Transverse tectonics control on the Late Quaternary development of the Central Main Ethiopian Rift

Extension of continental plates should typically result in the development of normal faults perpendicular or sub-perpendicular to the plate motion vector. However, several factors such as linkage of rift segments and the presence of pre-existing fabrics may result in the development of complex fault systems, with structures oblique or even sub-parallel to the extension vector. This paper is focused on the extension-related deformation of the central sector of the Main Ethiopian Rift (MER) and shows the presence of a transverse structure (ie., sub-parallel to extension) in the central MER that played an important role during the Late Quaternary, influencing the hydrographic evolution in this area. Structural data evidence its tectonic activity and the analysis of distribution of magmatic centres and other volcanic features shows that interaction between transverse structures and the faults delimiting the rift may favour formation of volcanic centres. The orientation of this transverse structure, sub-parallel to extension, is interpreted as being caused by the linkage of major segments of the MER that likely exploited pre-existing structures, as widely documented in the MER.