Magnetotelluric Exploration at Tendaho High Temperature Geothermal Field in North East Ethiopia

Abstract

We report on a recent magnetotelluric (MT) survey across Tendaho geothermal field within the Tendaho graben in the Afar Depression in northeastern Ethiopia. Twenty-two broadband MT sites with ∼1 km station spacing were deployed along a profile with the recorded data covering a period range from0.003 s to1000 s. A two-dimensional (2-D) resistivity model reveals an upper crustal fracture zone (fault) and partial melt with resistivity of 1–10 Ωm at a depth of more than 1 km. The low resistivity surface layer is associated with sediments, geothermal fluids or zeolite-clay alteration zone. Below the conductive layer, a high resistivity zone that can be correlated to the back ground resistivity of Afar Stratoid basalts or epidote alteration zone. The inferred presence of a conductive fracture zone or fault with hydrothermal fluid and shallow heat sourcing magma reservoir makes the Tendaho graben a promising prospect for the development of conventional hydrothermal geothermal energy.