The sismotectonic investigation of the western side of the Kivu rift allowed to identify and characterise some sismogenic faults on the basis of tectonic parameters such as the tensor of the orthogonal principal stress (1, 2 and 3), the tectonic regime index (R and R ) and the azimuths of the maximal (SHmax) and minimal (Shmin) horizontal principal stresses. Those parameters were obtained with the help of the Win-Tensor software using orientation data of striated fault planes and various fractures measured during field work and also of earthquake focal mechanisms. Using this approach, the morphotectonic markers observed in the field have been associated with two distinct large sismotectonic zones of the western branch of the East-African rift system. The first one comprises the northern part of the basin of Lake Kivu in which we have observed faults with general NNE-SSW orientation. The second zone comprises the southern part of Lake Kivu, including the depression of the Rusizi River until the northern tip of the Lake Tanganyika basin. The faults in this zone are preferably N-S oriented.