Geophysical Investigation of Foundation Condition of a Site in Agbura Town Bayelsa State Using Electrical Resistivity Method

This study presents a geophysical investigation of the foundation conditions at a proposed construction site in Agbura Town, Bayelsa State, Nigeria, using the electrical resistivity method. The research is motivated by the increasing incidence of building failures in Nigeria, often attributed to inadequate understanding of subsurface conditions and neglect of pre-construction site investigations. The study area lies within the Niger Delta, characterized by soft, water-saturated, and compressible alluvial deposits that pose significant challenges to foundation stability. Vertical Electrical Sounding (VES) employing the Schlumberger array configuration was used to acquire subsurface resistivity data at selected locations. For interpretation, the IPI2Win software was employed. The data were processed and interpreted to delineate subsurface lithology, identify stratification, and determine the depth to competent layers suitable for foundation placement. The results enabled the identification of geoelectric layers, including topsoil, clayey formations, and more competent sandy strata at depth. Findings reveal the presence of weak, low-resistivity clayey and water-saturated zones in the near surface, which are unsuitable for supporting heavy structures due to their high compressibility and low bearing capacity. Conversely, relatively higher resistivity zones corresponding to sandy materials were identified at greater depths, indicating more competent layers for foundation support. The interpreted VES results revealed resistivity values ranging from 1.61 to 22,430 Ωm, indicating a subsurface sequence composed of conductive clayey materials, sandy/lateritic topsoil, weathered or fractured basement, and fresh basement rock. The low-resistivity zones, ranging from 1.61 to 15.3 Ωm, were interpreted as clayey or saturated clayey layers, while the higher-resistivity sandy/lateritic materials ranged from 99.4 to 575 Ωm. Fresh basement was identified by very high resistivity values between 6,133 and 22,430 Ωm. The study demonstrates that electrical resistivity methods provide a reliable, cost-effective, and non-invasive approach for evaluating subsurface conditions. It emphasizes the importance of integrating geophysical investigations into engineering site assessments to mitigate risks of structural failure. The results offer valuable insights for safe and sustainable foundation design in flood-prone and geologically complex environments like Agbura. It is recommended that geophysical investigations be integrated into pre-construction planning to minimize structural failure risks in the Niger Delta region.

Electrical, Resistivity, Geophysical, Foundation, Subsurface.

1. Abam, T. K. S. (2015). Geotechnical aspects of foundation engineering in Nigeria. Journal of Earth Sciences, 10(2), 45–60. [Google Scholar] [Crossref]

2. Adeyemo, I. A. (2004). Application of dipole-dipole array in road failure investigation. Nigerian Journal of Geophysics, 18(1), 23–30. [Google Scholar] [Crossref]

3. Akintorinwa, O. J., & Adesoji, J. I. (2009). Integrated geophysical and geotechnical investigation for engineering site characterization. Journal of Applied Sciences, 9(4), 561–567. [Google Scholar] [Crossref]

4. Ede, A. N., et al. (2025). Electrical resistivity studies of oil-impacted soils in Bayelsa State. Environmental Geophysics Journal, 12(1), 88–102. [Google Scholar] [Crossref]

5. Ibrahim, M., & Olatunji, S. (2021). Application of resistivity methods in engineering site investigations in southern Nigeria. African Journal of Earth Sciences, 45(3), 112–125. [Google Scholar] [Crossref]

6. Kehinde, O. O., et al. (2021). Causes of building collapse in Nigeria: A geotechnical perspective. Nigerian Journal of Engineering, 28(2), 67–75. [Google Scholar] [Crossref]

7. Mesida, E. A. (1987). Geotechnical properties of residual soils in southwestern Nigeria. Engineering Geology Journal, 25(3), 215–225. [Google Scholar] [Crossref]

8. Nwankwoala, H. O., & Walter, R. (2020). Subsurface characterization of Niger Delta soils. International Journal of Geosciences, 11(5), 301–315. [Google Scholar] [Crossref]

9. Oghenero, A. E., & Akankpo, A. O. (2019). Foundation challenges in the Niger Delta region. Journal of Environmental Geology, 7(2), 55–63. [Google Scholar] [Crossref]

10. Oyedele, A. A., et al. (2015). Electrical resistivity imaging for foundation studies. Geophysical Research Letters, 42(6), 210–218. [Google Scholar] [Crossref]

• Geophysical Investigation for Marl Exploration Using Vertical Electrical Sounding in Akpokponke Ibii Afikpo Southeast Nigeria
• Logging Data-Driven Geomechanical Parameter Estimation Using Advanced Machine Learning Techniques
• Seismic Refraction Tomography for Engineering Site Characterization in Awka, Southeastern Nigeria
• Design of a Competency Framework for BIM-Based Collaboration among Construction Professionals in Delta State
• Aeromagnetic Investigation of the Subsurface Sturctures in Parts of Niger Delta, Nigeria