Geoelectrical Resistivity Imaging Research Articles

Application of 2D and 3D geoelectrical resistivity imaging for engineering site investigation in a crystalline basement terrain, southwestern Nigeria

Orthogonal set of 2D geoelectrical resistivity field data, consisting of six parallel and five perpendicular profiles, were collected in an investigation site using the conventional Wenner array. Seven Schlumberger soundings were also conducted on the site to provide ID layering information and supplement the orthogonal 2D profiles. The observed 2D apparent resistivity data were first processed individually and then collated into 3D data set which was processed using a 3D inversion code. The 3D model resistivity images obtained from the inversion are presented as horizontal depth slices. Some distortions observed in the 2D images from the inversion of the 2D profiles are not observed in the 2D images extracted from the 3D inversion. The survey was conducted with the aim of investigating the degree of weathering and fracturing in the weathered profile, and thereby ascertaining the suitability of the site for engineering constructions as well as determining its groundwater potential.

Determination of cave geometry by using a geoelectrical resistivity inverse model

Determination of the geometry and the dimensions of a cave is an important factor considered for planning geotechnical, archeological, speleological studies, and quarrying activities. In recent years, researchers have raised an increasing number of questions related to the shape and size of cavities using 2D geoelectrical resistivity imaging techniques. The inverse model is valuable in detecting the location and extent of subterranean cavities. In this study, a 2D geoelectrical resistivity imaging technique is employed to determine the geometry of a known subterranean cavity. The results provided valuable information and demonstrated the effectiveness of the technique for exploring the size of cavities.

Geophysical mapping of saltwater intrusion in the Kerpan coastal area, Kedah

The salinity of the ground water in the coastal alluvial aquifer between Kerpan-Air Hitam and Sang lang area in Kedah was investigated using both vertical geoelectrical sounding (VES) and 2-D geoelectrical resistivity imaging techniques. The resistivity measurements were made using ABEM SAS 300C and SAS4000 terrameters. A total of 61 VES stations were established over an area of approximately 100 km2 of Quaternary alluvium. The 2-D imaging was used to study the lateral and vertical changes in resistivity of the alluvial sediments. Salinity of the ground water was interpreted based on the apparent resistivity values. Ground water with resistivity values less than 5 ohm-m is considered as saline and those of greater than 100 ohm-m is fresh water. The resistivity values ranging from 5 to 100ohm-m is for brackish water. The VES and imaging results show that the ground water has resistivities ranging from 0.53 to 670.5 ohm-m. The results of spatial distributions of apparent resistivity indicate that the ground water is mainly brackish with the salt-water affected aquifer confined to the coastal part of the study area. Vertical variations of the resistivity values plotted along profiles perpendicular to the coastal line, indicate that the saltwater has significantly affected the ground water at depth and far away from the coastal area.

High resolution seismic reflection and geoelectrical resistivity imaging at Pengkalan School Teacher\'s Quarters, Pegoh, Ipoh, Malaysia

Seismic reflection and geoelectrical resistivity imaging techniques were employed to investigate the shallow features of buried karstic limestone of Kinta Valley limestone formation because the sinkholes and cavities are quite common in this formation. The techniques were conducted along three traverse lines to evaluate the subsurface ground conditions for construction work of the school teacher's quarters blocks. The site is located at Pengkalan, Pegoh in Ipoh district ofPerak. The limestone bedrock topography has complex phenomena and highly relief subsurface topography due to the presence of karstic features. These features rise considerable difficulties in both the design and construction of the foundations, such as: foundation stability, settlement, and subsidence during the construction in this site. These geotechnical problems arise whenever foundations are established on the surface of the limestone bedrock or within the overburden soils. The common depth point (CDP) shallow seismic reflection sections of the traverse lines show clearly the displacement system within the bedrock and the poor reflection data. This displacement system is usually associated with sinkholes or slow subsidence in the site caused by chemical dissolution. The poor reflection data qualities in the CDP sections were interpreted as voids of cavity zone. The Two dimensional resistivity inverse models of the traverse lines are showing the low resistivity anomalies. These anomalies are interpreted to represent swallow holes and determine the location of cavities zone. Interpretation based on the combination of seismic reflection and electrical resistivity imaging survey has been a successful and satisfactory way to identify the location of the surface depression and subsurface conditions.