Seismic safety of places of worship in Italy's Gran Sasso and Monti della Laga National Park

The abundance of historic architectural heritage within Italy and its vulnerability to earthquake heighten the need for a risk analysis aimed at preserving buildings and their contents. In particular, churches are often more vulnerable than other buildings, even in the case of brief tremors. The reasons for this increased vulnerability are due to structure and peculiar geometrical proportions: presence of large open areas without internal walls to provide bracing, absence of intermediate ceilings, thinness of walls and certain vaulted structures, presence of thrust-exerting elements (arches, vaults). These features of churches, along with the use of architectural and structural criteria that are recognisable and comparable, albeit within the unique nature of each object, has led to a quest for specific procedures to assess seismic vulnerability, these being different to those utilised for ordinary buildings. The method involves dividing the building into macroelements, i.e. architectural sections of recognisable construction technique and showing similar seismic response (facade, apse, bell tower, etc.). The way in which damage can occur and the collapse mechanisms that the earthquake can provoke are therefore identified for each macroelement. A specific risk analysis of places of worship has been carried out as part of the European project RECES modiquss "The network of small old town centres as a model of urban quality and sustainable development" - INTERREG IIIA Adriatic cross-border programme. Research has been concentrated on places of worship located in an area comprising six communes of the L'Aquila province in central Italy. Many of the churches involved underwent a vulnerability analysis. The earthquake that struck central Italy on 6th April 2009 seriously damaged many of the churches surveyed prior to this event. It is now possible to compare the damage suffered and the mechanisms unleashed with the mechanisms predicted during survey and analysis. Keywords: seismic vulnerability, churches, collapse mechanisms, damage, macroelements.