| Title | 1D Inversion of Magnetotelluric Data from Ashute, Butajira Geothermal Prospect, South-East Ethiopia and Its Geothermal Implications |
|---|---|
| Authors | Tsegaye Wondifra TADESSE |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Magnetotelluric (MT), 1D inversion model, Ashute, Butajira , resistivity , anomaly |
| Abstract | Geophysical surveying is one of the Earth science disciplines which is used for exploration of geothermal energy. Magnetotelluric (MT) survey was conducted in Ashute Geothermal prospect area acquiring 28 soundings. The major objectives of the study were to define the assumed up flow zone of the geothermal fluid. North-South of the major hydrothermal manifestations in the Ashute field and to make the suggest cross-section maps and 1D inversion model, to study the subsurface resistivity structure of the geothermal system at the Ashute, Butajira field, its relation to the geothermal field marked Aligned volcanic cones and the group of thermal spring in the axial part of Debre zait Selti graven suggest the main NE – SW Debre zait _ Selti fault system and transverse NW – SE older rift structure beyond to control Magmatism (heat source), water recharge and permeability of the system. Two possible heat source are suppose these are are straight associated with this young basaltic eruptions and intrusion less than 0.13 Ma and silicic centers centers identify position of in the southern part of the area. The project area which covered by more of pyroclastic ash flow and volcanic sediment this unit is organized according to mapped as a single unit. Within it we have pyroclastic ash flow deposit, graded sediment deposit ranging from ash to gravel sized originally solid rock. The flat low land of Butajira and Ashute plane is covered by this pyroclastic and sediment deposit. Both this pyroclastic and sediments are deposited at the same geologic time and stratigraphically they are set together one on another in undefined pattern. As a result of low conductivity zone less than (10 Ωm) in the North-South Ashute field delineates the up flow zone of the geothermal fluid and circulation of geothermal fluid was deduced to be related to the structure and all thermal springs in the area found on single fault, which is on the Southward extension of Ajira –Afuno normal fault. We have identified two separate structural patterns from aerial photograph and from the resistivity cross section interpretation map. The trend of high and low resistivity anomaly and the discontinuities (NE-SW alignment) structure and transverse NW-SE faults and opening fissures, that indicated the possibility of the connection of the Ashute, Butajira geothermal systems. In Addition to this MT soundings towards NE-SW Ashute geothermal field and BTJ-068 in the Ashute field and reinterpretation of result using TEM data were recommended for a better definition of the anomalies and achieve the stated objectives. |