scholarly journals Determination of cavities using electrical resistivity tomography

2012 ◽  
Vol 42 (2) ◽  
pp. 201-211 ◽  
Author(s):  
René Putiška ◽  
Maroš Nikolaj ◽  
Ivan Dostál ◽  
David Kušnirák
Keyword(s):  
Thin Layer ◽  
Electrical Resistivity Tomography ◽  
Electrode Arrays ◽  
Array Analysis ◽  
Resistivity Tomography ◽  
Cavity Detection ◽  
Model Situation ◽  
Geophysical Surveys ◽  
Resistivity Image

Abstract Geophysical surveys for cavity detection are one of the most common nearsurface applications. The usage of resistivity methods is also very straightforward for the air-filled underground voids, which should have theoretically infinite resistivity in the ERT image. In the first part of the paper, we deal with the comparison of detectability of the cavity by several types of the electrode arrays, the second part discusses the effect of a thin layer around the cavity itself, by means of 2D modelling. The presence of this layer deforms the resistivity image significantly as the resistive anomaly could be turned into a conductive one, in the case when the thin layer is more conductive than the background environment. From the electrical array analysis for the model situation a dipole-dipole and combined pole-dipole shows the best results among the other involved electrical arrays.

scholarly journals Determination of dipping contacts using electrical resistivity tomography

2012 ◽  
Vol 42 (2) ◽  
pp. 161-180
Author(s):  
René Putiška ◽  
Ivan Dostál ◽  
David Kušnirák
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Image Resolution ◽  
High Resistivity ◽  
Depth Range ◽  
Electrode Arrays ◽  
Resistivity Tomography ◽  
Imaging Geometry ◽  
Lithostratigraphic Units

Determination of dipping contacts using electrical resistivity tomographyGenerally, all electrode arrays are able to delineate the contact of two lithostratigraphic units especially with very high resistivity contrast. However, the image resolution for the location of vertical and dipping structures is different. The responses of dipole-dipole (DD), Wenner alpha (WA), Schlumberger (SCH) and combined pole-dipole (PD) arrays have been computed using the finite difference method. Comparison of the responses indicates that: (1) The dipole-dipole array usually gives the best resolution and is the most detailed method especially for the detection of vertical structures. This array has shown the best resolution to recognize the geometrical characterisation of the fault. (2) The pole-dipole has shown the second best result in our test. The PD is an effective method for detection of vertical structures with a high depth range, but the deepest parts are deformed. (3) Wenner alpha shows a low resolution, inconvenient for detailed investigation of dip structures. (4) The Schlumberger array gives a good and sharp resolution to assess the contact between two lithological units but gives poor result for imaging geometry of dipping contact.

scholarly journals An Extension of the Data-Adaptive Probability-Based Electrical Resistivity Tomography Inversion Method (E-PERTI)

Geosciences ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 380
Author(s):  
Marilena Cozzolino ◽  
Paolo Mauriello ◽  
Domenico Patella
Keyword(s):  
Electrical Resistivity ◽  
Apparent Resistivity ◽  
Electrical Resistivity Tomography ◽  
Inversion Method ◽  
Resistivity Tomography ◽  
Synthetic Test ◽  
Statistical Determination ◽  
Data Adaptive ◽  
Tomography Inversion

About a decade ago, the PERTI algorithm was launched as a tool for a data-adaptive probability-based analysis of electrical resistivity tomography datasets. It proved to be an easy and versatile inversion method providing estimates of the resistivity values within a surveyed volume as weighted averages of the whole apparent resistivity dataset. In this paper, with the aim of improving the interpretative process, the PERTI method is extended by exploiting some peculiar aspects of the general theory of probability. Bernoulli’s conceptual scheme is assumed to comply with any resistivity dataset, which allows a multiplicity of mutually independent subsets to be extracted and analysed singularly. A standard least squares procedure is at last adopted for the statistical determination of the model resistivity at each point of the surveyed volume as the slope of a linear equation that relates the multiplicity of the resistivity estimates from the extracted data subsets. A 2D synthetic test and a field apparent resistivity dataset collected for archaeological purposes are discussed using the new extended PERTI (E-PERTI) approach. The comparison with the results from the original PERTI shows that by the E-PERTI approach a significantly greater robustness against noise can be achieved, besides a general optimisation of the estimates of the most probable resistivity values.

scholarly journals The Discovery of the Theater of Akragas (Valley of Temples, Agrigento, Italy): An Archaeological Confirmation of the Supposed Buried Structures from a Geophysical Survey

Geosciences ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 161 ◽  
Author(s):  
Marilena Cozzolino ◽  
Luigi Maria Caliò ◽  
Vincenzo Gentile ◽  
Paolo Mauriello ◽  
Andrea Di Meo
Keyword(s):  
Electrical Resistivity Tomography ◽  
Research Work ◽  
Archaeological Excavation ◽  
Resistivity Tomography ◽  
Buried Structures ◽  
Multi Scale ◽  
Non Invasive ◽  
Ancient City ◽  
Geophysical Surveys

The theater of the ancient city of Akragas has been researched for centuries and, in 2016, a multidisciplinary and multi-scale research work that involved topographic studies, analysis of satellite images, geomorphological characterization of the land, archaeological surveys, and non-invasive geophysical surveys led to its discovery. In this work, a comparison between the archaeological structures hypothesized by geophysical results and the archaeological structure excavated is presented. The area of about 5.500 m2 was investigated using electrical resistivity tomography (ERT). The survey highlighted a series of resistivity highs arranged on concentric semicircles defining perfectly the presence of an articulate building attributable to a theatrical complex of imposing dimensions (diameter of about 95 m). Archaeological excavation led to the identification of the summa cavea with the discovery of foundation-level structures arranged on a semicircle, on which the tiers were located, and cuts in the rock with seat imprints. The overlap of the technical layouts obtained from the documentation of archaeological excavation on the modelled resistivity maps shows the perfect correspondence between the features of the resistivity highs and the ancient structures actually found.

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