Marcello Bianca

Methods and Technologies for the Cultural Heritages in Basilicata region: a case-study from the coastal belt of Metapontum

The protection and promotion of Cultural Heritage require the application of innovative and non-invasive monitoring techniques for developing complete and detailed projects. The demand of cost-effective and rapid tools promoting long-term strategies for cultural heritage promotion and risk assessment is, therefore, urgent. These issues become indeed of paramount importance in the case of very large areas, such as the coastal ones, where the landscape morphoevolution - driven by climate changes - and the landscape modification - due to agricultural and industrial activities - have dramatically increased the exposure risk of Cultural Heritage. In such a framework, traditional monitoring methodologies appear impracticable. This is the reason why the MeTIBas (Italian acronym for Innovative Methods and Technologies for the Cultural Heritage in the Basilicata region) project has been developed. MeTIBas aims to develop an innovative geoarchaeological investigation approach for large areas (implementation of a Territorial Information System, drawing-up of an experimental digital geoarchaeological map, and creation of an open geoarchaeological database). MeTIBas has been developed in the coastal area of Metaponto, which roughly coincides with the ancient territory of the Greek settlement of Metapontum and its chora and includes a region of about 400 km2 in the Ionian sector of the Basilicata region (southern Italy). The data integration and joint analysis of the huge amount of MeTIBas heterogeneous data have been conveniently carried out in a GIS environment, thus allowing an effective combination of the information from different cognitive levels. Besides, the adoption of a Web GIS environment (a Geoplatform operating in Open Source Framework for Rich Web GIS Applications performed by geoSDI; www.geosdi.org) allows a wide dissemination of the information structured in the MeTIBas project.

Stratigraphy of the subsurface of the Metaponto Plain vs a geophysical 3D view of the late Pleistocene incised-valleys (Basilicata, Southern Italy)

The stratigraphical analysis of several boreholes drilled in the Metaponto coastal plain (Basilicata region, southern Italy) highlighted the occurrence of two irregular erosional surfaces bounding three main overlapping sedimentary units. The upper unit, which base has been detected by using a geophysical method for the H/V spectral ratio (HVSR) of microtremors, fills and covers some paleovalleys that were incised during the Last Glacial Maximum (LGM). A 3D view of a main geophysical unconformity shows a surface with the occurrence of some deeper, narrow, and sinuous zones running roughly perpendicular to the present-day coastline and at depths of up to 90 m below the present-day sea level. These narrows likely correspond to the paleovalleys that developed in the region during the LGM and are buried below the Metaponto coastal plain. Some discrepancies between the geophysical and the geological data may be explained either as induced by a not well constrained projections of boreholes (from which derive the lithostratigraphic interpretations) or considering that the sedimentary models of incised-valley fills suggest the presence of different coeval deposits along dip through paleovalleys, inducing a contrast of seismic impedance readable as paleotopography rises.

Using the limit equilibrium method for assessing slope failure conditions in an archaeological site of the 4th century B.C.

The impact on the territory of important archaeological sites and related human activities has induced, as a rule, modifications in the local environmental system. An example is represented by the sanctuary of the goddess Mefitis in Macchia Rossano, in the territory of Vaglio Basilicata, close to the town of Potenza (southern Italy). This archaeological site has been affected by swelling in historical times that occurred in the allochthonous, chaotic, heterogeneous, and anisotropic polychrome scaly clays of the geological formation called Argille Varicolori. In such structural conditions, the collapse mechanisms of the Argille Varicolori seem to be strongly influenced by pre-failure phenomena and, therefore, the application of the limit equilibrium method does not always seem to be suitable. Nonetheless, the analysis in terms of total stress and the in situ assessment of the relationship between rainfall and fluctuations of the groundwater level by long-term monitoring have allowed to determine the amount of rainfall related to the piezometric level of collapse and, consequently, to assess the conditions of the sanctuary in the historical times when the landslides occurred.