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Georadar data collection, anomaly shape and archaeological interpretation – a case study from central Italy
Author(s) -
Orlando Luciana
Publication year - 2007
Publication title -
archaeological prospection
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.785
H-Index - 38
eISSN - 1099-0763
pISSN - 1075-2196
DOI - 10.1002/arp.311
Subject(s) - geology , magnetic anomaly , anomaly (physics) , excavation , interpretation (philosophy) , ground penetrating radar , seismology , geophysics , paleontology , radar , telecommunications , physics , computer science , programming language , condensed matter physics
Georadar data were acquired on an area 50 m long (X direction) by 30 m wide (Y direction), with profiles respectively 0.5 and 1 m apart. The data were processed with the goal of increasing the signal to noise ratio. Stacks of two and four samplings in time were applied in order to enhance the reflectivity of weak anomalies on time slices. The time slices were also used to analyse the effects on image quality of the distance between profiles and the profile direction with respect to anomaly location. The study shows that time slices obtained from profiles acquired 1 m apart detect the same anomalies acquired with profiles 0.5 m apart but with incorrect geometries. The interpretation was performed on both vertical profiles and time slices. The most meaningful anomalies have been mapped and grouped into three types according to archaeological significance: surficial anomalies, which are easily reached in the preliminary excavation trials, and deep, separate single and complex anomalies, the latter being formed by several anomalies. The magnetic gradient was sampled on a 0.5 × 0.5 m grid, and values of more than ±500 nT were detected. The western zone is characterized by several chaotic magnetic anomalies, whereas the rest of the area has a few anomalies of dipole shape. The joint interpretation of the georadar and magnetic data reveals a good overlap of magnetic and georadar anomalies in the west zone. They are surficial and have been correlated to earthenware remains, probably medieval in age. The anomalies detected by georadar and magnetic methods in the centre and eastern zones do not, in most of the cases, overlap, so we presume that the two methods detected different features. The joint interpretation of the georadar and magnetic data has allowed the mapping of the main archaeological anomalies, thus providing a useful tool for planning the archaeological excavation. Copyright © 2007 John Wiley & Sons, Ltd.