Onwubuariri, Chukwuebuka Nnamdi2026-05-302026-05-302015-11Onwubuariri, C. N. (2015). Identification of neo-tectonic zones and their effect in the development of gullies within Orlu and environs, SouthEastern Nigeria [Unpublished Master's Thesis]. Federal University of Technology Owerri, Nigeriahttps://repository.futo.edu.ng/handle/20.500.14562/2784This thesis is for the award of Master of Science (MSc.) in GeophysicsA detailed geoscientific study was carried out within Orlu and environs with the objective of evaluating the influence of tectonic and neo-tectonic features on gully development and propagation in the study area. Field geological mapping was carried out to characterize the gullies and to estimate the strikes and directional attributes of the gullies. Similarly, GIS interpreted Landsat-ETM imageries were used to map lineaments, evaluate their trends and to infer their possible tectonic significance in the study area. Azimuthal resistivity sounding was carried out at various locations within the study area to determine the direction of electrical anisotropy as well as the coefficient of anisotropy. They were rotated in four azimuths at angles of 00 , 450 , 900 and 1350 corresponding to the N-S, NE-SW, E-W and NW-SE directions. Similarly, vertical electrical sounding (VES) was also carried out using a maximum current electrode separation of 400m. Finally, a detailed geotechnical analysis of the soils within the locations of the gully sites was carried out to evaluate the properties of the soils within the study area. Results of the geotechnical analysis revealed that the soils in the study area are predominantly moderately sorted sand, poly-modal, symmetrical and leptokurtic. The Optimum Moisture Content ranges from 8.8% to 11%, while the Maximum Dry Density ranges from 1.91% to 1.99%.Atterberg test results revealed Liquid Limits ranging between 22.8% and 35%, Plasticity Limit of between 13.7% and 25%, and Plasticity Index varying between 6% and 10.6%.Results of Vertical Electrical Sounding(VES) carried out in the study area revealed that the resistivity of the first layer varies from 65.168 m to5,970 m with an average of 1,155.209 m with thickness values of 0.6106m to 4.8m respectively. Geological field mapping of the study area revealed that the gullies in the study area trend approximately in the NW-SE and NE-SW directions with the NE-SW direction being preponderant. Similarly, Rose diagrams generated from the strikes and lengths of lineaments interpreted from Landsat-ETM+ images revealed two structural trends of NW-SE and NE-SW with the NW-SE being dominant. Results of the azimuth frequency diagrams generated from the anisotropic resistivity soundings revealed uni-modal to poly- modal pattern with the dominant trend directions observed to be in the NW-SE and NE-SW directions. The correlation of the trends of the gullies with the lineament trends from landsat and the direction of electrical anisotropy suggests that gully origin and propagation in the study area may be structurally or tectonically controlled.enAttribution-NonCommercial-ShareAlike 4.0 InternationalNeo-tectonismlandsat-ETMerosionazimuthlineamentsresistivityatterbergDepartment of GeologyMaster’s Thesis