Vernacular architecture and seismic cultures in small towns: knowledge analysis and strategies for conservation. The case of Ugliancaldo in Tuscany

Since the 1960s and 1970s, the so-called ‘inland areas’ in Italy have been subjected to progressive depopulation caused by the shift from rural life models towards urban life models. In such areas, the small towns, particularly those located in inaccessible mountainous contexts, have undergone exponential abandonment. Here we focus on the small towns of Lunigiana, a land of transit located in the inland areas of northern Tuscany, crossed by important roadways that exploit the natural valleys and passes of the Apennines and the Apuan Alps. This area is historically characterized by high seismicity so that the local vernacular architecture was built according to specific anti-seismic techniques, tested, and replicated by the local communities, and expression of their own “seismic culture” (Pierotti and Ulivieri, 2001). To give some examples: the use of discharging counter arches, cantonments, buttresses, scarp walls, masonry vaults, and external staircases adjacent to the building, all of which play an important role in reinforcement (Ulivieri, 2016). In this area, building regulations have often drawn on the experience of local seismic cultures, and Ugliancaldo – a small town situated at 750 m above sea level, in the municipality of Casola in Lunigiana (Ms) – is a paradigmatic example in this sense (Pierotti and Ulivieri, 2001). Here, the engineer Francesco Guasti was sent by the Grand Duke to draw up a report of the damages caused by the earthquake of 1837. After understanding the effectiveness of local building techniques, he engaged local workers to build a new complex of terraced houses, which survived all the following seismic events, including the most ruinous in 1920 and 2013. Here, the local community – the few remaining inhabitants and the second-homes owners – has repaired the damages caused by the 2013 earthquake after the village was declared uninhabitable. In the current technical standards for construction (MIT, 2018; MIT, 2019) and the guidelines for the assessment and reduction of seismic risk in cultural heritage (MiBACT, 2010), no specific criteria are given for vernacular architecture and its irregular structural schemes (Coisson, 2019). For this reason, here we aim to understand the role and significance associated with small towns in Lunigiana by the regional and urban planning tools (Ulivieri and Landi, 2019) and to analyze some buildings and aggregates of Ugliancaldo, which are characterized by various local earthquake-resistant techniques. The methodology will be based on direct observation, analysis of archival data, architectural and structural survey, inventory of construction systems, and techniques, conceived as a base for the structural modelling. The expected outcome is to propose flexible conservation and seismic retrofit strategies based on vernacular earthquake -resistant techniques, that should be customized on a case-by-case basis.