High-Resolution Geophysical 3D Imaging for Archaeology by Magnetic and EM data: The Case of the Iron Age Settlement of Torre Galli, Southern Italy
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Magnetic and electromagnetic surveying are effective techniques frequently used in archaeology because the susceptibility and the electric resistivity contrast between the cover soil and several buried finds often lead to detectable anomalies. Significant advances were recently achieved by 3D imaging methods of potential field data that provide an estimate of the magnetization distribution within the subsurface. They provide a high-resolution image of the source distribution, thanks to the differentiation of the field and to the stability of the process. These techniques are fast and quite effective in the case of a compact, isolated, and depth-limited source, i.e., just the kind of source generally occurring in archaeological investigations. We illustrate the high-resolution imaging process for a geophysical study carried out at Torre Galli (Vibo Valentia, Calabria, Italy), one of the most significant sites of the early Iron Age in Italy. Multi-scale derivative analysis of magnetic data revealed the trends of anomalies shaped and aligned with a regular geometry. This allowed us to make an outline of the buried structures, and then to characterize them in terms of size, shape, and depth by means of the imaging technique. Targeted excavations were therefore addressed to the locations selected by our analysis, revealing structures showing exactly the predicted features and confirming the archaeological hypothesis concerning the settlement organization partitioned in terms of functional differentiation: an intermediate area occupied mostly by defensive structures placed between the village, westward, and the necropolis, eastward.
KeywordsArchaeogeophysics 3D imaging Multi-scale analysis Iron Age communities Magnetic methods EM methods Calabria, Italy
The research was supported by the Ministero dell’Istruzione, dell’Università e della Ricerca of Italy (PRIN MIUR 2009 D.M. n.404/ric., 14.07.2011). Field work was carried out under contract by the Laboratorio Mobile di Archeogeofisica of INNOVA—Centro per lo Sviluppo ed il Trasferimento dell’Innovazione nel Settore dei Beni Culturali e Ambientali. We are grateful to Marco Pacciarelli for providing us with images and information about the archaeological excavation. We also thank the referees for their useful comments and the Editor in Chief for precious and detailed editing work carried out in this paper.
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