We test here the feasibility of ground-penetrating radar (GPR) and microgravity methods in identifying underground voids, such as cellars, tunnels, abandoned mine-workings, etc., in complex urban conditions. For this purpose, we selected a cellar located under a private lot in a residential quarter of the town of Senec in Western Slovakia, which was discovered by chance when a small sinkhole developed on the yard just two meters away from the house. The size of our survey area was limited 1) by the presence of a technical room built at the back of the yard with a staircase leading to the garden, and 2) by the small width of the lot. Therefore the geophysical survey was carried out only in the backyard of the lot as we were not permitted to measure on neighbouring estates. The results from the GPR measurements obtained by the GSSI SIR-3000 system with 400 MHz antenna were visualized in the form of 2D radargrams with the corresponding transformed velocity model of studied cross-sections. Only the profiles running over the pavement next to the house yielded interpretable data because the local geological situation and the regular watering of the lawn covering prevailingly the backyard caused significant attenuation of the emitted GPR signal. The Bouguer gravity map is dominated by a distinctive negative anomaly indicating the presence of a shallow underground void. The quantitative interpretation by means of Euler deconvolution was utilized to validate the depth of the center and location of the cellar. Comparison with the gravitational effect of the cellar model calculated in the in-house program Polygrav shows a quite good correlation between the modelled and observed fields. Only a part of the aerial extent of the anomaly could be traced by the used geophysical methods due to accessibility issues. Nevertheless, the test cellar was successfully detected and interpreted by both methods, thus confirming their applicability in similar environmental and geotechnical applications, even in complex urban conditions.
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Al-Rifaiy I. A. 1990: Land subsidence in the Al-Dahr residential area in Kuwait: a case history study. Quarterly Journal of Engineering Geology and Hydrogeology 23 337–346.
Banham S. G. Pringle J. K. 2011: Geophysical and intrusive site investigations to detect an abandoned coal-mine access shaft Apedale Staffordshire UK. Near Surface Geophysics 9 483–496.
Cardarelli E. Cercato M. Cerreto A. Di Filippo G. 2010: Electrical resistivity and seismic refraction tomography to detect buried cavities. Geophysical Prospecting 58 685–695.
Corel Draw Version 12 2004 Corel Corporation USA Canada. Reflex-Win PreVersion 7.0 1997–2012 Sandmeier software Karlsruhe Germany.
Daniels J. 1988: Locating caves tunnels and mines. Geophysics: the Leading Edge 7 32–37 and 52.
Daniels D. J. 2004: Ground penetrating radar 2nd edition. Published by the Institution of Electrical Engineers London United Kingdom. p. 734.
Götze H. J. Lahmeyer B. 1988: Application of three-dimensional interactive modeling in gravity and magnetic. Geophysics 53 1096–1108.
Grapher Version 9 2012 Golden Software Colorado USA. SIR System – 3000 Manual 2011 Geophysical Survey Systems Inc New Hampshire USA.
Jol H. M. 2009: Ground Penetrating Radar: Theory and Applications. Elsevier Science Amsterdam First edition 2009 p. 508.
Long L. T. Kaufmann R. D. 2013: Acquisition and Analysis of Terrestrial Gravity Data. Cambridge University Press Cambridge UK p. 171.
Marušiak I. Mikuška J. 2013: Toposk – software for terrain corrections evaluation. Manual G-trend Ltd. Bratislava manuscript 1–12 (in Slovak).
Negri S. Margiotta S. Maria Quarta T. A. Castiello G. Fedi M. Florio G. 2015: Integrated analysis of geological and geophysical data for the detection of underground man-made caves in an area in southern Italy. Journal of Cave and Karst Studies. 77 52–62.
Pánisová J. Pašteka R. Papčo J. Fraštia M. 2012: The calculation of building corrections in microgravity surveys using close range photogrammetry. Near Surface Geophysics 10 391–399.
Pašteka R. Richter P. Karcol R. Brazda K. Hajach M. 2009: Regularized derivatives of potential fields and their role in semi-automated interpretation methods. Geophysical Prospecting. 57 507–516.
Reid A. B. Allsop J. M. Granser H. Millett A. J. Somerton I. W. 1990: Magnetic interpretation in three dimensions using Euler deconvolution. Geophysics 55 80–91.
Scintrex 2006: CG-5 Scintrex Autograv System Operation Manual 2006: Ontario Canada. Scintrex Limited Nr. 867700 Rev. 4 p. 308.
Styles P. McGrath R. Thomas E. Cassidy N. J. 2005: The use of microgravity for cavity characterization in karstic terrains. Quarterly Journal of Engineering Geology and Hydrogeology 38 155–169.
Styles P. Toon S. Thomas E. Skittrall M. 2006: Microgravity as a tool for the detection characterization and prediction of geohazard posed by abandoned mining cavities. First Break 2 4 51–60.
Tuckwell G. Grossey T. Owen S. Stearns P. 2008: The use of microgravity to detect small distributed voids and low-density ground. Quarterly Journal of Engineering Geology and Hydrogeology 41 371–380.
Yule D. E. Sharp M. K. Butler D. K. 1998: Microgravity investigations of foundation conditions. Geophysics. 63 95–103.