Common‐ and multi‐offset ground‐penetrating radar study of a Roman villa, Tourega, Portugal

Abstract

A ground-penetrating radar (GPR) survey was conducted at the site of the first to fourth century AD Roman villa of Tourega, near E ¤ vora, Alentejo region, Portugal.This site has been partially excavated, revealing a bathhouse complex consisting ofa tank reservoir, multiple bathingrooms and a major corridor.The excavated portion of Tourega provides direct archaeological feedback as to the size, shape, depth and orientation of structures revealed by GPR surveys. A 4500 m 2 area surrounding the known site was surveyed using common-offset 500 MHz and 200 MHz pseudo-three-dimensional acquisition. Amplitude time-slice analysis reveals a large numberof well-defined additional structures confirming a much broader extension of the site. For shallow buried rectilinear structural targets, the high frequency 500 MHz common-offset data provide excellent imaging. However, limited depth penetration at 500 MHz necessitated a lower frequencyofinvestigation; therefore 200 MHz commonoffset and multi-offset data were also acquired.Two 200 MHz multi-offset GPR profiles were obtained over the large double-walled structure identified on the time-slices, acquired using a newly proposed multi-offset acquisition technique^rapid multi-offset acquisition. This acquisition technique uses the existing single-channel GPR system, is extremely cost-effective, and easily acquires a high fold. Rapid multi-offset acquisition provides an average time saving up to five times that of stationary multioffset profiling. The 200 MHz multi-offset profiles provide a greater depth penetration and enhanced structural detail (i.e. improved imaging of dipping structures) than comparable 200 MHz common-offset profiles. Post-stack, inverse-Q filtering increases vertical resolution and interpretability of the multi-offset sectionsvia removalof wavelet dispersion.Althoughmulti-offset data arelessfeasible for characterizing this site in three dimensions because of the large time commitment in data collection, two multi-offset profiles over key structures of interest improved the final site interpretation, with enhanced image quality and higher resolution than comparable common-offset profiles. The combined results of the multi-offset survey with a common-offset grid should encourage a more frequent use of multi-offset data at archaeological sites when the depth extent of the archaeological site is uncertain.

Large‐area high‐resolution ground‐penetrating radar measurements for archaeological prospection

“…Multi‐offset, as well termed multi‐static GPR surveys have been investigated by Berard and Maillol () and Booth, Linford, Clark, and Murray (). Berard and Maillol () conducted a multi‐offset survey with a 200 MHz antenna system along two profiles using a rapid multi‐offset acquisition technique, with 0.5 m minimum and 5.0 m maximum offsets at 0.15 m source spacing and a 16‐fold trace stacking. The resulting data displays greater depth penetration and considerably enhanced imaging resolution and structural detail when compared to common‐offset data.…”

Integrated Geophysical and Archaeological Investigations of Aquinum in Frosinone, Italy

“…Magnetometry datasets can be complimented by the collection of GPR data, which has a successful history in discovering Roman villas and towns, usually in isolated wide-open areas (Neubauer et al, 2002;Leckebusch, 2003;Piro et al, 2003;Goodman et al, 2004;Linford, 2004;Seren et al, 2004;Berard and Maillol, 2008).…”

From pseudo‐3D to full‐resolution GPR imaging of a complex Roman site

“…GPR has already a successful history in discovering Roman villas and towns, usually located in isolated wide‐open areas (Utsi and Alani 2002; Leckebusch 2003; Piro et al 2003; Linford 2004; Urbini et al 2007; Berard and Maillol 2008). However, the survey area of the presented work is situated on the outskirts of the city of Lugo.…”