Electrical Resistivity as a Geophysical Mapping Tool; A Case Study Of The New Art Department, Knust- Ghana (original) (raw)
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The study of electrical resistivity anisotropy in rocks has become important in increasing the accuracy of geological mapping using electrical resistivity survey. The study area, Odo Ara near Egbe, west central Nigeria, has been surveyed using electrical resistivity soundings. Sixty Radial Vertical Electrical sounding (RVES) measurements were carried out in the study area which comprises of the banded gneiss, amphibolites, schist and intrusive pegmatites. The aim of the study is to use the electrical resistivity anisotropy properties of the area to resolve its geological setup. The VES data showed a significant presence of electrical resistivity anisotropy. The VES curves obtained were predominantly of 3 geoelectric layer of H-type ( 1 > 2 < 3 ) curves; the topsoil, sandy clay/ clay layer and fractured basement. The pseudo-sections show a good correlation with the geoelectric section. Moreover, the iso-resistivity and isopach maps also show a significant correlation with the lithological and strike of the rocks in the area but due to the non uniqueness of electrical resistivity, the lithologic difference between the banded gneiss and the amphibolite at the south western part of the area could not be totally resolved. However, the combination of the anisotropy polygons and the iso-resistivity map has reduced the ambiguity inherent in using a single geophysical parameter.
Geological and Electrical Resistivity Sounding of Olokonla Area in North-Central Nigeria
Geological mapping and Electrical resistivity sounding were carried out in Olokonla area in Moro Local Government of Kwara State in order to determine the apparent resistivities of the subsurface lithologies and correlate them with the exposed rocks observed during the geological mapping. The studies also delineate the pattern of fractures in the area which form prefential pathways for ground water. Three vertical electrical soundings (VES) were performed radially adopting the Schlumberger electrode configuration, with half-current electrode separation (AB/2) varying from 1m to 100m. Anisotropy polygon was also constructed based on the radial electrical sounding. The geoelectric parameters revealed five subsurface layers which were interpreted as topsoil, lateritic soil, dry sand soil, weathered granite and granite respectively. The geological mapping showed that the area is underlain by crystalline rocks comprising biotite granite, granite-gneiss and migmatite. The anisotropy polygon showed that a major fracture direction along 60 0 (northeast to southwest) and the coefficient of anisotropy is 0.79. Based on the apparent resistivities and the structural disposition, a potential aquifer was inferred at a depth of 45m. The fracture pattern in the area was constrained to northeast to southwest direction. The data obtained would be useful in borehole drilling for water within the study area.
International Journal of Environmental Monitoring and Analysis, 2020
2D electrical resistivity imaging (ERI) and vertical electrical sounding (VES) were integrated to map the subsurface lithology at a pre-engineering construction site in Akure, southwestern Nigeria, in order to ascertain the competence and suitability of the site for engineering structures. Four 2D horizontal profiling (Wenner array) was used to qualitatively study and interprete the geoinformation of the lithological nature of each geoelectric layer within the study site. Four vertical electrical sounding were also conducted using Schlunberger configuration. The VES data were processed and inverted using master curves and WinResist computer software, while the 2D inversion was done using Diprowin. The results of the 2D horizontal profiling revealed that the study area is composed of four subsurface geo-electric layers with resistivities ranging between 6.91Ωm to 93.6Ωm. These results revealed an expansive clay formation to the depth probed. While the VES results showed a three subsurface geo-electric layers with resistivities ranging between 8.4Ωm to 640Ωm with the second layers where the foundation is supposed to be laid confirmed the presence of clay with resistivities ranging between 8.4Ωm to 13.0Ωm with depth ranging between 4.9m to 7.9m. The results revealed the site to be an expansive clay formation and showed that shallow foundation may not be feasible or advisable for massive engineering structures because of the presence of clay materials in the area. But small or light engineering structures may be recommended.
Journal of Physics: Conference Series, 2019
Electrical resistivity method has been performed using Vertical Electrical Sounding (VES) technique at a Bishop Smith Memorial College, Ilorin, Kwara State to examine the geophysical parameters that can be used to evaluate the subsurface competency. Eight VES stations were sounded, using Schlumberger configuration for data acquisition with current electrode spacing varying from 1.0 to 140.0 m. The VES data obtained were interpreted using ipi2win+ip Software. The field data acquired was presented as geoelectric sounding curves and geoelectric section. The interpretation of the field results revealed heterogeneous subsurface geologic sequence probed to 34.6 m and beyond. It also showed presence of near surface linear geologic structures of varying lengths, depths and attitude which suggest the competent zones for foundation laying. The major subsurface layers are the top soil which consists of interlocking and concretional lateritic stones and clayey sand, weathered basement, fracture...
The electrical resistivity investigation of Zuba and Tungamaje area, of Gwagwalada Area Council, Abuja, was carried out with a view to providing geology and geophysical information on the different sub-surface layers, depth, thickness, and distribution of the fractured basement as potential sources of groundwater. The basement rocks consist of a migmatite-gneisses, granite gneiss, and granite. The granite occurs in several locations of the study area. Twelve vertical electrical sounding stations were established utilizing the Schlumberger electrode configuration. The electrical resistivity data obtained where interpreted using IPI2win software. The results obtained from the analysis of the geophysical data showed that the study area is underlined by three geo-electrical layers. These layers are the topsoil, weathered layers, and fractured basement. The top soil layer of thickness and resistivity values ranging from 1.31-2.16m and 236-990 ohms meters, weathered layer ranging from 1.22-5.19m and 33.8-213 ohms meters and the fractured basement ranging from infinity in thickness and 397-966 ohms meters. Also, the study area lacks sufficient fractures and the thickness of the overburden was also thin for groundwater exploration activities.
Indonesian Journal of Earth Sciences/Indonesian Journal Of Earth Sciences, 2024
The electrical resistivity method was used to conduct a detailed examination of subsurface geology and hydrogeological parameters at the Petroleum Training Institute (PTI) Main Campus in Effurun, Nigeria. The research includes field data collecting, sounding curve interpretation, and dipole-dipole data processing. Both qualitative and quantitative methods were employed to gain a complete understanding of the hydrogeophysical features of the research area. The analysis revealed A and AK formations, which include four, five, and six-layer structures, highlighting the subsurface's intricacy. A frequency table was utilised to categorise the distribution of VES curves within the study area into three major groups. This classification was critical for characterising and comprehending the area's hydrogeological and geological complexity. Geo-electric sections were created to illustrate the different underlying layers, such as topsoil, clayey sand, sand, sandstone, and fracture. The study analyzed geoelectric properties and aquifer zones using resistivity isopach maps in 2D and 3D formats. The northeastern part of the study area had higher resistivity values, indicating geological variables affecting rock composition and groundwater supply. The findings are crucial for effective groundwater resource management, environmental assessments, and regional development planning. The geological model, combining data from dipole-dipole, geo-electric, and VES sections, accurately characterized subsurfaces in the PTI Campus area. The study identified six subsurface layers, providing baseline data for future infrastructure development. Recommendations include using advanced geophysical methods and a more detailed assessment of subsurface geology in the Warri region. This study adds to our understanding of the hydrogeological and geological aspects of the PTI Campus area, allowing us to make more informed judgements concerning environmental and infrastructure design. The study offers a comprehensive analysis of subsurface geology and hydrogeological parameters at PTI Main Campus, contributing valuable insights for groundwater management, environmental assessments, and regional development planning.
Journal of Geography and Mining Research, 2017
Fifteen vertical electrical sounding (VES) stations were sounded using Schlumberger electrode configuration. The result revealed a total of 3 to 4 geoelectric layers. The first layer with resistivity values range from 2.8 to 149.2 Ωm and has thickness and depth of 0.1 to 6.5 m. The second layer has resistivity which ranges from 245.9 to 7761.2 Ωm, thickness of 1.1 to 10.7 m and depth of 1.2 to 17.2 m. This layer was observed to be more resistive than the overlain layer. The third layer was delineated with the resistivity range of 49.4 to 2161.4 Ωm, thickness of 4.5 m-∞ and depth of 5.7 m-∞. The fourth layer has resistivity values which range from 203.3 Ωm-∞ within the maximum current electrode separation. The observed curve types are K, Q, KH and QK with K being the dominant curve type. The contour maps generated display the variation of the electrical properties of the subsurface layers. The lithology layer with clay is not suitable for building foundation due to their expansive nature while the laterite which is mechanically stable is suitable for building foundation. The lateritic layer to a depth of 1.2 to 3.0 m is considered suitable for massive engineering structures with strong base for solid foundation.
Indonesian Journal of Earth Sciences
This research was carried out within Institute of Agriculture Research and Training Moor Plantation Ibadan, Southwestern Nigeria, with the aim to ascertain suitability of the proposed site for building construction and usage. The geophysical investigation involved three electrical resistivity techniques; Vertical Electrical Sounding (VES) using the Schlumberger configuration, 2D ERT and 2-D electrical imaging using Dipole-dipole electrode configuration. Two traverses were established E–W direction cutting across geologic strike with a distance of 80 m and of varying inter-traverse spacing. Eight (8) VES stations were occupied covering the entire study area for layer stratification and geoelectric parameters. The results were qualitatively and quantitatively interpreted and are presented as sounding curves and geoelectric sections. The 2-D imaging gave information on the subsurface characteristic in the area with generally low apparent resistivity indicating low competence material. ...
2020
Geophysical investigation for engineering and environmental studies has been undertaken at the permanent site of Federal University Dutsin-ma, Katsina state. The study was aimed at assisting in the planning and development of infrastructure at the University, and also to investigate the groundwater potential of the permanent site at Turare which is less than 20km south of the current site the University occupies. Twenty-four Vertical Electrical Soundings (VES) were conducted along predetermined profiles at the permanent site in Dutsin-ma. Terrameter SAS 300 system was used for data acquisition at stations interval of 100m using Schlumberger array. Maximum current electrode separation (AB) of 200m was used. Interpretation was performed using computer software (Ipi2win and surfar7). The interpreted result was used to produce geoelectric and geologic sections. The result of the study indicated that the area is underlain by three to four subsurface layers. The resistivity of the first l...
The Vertical Electrical Survey (VES) survey of intrusive rocks in Lokpaukwu, Leru Community in Umunneochi Local Government Area of Abia State was carried out with a view to providing geology and geophysical information on the different sub-surface layers, depth, thickness, and to determine the viability of commercial mining of quarry rock materials within the study area. Eleven vertical electrical soundings were conducted using the Schlumberger array configuration covering the study area, with current electrode separation (AB/2) at 90m. The Electrical resistivity data were processed and interpreted by using IP12win software and the curve matching technique. Interpretations from the vertical electrical sounding (VES) data were used to generate Isopach and Isoresistivity contour maps in terms of thickness and resistivity of sub-surface layer using SURFER 10 software. The interpretation of the 11 VES locations suggested that only 4 of the locations could be considered to have appreciable presence of intrusive rock and the locations are VES 4, 5, 6 and 7. The overburden thickness of these VES locations is 15.8m, 10.8m, 3.42m and 15.3m respectively. From the analyses of the VES curves, it was revealed that the subsurface structure of 6 out of the 11 VES points were underlain by three layers while 4 were of five layer types and only 1 curve showed the presence of four layers in the sub-surface structure. The predominance of the three layer types as well as the low resistivity values obtained at most of the VES locations suggests the extent of fracturing in the study area. Quantitative analysis of data from the study area shows that the 'HK' type curves predominates in Lokpaukwu followed by 'A', 'H' and 'Q' type. 'A' type curves are obtained mostly in hard rock formations with conductive top soils. In this case, the resistivity of the layers will be continuously increasing (ρ1<ρ2<ρ3).