Magnetotelluric Analysis of Central Kenya Kenyan Rift Volcanoes for Geothermal Development

Anna Wairimu Mwangi, University of Texas at El Paso


High temperature geothermal resources are vast along rift margins because of emplacement of magma in shallow crust. This is the case along the Kenyan Rift valley also known as the Gregory Rift. It is the Eastern arm of the East African rift and a chain of volcanoes along the rift graben characterizes it. We use (MT) magnetotelluric method to image beneath the peralkaline province of the Kenya Rift i.e. Olkaria, Eburru, Badlands, and Longonot volcanoes. The resistivity structure shows active geothermal activity happening at the upper 3km from the subsurface as evidenced by low resistivity cap rock comprised of low resistivity minerals. The cap is significantly thick on the Longonot volcano than any of the other case study areas depicting a shallow magma heat source closer to the surface compared to the rest of the volcanoes. We observe significantly large high resistivity blocks, which are faulted and intruded by magma. The depth to the large magma reservoir is about 8-10km below surface and it upwells to a shallow depth of 5-6 km, however, it much shallower at Mt Longonot occurring at about 3km below surface. A deep connection of magma intrusions in Olkaria Domes and Longonot strato volcano is observed. Eburru and Badlands have two major heat sources, the large one is associated with Eburru crater and the other is located northwest side of Badlands. The geothermal reservoirs observed in the peralkaline province are high temperature systems because they are supported by shallow magma intrusions. Major faults structures present in these fields play a significant role in fluid movement controlling hot up flows and circulation within the reservoirs.

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Recommended Citation

Mwangi, Anna Wairimu, "Magnetotelluric Analysis of Central Kenya Kenyan Rift Volcanoes for Geothermal Development" (2018). ETD Collection for University of Texas, El Paso. AAI13421906.