Using GPR to Evaluate the Stratigraphic Condition of the Mosaic of the Dolphins in Delos Island, Greece, in order to Adopt the necessary Conservation measures

Summary The mosaics of Delos island are a significant body of the ancient Greek art of the Hellenistic period that are inscribed to UNESCO’s World Heritage List. In this study, GPR systems with frequencies of 1600MHz, 500MHz and 250MHz are used to evaluate the stratigraphic condition of the mosaic at house of the Dolphins that decorates the peristyle impluvium. All the obtained data were processed in MATLAB and both Bscans and depth slices were used for the interpretation. The 1600MHz system performed the best and it was possible to identify the boundaries of the mosaic layers as well as problematic areas, such as bulges and high levels of moisture that may cause deterioration. The results obtained from the 500MHz and 250MHz are complimentary to the ones obtained from the high frequency system as the emitted signals can reach deeper levels. Structural characteristics of the cistern below the main mosaic floor were mapped in some detail including five stone arches. The overall performance of the GPR was satisfactory and the resulted information will be taken into account for the upcoming conservation plans.