Scholarly works
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Item Peak particlevelocitydataacquisitionfor monitoring blast induced earth quakes in quarry sites(Elsevier Inc., 2018) Hammed, O. S.; Popoola, O. I.; Adetoyinbo, A. A.; Awoyemi, M. O.; Adagunodo, T. A.; Olubosede, O.; Bello, A. K.The peak particle velocity datasets recorded during quarry blasts in the neighborhood villages and towns in Ibadan and Abeokuta were processed and analyzed in order to recommend a safe blast design for each of the quarries. The minimum peak particle velo- city of 48.27 mm/s was recorded near the foundation of the nearest residence at the shot to monitored distance of 500m. The ten- dency of ground vibration emanating from the quarry sites to cause damage to the structures in the nearby dwelling areas is very high. The peak particle velocity datasets recorded were not within the safe limit. Therefore, the peak particle velocity that will not exceed 35 mm/s is recommended for a safe blast designItem Focal depth, magnitude, and frequency distribution of earthquakes along oceanic trenches(Springer, 2013) Hammed, O. S.; Popoola, O. I.; Adetoyinbo, A. A.; Awoyemi, M. O.; Badmus, G. O.The occurrence of earthquakes in oceanic trenches can pose a tsunami threat to lives and properties in active seismic zones. Therefore, the knowledge of focal depth, magnitude, and time distribution of earthquakes along the trenches is needed to investigate the future occurrence of earthquakes in the zones. The oceanic trenches studied, were located from the seismicity map on: latitude +51˚ to +53˚ and longitude -160˚ to 176˚ (Aleutian Trench), latitude +40˚ to +53˚ and longitude +148˚ to +165˚ (Japan Trench), and latitude -75˚ to -64˚ and longitude –15˚ to +30˚ (Peru–Chile Trench). The following features of seismic events were considered: magnitude distribution, focal depth distribution, and time distribution of earthquake. The results obtained in each trench revealed that the earthquakes increased with time in all the regions. This implies that the lithospheric layer is becoming more unstable. Thus, tectonic stress accumulation is increasing with time. The rate of increase in earthquakes at the Peru–Chile Trench is higher than that of the Japan Trench and the Aleutian Trench. This implies that the convergence of lithospheric plates is higher in the Peru–Chile Trench. Deep earthquakes were observed across all the trenches. The shallow earthquakes were more prominent than intermediate and deep earthquakes in all the trenches. The seismic events in the trenches are mostly of magnitude range 3.0–4.9. This magnitude range may indicate the genesis of mild to moderate tsunamis in the trench zone in near future once sufficient slip would occur with displacement of water column.Item Assessment of ground water pollution in Itagunmodi, South-West, Nigeria(2012-02) Adetoyinbo, A. A.; Bello, A. K; Hammed, O. S.Some investigations have been earned out on geochemical characteristics of soil samples that embedded the ore deposits. Physiochemical analysis of water collected within gold mining area and the water consumed in the town of Itagunmodi was earned out to determine their hygienic conditions. The major objective of this study was to determine the suitability of the available water consumed in the town based on the Physiochemical analysis test carried out. In this regards, four major sources of water were analyzed. Analysis shows that the water within the town of Itagunmodi was hygienic with the inclusion of water within the mining site. The analysis includes; conductivity test, the pH test and others. It was noticed that the pH of the sample from the gold mining site was also suitable for drinking according to the World Health Organization standard. For a safe drinking water, the pH should be between (6.5 -8.5).Item Variation of height integrated eastward current intensity of the equatorial electrojet during solar maximum and minimum years(2012) Adetoyinbo, A. A.; Hammed, O. S.; Bello, A. K.Variation of the height integrated eastward current intensity of the equatorial electrojet was examined in the solar maximum years (1991 and 2002) and solar minimum years (1995 and 2006) respectively using CHAMP satellite data. Data were selected from the hours of 10 to 13 around local noon and during magnetically quiet periods when the Equatorial electrojet was expected to be strongest. Daily averages over all longitudes were used to obtain mean monthly variation. Mean monthly variations in all the seasons were averaged to obtain the mean seasonal variations. The mean monthly and mean seasonal variabilities were also obtained using standard methods. Daily variability exists in the eastward current intensity both in the solar maximum and solar minimum years. The magnitude of the mean monthly eastward current intensity is higher in the solar maximum than in the solar minimum. The eastward current intensity is highest during the equinoctial months than other months in both solar maximum and solar minimum years.Item High temperature and pressure impact on volume of Ore deposits; itagunmodi gold deposit, South West Nigeria as a case study(2012) Adetoyinbo, A. A.; Bello, A. K.; Hammed, O. S.An understanding of the Earth’s interior depends on information about the behavior and properties of matter under high pressures and temperatures. An equation of state that connects pressure (P), volume (V), and temperature (T) is very important. This work examines the impact of high temperature and pressure on the formation and maturity of sediment-hosted disseminated gold (SHDG) deposits in Itagunmodi, Osun State, Nigeria located in the clayey soil types derived from variably migmatised gneiss, biotite-and-biotite-homblende- gneiss and weathered amphibolites respectively. The melting temperatures of gold were determined by differential thermal analyses. After application of appropriate correction for the effect of pressure on emf of thermocouples, the melting curves are linear with the isothermal volume of the melting solid to within the precision of the measurement. This melting point of gold at variable high temperature and pressure, if extrapolated could be used as a primary standard for measurements.Item The geological and geochemical characteristics of soil on Ore deposits, Itagunmodi gold deposits as a case study(2011-02) Adetoyinbo, A. A.; Bello, A. K.; Hammed, O. S.This work examines the geological and geochemical characteristics of soil on Ore deposits on the formation and maturity of (SHDG) deposits in Itagunmodi, Osun State, Nigeria. Although, some investigations have been carried out on their geological and geochemical characteristics in general, most of the studies are based on limited database. The source and the nature of the gold in the deposits are still not clear. The major objective of this study is to determine the geochemical characteristics of host soil. The plots of major elements collected from five different locations in the mining areas named A-E and three locations outside the mining areas F-H shows that the concentrations of the element is higher within the mining site than area outside the mining site.Item Fabrication of an induction coil magnetometer for geomagnetic field measurement(2010-11) Adetoyinbo, A. A.; Hammed, O. S.; Ogunsua, B. O.The measurement of magnetic variations within the low frequency range of 0.1 to 40Hz requires a highly sensitive magnetometer. A magnetometer based on the induction coil principle was designed, simulated, and constructed in this research. The search coil was designed by winding 4,500 turns of insulated coil on PVC pipe with 3 silicon-iron strips mounted on the PVC for higher magnetic susceptibility. The sensory method of the coil is based on the faraday’s law of electromagnetic induction. The output of the coil was amplified and filtered with a band pass electronic system designed to pass the desired frequency range of 0.1 to 40Hz. A simple calibration system using the Helmoltz coil pair was designed for the calibration of the sensor to determine the conversion factor of the output root mean square (r.m.s.) voltage with the external magnetic field (Hs), since the Helmoltz coil can generate very uniform magnetic field up to 25% or more of the covered area from the centre axis. The output voltage and applied magnetic field obtained as the calibration data were fitted into a linear graph. A relatively high sensitivity of 299mv/pT was obtained.Item Quite time longitudinal and UT variation of the equatorial electrojet inferred from CHAMP satellite(2010-05) Adetoyinbo, A. A.; Hammed, O. S.; Ijeoma, E. U.Analysis of the longitudinal and UT variations of the height integrated eastward current intensity of the equatorial electrojet in the solar maximum and solar minimum years (2002) and (2006) using CHAMP Satellite data is presented here. The low orbit of the CHAMP and its high precision instrumentation makes it suitable for the study. Data were selected from the hours of 10 to 13 around local noon and during magnetically quiet periods when the equatorial electrojet was expected to be highest. The results obtained showed that the amplitudes of the longitudinal variation were higher in the solar maximum year than in the solar minimum year and the regularities and irregularities in the longitudinal variations were almost the same in both the solar maximum and solar minimum years. Similarly, the regularities and irregularities in the Universal time (UT) variations were almost the same in both years. We observed that the systematic and unsystematic variations of the EEJ with longitudes and UT were not affected by the solar activity.Item Detection of seismic ULF geo-electrical potential variations as tremor precursors prior to quarry blasts(2009-05) Adetoyinbo, A. A.; Popoola, O. l.; Hammed, O. S.; Sumonu, L. A.A seismic ultra low frequency geo-electrical signal recording instrument was set up in three different quarry sites in the south-western part of Nigeria. This research was embarked upon to detect geo- seismic electrical signals produced from the brittle upper crust during rock loading and fracture as a simulated earthquake precursor. The seismic electromagnetic signals emitting from the interior earth in analogical pattern and detected at the earth surface through the signal detectors were transmitted to a conditioning circuit which not only protected the recording instruments from transients caused by ionospheric disturbances but also attenuated the 50 or 60 Hertz frequency caused by high voltage power transmission lines. The spectral analysis of the ULF signals with sampling of 48 KHz recorded during rock loading and fracture in each of the stations revealed that the amplitudes of the signals decrease with increasing frequency. The geo-electrical potential signals associated with ULF waves were varying during deformation stages of crustal layers of rocks. These signals were recorded a few seconds before and after fracture of the rocks as systematic precursors to the main tremors observed in each of the stations and felt five (5) kilometers away.