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- Volume 13, Issue 6, 2015
Near Surface Geophysics - Volume 13, Issue 6, 2015
Volume 13, Issue 6, 2015
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Integrated geophysical investigations at a sacred Hittite Area in Central Anatolia, Turkey
Authors Mahmut G. Drahor, Meriç A. Berge, Caner Öztürk and Buket OrtanIn this paper, an integrated geophysical investigation of a sacred area in the archaeological site of Šapinuwa is presented. Šapinuwa was one of the important cities in the Hittite Empire. The archaeological site of Šapinuwa is located in the Çorum region of Central Anatolia, Turkey. The goal of the here presented integrative archaeological prospection investigation was to explore buried structures inside the so‐called sacred Taşdöşem area (Taşdöşem means “the stone pavement”) by employing a number of different near‐surface geophysical prospection methods. To this purpose, magnetic gradiometry, ground‐penetrating radar, electrical resistivity tomography, seismic refraction tomography, and multi‐channel analysis of surface wave tomography were applied in this specific area. Overall, the results of the individual geophysical investigations were superimposed in order to obtain more detailed and comprehensive integrative interpretations on the burials contained inside this sacred area. Electrical tomography depth slices revealed the presence of an important structure buried inside the Taşdöşem area. Surprisingly, the velocity variations observed in the depth slices of the multi‐channel analysis of surface wave tomography provided important information on the character of the burial structure. Additionally, seismic refraction tomography sections and depth slices confirmed the presence of the structures in the same locations. The result of the ground‐penetrating radar investigation did not present sufficient certainty regarding the possible deeper burials, whereas the magnetic gradiometry survey gave some insight into near‐surface structures. The combination of the employed geophysical prospection techniques was successfully able to characterize the structures that are assumed to have been buried within the Taşdöşem area. It is concluded that the integrated non‐invasive geophysical archaeological prospection study conducted at Šapinuwa provides a good example on how to approach the investigation and documentation of sites similar to the Taşdöşem.
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3D inversion of ERT data on an archaeological site using GPR reflection and 3D inverted magnetic data as a priori information
Authors A. Arato, S. Piro and L. SambuelliNon‐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. In 1996, at the Archaeological Test Site of the Sabine Necropolis at Research Area of National Research Council of Rome (Montelibretti, Italy), a 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 single‐offset 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.
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Still searching for graves: an analytical strategy for interpreting geophysical data used in the search for “unmarked” graves
Authors C. Gaffney, C. Harris, F. Pope‐Carter, J. Bonsall, R. Fry and A. ParkynSearching for and mapping the physical extent of unmarked graves using geophysical techniques has proven difficult in many cases. The success of individual geophysical techniques for detecting graves depends on a site‐by‐site basis. Significantly, detection of graves often results from measured contrasts that are linked to the background soils rather than the type of archaeological feature associated with the grave. It is evident that investigation of buried remains should be considered within a 3D space as the variation in burial environment can be extremely varied through the grave. Within this paper, we demonstrate the need for a multi‐method survey strategy to investigate unmarked graves, as applied at a “planned” but unmarked pauper’s cemetery. The outcome from this case study provides new insights into the strategy that is required at such sites. Perhaps the most significant conclusion is that unmarked graves are best understood in terms of characterization rather than identification. In this paper, we argue for a methodological approach that, while following the current trends to use multiple techniques, is fundamentally dependent on a structured approach to the analysis of the data. The ramifications of this case study illustrate the necessity of an integrated strategy to provide a more holistic understanding of unmarked graves that may help aid in management of these unseen but important aspects of our heritage. It is concluded that the search for graves is still a current debate and one that will be solved by methodological rather than technique‐based arguments.
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Investigating behind the lining of the Tunnel of Eupalinus in Samos (Greece) using ERT and GPR
The 2.5‐km‐long Eupalinian Aqueduct in the island of Samos, Greece, comprises the most impressive sample of ancient Greek engineering surviving almost intact. The main construction is a tunnel 1036 m long and almost 1.8 m wide excavated from both ends into mainly the massif limestone. In some parts of the overall length of about 240 m, the tunnel is dressed by lining of archaic and Roman age. This is of remarkable quality, and presumably, it protected the parts of the tunnel that were affected by subsidence and cave‐ins. At some particular locations, it suffers deformations and other failures.
Thus, prior to its restoration and protection measures design, an integrated geophysical survey was carried out on the faces of the supporting walls, consisting in ground‐penetrating radar and electrical resistivity tomography works. The survey aimed to investigate the structure at the unseen area behind the lining.
The thickness of the lining walls was accurately assessed by the ground‐penetrating radar method and proved to be about 0.3 m–0.5 m on average. On the other hand, the width of the excavation behind the walls was predicted and checked at some particular locations with the electrical resistivity tomography works.
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Case history: integrated geophysical survey at Katarínka Monastery (Slovakia)
Authors D. Wilken, T. Wunderlich, H. Stümpel, W. Rabbel, R. Pašteka, E. Erkul, J. Papčo, R. Putiška, M. Krajňák and D. KušnirákKatarínka (St. Catherine) is the ruin of an abandoned Franciscan monastery from the early 17th century located in the western Small Carpathians in Slovakia. Historical sources and paintings suggest that, beside the remains of the monastery that are still visible, a circle of eight chapels, a pilgrim’s hospice, a cemetery, and garden terraces originally surrounded the main building of the monastery. From 2009 to 2012, geophysical campaigns were performed to find evidences and positions of remains of these buildings of the monastery campus. An initial magnetic overview survey revealed multiple local accumulations of disordered dipole anomalies. Since these accumulations did not allow a structural interpretation, ground penetrating radar measurements were conducted. The ground penetrating radar results clearly showed wall structures beneath almost all magnetic anomaly accumulations. In between the remains of the monastery main building, ground penetrating radar and electrical resistivity tomography were performed at different areas that were difficult to access because of a strong cover of vegetation and steep topography.
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Archaeological investigations in the shallow seawater environment with electrical resistivity tomography
More LessThis work explores the applicability and effectiveness of electrical resistivity tomography in mapping archaeological relics in the shallow marine environment. The approach consists of a methodology based on numerical simulation models validated with comparison to field data. Numerical modelling includes the testing of different electrode arrays suitable for multi‐channel resistivity instruments (dipole–dipole, pole–dipole, and gradient). The electrodes are placed at fixed positions either floating on the sea surface or submerged at the bottom of the sea. Additional tests are made concerning the resolving capabilities of electrical resistivity tomography with various seawater depths and target characteristics (dimensions and burial depth of the targets). Although valid a priori information, in terms of water resistivity and thickness, can be useful for constraining the inversion, it should be used judiciously to prevent erroneous information leading to misleading results. Finally, an application of the method at a field site is presented not only for verifying the theoretical results but also at the same time for proposing techniques to overcome problems that can occur due to the special environment. Numerical and field electrical resistivity tomography results indicated the utility of the method in reconstructing off‐shore cultural features, demonstrating at the same time its applicability to be integrated in wider archaeological projects.
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Integration of multisensor data: an experiment in the archaeological park of Egnazia (Apulia, Southern Italy)
Authors Loredana Matera, Mariangela Noviello, Marcello Ciminale and Raffaele PersicoIn this paper, we present a case study conducted in the archaeological park of Egnazia (Apulia, Southern Italy) based on the integrated use of two different ground‐penetrating radar systems plus a magnetometer. The surveys were carried out using a pulsed ground‐penetrating radar system, a prototypal reconfigurable stepped frequency ground‐penetrating radar and a high‐resolution magnetometer. The most important anomalies identified are ascribable to the presence of a massive building structure mainly consisting of masonry, probably dating from the Roman age. Emphasis is on the integration of the results, which has made it possible to produce enhanced images. In particular, two different approaches based on (i) algebraic and (ii) RGB combinations of the data gathered with the three sensors are illustrated and discussed.
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Chasing aeroplanes: developing a vehicle‐towed caesium magnetometer array to complement aerial photography over three recently surveyed sites in the UK
Authors Neil Linford‐X., Paul Linford and Andy PayneAerial photography combined with airborne lidar can often provide information on the location of archaeological sites at a near landscape level of coverage. Ground‐based geophysical techniques may then be deployed to complement the aerial survey, particularly where the soils or land use may not be ideal for either producing crop marks or preserving topographic features. This paper describes the development of a vehicle‐towed caesium magnetometer array, from an original hand‐pushed system, to allow high‐density datasets to be rapidly acquired over large areas required to provide a meaningful comparison at the scale demanded by the aerial survey results. Technical details of the system are presented together with methodological considerations for both data acquisition in the field and appropriate post processing to obtain high‐sensitivity field measurements over more weakly magnetized sites. Results are presented from a number of recent collaborative research projects within the English Heritage Remote Sensing Team to illustrate the benefits of a combined aerial and ground‐based approach to mapping the historic environment.
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How efficient is an integrative approach in archaeological geophysics? Comparative case studies from Neolithic settlements in Thessaly (Central Greece)
Authors F.‐X. Simon, T. Kalayci, J.C. Donati, C. Cuenca Garcia, M. Manataki and A. SarrisThe geophysical prospection of Neolithic tells imposes specific challenges due to the preservation and nature of the architectural context and the multiple, usually disturbed, soil strata. Contrary to the usual application of a single method, this paper deals with the advantages of using an integrated geophysical approach through the employment of various methodologies to map the Neolithic cultural and environmental landscape of Thessalian tells (magoules) in Central Greece. The success and failure of each method in resolving the various features of the magoules are discussed in detail, and as a whole, they demonstrate the benefits of a manifold geophysical prospection of the sites.
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Analysis and interpretation of GPR datasets for integrated archaeological mapping
More LessAn integrated approach to ground‐penetrating radar interpretation should include not only the standard amplitude slice maps and isosurface renderings but also an analysis of individual reflection traces and adjusted and processed reflection profiles. Only when all those basic datasets are interpreted can the plethora of reflection features at various depths and locations within a grid be understood, especially in complex geological and archaeological settings. Topographically adjusted profiles can provide important clues to changes in reflectivity along a transect, indicating why certain amplitude features are visible (or not) in slice maps. An integration of excavation and outcrop data with reflection profiles can often indicate what features are producing high‐amplitude reflections and which are yielding no reflection at all. Even individual reflection traces can be studied for polarity changes, which can help in identifying the types of buried materials that are producing reflections. All these datasets, some of which are often overlooked, must be integrated during interpretation, especially in complicated ground conditions.
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Volumes & issues
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Volume 22 (2024)
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Volume 21 (2023)
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Volume 20 (2022)
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Volume 19 (2021)
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Volume 18 (2020)
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Volume 17 (2019)
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Volume 16 (2018)
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Volume 15 (2017)
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Volume 14 (2015 - 2016)
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Volume 13 (2015)
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Volume 12 (2013 - 2014)
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Volume 11 (2013)
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Volume 10 (2012)
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Volume 9 (2011)
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Volume 8 (2010)
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Volume 7 (2009)
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Volume 6 (2008)
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Volume 5 (2007)
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Volume 4 (2006)
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Volume 3 (2005)
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Volume 2 (2004)
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Volume 1 (2003)