APPLICATION OF GEOPHYSICAL METHODS FOR THE EVALUATION OF THERMAL CENTERS AND THEIR STRUCTURAL CONTROLS IN BOKU, MAIN ETHIOPIAN RIFT

ABSTRACT

The results of integrated geophysical surveys involving thermal, magnetic, electrical and gravimetric methods carried out over the Boku thermal centers in the Main Ethiopian Rift are reported in this paper. The aim of these investigations was to reconstruct the geometry of the aquifers and the thermal paths. The geological studies show that the Boku thermal field is a vapor-dominated, dry type geothermal system tapping heat from the shallow acidic magma chamber of Quaternary volcanic rocks of the Rift floor. The aquifer system consists of the Quaternary Rift fljoor ignimbrites that are fractured intensively.

The geophysical investigations have mapped the Quaternary faults that are the major tectonic structures for the passage of the deep-seated heat and the rising steam to the surface, and the recharging of the geothermal reservoir. The shallow aquifer systems are mapped and preferred bore hole sites for the extraction of thermal fluids and the depth to these aquifers are suggested.

Keywords: Ethiopian Rift, geothermal energy, geophysics, electro-magnetic soundings.

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