Structural analysis of subsurface stability using aeromagnetic data: a case of Ibadan, southwestern Nigeria

This study is aimed at investigating the subsurface stability of Ibadan against tremor occurrence and to check how safe the subsurface is for civil engineering constructions. High resolution aeromagnetic data of Ibadan (Sheet 261) were processed using automated approach. The data were further enhanced using the Total Horizontal Derivative (THDR) in order to determine the orientations of the lineaments in the study area. The orientations of the lineaments obtained from the THDR map revealed that the Pan African orogeny constitutes 50%; Kibaran orogeny constitutes 33%, while Liberian orogeny constitutes 17% lineaments in the study area. Based on orientation of faults on magnetic fault map obtained from the superposition of the lineaments extracted from THDR map on the geological map of the study area, three distinct set of sinistral/dextral faults were recognized in Ibadan. These include: NE-SW, ENE-WSW and NW-SE fault trend. This suggests that NE-SW and ENE-WSW fault-set could be responsible for the tremor experienced in Ogun state and Ibadan respectively. It is concluded that the study area is not immune from experiencing occurrences of tremors from time to time.