Two‐dimensional joint inversion of magnetotelluric and dipole‐dipole resistivity data

Sasaki, Yutaka

doi:10.1190/1.1442649

Cited by 275 publications

(179 citation statements)

References 19 publications

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“…By reducing the problem to a 2D geometry, the computer time required for the finite-element subroutine can be significantly reduced. Only a brief outline of the finite-element method is given here as the details can be found in other sources (Coggon, 1971;Sasaki, 1989). The DC response of a 2D structure is given by Poisson's equation,…”

Section: Numerical Inversionmentioning

confidence: 99%

Noninvasive monitoring of DNAPL migration through a saturated porous medium using electrical impedance tomography

Chambers

Loke

Ogilvy

et al. 2004

Journal of Contaminant Hydrology

112

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Electrical impedance tomography was used to monitor the movement of a fluorinated hydrocarbon DNAPL through a saturated porous medium within a laboratory column. Impedance measurements were made using a horizontal plane of twelve electrodes positioned at regular intervals around the centre of the column. A 2D inversion algorithm, which incorporated the cylindrical geometry of the column, was used to reconstruct resistivity and phase images from the measured data. Differential time-lapse images of DNAPL movement past the plane of electrodes were generated by the cell-bycell subtraction of resistivity and phase baseline models from those associated with the DNAPL release stage of the experiment.The DNAPL pulse was clearly delineated as resistive anomalies in the differential time-lapse resistivity images. The spatial extent of the resistive anomalies indicated that, in addition to vertical migration, some lateral spreading of the DNAPL had occurred. Residual contamination could be detected after quasi-static conditions were re-established. Residual DNAPL saturation was estimated from the resistivity model data by applying Archie's second equation. Despite significant measured phase changes due to DNAPL contamination, the differential phase images revealed only weak anomalies associated with DNAPL flow; these anomalies could be seen only in the initial stages of the experiment during peak flow through the plane of electrodes.

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Section: Numerical Inversionmentioning

confidence: 99%

Noninvasive monitoring of DNAPL migration through a saturated porous medium using electrical impedance tomography

Chambers

Loke

Ogilvy

et al. 2004

Journal of Contaminant Hydrology

112

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“…Apparent resistivity data from individual profiles were inverted using RES2DINV inversion algorithms developed by Loke & Baker (1996). The algorithm employs forward modeling subroutine to determine the apparent ground resistivity and thereafter uses a non-linear least squares optimisation techniques to invert the apparent ground resistivity data, clean the data by filtering out noisy data and effect correct depth matching based on electrode spacing to generate a two-dimensional (2D) true ground resistivity model of the subsurface (Sasaki 1989, Loke 1999, 2000, Loke et al 2013. The resultant inverted resistivity data from individual profiles were depth sorted into their corresponding depths of measurements as indicated in the inverted resistivity data.…”

Section: Data Processingmentioning

confidence: 99%

Application of radial electrical resistivity profile array for mapping deep vertical fractures in a proposed engineering construction site within the University of Ibadan Campus, Southwestern Nigeria

Osinowo

Falufosi

2018

geol

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Abstract:In this study we demonstrate the efficacy of radial electrical resistivity profile array in delineating deep narrow linear fracture that could constitute weakness in the subsurface, thus hindering foundation material in providing necessary support to proposed engineering construction, in the southeastern part of the University of Ibadan Campus, southwestern Nigeria, where nearby buildings show stress induced failure traceable to defect in foundation upon which the buildings were founded. Six electrical resistivity profile arrays were occupied at 0°/180°, 30°/210°, 60°/240°, 90°/270, 120°/300° and 150°/330° orientations to complete a clockwise 360° sweep at 30° interval. The radial profile array enabled subsurface features to be intersected at relatively high angle, thus making measurement of linear features of limited lateral extent feasible irrespective of their orientations. Low resistivity distribution which decreases in value with depth (300-8 Ωm) characterizes the northern part of the study area while relatively higher value that increases with depth (420-4150 Ωm) dominates the south. The occurrence of a narrow strip of low resistivity zone (8-170 Ωm) at 20 m, which gains prominence with depth, dividing relatively resistive zone in the southern part of the study area indicate the presence of a deep vertical fracture whose detection is essential to guide further foundation geotechnical studies as well as aid the design of appropriate foundation that would support the proposed engineering structure.

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“…Among these routines, the regularized least-squares optimization particularly with a smoothness constraint (Sasaki, 1989;deGroot-Hedlin and Constable, 1990;Loke and Barker, 1996;Li and Oldenburg, 2000;Loke et al, 2003) has become a popular technique for interpreting the ERT data sets. It is considered a flexible method that allows including some constrains during the inversion procedures.…”

Section: Inversion Schemementioning

confidence: 99%

Contribution of 3-D electrical resistivity tomography for landmines detection

Metwaly

El-Qady

Matsushima

et al. 2008

Nonlin. Processes Geophys.

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Abstract. Landmines are a type of inexpensive weapons widely used in the pre-conflicted areas in many countries worldwide. The two main types are the metallic and nonmetallic (mostly plastic) landmines. They are most commonly investigated by magnetic, ground penetrating radar (GPR), and metal detector (MD) techniques. These geophysical techniques however have significant limitations in resolving the non-metallic landmines and wherever the host materials are conductive. In this work, the 3-D electric resistivity tomography (ERT) technique is evaluated as an alternative and/or confirmation detection system for both landmine types, which are buried in different soil conditions and at different depths. This can be achieved using the capacitive resistivity imaging system, which does not need direct contact with the ground surface. Synthetic models for each case have been introduced using metallic and non-metallic bodies buried in wet and dry environments. The inversion results using the L 1 norm least-squares optimization method tend to produce robust blocky models of the landmine body. The dipole axial and the dipole equatorial arrays tend to have the most favorable geometry by applying dynamic capacitive electrode and they show significant signal strength for data sets with up to 5% noise. Increasing the burial depth relative to the electrode spacing as well as the noise percentage in the resistivity data is crucial in resolving the landmines at different environments. The landmine with dimension and burial depth of one electrode separation unit is over estimated while the spatial resolutions decrease as the burial depth and noise percentage increase.Correspondence to: M. Metwaly (mmetwaly70@yahoo.com)

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Two‐dimensional joint inversion of magnetotelluric and dipole‐dipole resistivity data

Cited by 275 publications

References 19 publications

Noninvasive monitoring of DNAPL migration through a saturated porous medium using electrical impedance tomography

Noninvasive monitoring of DNAPL migration through a saturated porous medium using electrical impedance tomography

Application of radial electrical resistivity profile array for mapping deep vertical fractures in a proposed engineering construction site within the University of Ibadan Campus, Southwestern Nigeria

Contribution of 3-D electrical resistivity tomography for landmines detection

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