Gravity Analysis of the Tendaho Graben, Afar Depression, Ethiopia

The Tendaho graben (TG) is located at the intersection of the East African, Red Sea and Gulf of Aden rifts. The TG lies within the southern portion of the Red Sea propagator, which is the landward extension of the Red Sea spreading center. The region has experienced extensional forces resulting in thinned crust and formation of oceanic crust. To investigate the crustal structure of the TG, previous detailed gravity, magnetic, and seismic surveys were completed for geothermal resources. I performed a detailed gravity and magnetic survey within the graben to aid in determining the crustal structure. Bouguer gravity anomaly maps of the Afar indicate a regional gravity maximum in comparison to the Ethiopian and Somalian plateau, which is related to crustal thinning. Additionally, smaller wavelength gravity maxima occur over both the Red Sea and Gulf of Aden propagators. Wavelength filtered gravity maps show that the maximum of the Red Sea propagator terminates in the south-central portion of the TG and does not intersect the Gulf of Aden propagator. Four models, which were constrained by magnetic modeling and drill hole data, indicate that the graben is 1.6 km thick with a 6-8 km wide high density zone correlating to recent volcanic activity. The data suggest the basin evolved from being tectonically controlled and transitioned to being magmatically controlled