Gravity Survey of Moinonin Area in Lake Baringo Geothermal Prospect, Kenya
Chemosong, Charles Chirchir
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Geothermal energy has become increasingly important around the world for the past few decades. This renewable energy has been utilized for electricity generation in Kenya. Before harnessing and utilizing this energy, survey of the geothermal area must be done. Moinonin has several geothermal manifestations in form of fumaroles, hot altered ground and steaming grounds among others. Even with these geothermal manifestations, gravity survey has not been done in the area. There is need to explore the area in order to ascertain the presence of a heat source and to determine its depth from the surface. Ground gravity measurements of 132 gravity stations in Moinonin, west of Lake Baringo were carried out to image the subsurface geology and map out areas associated with high temperature intrusive bodies. At each station, elevation and location coordinates were measured using a Global Positioning System (GPS). The time at which the measurement in each station was carried out was also recorded. Measurement of the gravitational attraction exerted by the earth at the measurement station on the surface was done using a gravimeter with an accuracy of ± 0.1 mGal. Data reduction on the gravity data was done to take care of corrections. Gridding was then done using surfer software and bouguer anomaly map plotted. Profiles were drawn on the contour map along the discerned anomalies. Modeling was then done using Grav2dc software, along the selected profiles. This was to attempt to identify possible fault lines, presence and depths of anomalous bodies that may be heat sources. Gravity highs were observed to be widely spread on the northern and the southern part of the area. 2-D Euler deconvolution along the profiles shows that there are fault lines in Moinonin area, which form conduits for thermal fluid flow. The models developed show heat sources protruding up to between 500m and 700m below the surface. The density contrast of the models was between 0.2475gcm-3 and 0.2850gcm-3, which is the density of an intrusive igneous rock. It was therefore concluded that there are thermal bodies in Moinonin. This confirms that the area has high potential for electricity production and there is need for exploration. The heat should be tapped to generate electricity. Other methods can now be used for confirmation and verifications of the heat reservoir.