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Joint geophysical measurements to investigate the Rossano of Vaglio archaeological site (Basilicata Region, Southern Italy)
Journal of Archaeological Science 37 (2010) 2237e2244
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Joint geophysical measurements to investigate the Rossano of Vaglio archaeological site (Basilicata Region, Southern Italy) D. Chianese a, *, V. Lapenna a, S. Di Salvia b, A. Perrone a, E. Rizzo a a b
Institute of Methodologies for Environmental Analysis, CNR e 85050 Tito Scalo, Italy University of Basilicata, Potenza, Italy
a r t i c l e i n f o
a b s t r a c t
Article history: Received 9 February 2008 Received in revised form 15 February 2010 Accepted 31 March 2010
A high resolution geophysical survey was carried out in the archaeological site of Rossano di Vaglio (Basilicata Region, Southern Italy), where an important ancient sanctuary is located. It was built during the IV century B.C. and devoted to the goddess Mephitis. The sanctuary rises in an area affected by a multiple and retrogressive rototraslational landslide, historically and presently subject to reactivation. The main objective of this work was the identification of buried structures of archaeological interest in an area designated by the Archaeological Superintendence of the Basilicata Region. The study was performed by means of the use of high resolution geophysical surveys. In particular, we made use of the joint application of three highly sensitive and non-invasive geophysical techniques, namely the Geoelectrical, the Magnetic and the Ground Probing Radar (GPR) methodologies. In such a way, we obtained two important results: first, we provided the archaeologists with information about the limits of the areas to be excavated; second, we could verify in real time the reliability of the geophysical results. The experimental results showed four main magnetic anomalies in the area of study, in agreement with the GPR results obtained for the same target. Finally, a partial excavation test of the investigated area revealed a buried building structure, located in correspondence of an anomaly identified by means of the geophysical prospecting. Ó 2010 Elsevier Ltd. All rights reserved.
Keywords: Magnetometry GPR Electrical resistivity Rossano di Vaglio sanctuary Southern Italy
1. Introduction Basilicata region (Fig. 1), located in Southern Italy, starting from the IV century B.C. felt the roman influence, which contributed to the development of a local social community and the rising of many populated areas and places of worship. This development is reflected in the foundation of several cult-places with different architectural complexity (sanctuaries of Torre di Satriano, Rossano di Vaglio, Armento, Timmari, Accettura, etc.) (Archeologia in Basilicata, 2000a, b; Nava and Cracolici, 2005). In particular, the location of the religious sanctuaries has been influenced by the geological and geomorphological features of the lucanian environment: most of them were built along the main lines of communication and near sulphurous springs, which could have the many-sided religious, curative and purificatory sense. The sanctuaries were built on different levels, exploiting the presence of broad morphological terraces, which were often due to
* Corresponding author. Tel.: þ39 971 427206; fax: þ39 971 427271. E-mail address: [email protected] (D. Chianese). 0305-4403/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jas.2010.03.021
the presence of ancient landslides, at present subject to renewed activity. The ancient lucanian people has developed a good use of the surfaces of coalescing morphological terraces, which often are generated by the reactivation of huge and ancient landslides both in historical times and at present (Sdao and Simeone, 2007). For a long time, the authors have been researching in the previous and present conditions of instability of archaeological sites (sacred areas, sanctuaries, necropolis) of the classic period, which are located in the central-western portion of the Lucanian Apennines (Chianese et al., 2003; Sdao and Simeone, 2007). Starting from this foreword, in the framework of a project funded by the Italian Research Ministry for the monitoring of archaeological areas subject to hydrogeological instability, named: “Geomorphological study and landslides control in some areas of the Basilicata region characterized by historical-cultural heritage”, we developed a research activity focussed on the realization of combined geophysical measurements for the study of archaeological areas affected by landslide phenomena in Basilicata Region (Southern Italy). In particular, in the Rossano di Vaglio Archaeological site (Fig. 2) the research activity included geomorphological and geological surveys to analyse the mass movements of the subsoil, on one side,
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Fig. 1. Map of Basilicata Region with the location of Rossano di Vaglio.
and magnetic, geoelectrical and GPR soundings to characterise the geometry of the deep structures and to investigate the presence of ancient buried structures of the sanctuary, on the other side. In this site is still present and well preserved an ancient sanctuary devoted to the Oscan goddess Mephitis, build in the late IV century B.C. (Adamasteanu and Dilthey, 1992; Masseria and D’Anisi, 2001; Nava and Cracolici, 2005). The sacred area was affected by a multiple and retrogressive rototranslational slide, historically and actually subject to reactivation. We remember here that in a retrogressive landslide the rupture surface is extending in the direction opposite to the movement of the displaced material (WP/WLI a, 1993; WP/WLI b, 1993). The main results of the geomorphological surveys, integrated by the interpretation of aerial photos, carried out in the investigated site, were already discussed and published in a previous paper (Sdao and Simeone, 2007). In this paper we show the main results derived by the application of high resolution 2D electrical resistivity tomographies, electromagnetic and magnetic methods, aimed to the identification
of buried structures at the ancient sanctuary of Rossano di Vaglio archaeological site. During the last years, in fact, the application of non-invasive electromagnetic techniques for archaeological investigation became an almost usual tool to help the archaeologists to limit the areas to be excavated, in such a way to reduce the time and cost of archaeological campaigns. In this framework, the most suitable geophysical investigation techniques employed for archaeological purposes are the magnetic method (Bates and Bates, 2000; Bavusi et al., 2004; Chavez et al., 1995, 2001; Godio and Piro, 2005; Powell et al., 2002), the geoelectrical method (Cammarano et al., 2000; Di Fiore and Chianese, 2008; Rizzo et al., 2005; Sambuelli et al., 1999; Tsokas et al., 1994) and the GPR method (Basile et al., 2000; Chadwick and Madsen, 2000; Chianese et al., 2004; Masini et al., 2007; Perez Garcia et al., 2000; Sambuelli et al., 1999; Savvaidis et al., 1999; Tsokas et al., 2007). In fact, they provide non-destructive and broad range of application means of exploring for the archaeological purpose, especially because they are noninvasive and prompt techniques. The geophysical results, obtained combining advanced technologies for data acquisition and new methods for data inversion (Ciminale and Loddo, 2001; Loke and Barker, 1996; Nuzzo et al., 2002), allowed us to identify part of the buried structures of the ancient sanctuary. Finally, a partial excavation test of the area investigated by means of the joint application of the different geophysical techniques revealed a buried building structure, located in correspondence of an anomaly identified by means of the geophysical prospecting.
2. Geological and geomorphological setting
Fig. 2. Photo of the Rossano di Vaglio Sanctuary.
The Sanctuary of Rossano di Vaglio is located in an area affected by a multiple and retrogressive rototraslational slide, historically and actually subject to reactivation. The area is mainly characterized by the outcropping of the structurally complex clayey-marly succession, strongly fractured and deformed, referred to Lagonegro Unit and in particular to the Flysch Rosso formation (Upper
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Cretaceous e Eocene). This formation is made up by marly clays and clayey marls finely scaly randomly alternated with level of mudstones, marly calcilutites, bioclastic calcarenites, cherty radio-larites, clays and marly clays. These materials are strongly fractured, severely deformed and particularly prone to slope instability phenomena (Sdao and Simeone, 2007). The morphology of the whole area is strictly related to the landslide phenomena affecting the Flysch Rosso formation. The landslide, having a retrogressive evolution, created a sort of fanshape landslide area converging toward the lower part of the slope where the sacred area has been built. During its whole existence, the sacred site was subjected at least to three distinct phases of restructuring, probably due to the reactivation of the landslides occurring in the study area (Fig. 3). At the moment, the studied landslide shows a general dormant state of activity. Perhaps only the lower part of this landslide is active. In this area there are clear signs of landslide reactivations, depression of the ground, fissure and swelling of the ground surface and creep phenomena.
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3. The archaeological site During the IV century B.C., across the transition from the Greek to the Roman domination, the rule of the Sanctuaries in the Lucanian tradition became central for political and religious purposes; a number of sanctuaries annexed to the houses rose near the springs (Archeologia in Basilicata, 2000b). In particular, the Sanctuary built in Rossano di Vaglio, characterised by monumental structures and by marble and bronze statues for worship, can be considered a true federal Sanctuary of all the communities that had settled in the inland of the Basilicata Region. The native Sanctuary of Rossano, founded during the IV century B.C., in the next century is controlled by the Roman senatorial families, but continues to be a sacred place until the Augustan age. The main divinity of the Lucanians is the Oscan goddess Mephitis, who represents the afterlife. The Greeks attributed this role to Aphrodite, Demetra and Persephone.
Fig. 3. a) Geomorphological sketch of the archaeological site of Rossano di Vaglio (modified by Sdao and Simeone, 2007); b) Geomorphological cross-section (modified by Sdao and Simeone, 2007).
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In this period, the dead are generally deposed in supine position inside a simple grave dug in the ground. At times they are deposed in a saddle-roof sarcophagus made with tiles or a wooden coffin. The Rossano sanctuary was characterized by an architectural complex built on several levels jointed by a large staircase. The entirely discovered level expands all around a large church-square, in the centre of which is located a large altar built up with arenaceous blocks. The sanctuary has been definitively abandoned at the end of the first half of the first century B.C.. Probably in consequence of the frequent instability crisis of the landslides present in the area, and in particular of the landslide on which the cult-site was built (Adamasteanu and Dilthey, 1992; Sdao and Simeone, 2007). Landslide movements and their frequent reactivation have been shown by archaeological excavations since 1969 (Adamasteanu and Dilthey, 1992). The whole monument has a clear back-slope inclination (5 e10 ) toward NW. There are tilted and sometimes destroyed walls, damned walking area, and archaeological levels strongly disturbed or remoulded. Finally, coins have also been found. This suggests the offering paid to Charon so he could successfully ferry the deceased in the afterlife. 4. Geophysical methods The Geophysical investigation, aimed to define the buried ancient structure of the sanctuary, involved the joint application of Electric Resistivity Tomography (ERT) sections, Ground Probing Radar (GPR) profiles and Magnetic surveys. These methods are characterized by high resolution, rapid data acquisition rate and reduced costs and measurement time; furthermore, by means of their use, it is possible to provide useful information for identifying and mapping shallow structures and giving guidelines for the subsequent excavations and archaeological studies (Sharma, 1997). 4.1. Electric Resistivity Tomography (ERT) The ERT technique allows to obtain high resolution images of the resistivity subsurface patterns and it is largely applied in the study of a wide class of geological and environmental problems (i.e. structural studies, fault mapping, landslide surveying, polluted site monitoring, etc..) (Caputo et al., 2003; Colella et al., 2004; Lapenna et al., 2005). The geoelectrical method is nowadays applied also for archaeological purposes, because of the buried targets (walls, roof, road, etc.) present different electrical peculiarities (electrical resistivity) in respect of the homogeneous surrounding soil. The resistivity data coming from inverted 3D ERT models are interpolated by means of the use of Slicer software.
reliability and for the aptitude to provide quick data acquisition, non-invasive investigation and high resolution experimental data. The magnetic measurements were performed by means of the use of an optical pumping magnetometer G-858 Geometrics in gradiometric configuration, with the two magnetic probes set in vertical direction at a distance of about 1 m each by other, in such a way to automatically remove the diurnal variations of the natural magnetic field (Sharma, 1997; Tabbagh, 2003). This equipment allows us to obtain a great amount of high resolution experimental data in a relatively brief time period, thanks to its feature to be used in a continuous fashion with a sample frequency of 10 Hz. In such a way, it is possible to investigate very broad areas in a few hours (Bavusi et al., 2004). Among the various acquisition modalities provided by the magnetic sensors, we selected the mapped survey mode that allows us to previously specify and visualize the survey area and to move around within the investigated area in a non-continuous fashion by means of regular grids. 5. Results The geophysical prospecting was carried out in an area indicated by the Archaeological Superintendence as the target for an excavation test, that was made after the geophysical measurements. The dimension of the investigated area are 29 m 18 m (Fig. 4). 5.1. Electric Resistivity Tomography (ERT) We carried out seven parallel ERT profiles with a dipoleedipole array layout using the Syscal R2 multielectrode system. Each ERT was performed using 16 electrodes with an electrode spacing of 1.5 m and for each profile more than 100 measurements of apparent resistivity have been computed according to the 2D pseudosection scheme. The distance between parallel profiles was 1.5 m. In this way, we acquired a grid of extent 22.5 m 15 m with more then 700 electrical resistivity data. Finally, in order to obtain a 3D electrical model, all the acquired apparent resistivity data were inverted using the RES3Dinv method (Loke and Barker, 1996). The inversion routine is based on the smoothness constrained least-squares inversion (Sasaki, 1992) implemented by a quasi-
4.2. Ground Probing Radar (GPR) The GPR prospecting is mainly applied to solve engineering and environmental problems (Lambot et al., 2005; Steeples, 2001 and reference therein) and to support archaeological prospecting (Chianese et al., 2004; Nuzzo et al., 2002; Piro et al., 2003; Piscitelli et al., 2007; Rizzo et al., 2005). It can be considered as a powerful tool for detecting and imaging shallow subsurface targets characterised by dielectric and conductive properties that are very different from the surrounding ground. 4.3. The magnetic method Among the geophysical techniques which can be employed for the archaeological research, the magnetic method seems to be the most suitable and the most largely exploited because of its
Fig. 4. The area interested by the Geophysical investigation; the black rectangle refers to the actual dimensions of the investigated area.
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Newton optimisation technique. The subsurface is subdivided in blocks whose number is related to those of measuring points. The optimisation method adjusts the 3D resistivity model trying to reduce iteratively the difference between the calculated and measured apparent resistivity values. The 3D electrical resistivity inverted data are showed in Fig. 5. The figure shows the different layers which are associated to different depth ranges, until the depth of 4.60 m. The layers 1 (depth 0e0.52 m) and 2 (depth 0.52e1.13 m) are more significant, as they show very high resistivity values(>155 Ohm m) between 3 m and 9 m along the ordinate and from 20 m to the end along the abscissa. Moreover, a relative resistivity zone (between 60 Ohm m and 80 Ohm m) is located on the south side of the layer 2. The other layers show homogeneous resistivity values (<10 Ohm m) related to the clay material outcropped in the investigated area. The 3D electrical resistivity image of Fig. 6 shows only resistivity data greater than 50 Ohm m. The two resistivity zones (A and B) can be associated to the buried walls of the archaeological area, surrounded and included in the homogeneous geological deposit (clay material) with resistivity values lower than 20 Ohm m.
5.2. Ground Probing Radar (GPR) In correspondence of the same area, we carried out the GPR survey, using the Subsurface Interface Radar (SIR) 2000 manufactured by Geophysical Survey Systems. The SIR 2000 consists of a digital control unit with keypad, VGA video screen and connector panel. The unit is backpack portable, requiring one or two operators, and powered by a 12-V DC battery. The system was equipped with
Fig. 6. The 3D visualization map obtained by means of the use of Slicer Software. The resistivity zone A is localized on shallow part, while the resistivity zone B is deeper (between 0.52 m and 1.13 m). Resistivity values lower than 50 Ohm were represented as transparent.
a 400 MHz (by GSSI) monostatic antenna. The GPR profiles were carried out in continuous mode with a two-way time range of 60 ns, and an interval band pass filter of 100e800 ns. The investigation area was represented by a grid of 29 m 18 m (Fig. 4). 19 parallel profiles have been carried out with a step-size of 1 m between the survey
Fig. 5. 3D electrical resistivity inverted data maps obtained by means of the application of RES3D software. Each slice refers to a layer with a peculiar depth range.
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lines. The measurements were acquired without a “wheel accessory”, so that a speed variation could be occurred in the survey. However, a reference metre rule was located along each profile and marked at each meter, in such a way to allow us to adopt a distance normalization (DN) to mitigate uncertainties on the antenna positions. The Radan NT software has been used to process the data, the high quality of the traces requires only standard analysis techniques for data processing (colour transforms, table customizing and Distance Normalization processing) and to reduce the background noise. The Distance Normalization processing is a standard GPR analysis procedure used to ensure a correct distance along the length of the profile (Piscitelli et al., 2007). The more significant results of the GPR survey are showed in Fig. 7. The two sections of the 3D GPR image show very clear reflected signals associated to walls. The reflected signals of buried walls on section A occur close to the surface around 5 nse10 ns, while those on section B are localized more deep (25 ns). These considerations are supported from the results of 3D geoelectrical inversion model. The resistivity zone A is localized on shallow part, while the resistivity zone B is deeper (between 0.52 m and 1.13 m, Fig. 6).
5.3. Magnetic results The magnetic map carried out on the investigated site covers an area of 17 m 18 m, in which we performed 35 profiles, at a distance of 0.5 m each other in the x direction, with a sample step of 0.5 m along each profile, in such a way to obtain magnetic data
with a spatial resolution comparable with the dimension of the buried structures to be found. The unfiltered magnetic map was characterised by the presence of many spikes and very intense anomalous values (of about 180 nT/ m in modulus) in the western and upper eastern part of the investigated area, due to the presence of shallow little iron objects, for the first case, and to the presence of buried electric cables, for the second case. For this reason, the rough magnetic data were filtered by means of the application of a new filtering procedure based on the hypothesis to regard the point anomalies as spikes (Chianese et al., 2004). This automatic procedure allows us to remove the anomalies due to the presence of many of the little iron objects, while in the case of the buried electric cables, it helps us only to reduce their effects, but unfortunately not to definitely remove them. The resulting filtered map is shown in Fig. 8. As it can be observed, there are many anomalies, whose intensity gets to the maximum of 20 nT/m in modulus in the upper part of the map. Anyway, these values, as depicted before, are still due to the presence of buried electric cables, so that we didn’t take in account them. On the other hand, we knew that the central and lower part of the investigated area was free of buried anthropic noise, so that our attention was focussed on the magnetic anomalies observed in this part of the map. The magnetic anomalies we take usually in account are those presenting both a gradiometric intensity comparable to that of similar material often outcropping in the proximity of the investigated site, and regular shapes, ascribing to the presence of buried
Fig. 7. The 3D GPR visualization map using Slicer Software. The slice A represents a section crossing the high resistivity zone A in Fig. 5, while the section B crosses the resistivity zone B.
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Fig. 8. Gradiometric filtered map. Four most interesting anomalies are put in evidence by black boxes.
linear structures of anthropic origin. In these two directions, the magnetic map is characterised by the presence of four main magnetic anomalies, put in evidence by black boxes. A first magnetic anomaly, 14 m long, is well evident in the lower part of the map, having a gradiometric intensity of about 10e15 nT/ m; this magnetic anomaly is probably due to some collapses, partly visible on the lower edge of the investigated area, as can be clearly
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Fig. 10. Images of the investigated area showing the remains of structures partly collapsed in the lower part of the investigated area.
seen in the two pictures in Fig. 10. Furthermore, this anomaly partly corresponds to the A zones put in evidence both by the ERT and the GPR surveys. Two magnetic anomalies are visible in the central part of the map, the first from 6 m to 11 m in the x direction and from 2 m to 8 m in the y direction, the second from 14 m to 16 m in thex direction and from 5 m to 13 m in the y direction, both with gradiometric intensity of about 10 nt/m. In these two cases, we can presume the presence of well defined walls in the subsoil, partly collapsed, such as other fragments brought to light nearby. Finally, a weak gradiometric anomaly is represented in the western part of the map, in oblique direction in respect to the other, with gradiometric intensity less than 10 nT/m. The western part of this anomaly overlaps to the B zones put in evidence both by the ERT and the GPR surveys (Figs. 6 and 7, respectively). In correspondence of this anomaly, in a second step a partial excavation test was made by the archaeological superintendence (Fig. 9), which brought to light a partly collapsed wall, covered by white ground cloth, with a direction correspondent to that of the magnetic anomaly (approximately in NeS direction).
6. Conclusions
Fig. 9. Excavation test carried out by the Archaeological Superintendence of the Basilicata region.
In this paper, we showed the main results of a joint application of high resolution and non-invasive geophysical techniques for the investigation of an area located in the Rossano of Vaglio archaeological site, namely the ERT, GPR and magnetic techniques.
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The simultaneous use of magnetic, electric and electromagnetic measurements represents the key for obtaining information about the shape, the dimension and the depth of the investigated structures in archaeological areas. In particular, we carried out a high velocity data acquisition and high resolution magnetic survey, to limit the dimension of the ancient structures; GPR outlines, to delineate the internal walls; and geoelectrical tomographies, to have information about the depth of the ancient structures. The results of the three sets of measurements seem to agree in two zones of the investigated area (A and B in Figs. 6 and 7), putting in evidence the presence of probably partly collapsed walls. Furthermore, the magnetic survey evidenced the presence of two other anomalies, probably due to buried structures with a low resistivity contrast in respect of the surrounding ground. Finally, an excavation test carried out by the Archaeological Superintendence of the Basilicata Region brought to light the remains of a long wall, partly collapsed, in correspondence of the zone B previously underlined by the geophysical surveys. This occurrence confirmed once more the fact that the geophysical soundings represent a useful tool to limit the dimension of the excavation areas, in order to reduce the time and the costs of archaeological campaigns. In fact, the results obtained by the multidisciplinary approach depicted in this paper gave rise to a more active cooperation between archaeologists and geophysicists. Acknowledgements This work was carried out in cooperation with the Superintendence for the Archaeological Heritage of Basilicata Region, especially Prof. M. Osanna and V. Cracolici. For the Geophysical measurements, we want to thank the TOMOGEA s.r.l. Society (www.tomogea.it). Finally, the authors wish to thank Prof. Maria Perna for her support in the English review. References Adamasteanu, D., Dilthey, H., 1992. Macchia di Rossano. Il Santuario della Dea Mefitis. Rapporto Preliminare, Galatina. Archeologia in Basilicata, 2000a. Musei Archeologici Nazionali e Provinciali Della Basilicata. Regione Basilicata (Assessorato alla Cultura e Ufficio Beni Culturali). Archeologia in Basilicata, 2000b. La Basilicata Antica tra Archeologia e Storia. Regione Basilicata (Assessorato alla Cultura e Ufficio Beni Culturali). Basile, V., Carrozzo, M.T., Negri, S., Nuzzo, L., Quarta, T., Villani, A.V., 2000. A groundpenetrating radar survey for archaeological investigations in an urban area (Lecce, Italy). J. Appl. Geoph. 44, 15e32. Bates, M.R., Bates, C.R., 2000. Multidisciplinary approaches to the geoarchaeological evaluation of deeply stratified sedimentary sequences: examples from Pleistocene and Holocene deposits in Southern England, United Kingdom. J. Arch. Sci. 27, 845e858. Bavusi, M., Chianese, D., Giano, S.I., Mucciarelli, M., 2004. Multidisciplinary investigations on the roman aqueduct of Grumentum (BasilicataeSouthern Italy). Ann. Geoph. 47/6, 1791e1802. Cammarano, F., Di Fiore, B., Mauriello, P., Patella, D., 2000. Examples of application of electrical tomographies and radar profiling to cultural heritage. Ann. Geoph. 43/2, 309e324. Caputo, R., Piscitelli, S., Oliveto, A., Rizzo, E., Lapenna, V., 2003. High-resolution resistivity tomographies in active tectonic studies. Examples from the Tyrnavos Basin, Greece. J. Geodyn. 36, 19e35. Chadwick, W.J., Madsen, J.A., 2000. The application of ground-penetrating radar to a coastal prehistoric archaeological site, Cape Henlopen, Delaware, USA. Geoarch. 15/8, 765e781. Chavez, R.E., Hernandez, M.C., Herrera, J., Camara, M.E., 1995. A magnetic survey over La Maya, an archaeological site in Northern Spain. Archaeom. 37, 171e184. Chavez, R.E., Camara, M.E., Tejero, A., Barba, L., Manzanilla, L., 2001. Site characterization by geophysical methods in the archaeological zone of Teotihuacan, Mexico. J. Arch. Sci. 28, 1265e1276. Chianese, D., Lapenna, V., Lorenzo, P., Perrone, A., Piscitelli, S., Rizzo, E., Sdao, F., 2003. Joint geophysical measurements to investigate the Rossano of Vaglio archaeological site affected by landslide phenomena (Basilicata region,
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The location and mapping of ancient ruins on the castle of Lefkas (Greece) by resistivity and GPR methods. Arch. Prosp. 6, 63e73. Sdao, F., Simeone, V., 2007. Mass movements affecting goddess Mefitis sanctuary in Rossano di Vaglio (Basilicata, Southern Italy). J. Cult. Herit. 8, 77e80. Sharma, P.S., 1997. Environmental and Engineering Geophysics. Cambridge University Press, London. Steeples, D.W., 2001. Engineering and environmental geophysics at the millennium. Geoph. 66, 31e35. Tabbagh, J., 2003. Total field magnetic prospection: are vertical gradiometer measurements preferable to single sensor survey? Arch. Prosp. 10, 75e81. Tsokas, G.N., Giannopoulos, A., Tsourlos, P., Vargemezis, G., Tealby, J.M., Sarris, A., Papazachos, C.B., Savvopoulou, T., 1994. A large scale geophysical survey in the archaeological site of Europos (N. Greece). J. Appl. Geoph. 32, 85e98. Tsokas, G.N., Stampolidis, A., Mertzanidis, I., Tsourlos, P., Hamza, R., Chrisafis, C., Ambonis, D., Tavlakis, I., 2007. Geophysical exploration in the church of Protaton at Karyes of Mount Athos (HolyMountain) in Northern Greece. Arch. Prosp. 14, 75e86. WP/WLI a (International Geotechnical Societies ¼ UNESCO Working Party on World Landslide Inventory), 1993. A suggested method for describing the activity of a landslide. Bull. Int. Assoc. for Eng. Geol. 47, 53e57. WP/WLI b (International Geotechnical Societies ¼ UNESCO Working Party on World Landslide Inventory), 1993. Multilingual Landslide Glossary. BiTech Publishers Ltd, Canada.
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Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas
Joint geophysical measurements to investigate the Rossano of Vaglio archaeological site (Basilicata Region, Southern Italy) D. Chianese a, *, V. Lapenna a, S. Di Salvia b, A. Perrone a, E. Rizzo a a b
Institute of Methodologies for Environmental Analysis, CNR e 85050 Tito Scalo, Italy University of Basilicata, Potenza, Italy
a r t i c l e i n f o
a b s t r a c t
Article history: Received 9 February 2008 Received in revised form 15 February 2010 Accepted 31 March 2010
A high resolution geophysical survey was carried out in the archaeological site of Rossano di Vaglio (Basilicata Region, Southern Italy), where an important ancient sanctuary is located. It was built during the IV century B.C. and devoted to the goddess Mephitis. The sanctuary rises in an area affected by a multiple and retrogressive rototraslational landslide, historically and presently subject to reactivation. The main objective of this work was the identification of buried structures of archaeological interest in an area designated by the Archaeological Superintendence of the Basilicata Region. The study was performed by means of the use of high resolution geophysical surveys. In particular, we made use of the joint application of three highly sensitive and non-invasive geophysical techniques, namely the Geoelectrical, the Magnetic and the Ground Probing Radar (GPR) methodologies. In such a way, we obtained two important results: first, we provided the archaeologists with information about the limits of the areas to be excavated; second, we could verify in real time the reliability of the geophysical results. The experimental results showed four main magnetic anomalies in the area of study, in agreement with the GPR results obtained for the same target. Finally, a partial excavation test of the investigated area revealed a buried building structure, located in correspondence of an anomaly identified by means of the geophysical prospecting. Ó 2010 Elsevier Ltd. All rights reserved.
Keywords: Magnetometry GPR Electrical resistivity Rossano di Vaglio sanctuary Southern Italy
1. Introduction Basilicata region (Fig. 1), located in Southern Italy, starting from the IV century B.C. felt the roman influence, which contributed to the development of a local social community and the rising of many populated areas and places of worship. This development is reflected in the foundation of several cult-places with different architectural complexity (sanctuaries of Torre di Satriano, Rossano di Vaglio, Armento, Timmari, Accettura, etc.) (Archeologia in Basilicata, 2000a, b; Nava and Cracolici, 2005). In particular, the location of the religious sanctuaries has been influenced by the geological and geomorphological features of the lucanian environment: most of them were built along the main lines of communication and near sulphurous springs, which could have the many-sided religious, curative and purificatory sense. The sanctuaries were built on different levels, exploiting the presence of broad morphological terraces, which were often due to
* Corresponding author. Tel.: þ39 971 427206; fax: þ39 971 427271. E-mail address: [email protected] (D. Chianese). 0305-4403/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jas.2010.03.021
the presence of ancient landslides, at present subject to renewed activity. The ancient lucanian people has developed a good use of the surfaces of coalescing morphological terraces, which often are generated by the reactivation of huge and ancient landslides both in historical times and at present (Sdao and Simeone, 2007). For a long time, the authors have been researching in the previous and present conditions of instability of archaeological sites (sacred areas, sanctuaries, necropolis) of the classic period, which are located in the central-western portion of the Lucanian Apennines (Chianese et al., 2003; Sdao and Simeone, 2007). Starting from this foreword, in the framework of a project funded by the Italian Research Ministry for the monitoring of archaeological areas subject to hydrogeological instability, named: “Geomorphological study and landslides control in some areas of the Basilicata region characterized by historical-cultural heritage”, we developed a research activity focussed on the realization of combined geophysical measurements for the study of archaeological areas affected by landslide phenomena in Basilicata Region (Southern Italy). In particular, in the Rossano di Vaglio Archaeological site (Fig. 2) the research activity included geomorphological and geological surveys to analyse the mass movements of the subsoil, on one side,
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Fig. 1. Map of Basilicata Region with the location of Rossano di Vaglio.
and magnetic, geoelectrical and GPR soundings to characterise the geometry of the deep structures and to investigate the presence of ancient buried structures of the sanctuary, on the other side. In this site is still present and well preserved an ancient sanctuary devoted to the Oscan goddess Mephitis, build in the late IV century B.C. (Adamasteanu and Dilthey, 1992; Masseria and D’Anisi, 2001; Nava and Cracolici, 2005). The sacred area was affected by a multiple and retrogressive rototranslational slide, historically and actually subject to reactivation. We remember here that in a retrogressive landslide the rupture surface is extending in the direction opposite to the movement of the displaced material (WP/WLI a, 1993; WP/WLI b, 1993). The main results of the geomorphological surveys, integrated by the interpretation of aerial photos, carried out in the investigated site, were already discussed and published in a previous paper (Sdao and Simeone, 2007). In this paper we show the main results derived by the application of high resolution 2D electrical resistivity tomographies, electromagnetic and magnetic methods, aimed to the identification
of buried structures at the ancient sanctuary of Rossano di Vaglio archaeological site. During the last years, in fact, the application of non-invasive electromagnetic techniques for archaeological investigation became an almost usual tool to help the archaeologists to limit the areas to be excavated, in such a way to reduce the time and cost of archaeological campaigns. In this framework, the most suitable geophysical investigation techniques employed for archaeological purposes are the magnetic method (Bates and Bates, 2000; Bavusi et al., 2004; Chavez et al., 1995, 2001; Godio and Piro, 2005; Powell et al., 2002), the geoelectrical method (Cammarano et al., 2000; Di Fiore and Chianese, 2008; Rizzo et al., 2005; Sambuelli et al., 1999; Tsokas et al., 1994) and the GPR method (Basile et al., 2000; Chadwick and Madsen, 2000; Chianese et al., 2004; Masini et al., 2007; Perez Garcia et al., 2000; Sambuelli et al., 1999; Savvaidis et al., 1999; Tsokas et al., 2007). In fact, they provide non-destructive and broad range of application means of exploring for the archaeological purpose, especially because they are noninvasive and prompt techniques. The geophysical results, obtained combining advanced technologies for data acquisition and new methods for data inversion (Ciminale and Loddo, 2001; Loke and Barker, 1996; Nuzzo et al., 2002), allowed us to identify part of the buried structures of the ancient sanctuary. Finally, a partial excavation test of the area investigated by means of the joint application of the different geophysical techniques revealed a buried building structure, located in correspondence of an anomaly identified by means of the geophysical prospecting.
2. Geological and geomorphological setting
Fig. 2. Photo of the Rossano di Vaglio Sanctuary.
The Sanctuary of Rossano di Vaglio is located in an area affected by a multiple and retrogressive rototraslational slide, historically and actually subject to reactivation. The area is mainly characterized by the outcropping of the structurally complex clayey-marly succession, strongly fractured and deformed, referred to Lagonegro Unit and in particular to the Flysch Rosso formation (Upper
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Cretaceous e Eocene). This formation is made up by marly clays and clayey marls finely scaly randomly alternated with level of mudstones, marly calcilutites, bioclastic calcarenites, cherty radio-larites, clays and marly clays. These materials are strongly fractured, severely deformed and particularly prone to slope instability phenomena (Sdao and Simeone, 2007). The morphology of the whole area is strictly related to the landslide phenomena affecting the Flysch Rosso formation. The landslide, having a retrogressive evolution, created a sort of fanshape landslide area converging toward the lower part of the slope where the sacred area has been built. During its whole existence, the sacred site was subjected at least to three distinct phases of restructuring, probably due to the reactivation of the landslides occurring in the study area (Fig. 3). At the moment, the studied landslide shows a general dormant state of activity. Perhaps only the lower part of this landslide is active. In this area there are clear signs of landslide reactivations, depression of the ground, fissure and swelling of the ground surface and creep phenomena.
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3. The archaeological site During the IV century B.C., across the transition from the Greek to the Roman domination, the rule of the Sanctuaries in the Lucanian tradition became central for political and religious purposes; a number of sanctuaries annexed to the houses rose near the springs (Archeologia in Basilicata, 2000b). In particular, the Sanctuary built in Rossano di Vaglio, characterised by monumental structures and by marble and bronze statues for worship, can be considered a true federal Sanctuary of all the communities that had settled in the inland of the Basilicata Region. The native Sanctuary of Rossano, founded during the IV century B.C., in the next century is controlled by the Roman senatorial families, but continues to be a sacred place until the Augustan age. The main divinity of the Lucanians is the Oscan goddess Mephitis, who represents the afterlife. The Greeks attributed this role to Aphrodite, Demetra and Persephone.
Fig. 3. a) Geomorphological sketch of the archaeological site of Rossano di Vaglio (modified by Sdao and Simeone, 2007); b) Geomorphological cross-section (modified by Sdao and Simeone, 2007).
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In this period, the dead are generally deposed in supine position inside a simple grave dug in the ground. At times they are deposed in a saddle-roof sarcophagus made with tiles or a wooden coffin. The Rossano sanctuary was characterized by an architectural complex built on several levels jointed by a large staircase. The entirely discovered level expands all around a large church-square, in the centre of which is located a large altar built up with arenaceous blocks. The sanctuary has been definitively abandoned at the end of the first half of the first century B.C.. Probably in consequence of the frequent instability crisis of the landslides present in the area, and in particular of the landslide on which the cult-site was built (Adamasteanu and Dilthey, 1992; Sdao and Simeone, 2007). Landslide movements and their frequent reactivation have been shown by archaeological excavations since 1969 (Adamasteanu and Dilthey, 1992). The whole monument has a clear back-slope inclination (5 e10 ) toward NW. There are tilted and sometimes destroyed walls, damned walking area, and archaeological levels strongly disturbed or remoulded. Finally, coins have also been found. This suggests the offering paid to Charon so he could successfully ferry the deceased in the afterlife. 4. Geophysical methods The Geophysical investigation, aimed to define the buried ancient structure of the sanctuary, involved the joint application of Electric Resistivity Tomography (ERT) sections, Ground Probing Radar (GPR) profiles and Magnetic surveys. These methods are characterized by high resolution, rapid data acquisition rate and reduced costs and measurement time; furthermore, by means of their use, it is possible to provide useful information for identifying and mapping shallow structures and giving guidelines for the subsequent excavations and archaeological studies (Sharma, 1997). 4.1. Electric Resistivity Tomography (ERT) The ERT technique allows to obtain high resolution images of the resistivity subsurface patterns and it is largely applied in the study of a wide class of geological and environmental problems (i.e. structural studies, fault mapping, landslide surveying, polluted site monitoring, etc..) (Caputo et al., 2003; Colella et al., 2004; Lapenna et al., 2005). The geoelectrical method is nowadays applied also for archaeological purposes, because of the buried targets (walls, roof, road, etc.) present different electrical peculiarities (electrical resistivity) in respect of the homogeneous surrounding soil. The resistivity data coming from inverted 3D ERT models are interpolated by means of the use of Slicer software.
reliability and for the aptitude to provide quick data acquisition, non-invasive investigation and high resolution experimental data. The magnetic measurements were performed by means of the use of an optical pumping magnetometer G-858 Geometrics in gradiometric configuration, with the two magnetic probes set in vertical direction at a distance of about 1 m each by other, in such a way to automatically remove the diurnal variations of the natural magnetic field (Sharma, 1997; Tabbagh, 2003). This equipment allows us to obtain a great amount of high resolution experimental data in a relatively brief time period, thanks to its feature to be used in a continuous fashion with a sample frequency of 10 Hz. In such a way, it is possible to investigate very broad areas in a few hours (Bavusi et al., 2004). Among the various acquisition modalities provided by the magnetic sensors, we selected the mapped survey mode that allows us to previously specify and visualize the survey area and to move around within the investigated area in a non-continuous fashion by means of regular grids. 5. Results The geophysical prospecting was carried out in an area indicated by the Archaeological Superintendence as the target for an excavation test, that was made after the geophysical measurements. The dimension of the investigated area are 29 m 18 m (Fig. 4). 5.1. Electric Resistivity Tomography (ERT) We carried out seven parallel ERT profiles with a dipoleedipole array layout using the Syscal R2 multielectrode system. Each ERT was performed using 16 electrodes with an electrode spacing of 1.5 m and for each profile more than 100 measurements of apparent resistivity have been computed according to the 2D pseudosection scheme. The distance between parallel profiles was 1.5 m. In this way, we acquired a grid of extent 22.5 m 15 m with more then 700 electrical resistivity data. Finally, in order to obtain a 3D electrical model, all the acquired apparent resistivity data were inverted using the RES3Dinv method (Loke and Barker, 1996). The inversion routine is based on the smoothness constrained least-squares inversion (Sasaki, 1992) implemented by a quasi-
4.2. Ground Probing Radar (GPR) The GPR prospecting is mainly applied to solve engineering and environmental problems (Lambot et al., 2005; Steeples, 2001 and reference therein) and to support archaeological prospecting (Chianese et al., 2004; Nuzzo et al., 2002; Piro et al., 2003; Piscitelli et al., 2007; Rizzo et al., 2005). It can be considered as a powerful tool for detecting and imaging shallow subsurface targets characterised by dielectric and conductive properties that are very different from the surrounding ground. 4.3. The magnetic method Among the geophysical techniques which can be employed for the archaeological research, the magnetic method seems to be the most suitable and the most largely exploited because of its
Fig. 4. The area interested by the Geophysical investigation; the black rectangle refers to the actual dimensions of the investigated area.
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Newton optimisation technique. The subsurface is subdivided in blocks whose number is related to those of measuring points. The optimisation method adjusts the 3D resistivity model trying to reduce iteratively the difference between the calculated and measured apparent resistivity values. The 3D electrical resistivity inverted data are showed in Fig. 5. The figure shows the different layers which are associated to different depth ranges, until the depth of 4.60 m. The layers 1 (depth 0e0.52 m) and 2 (depth 0.52e1.13 m) are more significant, as they show very high resistivity values(>155 Ohm m) between 3 m and 9 m along the ordinate and from 20 m to the end along the abscissa. Moreover, a relative resistivity zone (between 60 Ohm m and 80 Ohm m) is located on the south side of the layer 2. The other layers show homogeneous resistivity values (<10 Ohm m) related to the clay material outcropped in the investigated area. The 3D electrical resistivity image of Fig. 6 shows only resistivity data greater than 50 Ohm m. The two resistivity zones (A and B) can be associated to the buried walls of the archaeological area, surrounded and included in the homogeneous geological deposit (clay material) with resistivity values lower than 20 Ohm m.
5.2. Ground Probing Radar (GPR) In correspondence of the same area, we carried out the GPR survey, using the Subsurface Interface Radar (SIR) 2000 manufactured by Geophysical Survey Systems. The SIR 2000 consists of a digital control unit with keypad, VGA video screen and connector panel. The unit is backpack portable, requiring one or two operators, and powered by a 12-V DC battery. The system was equipped with
Fig. 6. The 3D visualization map obtained by means of the use of Slicer Software. The resistivity zone A is localized on shallow part, while the resistivity zone B is deeper (between 0.52 m and 1.13 m). Resistivity values lower than 50 Ohm were represented as transparent.
a 400 MHz (by GSSI) monostatic antenna. The GPR profiles were carried out in continuous mode with a two-way time range of 60 ns, and an interval band pass filter of 100e800 ns. The investigation area was represented by a grid of 29 m 18 m (Fig. 4). 19 parallel profiles have been carried out with a step-size of 1 m between the survey
Fig. 5. 3D electrical resistivity inverted data maps obtained by means of the application of RES3D software. Each slice refers to a layer with a peculiar depth range.
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lines. The measurements were acquired without a “wheel accessory”, so that a speed variation could be occurred in the survey. However, a reference metre rule was located along each profile and marked at each meter, in such a way to allow us to adopt a distance normalization (DN) to mitigate uncertainties on the antenna positions. The Radan NT software has been used to process the data, the high quality of the traces requires only standard analysis techniques for data processing (colour transforms, table customizing and Distance Normalization processing) and to reduce the background noise. The Distance Normalization processing is a standard GPR analysis procedure used to ensure a correct distance along the length of the profile (Piscitelli et al., 2007). The more significant results of the GPR survey are showed in Fig. 7. The two sections of the 3D GPR image show very clear reflected signals associated to walls. The reflected signals of buried walls on section A occur close to the surface around 5 nse10 ns, while those on section B are localized more deep (25 ns). These considerations are supported from the results of 3D geoelectrical inversion model. The resistivity zone A is localized on shallow part, while the resistivity zone B is deeper (between 0.52 m and 1.13 m, Fig. 6).
5.3. Magnetic results The magnetic map carried out on the investigated site covers an area of 17 m 18 m, in which we performed 35 profiles, at a distance of 0.5 m each other in the x direction, with a sample step of 0.5 m along each profile, in such a way to obtain magnetic data
with a spatial resolution comparable with the dimension of the buried structures to be found. The unfiltered magnetic map was characterised by the presence of many spikes and very intense anomalous values (of about 180 nT/ m in modulus) in the western and upper eastern part of the investigated area, due to the presence of shallow little iron objects, for the first case, and to the presence of buried electric cables, for the second case. For this reason, the rough magnetic data were filtered by means of the application of a new filtering procedure based on the hypothesis to regard the point anomalies as spikes (Chianese et al., 2004). This automatic procedure allows us to remove the anomalies due to the presence of many of the little iron objects, while in the case of the buried electric cables, it helps us only to reduce their effects, but unfortunately not to definitely remove them. The resulting filtered map is shown in Fig. 8. As it can be observed, there are many anomalies, whose intensity gets to the maximum of 20 nT/m in modulus in the upper part of the map. Anyway, these values, as depicted before, are still due to the presence of buried electric cables, so that we didn’t take in account them. On the other hand, we knew that the central and lower part of the investigated area was free of buried anthropic noise, so that our attention was focussed on the magnetic anomalies observed in this part of the map. The magnetic anomalies we take usually in account are those presenting both a gradiometric intensity comparable to that of similar material often outcropping in the proximity of the investigated site, and regular shapes, ascribing to the presence of buried
Fig. 7. The 3D GPR visualization map using Slicer Software. The slice A represents a section crossing the high resistivity zone A in Fig. 5, while the section B crosses the resistivity zone B.
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Fig. 8. Gradiometric filtered map. Four most interesting anomalies are put in evidence by black boxes.
linear structures of anthropic origin. In these two directions, the magnetic map is characterised by the presence of four main magnetic anomalies, put in evidence by black boxes. A first magnetic anomaly, 14 m long, is well evident in the lower part of the map, having a gradiometric intensity of about 10e15 nT/ m; this magnetic anomaly is probably due to some collapses, partly visible on the lower edge of the investigated area, as can be clearly
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Fig. 10. Images of the investigated area showing the remains of structures partly collapsed in the lower part of the investigated area.
seen in the two pictures in Fig. 10. Furthermore, this anomaly partly corresponds to the A zones put in evidence both by the ERT and the GPR surveys. Two magnetic anomalies are visible in the central part of the map, the first from 6 m to 11 m in the x direction and from 2 m to 8 m in the y direction, the second from 14 m to 16 m in thex direction and from 5 m to 13 m in the y direction, both with gradiometric intensity of about 10 nt/m. In these two cases, we can presume the presence of well defined walls in the subsoil, partly collapsed, such as other fragments brought to light nearby. Finally, a weak gradiometric anomaly is represented in the western part of the map, in oblique direction in respect to the other, with gradiometric intensity less than 10 nT/m. The western part of this anomaly overlaps to the B zones put in evidence both by the ERT and the GPR surveys (Figs. 6 and 7, respectively). In correspondence of this anomaly, in a second step a partial excavation test was made by the archaeological superintendence (Fig. 9), which brought to light a partly collapsed wall, covered by white ground cloth, with a direction correspondent to that of the magnetic anomaly (approximately in NeS direction).
6. Conclusions
Fig. 9. Excavation test carried out by the Archaeological Superintendence of the Basilicata region.
In this paper, we showed the main results of a joint application of high resolution and non-invasive geophysical techniques for the investigation of an area located in the Rossano of Vaglio archaeological site, namely the ERT, GPR and magnetic techniques.
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The simultaneous use of magnetic, electric and electromagnetic measurements represents the key for obtaining information about the shape, the dimension and the depth of the investigated structures in archaeological areas. In particular, we carried out a high velocity data acquisition and high resolution magnetic survey, to limit the dimension of the ancient structures; GPR outlines, to delineate the internal walls; and geoelectrical tomographies, to have information about the depth of the ancient structures. The results of the three sets of measurements seem to agree in two zones of the investigated area (A and B in Figs. 6 and 7), putting in evidence the presence of probably partly collapsed walls. Furthermore, the magnetic survey evidenced the presence of two other anomalies, probably due to buried structures with a low resistivity contrast in respect of the surrounding ground. Finally, an excavation test carried out by the Archaeological Superintendence of the Basilicata Region brought to light the remains of a long wall, partly collapsed, in correspondence of the zone B previously underlined by the geophysical surveys. This occurrence confirmed once more the fact that the geophysical soundings represent a useful tool to limit the dimension of the excavation areas, in order to reduce the time and the costs of archaeological campaigns. In fact, the results obtained by the multidisciplinary approach depicted in this paper gave rise to a more active cooperation between archaeologists and geophysicists. Acknowledgements This work was carried out in cooperation with the Superintendence for the Archaeological Heritage of Basilicata Region, especially Prof. M. Osanna and V. Cracolici. For the Geophysical measurements, we want to thank the TOMOGEA s.r.l. Society (www.tomogea.it). Finally, the authors wish to thank Prof. Maria Perna for her support in the English review. References Adamasteanu, D., Dilthey, H., 1992. Macchia di Rossano. Il Santuario della Dea Mefitis. Rapporto Preliminare, Galatina. Archeologia in Basilicata, 2000a. Musei Archeologici Nazionali e Provinciali Della Basilicata. Regione Basilicata (Assessorato alla Cultura e Ufficio Beni Culturali). Archeologia in Basilicata, 2000b. La Basilicata Antica tra Archeologia e Storia. Regione Basilicata (Assessorato alla Cultura e Ufficio Beni Culturali). Basile, V., Carrozzo, M.T., Negri, S., Nuzzo, L., Quarta, T., Villani, A.V., 2000. A groundpenetrating radar survey for archaeological investigations in an urban area (Lecce, Italy). J. Appl. Geoph. 44, 15e32. Bates, M.R., Bates, C.R., 2000. Multidisciplinary approaches to the geoarchaeological evaluation of deeply stratified sedimentary sequences: examples from Pleistocene and Holocene deposits in Southern England, United Kingdom. J. Arch. Sci. 27, 845e858. Bavusi, M., Chianese, D., Giano, S.I., Mucciarelli, M., 2004. Multidisciplinary investigations on the roman aqueduct of Grumentum (BasilicataeSouthern Italy). Ann. Geoph. 47/6, 1791e1802. Cammarano, F., Di Fiore, B., Mauriello, P., Patella, D., 2000. Examples of application of electrical tomographies and radar profiling to cultural heritage. Ann. Geoph. 43/2, 309e324. Caputo, R., Piscitelli, S., Oliveto, A., Rizzo, E., Lapenna, V., 2003. High-resolution resistivity tomographies in active tectonic studies. Examples from the Tyrnavos Basin, Greece. J. Geodyn. 36, 19e35. Chadwick, W.J., Madsen, J.A., 2000. The application of ground-penetrating radar to a coastal prehistoric archaeological site, Cape Henlopen, Delaware, USA. Geoarch. 15/8, 765e781. Chavez, R.E., Hernandez, M.C., Herrera, J., Camara, M.E., 1995. A magnetic survey over La Maya, an archaeological site in Northern Spain. Archaeom. 37, 171e184. Chavez, R.E., Camara, M.E., Tejero, A., Barba, L., Manzanilla, L., 2001. Site characterization by geophysical methods in the archaeological zone of Teotihuacan, Mexico. J. Arch. Sci. 28, 1265e1276. Chianese, D., Lapenna, V., Lorenzo, P., Perrone, A., Piscitelli, S., Rizzo, E., Sdao, F., 2003. Joint geophysical measurements to investigate the Rossano of Vaglio archaeological site affected by landslide phenomena (Basilicata region,
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