Cavity Detection in the Southwestern Hilly Portion of Mexico City by Resistivity Imaging

Tejero, A.; Chávez, René E.; Urbieta, Javier; Márquez, Elsa Leticia Flores

doi:10.4133/jeeg7.3.130

Cited by 33 publications

(17 citation statements)

References 6 publications

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“…The potential function for a point electrode can be expressed as (Tejero et al . ):

U (\overset{r}{true}) = - \int_{V} σ ({\overset{r}{true}}^{'}) \overset{j}{true} ({\overset{r}{true}}^{'}) \cdot \nabla G (\overset{r}{true}, {\vec{r}}^{'}) d V .

…”

Section: The Attribution Point and The Sensitivity Functionmentioning

confidence: 99%

“…Unfortunately, in urban areas, there are few unobstructed spaces such as streets where it is possible to carry out the geophysical observations along 2D profiles (Tejero et al 2002). The separation between parallel streets can be much greater than the minimum distance recommended if grids or quasi-3D methods are considered.…”

Section: The Attribution Point and The Sensitivity Functionmentioning

confidence: 99%

“…Geophysical prospecting methods are challenged when it is necessary to characterize the subsoil beneath a building or a For a given electrode array, it is important to know the region of the half-space that most contributes to the observed response. The potential function for a point electrode can be expressed as (Tejero et al 2002): .…”

Section: The Attribution Point and The Sensitivity Functionmentioning

confidence: 99%

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L‐ and CORNER‐arrays for 3D electric resistivity tomography: an alternative for geophysical surveys in urban zones

Tejero‐Andrade

Cifuentes

Chávez

et al. 2015

Near Surface Geophysics

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Three‐dimensional electric resistivity tomography surveys carried out on heavily urbanized areas represent a cumbersome task since buildings, houses, or other types of obstacles do not allow parallel electric resistivity tomography lines to be deployed. This paper proposes applying any four‐electrode configuration to provide subsurface information in complex urban areas. Such a procedure allows acquiring information beneath a construction by simply surrounding the structure of interest by a series of electric resistivity tomography profiles. Apparent resistivity is obtained from ‘L’‐ and ‘Corner’‐shaped profiles, where alternations between current and potential electrodes are carried out in an automatic way. Four ‘L’‐arrays and four ‘Corner’‐arrays are employed in a square geometry that allows surrounding the studied target to cover the subsurface. The first mentioned array will provide deep information. The second array will cover more of the shallow subsurface information. For the ‘L‐’ and ‘Corner’‐arrays, a mixture of traditional arrays are employed, like the Wenner–Schlumberger, axial, equatorial, azimuthal, and perpendicular dipole arrays. Two synthetic examples are presented to demonstrate the possibilities of the proposed electric arrays. A resistive cube set at the centre of a working cube is modelled. The ‘L‐’ and ‘Corner‐’ arrays are capable to detect such a model; however, dimensions are exaggerated. Later on, an extended wall model is dealt with. Similar results as in the first synthetic example are obtained in terms of geometry and resistivity. However, depth to the top of the wall model is not adequately recovered in comparison with the traditional methodology. Finally, the ‘L’‐ and ‘Corner’‐arrays are applied in an archaeological site named El Pahñu, located in Central Mexico. The new methodology described here is compared with the traditional 3D procedure employing a grid of electric resistivity tomography transects. As expected, the approach discussed in this investigation produced a reasonable solution towards the central portion of the working cube. However, shallow resistive anomalies (size about the electrode interval) were not fully detected, in comparison to a traditional 3D survey, where parallel lines forming a grid could be deployed. The reason is that no electrodes were set towards the central portions of the structure under study. However, the L‐ and Corner‐arrays are more sensitive to anomalies produced by deeper objects, which cannot be observed in the traditional method, especially when objects are located in between the electric resistivity tomography transects.

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“…The potential function for a point electrode can be expressed as (Tejero et al . ):

U (\overset{r}{true}) = - \int_{V} σ ({\overset{r}{true}}^{'}) \overset{j}{true} ({\overset{r}{true}}^{'}) \cdot \nabla G (\overset{r}{true}, {\vec{r}}^{'}) d V .

…”

Section: The Attribution Point and The Sensitivity Functionmentioning

confidence: 99%

Section: The Attribution Point and The Sensitivity Functionmentioning

confidence: 99%

Section: The Attribution Point and The Sensitivity Functionmentioning

confidence: 99%

See 1 more Smart Citation

L‐ and CORNER‐arrays for 3D electric resistivity tomography: an alternative for geophysical surveys in urban zones

Tejero‐Andrade

Cifuentes

Chávez

et al. 2015

Near Surface Geophysics

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“…Resistivities were measured with STING (AGI) equipment, using a Wenner-Schlumberger configuration for better vertical and horizontal resolution (Tejero et al, 2002) with an electrode spacing of 1 m. Three profiles were collected in the E-W direction with a length of 60 m (profiles ET-1, ET-2 and ET-3), and the other three profiles in the S-N direction with lengths of 40 m (ET-4, ET-5 and ET-6). Real resistivities were computed by an inverse process employing the algorithm RES2Dinv (Loke and Barker, 1996;Tejero et al, 2002). An iterative process was carried out for each set of data until changes in the inverted resistivity values did not vary by 5% of error.…”

Section: Electric Tomographymentioning

confidence: 99%

Geophysical study of a Pre‐Hispanic lakeshore settlement, Chiconahuapan Lake, Mexico

Chávez

Tejero

Argote

et al. 2009

Archaeological Prospection

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Results ofa combined geophysical survey carried out along the northern shore of Lake Chiconahuapan in central Mexico are presented.The site contains a series of mounds found between the lakeshore and the ceremonial centre named La Campana-Tepozoco Hill. Those features are the remains of habitation complexes built by the lake residents about 1100 years ago. Archaeological excavations performed towards the northeastern margins of the lake uncovered rectangular clusters of basaltic rocks forming the foundations of ancient dwellings, surrounded by a barrier ('bordo'), built to prevent floods. A moundlocated close to the ceremonial centre was studied using the verticalmagnetic gradient (VMG), ground-penetrating radar (GPR) and electric tomography (ET) methods. Interesting magnetic anomalies were found towardsthe central portion of the mound and one ofthese was modelled with a three-dimensionalmagnetic polygon.The GPR studiesunveileda circular featureinthe centralportionofthemoundthat couldbeassociatedwitha bordo. A rectangular structure was also interpreted within the limits of that structure, which is probably the location of ancient dwelling foundations. Electric tomography profiles were collected in the area, around the VMG anomaly.The resistivity model computed shows the presence of a high-resistivity layer, which displays discontinuities within the area defined by the bordo. Presumably, the ancient settlers built their constructions on top of this horizon. The geophysical results reveal a rather complex habitat within the mound. The larger size of the bordo (ca. 30 m in diameter) compared with others already studied by archaeologists makes us believe that the purpose of the site was of administrative use or hosted a wealthy group of people.Dwelling foundations are found within the limits of the barrier. 6R. E. Cha´vez et al. Figure 6. Stepsfollowedtomodel VMGanomaly A. (B) Accordingto ZietzandAndreasen (1967)theremnanteffectcanberemoved. (C) Therefore,we have used three-dimensional magnetic blocks to compute the synthetic response. (D) Three-dimensional view of the magnetic model computed. 8 R. E. Cha´vez et al.Figure 7. (A) Three-dimensionalvisualization ofa processed GPR slice 0.5 m thick istaken at a depth of1.5 m. Ageneralview ofthe UTPlayerat that depth is obtained.The dashed lines show the main features depicted in this slice.The bordolimit is shown, as well as magnetic features A and B that maybeassociatedwithdwellingfoundations. (B) Observedprofiles GPR 30,18 and 06 arepresented.The UTPlayercanbeseenintheseradargrams.It is also possible to map the discontinuities in this layer. Circled A correlates with the position at the surface of VMG anomaly A shown in Figure 5. Arrows depict the location of the bordo limits, where the UTP layer shows a discontinuity.Pre-Hispanic Lakeshore Settlement, Chiconahuapan Lake, Mexico 9 Figure 8. Electric tomography (ET) profiles are shown in the west^east (A) and north^south (B) directions. Resistivity values between 270 ohm-m and 700 ohm-m have been plotted.The bordo limit...

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“…Numerous studies describe efficient geophysical techniques for application in hydrogeological and geological hazards studies in a karstic environment (Davis and Annan, 1989;Beres and Haeni, 1991;Holub and Dumitrescu, 1994;Robert and De Bosset, 1994;Benson, 1995;Casas et al, 1996;Carrozzo et al, 2000Carrozzo et al, , 2001Leucci et al, 2000;Miller et al, 2002;Tejero et al, 2002;van Schoor, 2002). However, since each technique is generally considered individually in a specific context, it is difficult to compare the results because of different field conditions.…”

Section: Introductionmentioning

confidence: 96%

Geophysical and Geological Investigations in a Karstic Environment (Salice Salentino, Lecce, Italy)

Leucci

Margiotta

Negri

2004

JEEG

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Karstic forms (dolines and sinkholes) are notoriously difficult geophysical targets, and selecting an appropriate geophysical solution is not straightforward. The fundamental objective in the application of geophysical techniques to environmental studies is to assess and use the correct techniques for the investigation being undertaken.Electrical Resistivity Tomography (ERT) and Ground-Penetrating Radar (GPR) investigations were carried out, primarily to assess the feasibility of geophysical investigations to map the underground stratigraphy of shallow karstic aquifers, in order to help in the prevention of both groundwater pollution from agricultural activities and risk of ground surface collapse. This preliminary study was carried out at two test areas (labelled area A and area B respectively) near Salice Salentino village, located few kilometers north-west of Lecce (Italy).The main characteristics of these areas are the high density of superficial karstic formation (dolines and sinkholes), the presence of numerous water supply wells, the intense use of fertilizers and pesticides in agriculture (mainly in the numerous vineyards for production of fine wines) and, therefore, the significant risk of groundwater contamination and ground surface collapse. Selected areas are presented in this paper as an example of the capabilities of the geophysical methods used.A series of two-dimensional resistivity profiles collected in the two areas reveal substantial differences in depth of investigation and resolution using Wenner-Schlumberger and dipole-dipole data collection techniques.ERT profiles were acquired using short (2 m electrode spacing, 48 m profile length) arrays in the area A as well as long (5 m electrode spacing, 240 m profile length) arrays. Earth models generated from field data acquired by the dipole-dipole array reveal more detail but lower depth of investigation than Wenner-Schlumberger array. The dipole-dipole array uniquely imaged isolated high resistivity bodies while Wenner-Schlumberger array consistently indicated significant horizontal and vertical resistivity variations.GPR profiles, which overlapped the ERT profiles, were acquired using the 200 MHz (center frequency) antenna for shallow high-resolution structural images. Distinctly different results were observed at the two locations. Encouraging correlations were noted between GPR and ERT data in the area A. The diffraction hyperbolic anomalies, visible on the radar sections, coincide with highresistivity anomalies on the electric model sections and this suggests the validity of a joint application of GPR and ERT methods for mapping karstic cavities or karstified zones.The resistivity distribution in area B shows an almost horizontal stratigraphy (gently dipping to the north), with resistivity values increasing with depth. The high absorption of the electromagnetic energy, noted in the GPR data, is probably due to the resistivity values below 20 Q m in the first 4-5 m in depth. These results suggest that GPR might be unsuccessful in the area B.

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Cavity Detection in the Southwestern Hilly Portion of Mexico City by Resistivity Imaging

Cited by 33 publications

References 6 publications

L‐ and CORNER‐arrays for 3D electric resistivity tomography: an alternative for geophysical surveys in urban zones

L‐ and CORNER‐arrays for 3D electric resistivity tomography: an alternative for geophysical surveys in urban zones

Geophysical study of a Pre‐Hispanic lakeshore settlement, Chiconahuapan Lake, Mexico

Geophysical and Geological Investigations in a Karstic Environment (Salice Salentino, Lecce, Italy)

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