GPR microwave tomography for diagnostic analysis of archaeological sites: the case of a highway construction in Pontecagnano (Southern Italy)

Abstract

Interpretation of ground-penetrating radar (GPR) data usually involves data processing similar to that used for seismic data analysis, including also migration techniques. Alternatively, in the past few years, microwave tomographic approaches exploiting more accurate models of the electromagnetic scattering have gained interest, owing to their capability of providing accurate results and stable images. Within this framework, this paper deals with the application of a microwave tomography approach, based on the Born Approximation and working in the frequency domain. The case study is a survey performed during the realization ofthe thirdlane ofthe most important highway in southern Italy (the Salerno-Reggio Calabria, near Pontecagnano, Italy). It is shown that such an inversion approach produces well-focused images, from which buried structures can be more easily identified by comparison to traditional radar images. Moreover, the visualization of the reconstruction results is further enhanced through a three-dimensional volumetric rendering of the surveyed region, simply achieved by staggering the reconstructed GPR two-dimensional profiles. By means of this rendering it is possible to follow the spatial continuity of the buried structures in the subsurface thus obtaining a very effective geometrical characterization. The results are very useful in our case where, due to important civil engineering works, a fast diagnosis of the archaeological situation was needed. The quality of our GPR data modelling was confirmed by a test excavation, where a corner of a building and the eastern part of another house, with its courtyard, were found at the depth and horizontal position suggested by our interpretation.

A new reconfigurable stepped frequency GPR system, possibilities and issues; applications to two different Cultural Heritage Resources

“…At the moment, it is possible to compare the performances of both systems on several areas of interest, at the renaissancebaroque chapel of the ex hospital of the Holy Spirit in Lecce ) and the area of the "cryptoporticus" within the Messapian and Roman archaeological site of Egnazia (Caggiani et al 2012;Persico 2014). Both indoor measurements in historical monuments (Conyers 2004;Piscitelli et al 2007;Castaldo et al 2009;Kadioglu 2010;Persico et al 2010;Piro and Campana 2012;Soldovieri et al 2012;Goodman and Piro 2013) and outdoor campaigns in archaeological sites (Conyers and Goodman 1997;Ranalli et al 2004;Pieraccini et al 2006;Masini et al 2007;Masini et al 2010a,b;Calia et al 2012;Leucci et al 2012;Utsi 2012) are of great interest for GPR prospecting and the number of case histories in both situations is endless. In particular, indoor prospecting in historical monuments offers possibility of taking more precise geometric measurements and is usually less cumbersome in terms of required physical work, because there is no meaningful surface roughness, no grass and no wind.…”

Uncertainty in ground penetrating radar models

“…Or yet another approach with local tomographic imaging and inversion methods is to use regularization. Regularization methods use a mathematical constraint to the objective function [3,29,30,31,32]. This implies that the original field equation is not the only objective to satisfy with respect to the measured data, but another objective is added.…”

“…If the uncertainties of these models are known, ground penetrating radar could be of much more value as a tool in these application domains. Some examples where ground penetrating radar is frequently used are hydrology [1], civil and environmental engineering [2], archaeology [3], forensic studies [4], ecology [5] and agriculture [6].…”

Discovery of the Romanesque church of the Abbey of our lady of Bec (Le Bec‐Hellouin, Normandy, France) by means of geophysical methods

“…The GPR configurations in the field depends on the surface to be prospected. In monostatic (Castaldo et al, ; Yalçiner et al, ) or bistatic mode (Booth, Linford, Clark, & Murray, ), several parallel and transverse profiles defined on a grid at given space allow a 3D prospection and the result strongly depends on the space sampling. For large areas (Trinks et al, ), multistatic configuration is preferred.…”