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Geodynamics is the study of the forces and their effects on motion and physics of the processes and the phenomena attending the steady evolution of the earth and the changes that are still going on. This study revealled the significance of electrical resistivity method on effect of geodynamic activities on an existing Dam monitoring at Ojirami Dam, Edo State, Nigeria. The electrical resistivity method involved three techniques: 2D Electrical Resistivity Tomography (ERT), Vertical Electrical Sounding (VES) and Horizontal Profiling (HP). 2D ERT using Dipole-Dipole electrode array with inter-station separation of 5 m and an expansion factor that varied from 1 to 5 with Nine (9) VES were carried out using Schlumberger array with current electrode spacing varying from 1.0 to 65.0 m and HP using Wenner array with an electrode spacing of 20 m and electrode movement at 5 meters. The 2-D imaging (Dipole-Dipole) gave information on the subsurface characteristic which section delineated five major geologic layers comprising of the topsoil, weathered basement, fractured zone, partly fractured basement and the fresh basement. The geoelectric sections identified three to four geoelectric/geologic subsurface layers along the traverse. The HP revealled the pattern of resistivity variations within the subsurface. The entire results correlate well with one another showing that all the techniques used were complemented. The combination of these techniques has proved effective and useful in geodynamic activities of the existing dam. Ojirami Dam is at a critical point of yielding to activities of geodynamic processes that may occur from the main axis, of major weak zones as observed between 75 to 95.00 m and 115 to 145.00 m. Hence, there is need to call government attention for further confirmatory test using other

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As part of effort to examine the factors responsible for highway failure in the sedimentary terrain, geophysical survey involving Very Low Frequency Electromagnetic (VLF-EM), Schlumberger Vertical Electrical Sounding (VES), and dipole-dipole electrical resistivity techniques were carried out along Iruekpen-Ifon highway. This was aimed at using surface geophysics to characterize and identify the factors responsible the for road failures along Iruekpen-Ifon highway. ABEM WADI instrument was used to obtain electromagnetic-Very Low Frequency (VLF) field data, while ABEM resistivity meter was used to obtain electrical resistivity field data. The VLF-EM data were interpreted using the VLF Graphic software, VELFAN 1.0 double plot of filtered real and filtered imaginary against distance. The VES data obtained were interpreted using IP 2 Win software. Geoelectric parameters were used to generate the Dar Zarrouk second order parameters. 2-D inversion modeling of the dipole-dipole data was carried out using ZONDRES window software. VLF-EM result suggested varying degree of conductivity in the area and the wide spread of clay/metallic ore and water in the study area. Results show that the topsoil generally varies in composition from clay to clayey and laterite with resistivity values varying from 89 to 400 Ωm and thickness between 0.2 and 4.0 m. The fractured layers composed of clay and compacted clayey sand which represents the recent alluvial deposits with resistivity values of 2 to 89 Ωm and the thickness between 1.5 and 11 m. The fresh water zone is characterized by low resistivity ranging from 0.5 to 23 Ωm, which is diagnostic of saline water saturated with clay formation, fresh water ingression, and marls. The values of co-efficient of anisotropy () range from 1.03 to 2.19. The relatively higher values of λ (1.30 to 2.19) suggest that the subsurface rocks in these areas are likely to be more intensely fractured and more permeable. The saline water saturated with clay formation, fresh water ingression, fracture and marls clearly limit the lithological contacts and enhance high swelling potential which might be responsible for the road pavement failures in the studied area.