A project addressed toward mitigation of the sinkhole risk

Natural or anthropogenic sinkholes have become a serious hazard in Italy (Parise & Vennari, 2013), often causing damage to society. With the goal to provide a contribution toward mitigation of the related risk, we present the outcomes of a dedicated Project. It consisted in developing a variety of activities to identify and model failure mechanisms, to implement stability analysis and to define possible mitigation interventions. Articulated in two levels (from urban area to single cavity), the approach first aimed at defining the different aspects of the problem and selecting the case studies. Then, innovative survey technologies were applied, integrated by geomechanical studies and geotechnical modeling; further, a detailed economical analysis was performed, taking into account the historical-cultural values, as a necessary step before choosing appropriate stabilization works. The selected case studies are Canosa di Puglia and Massafra (Apulia), and the San Lazzaro di Savena area (Emilia Romagna). Canosa di Puglia is characterized by many underground calcarenite quarries (type E1 in the Artificial Cavities Classification; Parise et al., 2013), excavated to extract building materials. With expansion of the urban area, a number of sinkholes occurred, also causing casualties. Massafra is characterized by deep valleys incised in the carbonate rocks. In this territory, due to spreading of the rupestrian civilization (Fonseca, 1980), many cavities were dug, especially as worship sites. Eventually, the San Lazzaro di Savena area (Gessi Bolognesi e Calanchi dell’Abbadessa Park) was studied due to co-existence of natural and artificial caves, these latter being extensive gypsum mines, nowadays abandoned. The proposed multi-disciplinary approach can be applied from metropolitan areas to small cities, and is strongly based upon the main characters of the cave and its interaction with the built-up environment. The final goal is to identify the critical situations, to define the most proper analysis for stability evaluation, and to choose the actions aimed at mantaining the cavity in safety conditions, eventually allowing its public fruition, at least for those of historical and cultural value.