Charles Muturia Lichoro
Geothermal Development Company
The objectives of this study is to analyse resistivity of geothermal systems as revealed by 1D inversions and use the shallow structure in order to guess magma dimensions that can be resolved below the volcanoes. This study is focussed at the Paka volcano in order to speculate magma sizes that can be modelled through 2D inversions and help to explain why the 1D inversions may not be sufficient to recover deeper resistivity structure. A 3D profile through the Paka volcano reveals resistivity structure in the upper 1 km depth consistent with the 1D invariant inversion but differs as depth increases. However both 1D and 3D nversions do not reveal any indication of a deeper conductive magma segment suggesting that the dimensions of magma are too small to be imaged by the two approaches or are resistive. The application of magma modelling helps to reveal sizes of conductive structure that can be imaged and what cannot. Magma intercepted at Menengai will be used as the basis for evaluating the dimensions of magma that can be detected by geophysics. The inferred depth to the magma body in a geothermal field may be used to predict the reservoir volume and serve as a rough estimator of the base of the reservoir. This when complemented with the depth of seismicity at Paka may form a basis of predidicting economical depth for drill holes and aid in resource development strategy in the volcanic area. 2D modelling results will be used to speculate on the the size and depth of magma beneath the volcano that can be imaged and help to predict the reservoir depth and potentiality of encountering magma at the bottom of some wells.