The research program IGS is devoted to the structural evolution of the East-African continent, in western Tanzania, in the area affected by the Ubendian belt of Paleo Proterozoic origin, in which developed the western branch of the East African Rift. It involves multidisciplinary investigations in structural geology, petrology, geochronology, geophysics, remote sensing and quantitative tectonics. The major topics of the IGS program are (1) the Precambrian structural evolution of the Ubende belt, (2) the development of Phanerozoic rifts superimposed on the Ubende belt and (3) the relationships between rifting and Precambrian structures, mainly for inheritance aspects, with the basic idea that the older weakness zones are successively reactivated during the Precambrian and Phanerozeoic tectonic events.