3D inversion of ERT data on an archaeological site using GPR reflection and 3D inverted magnetic data as a priori information

Abstract

Non-destructive geophysical prospecting methods are increasingly used for the investigation of archaeological sites, where a detailed physical and geometrical reconstruction of structures is required prior to any excavation work. small area had been selected to test the integration of magnetic, ground-penetrating radar, and electrical resistivity tomography techniques.The magnetic data were acquired as the vertical gradient of the total magnetic field and were inverted by minimizing an L-2 norm. The ground-penetrating radar data were acquired as singleoffset measurements on a regular grid and processed to obtain time slices of reflection amplitude. The electrical resistivity tomography data were acquired with dipole-dipole array along parallel profiles in both east-west and north-south directions.In this work, we reprocessed the data collected in 1996 performing a three-dimensional inversion of electrical resistivity tomography data using ground-penetrating radar data and three-dimensional inversion results of the magnetic data. We inverted electrical resistivity tomography data according to L2 and L1 norm minimization. Both the mean apparent resistivity and different resistivity distributions derived from processed ground-penetrating radar and three-dimensional inversion of the vertical gradient of the total magnetic field data were used as a starting model.The results were then compared in the volume under the surveyed area: merits and shortcomings of the different techniques are pointed out and analyzed.From the results of the different applied techniques, it comes that both electrical resistivity tomography and vertical gradient of the total magnetic field locate the searched tomb as a volume, whereas ground-penetrating radar mainly identified the ceiling of the tomb. Vertical gradient of the total magnetic field data inversion obtained from minimization of the L2 norm properly locates both the chamber and the corridor but produces smeared overestimated volumes. Three-dimensional inversions of electrical resistivity tomography data with a priori information give an accurate picture of the chamber and delineates the corridor, even if the resistivity values are underestimated if compared with the expected resistivity of void. Results are compared with the archaeological findings as the area was unearthed and verified in 2001.tures built with the same material of the surrounding ground, as well as soil inhomogeneity and other environmental disturbances, can sometimes yield low signal-to-noise (S/N) ratios on geophysical data. This hinders the definition of the spatial position and extent of the buried structures.During the last decades, many approaches (Brizzolari et al.

Analysis of the Influence of the GPS Errors Occurred While Collecting Electrode Coordinates on the Electrical Resistivity of Tumuli

“…2D and 3D geophysical investigation of tumuli is a very challenging field of application, as a consequence of the prevailing rough topography conditions and complex subsoil resistivity distribution. Ancient buried anthropogenic structures are usually resistive, have dimensions of a few meters, and are generally located at low depths from the ground surface [18][19][20][21][22]. Since its first development, despite the successes of the ERT method, quality data (noise contamination/high signal to noise ratio) has affected the technique results resolution and reliability [14,[23][24][25].…”

Geophysical anomalies detected by electrical resistivity tomography in the area surrounding Tutankhamun's tomb

“…Geo-electrical methods have been widely used in archaeological prospection in different environments; in particular 2D and 3D ERT has been adopted since the end of the last century also in combination with other geophysical techniques (e.g. Loke and Barker, 1996;Yi at al., 2001;Papadopoulos et al, 2006;Cardarelli et al, 2008;Arato et a., 2015). As for any other geophysical method, the quality of the results depends on the contrast between the physical property of the target searched for and its hosting environment.…”

Vector analysis of pole–pole array for determining the 3D boundary of object

“…utilizes an inversion technique (Loke and Barker ; Dahlin and Loke ; Olayinka and Yaramanci ; Candansayar and Basokur ; Jackson, Earl and Reece ; Loke ). However, to properly utilize the complete 3D inversion software, the user must be familiar with the inverse theory (Arato, Piro and Sambuelli ). The result of an inversion is a model resistivity section, which displays areas of equal resistivity; some of these areas characterize the anomalous object, while others characterize the background environment.…”