Joint Use of GPR Surveys, Terrestrial and Aerial Photogrammetry for the Study of the Portico of the Cathedral of S. Pietro (Isernia, Italy)

In the field of built heritage preservation, the contribution of non-destructive testing and 3D documentation represents a fundamental requirement for any project of maintenance and restoration, recording the state of conservation and enhancing irregular features. This paper presents the combined use of Ground Penetrating Radar (GPR) technique, terrestrial and unnamed aerial photogrammetry for the study of the portico of the Cathedral of S. Pietro (Isernia, Italy). It is an articulated construction, rebuilt several times over the centuries. The intent of the investigations was to offer a complete reconstruction of the architectural artefact and the morphology of the surfaces in order to guide and support strategic choices for the restoration and improvement of the building’s seismic vulnerability, stopping the ongoing degradation phenomena. The results highlighted a series of critical issues such as the tilting of columns, the deformation of the morphology of the floor and the heterogeneous stratigraphy in some areas of the portico, which could affect the tolerance of the building to naturally induced flexural stresses.