Alemu, Abera (PhD)Demissie, Gemeda2021-11-242023-11-092021-11-242023-11-092021-06-05http://10.90.10.223:4000/handle/123456789/28919The Main Ethiopian Rift is one of the world’s most tectonically active areas with widespread volcanisms and enhanced geothermal gradient. However, the areal extent, nature and depth of the geothermal resources remain imprecise. The study area which mainly comprises the Aluto-Langano geothermal field, the Munesa escarpment and the Gedemota ridge is located in the central part of the Main Ethiopian Rift. The Aluto-Langano geothermal field is bounded by Lake Ziway to the north, Lake Langano to the southeast and Lake Abiyata to the southwest. The hydraulic gradient of Lake Ziway dips towards the south and is thought to feed water to the Aluto-Langano geothermal. The Aluto-Langano geothermal system encompasses younger NNE-SSW oriented en-echelon faults of the WFB and NE-SW oriented boarder faults. The fault systems belonging to the WFB are generally thought to generate fracturing of rocks that could favor the development of geothermal reservoirs beneath the study area. Gravity and magnetic studies constrained by the available geological, borehole and geophysical data are conducted over an area consisting of the Aluto-Langano geothermal field and its environs. Data enhancement techniques (upward continuation, analytical signal, tilt derivative, Euler deconvolution and reduction to pole) have been applied to the observed gravity and magnetic data in order to isolate the effects of deep seated and shallow origin geologic sources. Interpretations of the gravity and magnetic data in combination with the available data (seismic, geological and well-log data) have provided important clue about the geothermal sources of the study area. 2D gravity models computed for the study area and running across and along the rift axis reveal six density layers (silicic products, lacustrine sediments, basalts, Tertiary ignimbrite, Mesozoic sediments and crystalline basements). The computed 2D gravity models show occurrence of a magma chamber/intrusion occurring at depths between 2km and 3km beneath the Aluto volcanic complex. A detailed investigation of the shallow subsurface using 2D gravity models, volcano-tectonic evidences, surface thermal manifestations, various gravity and magnetic maps has revealed the existence of a potential heat source/magma chamber occurring beneath the Aluto volcanic complex. Quaternary faults of the Wonji Fault Belt are inferred to play a vital role in transporting melt from a deeper intrusion to the magma chamber, in acting as conduits for migration of surface and/or groundwater to the magma chamber and in transporting thermal fluid to the surface (detected as surface thermal manifestations) beneath the Aluto-Langano geothermal system.enAluto Langano Geothermal FieldGeothermal SourcesGravity Anomaly MapsMagnetic Anomaly Maps2d Gravity ModelsThesis