Magnetic Modelling of the Olkaria Geothermal Field, Kenya

Abstract

Three dimensional modelling of aeromagnetic data from Olkaria geothermal field has indicated a large zone, 20 km x 8 km, of reduced magnetisation, orientated ENE-WSW across the N-S trending Rift Valley. This zone, modelled as extending from to 4 km below the surface, appears to be further into three parts, of approximately equal but with different magnetic characteristics. The central part broadly coincides with the zone of surface manifestations,and a typical rock resistivity of 30 ohm-m. The western body, with a significantly lower magnetisation, is close to the rift escarpment in a zone characterized by no surface manifestations but a typical resistivity of 5 ohm-m at depths greater than The eastern body, also with lower magnetisation, is in an area that has not been surveyed by other geophysical techniques.