This study addresses geotechnical challenges in fractured limestone environments by integrating electrical resistivity tomography (ERT), seismic refraction, and direct current (DC) resistivity soundings with borehole data in New Minia city, Upper Egypt. The objective was to delineate shallow subsurface heterogeneity and structural discontinuities and to establish correlations between geophysical and geotechnical parameters. A genetic algorithm (GA) optimization was applied to DC resistivity inversion, reducing non-uniqueness and improving model convergence. Seventeen boreholes (10 m depth) provided constraints for calibration and validation. Results reveal three principal subsurface sequences: (1) sandy–silty soil with clay intercalations, (2) heterogeneous intermediate deposits, and (3) fractured limestone bedrock. Major structural features, including north–south trending faults, were clearly identified. The integrated approach enhances subsurface characterization, reduces interpretational uncertainty, and provides a robust framework for hazard assessment and urban planning in complex carbonate terrains.
Peat soils within Sarawak region pose significant challenges to road embankment construction due to their high compressibility, low shear strength, and spatial variability. This study employs 2D Electrical Resistivity Tomography (ERT) as a rapid, non-invasive technique to evaluate peat settlement behavior along the Sebuyau–Lingga (Package B1) section of the Sarawak Second Trunk Road (SSTR). Multiple ERT profiles were acquired across the alignment to delineate peat thickness, identify subsurface variability, and characterize soft ground conditions. In-Peat geomechanical monitoring data were integrated to correlate and validate resistivity interpretation. Results show a clear relationship between resistivity values and measured settlement magnitude, with low-resistivity zones corresponding to highly compressible peat layers. Field settlement observations further support these correlations. The integrated geophysical– geotechnical approach enhances the rapid detection of critical soft ground sections, improves investigation efficiency, and supports more informed design and construction decisions in peat-dominated terrain. Additionally, the resistivity method effectively differentiates between hard-filled embankment materials, peat, and clay, providing valuable subsurface characterization for construction control.
J. Tay, A. Hasan, Cassidy Morris et al.· E3S Web of Conferences· 0 citations
Rapid urban expansion along Egypt’s northwestern Mediterranean coast requires reliable subsurface characterization capable of supporting both geotechnical safety and sustainable groundwater management. This study integrates 87 Electrical Resistivity Tomography (ERT) profiles with borehole logging data, including gamma ray (GR), spontaneous potential (SP), and granulometric analyses, to establish a high-resolution geotechnical and hydro-stratigraphic framework for the Ras El-Hekma coastal zone in Egypt. The integrated dataset resolved four principal subsurface units with distinct resistivity signatures, lithological compositions, and engineering characteristics, calibrated through co-located borehole logs and laboratory granulometric analyses. Statistical analyses revealed strong inverse relationships between resistivity and both porosity (r ≈ − 0.52; r ≈ − 0.85 for thickness-corrected values) and clay content (r ≈ − 0.78; 95% CI (− 0.85, − 0.69)), while GR values showed a strong positive correlation with clay percentage (r ≈ 0.95; p < 0.001). The third geoelectrical layer, dominated by clay-rich Pliocene shale, represents the most problematic geotechnical unit, characterized by resistivity values below 12 Ω·m, clay content exceeding 34%, and thicknesses ranging from approximately 1.5 to 3.5 m. Spatial analysis demonstrates marked NE–SW heterogeneity associated with buried oolitic ridges, sabkha environments, and localized saline intrusion. Based on integrated petrophysical signatures, the study area was classified into four competency zones (A–D), each linked to specific foundation and ground-improvement recommendations. The proposed workflow provides a transferable, cost-effective framework for coastal arid regions by combining geophysical imaging, borehole calibration, and statistical interpretation to support sustainable urban planning, infrastructure development, and subsurface risk assessment.
Raghda M. Abd Elhamid, A. Basheer, M.S. Toni et al.· Scientific Reports· 0 citations
Local geological conditions strongly influence seismic-wave propagation and earthquake ground response, particularly in heterogeneous volcanic environments. This study aimed to characterize shallow subsurface conditions and assess local seismic site response in Setiling Village, Central Lombok, Indonesia, by integrating two-dimensional Electrical Resistivity Tomography (ERT) using the Wenner–Schlumberger configuration with Spatial Autocorrelation (SPAC)-based microtremor analysis. Three ERT profiles and twenty SPAC measurement points were acquired to evaluate subsurface heterogeneity and near-surface stiffness. The ERT results revealed significant resistivity variations associated with volcanic lithology, weathering intensity, moisture content, and groundwater conditions. Conductive zones (<100 Ωm) were interpreted as highly weathered volcanic deposits, whereas higher resistivity zones (>600 Ωm) represented relatively competent volcanic materials. SPAC-derived Vs30 values ranged from 150 to 525 m/s, corresponding to NEHRP Site Classes C, D, and E. Integrated interpretation demonstrated a consistent relationship between resistivity and Vs30, indicating that progressive volcanic weathering simultaneously reduces electrical resistivity and subsurface stiffness. The integrated ERT–SPAC approach provides a reliable framework for village-scale seismic site characterization, supporting seismic hazard assessment, risk-informed spatial planning, resilient infrastructure development, and disaster risk reduction in tropical volcanic regions.
With the accelerated advancement of smart city construction, the development of urban underground space in coastal areas faces significant safety challenges due to randomly distributed granite boulders. Conventional geophysical methods often struggle to identify these heterogeneous bodies efficiently. This study proposes a comprehensive detection approach fusing the Cone-based Transient Electromagnetic Method (CTEM) and Microtremor Array Surveying. Taking the eastern coast of Jiaozhou Bay, Qingdao, as the research area, we integrated borehole data to validate the geophysical interpretation. The results demonstrate that the joint inversion accurately delineates four stratigraphic interfaces with depths consistent with borehole logs: the artificial fill (bottom at ~8–12 m), Quaternary sediments (~28–33 m), strongly weathered granite (~59–74 m), and moderately weathered granite. Specifically, boulders within the Quaternary and strongly weathered layers are distinctly identified by dual high-value anomalies: high apparent resistivity (>220 Ωm, approximately 1.5–2 times that of the surrounding rock) and high shear-wave velocity (>660 m/s). Furthermore, the method effectively differentiates boulders from water-rich fractured zones, which exhibit contrasting low resistivity (<50 Ωm) and low shear-wave velocity (<420 m/s). These quantitative findings confirm that the fused CTEM and microtremor technique provides precise spatial localization and reliable identification of boulders in complex coastal geological environments.
Wenyue Li, Haiyan Yang, Zhixin Liu et al.· Applied Sciences· 0 citations
Groundwater resources within mining environments are increasingly threatened by contaminant infiltration and radionuclide migration resulting from intensive mineral exploitation. This study integrates Vertical Electrical Sounding (VES), Two-Dimensional Electrical Resistivity Tomography (ERT), and radiometric techniques to assess groundwater vulnerability and soil contamination in the Rayfield mining area of Jos Plateau, North-Central Nigeria. Geoelectrical investigations were conducted to delineate subsurface lithology, identify aquifer units, and evaluate groundwater vulnerability, while radiometric analyses were performed to determine the distribution and potential hazards of naturally occurring radionuclides. The VES results revealed a seven-layer geoelectric succession characterized by an HQ-type curve, with resistivity values ranging from 20.5 to 509 Ωm. A thick fractured basement aquifer with a resistivity of 271 Ωm and thickness of approximately 36.2 m constitutes the principal groundwater reservoir. ERT imaging delineated three distinct subsurface zones comprising a conductive contaminated zone, saturated weathered materials, and consolidated lateritic-basement formations. A prominent low-resistivity anomaly (<36.5 Ωm) was interpreted as a contaminant plume associated with mining-derived leachates and radionuclide-enriched pore fluids, indicating active contaminant migration through weathered and fractured pathways. Radiometric assessment showed mean values of 88.91 Bq kg⁻¹, 279.4 μSv y⁻¹, 0.24, 0.33, and 0.17 × 10⁻³ for Raeq, AGED, Hex, Hin, and ELCR, respectively, all below internationally recommended limits. However, localized radionuclide enrichment was observed at specific lithological horizons. The integrated interpretation indicates moderate to high groundwater vulnerability despite favourable groundwater potential. The study demonstrates that combining geoelectrical and radiometric methods provides an effective framework for identifying contaminant migration pathways, evaluating environmental risks,...
T. T. Bem, Y. Onifade, E. Agbalagba· FUDMA Journal of Sciences· 0 citations
The groundwater distribution in southern Egypt is primarily governed by the region’s inherited rift-related tectonic framework. We integrated aeromagnetic data with available hydrogeochemical and seismic data to investigate structural controls on groundwater accumulation in El-Gallaba Plain along the western margin of the Kom Ombo Basin. The magnetic data were processed using edge-detection filters and source-parameter imaging to estimate the depth of the basement rock. Moreover, three-dimensional geophysical inversion of magnetic data was performed using the iteratively re-weighted least-squares algorithm to map the basin geometry. The results of magnetic data interpretation delineated a NW-SE major trend and minor NE-SW-trending, fault-bounded depressions extending to depths of 2.5–3.0 km, interpreted as sediment-filled or altered-basement fractured basins favorable for groundwater accumulation. Uplifted basement blocks define structural highs that act as hydraulic barriers, compartmentalizing the area’s aquifer system. The interpreted magnetic structures were correlated with previously published land-surface temperature and hydrochemical data, revealing a spatial alignment among deep structural depressions, low-temperature corridors, and zones of fresher, isotopically depleted groundwater. This correlation confirms that reactivated Pan-African and Cenozoic faults control the vertical permeability and groundwater connectivity of the Nubian Sandstone Aquifer. Overall, this study highlights the effectiveness of three-dimensional inversion, along with edge-detection and depth-estimation filters applied to magnetic data to resolve subsurface architecture and interpret groundwater potential in arid, tectonically complex regions.
Mohammad A. Shehata, Tamer Attia, T. Farag et al.· Applied Water Science· 0 citations
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