| Abstract |
Geothermal energy sources are formed by heat stored in rocks at depth. In regions with high heat flow, like at volcanically active plate margins, high total thermodynamic energy is accumulated in the so called high enthalpy resources. Unaltered volcanic rocks generally have high resistivity which can be changed by hydrothermal activity. Hydrothermal fluids tend to reduce the resistivity of rocks by altering the rocks or by increasing salinity. Initial regional exploration for geothermal resources in Kenya indicated that the Quaternary volcanic complexes of the Kenya rift valley provided the most promising prospects for geothermal exploration. Consequently, detailed exploration for geothermal power has been concentrated around volcanic centres within the rift valley. Studies show that these centres have positive indications of geothermal resource that can be commercially exploited. The geothermal potential of the area is associated with these magma chambers that constitute the heat sources. Magnetotellurics (MT) data show that the heat sources are shallow beneath the volcanic centres. This abstract concentrates on the geophysical work that has been carried out in the Menengai Geothermal prospect using Magnetotellurics (MT). Data collected using magnetotellurics is used to determine the resistivity distribution within the earth to depths of many kilometers which is then interpreted in terms of lithology. The contrast in resistivities provides an excellent tool for identifying geothermal targets. So magnetotellurics is the standard method for mapping the alteration cap and via 3D inversion the underlying reservoir. |