GNGTS 2013 - Atti del 32° Convegno Nazionale

grounds”. Finally, Margiotta et al. (2012) claim the occurrence of collapse sinkholes inside the marsh deposits and suffosion sinkholes moving down sandy beach deposits. Such last Authors emphasize how their “data” with “particular regard to the stratigraphical succession, are in strong disagreement” with the model of Delle Rose and Leucci (2010) whereas in the same time they are suitable to “mapping the susceptibility to sinkhole” at Casalabate. So, apparently these three models are incompatible each with an other one. Really the divergence are mainly due to the different methods to achieve the scientific knowledge or, in other words, they concern epistemological aspects of the research. Both the models proposed by Delle Rose and Leucci (2010) and Calò et al. (2012) used a stratigraphy reconstruction based the boreholes drilled in the aforementioned project “actions to protect the soil in the hydrogeological risk areas”. However, “outcrops available to geological observations are scarce in the Casalabate area, so a borehole survey and sampling had been the key tools to reconstruct the main features of the local geological substratum” (Delle Rose and Leucci, 2010). The subsoil detection performed let us to recognize in the first ten meters of the bedrock two overlap units, the lower of which is a moderately cemented massive calcarenite and the upper unit is formed by sets of variably cemented thinly laminated and cross-stratified calcarenite. As regard the differences between the model proposed by Delle Rose and Leucci (2010) and Calò et al. (2012), these last Authors stressed how “the integrated analysis of information obtained from logs and georadar investigation evidences that […] no cavities and/or channels referable to parakarstic dissolution phenomena have been detected”. We point out that only 2 out of 23 boreholes performed on 2008 were performed within the area really affected by sinkholes (the “collapsed area” evidenced in Fig. 3a). Moreover, one of the such two boreholes crossed red residual soils that are a typical filling of dolines. So, in our opinion, the conclusion of Calò et al. (2011) can be relevant at the entire urban scale but is inconsistent with the scale of the dangerous area. As before said, such an area where sinkholes occurred is narrow (about 250 m long and 100 m wide) and close to the coast. However we have to observe that Calò et al. (2011) Fig. 2 – Geological 3D model (a) and cross sections of Casalabate urban area (b). Fig. 3 – ERT survey: location (a) and 2D resistivity model (b). 110 GNGTS 2013 S essione 3.2