GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Fig. 1 – The 1467 Siena seismic sequence according to CPTI15 v. 4.0 (Rovida et al., 2022). What led to the choice of this comparatvely “minor” earthquake (Mw 4.8 according to Rovida et al., 2022) was dictated by the awareness that the Archivio di Stato of Siena preserved a a so far unexploited source of exceptonal documentary value, the “Lira” of the year 1468. This is a huge collecton of tax statements compiled less than a year afer the earthquake, by all Sienese citzens and including details on the state of repair of their property. A careful sifing of this “Lira” allows to extract a “snapshot” of the state of conservaton of Sienese buildings in 1468. The thematc cartography derived from the collected data was transferred into a GIS environment and the data obtained from this analysis have been used as the basis for undertaking some specifc archaeological expeditous analyses of architectural complexes in the historic centre of Siena in order to verify whether the historical source data were legible in the stratgraphy of the buildings. This paper presents the preliminary results of the analysis carried out within the PROTECT project on the 1467 Siena earthquake. The picture of the seismic sequence – as handed down by the Italian “seismological traditon” and reconstructed by two separate teams of historical seismologists (Castelli et al., 1996; Guidoboni et al., 2007) on the basis of a set of mainly narratve, contemporary or nearly contemporary sources - is challenged by the output of the consultaton of the “Lira” of 1468. Was the 1467 earthquake a stronger and more damaging event than contemporary witnesses made it out to have been? Or, perhaps, did its moderate shaking interact with buildings whose vulnerability was already enhanced by some other factor? As it ofen happens in historical investgaton, looking at a “well-known” situaton from an unusual point of view makes way for new interpretatve perspectves.