Active fault systems are often controlled by the reactivation of pre-existing zones of weaknesses, especially in tectonic zones that remained weak during a long geological period. The active normal fault systems that affect the Ufipa plateau between the Rukwa and Tanganyika rift basins in Western Tanzania illustrates this concept very well. This area was hit by a Ms 7.3 earthquake a century ago near Sumbawanga Town and this event remains the strongest known earthquake that affected the East African rift system to date. The Ufipa plateau is affected by a series of morphologically well expressed normal fault systems, of which the Kanda fault is the most prominent one. Morphotectonic investigation has shown that these fault systems are composed of / originated as isolated fault segments that interact each other / progressively merged together. Earthquake geology in outcrops along the trace of the Kanda fault shows a complex fault-rock structure that evidence several tectonic stages and allowed to reconstruct the stress field evolution trough time in progressively shallower conditions. The Kanda fault appears to reactivate an old mylonitic fabric of probable Pan-African age. It initiated as thrust faulting during the late stages of the Pan-African deformation, was reactivated as a strike-slip fault during a Triassic inversion, and turned into a normal fault during the development of the East African rift system. Recognition of this multistage history has important implications for the understanding of the opening dynamics of the East African rift system.