Delineation of graves and other subsurface features using electrical resistivity tomography

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Date
September, 2015
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Abstract
In response to rumours that the study area (a relatively at ground) used to be a royal cemetery and for future developmental purposes, this study aimed at delineating graves and other subsurface features so that informed decisions can be made about the place if the need arises. The survey was conducted on a 10000 m2 plot of land using the electri- cal resistivity method. The multi-electrode or CVES was combined with the roll along technique for data collection. With inter pro le separation of 2 m, 51 pro le lines were obtained. The data were acquired in 2D with a minimum electrode separation of 1 m and later collated to 3D. The gradient array was used taking the Grad4L8 and Grad4S8 pro- tocols into consideration. Data processing with the RES2DINV and RES3DINV software indicated wide resistivity variations in the near subsurface suggesting a disturbance of the soil at this level. This might have been caused by digging (probably graves) and re lling activities . High and low resistivity anomalies relative to their backgrounds were identi- ed within the rst 4 m of the subsurface. These were suspected to be tombs because of their rectangular geometries, dimensions and resistivity contrast with the background materials. The linear arrangement of these anomalies similar to the arrangement of tombs in cemeteries heightened this suspicion. Other subsurface features observed were also as- sociated with dykes, unweathered granite, cracks, voids etc. Consequently, the study area could have been a cemetery but can still support infrastructural development since the entire place was not covered by the anomalies. A weak zone spotted between 26 and 58 m in the S-N direction and between 30 and 70 m in the E-W direction must however be taken into consideration when carrying out constructional projects in the study area.
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A thesis submitted to the Department of Physics, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Master of Philosophy(Geophysics), 2015
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