3D GPR MODEL OF A FLOOR MOSAIC OF THE LATOMIA DEI NICCOLINI (MARSALA, SICILY)

Abstract

The Latomie dei Niccolini archaeological complex is situated on the side of the Punic and Roman necropolis of Lilibeo (Marsala, Sicily). As a result of quarrying activities in the area, the construction of the modern cemetery along the eastern side of the Latomia and a long period of neglect, the state of conservation of the tombs was seriously compromised and precious frescoes were destroyed. An essential element of this funerary system is the floor that gives access to three arcosoli, consisting of precious polychrome mosaics. At the time of the discovery, this mosaic had a large lesion that extended diagonally to the length of the mosaic. Highfrequency Ground Penetrating Radar (GPR) was used to improve understanding of the causes of the fracture and differential subsidence found throughout the floor mosaic structure. The georadar uses the physical phenomena that an electromagnetic wave can undergo when it encounters discontinuities within an investigated medium (such as reflection, diffraction, and refraction). These physical phenomena are determined by variations in the magnetic and electrical properties of the materials passed (such as cavities, lithological variations, and buried bodies) and, in particular, the variation in the permittivity. A three-dimensional GPR model of the variation of the subsurface's electromagnetic reflectivity was constructed to define the primary fracture's geometric effect and map the geometry of the void area below the mosaic floor.