GROUNDMAGNETIC INVESTIGATION INTO THE CAUSE OF THE SUBSIDENCE IN THE ABANDONED LOCAL GOVERNMENT SECRETARIAT, OGBOMOSO, NIGERIA

Adagunodo, T. A. and Sunmonu, L. A. and Oladejo, Olagoke Peter and Olafisoye, Emmanuel Rotimi (2013) GROUNDMAGNETIC INVESTIGATION INTO THE CAUSE OF THE SUBSIDENCE IN THE ABANDONED LOCAL GOVERNMENT SECRETARIAT, OGBOMOSO, NIGERIA. Journal of Earth Sciences, 2 (3). pp. 101-109. ISSN 2305-493X

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Abstract

Groundmagnetic was used to investigate the cause of the subsidence at an Abandoned Local Government Secretariat, Ogbomoso, Southwestern Nigeria with a view to determining whether the sinking and cracks in the plasterworks experienced at the Eastern side of the study area is due to subsurface features or insufficient use of building materials. The study took place at an Abandoned Local Government Secretariat Ogbomoso, Southwestern Nigeria which falls within latitude 080 09′ 50.6″ - 080 09′ 55.9″ and longitude 0040 15′ 36.1″ - 0040 15′ 42.3″. Proton Precision Magnetometer model GSM-19T was used to carry out the geophysical survey along four traverses in East-West and North- South directions. The traverses length ranges from 70m to 150m with inter station spacing of 10m. The results were presented as groundmagnetic profiles of varying magnetic intensities, groundmagnetic contoured map and groundmagnetic surface map. The basement topography was obtained from the profiles using half-width of the amplitude method. Areas with high magnetic values are the competent zones for construction while areas with low magnetic values are the weak zones. The quantitative interpretation gave the overburden thickness to the top of the magnetic basement rock as varied between 7.0m to 13.0m. Interpretation of groundmagnetic data revealed that the weak zones present at the Southeastern, Eastern and Northeastern part of the study area are the cause for the subsidence that occurred towards the Eastern side of the building. Contrary to the opinion of people that the building contractor used inferior building materials for the construction, we found out that half of the building is constructed on either collapse tunnel, fault or fracture which resulted into the sinking and new cracks in plasterworks experienced at the Eastern part of the abandoned Local Government secretariat.

Item Type:	Article
Uncontrolled Keywords:	subsidence, magnetic intensities, competent zones, collapse tunnel, fault, fracture.
Subjects:	Q Science > Q Science (General) Q Science > QC Physics
Divisions:	Faculty of Engineering, Science and Mathematics > School of Physics
Depositing User:	Mrs Hannah Akinwumi
Date Deposited:	18 Jan 2018 07:49
Last Modified:	18 Jan 2018 07:49
URI:	http://eprints.covenantuniversity.edu.ng/id/eprint/10063

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