The Gravity Field Of The Southern Ethiopian Rift Systems Between 3.30 To 7.150 Latitude And 360 To 420 Longitude

1800 gravity data covering the research a rca are reduce to Bouguer and free air values and interpretedrnbased on the Bouguer anomaly map and a pair of short wave length (SWL, residual) and long wavernlength (LWL, regional) anomaly maps. All data are reduced to sea level wth uniform density of 2.67rnglcm'- Effect of Bouguer masses were calcu lated applying the simple Bouguer corrections. Terrainrncorrection "vas not applied.rnThe Bouguer anomly map of the rift zone between 3.3° N to 7.15° Nand 36° E to 42° E is presented.rnThe geologic and tectonic setting of the area is di scussed based on the compilation of gravity data andrnsynthesis of publi shed papers.rnA positive Bouguer gravity anomaly of - 165 mGal occur over the rift floor of the Abaya - Chamo riftrnand is flanked by negative anomalies that res ide on its shoulders. Gravity anomaly of magnitude -135rnmGal is observed over the Chew Bahir ri ft floor and flanked by relative positive anomalies on itsrnshoulders, which is different from the MER. This could be due to lacustrine deposits of the rift floor.rnThe free - air anomaly map is si mply relatcd to topographic relief. The uplifted blocks and horsts arerncharacterised by high free - air gravity anomaly and depressions defined by free - air minimum (-40 to -rn75 mGal ). The transition from grabens to horsts is marked by sharp free - air gravity gradients (0 torn+40 mGal).rnAfter removal of the long wave length components of the Bouguer gravity anomaly the residual gravityrnanomaly is interpreted. The residual gravity field exhibits rapid changes of gravity gradients over shortrndistance appears to show the presence of fa ults which bound major rift basins. Anomalous areas arerncorelated to their respective geologic in te rpretation.rnThe regional gravity anomaly map produced by trending analysis shows the deep structural features ofrnthe study area. It shows the transition from negative to positive gravity fie ld from MER to SER andrnnegative towards the Kenyan rift indicating the distinction between the SER and the other two riftrnsystems (MER and Kenyan rifts).

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