In this thesis work analysis of about 2220 gi'aVity' alia 75 liuigileli6 data' colieCted ih the 'LakesrnDistrict of the Main Ethiopia Rift (MER), between latitudes 6.88Â° - 7.75Â° and longitudes 38.00Â°rn- 39.00Â° consisting of the Corbetti caldera is made.rnA gravity survey covering about an area of 12100 sq. kms with obselvation points of about 2220rnstations are discussed (about 50 wavity and 75 magnetic stations, were occupied during fieldrnwork by the author of tlus thesis and Dr. Abera Alemu, advisor to tlus thesis work, wIllie the restrnof Wavity data were obtained from the Ethiopian Institute of Geological SUlveys and thernGeophysical Observatory of Addis Ababa University). Both the magnetic and gravity data setsrnare of senu-regional type, with station separations ranging on the average from about 1-10 kill.rnThe analysis includes compilation in a standard fonnat of the recent and the previous gravity datarnsets, wluch required homogelusation to IGSN-71 datum from the previous surveys that wasrnfound out not available in this datum.rnThe theoretical (nornml) gravity values for each stations were calculated by means of therninternational gravity fonnula (GRS-67) and all Wavity field stations are tied to the IGNS-71rndatum of the Geophysical Observatory of Addis Ababa Uluversity (whose gravity value is 977452. 16 mOaI). Similarly, the magnetic daia an! alr,o d.r,ffi cqll'e4t~:(or tlÂ¥ dilfiial v~llations:rnResults of both the gravity and magnetic surveys'll'ave' revealed sig'nwcailf achievetllehtsinrnmapping several zones of hydrothennal alterations, weak stmctural indications such as faults,rnlineaments, fi'actures, joints, etc. within the study area. The delineation of weak stmcturalrnfeatures and hydrothennal manifestations i.e. altered grounds with fumarolic activities that arernassociated with fissures, craters, fanlts and caldera rims, where tectonic stmctures give majorrnaccess for hydrothennal fluids which in tum are favourable for economic mineral potentials likernsulphides, epitennal gold deposits, etc. In addition, to these invaluable natural resources theserndata are also important in the mapping and location of potential geothennal zones. Both therngravity anomaly maps and the magnetic anomalies are found in agreement in mapping of therngeological and stmctural trends. The distinction between the lift and the adjacent plateaus andrnthe regional stmcture features were depicted fi'om the anomaly maps on the basis of the generalrnshape and wavelengths ofthe anomalies.