Journal of Environmental Hydrology
ISSN 1058-3912

Electronic Journal of the International Association for Environmental Hydrology

JEH Volume 16 (2008), Paper 38    Posted December 8, 2008

I.B. Osazuwa1
C.C. Chiemeke1
N.K. Abdullahi1
C.C. Akaolisa2

1Advanced Geophysical Research Laboratories, Department of Physics, Ahmadu Bello University, Zaria, Nigeria
2Department of Geology, Federal University of Technology Owerri, Nigeria

Geo-electric and seismic refraction tomography were carried out to investigate the depth to basement complex in a confined area where there are serious limitations in spread length as a result of obstacles. The major instruments used for this survey where Terraloc Mark6 digital seismograph, sets of vertical geophones, SAS 4000 Terrameter and Electrode Selector ES 464. The layout geometry was such that both the receivers and source were in a straight line. The 24 geophones and the source point were located at intervals of 5 m, for a spread length of 120 m. In addition to the initial shot point, shots were fired at each geophone point. In the case of the geo-electric survey, the electrodes were laid out along the profiles at an interval of 2.5 m between the 41 electrodes, for a spread length of 100 m. In each of the profiles, geo-electric tomography was only able to penetrate down to a depth of 15 m at optimum current ejection into the subsurface. The geo-electric tomography could not reach the basement rock, except for the points where the basement complex is at a depth shallower than or equal to 15 m. For seismic refraction tomography the depth of penetration was greater than 30 m. It was possible to delineate the basement topography beyond a depth of 15 m along the profiles.

Reference: Osazuwa,I.B., C.C. Chiemeke, N.K. Abdullahi, and C.C. Akaolisa. 2008. Improved depth of penetration of geoelectric imaging in a confined area using refraction tomography. Journal of Environmental Hydrology, Vol. 16, Paper 38.
Nasir Khalid Abdullahi
Advanced Geophysical Research Laboratories
Department of Physics
Ahmadu Bello University
Zaria, Nigeria


Return to JEH 2008 Papers

Return to HydroWeb Homepage