoboni et al. 2018 and 2019; Guidoboni and Valensise 2023, and to further references and quotatons therein. 12 th and 13 th centuries earthquakes and the structural reconfguraton of the Cathedral . The earliest known seismic efects are the local repercussion of the widespread earthquakes of 1117, and an event in 1128. A sequence of shocks occurred during the 1222 Christmas Day, between noon and sunset, within a seismic actvity framework afectng large portons of the Po Plain, known as “the Brescia earthquake”. In Ferrara, the shocks induced at least the collapse of chimneys, while more severe damage cannot be ruled out. Another earthquake hit Ferrara on March the 20 th 1234, associated with damage to buildings, in town and in the surrounding countryside, evaluated to the VII MCS, but the scantness of the available documentaton again prevents a precise estmaton of the damage level. The earthquakes of the frst half to the 13 th century, together with the poor geotechnical propertes of the foundaton soils played a major, but previously undetected, role in the architecture evoluton of the Cathedral. The building of the Romanesque fve-nave church started in 1135 and contnued through much of the century. The building was founded on Holocene, mainly cohesive sediments, deposited into interfuvial plain setngs, the geotechnical propertes of which were investgated through seismic cone penetraton and dilatometer tests. The spatally varying load of the building induced diferental foundaton setlement, which, together with the seismic acceleratons, damaged the thin wall structure of the