Non-invasive Geophysical Surveys in Search of the Roman Temple of Augustus Under the Cathedral of Tarragona (Catalonia, Spain): A Case Study

Abstract

An integrated geophysical survey has been conducted at the Tarragona's Cathedral (Catalonia, NE Spain) with the aim to confirm the potential occurrence of archaeological remains of the Roman Temple dedicated to the Emperor Augustus. Many hypotheses have been proposed about its possible location, the last ones regarding the inner part of the Cathedral, which is one of the most renowned temples of Spain (twelfth century) evolving from Romanesque to Gothic styles. A geophysical project including electrical resistivity tomography (ERT) and ground probing radar (GPR) was planned over 1 year considering the administrative and logistic difficulties of such a project inside a cathedral of religious veneration. Finally, both ERT and GPR have been conducted during a week of intensive overnight surveys that provided detailed information on subsurface existing structures. The ERT method has been applied using different techniques and arrays, ranging from standard Wenner-Schlumberger 2D sections to full 3D electrical imaging with the advanced Maximum Yield Grid array. Electrical resistivity data were recorded extensively, making available many thousands of apparent resistivity data to obtain a complete 3D image after a full inversion. In conclusion, some significant buried structures have been revealed providing conclusive information for archaeologists. GPR results provided additional information about shallowest structures. The geophysical results were clear enough to persuade religious authorities and archaeologists to conduct selected excavations in the most promising areas that confirmed the interpretation of geophysical data. In conclusion, the significant buried structures revealed by geophysical methods under the cathedral were confirmed by archaeological digging as the basement of the impressive Roman Temple that headed the Provincial Forum of Tarraco, seat of the Concilium of Hispania Citerior Province.

The ScanMars Subsurface Radar Sounding Experiment on AMADEE-18

“…Similar to seismic imaging, radar echoing returned by impinged signal reveals geological structures beneath the topographic surface. This technique has evolved under the name of ground penetrating radar (GPR) and has been applied to a broad range of studies, including glaciology (Annan and Davis, 1976;Arcone, 1996;Arcone et al, 2005;Bradford et al, 2009aBradford et al, , 2009bForte et al, 2013;Godio et al, 2015;Colucci et al, 2016;Del Gobbo et al, 2016;Godio and Rege, 2016;Santin et al, 2019), structural and sedimentary geology (Grasmueck, 1996;Bristow and Jol, 2003;Pipan et al, 2003;Neal, 2004;Ercoli et al, 2012), paleoenvironmental reconstructions (Pellicer et al, 2012;Tillmann and Wunderlich, 2014;Liu et al, 2019), seismotectonics (Liner, 1997;McClymont et al, 2008;Ercoli et al, 2014;Cinti et al, 2015), geotechnical engineering (Liu and Xie, 2013), and archaeology (Daniels, 2004;Jol, 2009;Solla et al, 2011;Ercoli et al, 2016;Kowalczyk et al, 2017;Casas et al, 2018). The GPR represents a powerful noninvasive imaging technique that is capable of collecting data from the subsurface with high spatial resolution in a relatively short time.…”

A Lightweight Prototype of a Magnetometric System for Unmanned Aerial Vehicles

“…In recent years, archaeological prospecting has benefited from important improvements due to the availability of high-resolution remote sensing techniques and their integration with geophysical methods with multiscale approaches [ 11 ]. This can provide a valid help in geoarchaeological contexts, with multiple purposes such as the historical reconstruction of landscapes and sites [ 12 , 13 ], preventive archaeology [ 14 ], management and conservation of the archaeological heritage [ 15 , 16 ], and non-invasive diagnosis through microgeophysical techniques [ 17 , 18 ].…”

Remote Sensing, Archaeological, and Geophysical Data to Study the Terramare Settlements: The Case Study of Fondo Paviani (Northern Italy)

“…Multichannel systems and new inversion techniques, developed between the 1980s and the 1990s, rapidly increased, in fact, the application and popularity of this technique in different archaeological contexts [7][8][9][10][11][12][13][14][15]. During the last 10 years, thanks to the development of 3D ERT surveys and new tools for 3D data inversion, this method enhances the possibility to reconstruct the spatial distribution and the shape of the archaeological targets, both in small or large areas, as well as in rural or urban context [16][17][18][19][20][21][22]. In this wide range of applications and possible uses of the ERT, undoubtedly, the main advantage offered by this method is An intensive agro-pastoral economy characterized the Terramare culture.…”