Preserving tangible heritage. Strategies for the consolidation, the construction site, and the reduction of the seismic risk of the urban aggregates of the Italian Apennines: the village of Castel d'Alfero (FC)

The essay proposes first a reflection on the settlement structure of the urban aggregate of Castel d’Alfero (FC), whose story takes place in the phase of population following the collapse of the Roman Empire and the introduction into the Savio valley of feudal power. The analysis focuses on the environmental and architectural system and on the dynamics that led first to the settlement, whose reasons lie in the structuring of specific production and travel systems, and second the abandonment, induced both by environmental characteristics and socio-cultural conditions, that nevertheless favored a model of urban development. Given these premises, the paper continues with careful considerations of the methods and strategies for securing, consolidating and, most importantly, jobsite activities coordination, which have now, more than ever, decisive role for the success of a proper conservation project in "technically adverse" areas. The fragility of these contexts, not only in relation to the buildings but also to the historical routes that constitute identifying elements of great historical testimonial value, requires great attention to the organization of the site, the mobilization of the means of work, the storage of the components and the building of retention and support systems. Having regard to recent and ongoing seismic events that have affected the Italian territory and, with it, part of its tangible and intangible heritage, reduction of seismic risk strategies requires careful consideration and poses new questions about how to approach the vulnerabilities of these structures, "poor" by their nature. The article also proposes the application possibilities of the so-called meta-barriers with resonant systems, capable of isolating seismically a building aggregate (or an isolated system) deviating surface waves having frequencies that, otherwise, would be particularly harmful. The peculiar dynamic properties of the constituent meta-materials are analyzed of in order to evaluate how the locally resonant structures can manipulate the superficial seismic waves.