East African Rift Dynamics

Abstract

The East African Rift (EAR) is a typical site for the study of dynamic processes leading to continental break-up and dislocation. In the context of global plate motion models, the kinematics of EAR system is less well defined. In this study, the analysis of repeated GPS geodetic data represents a quantum leap in accuracy that allows us to reassess the recent kinematics of EAR. Our results show that the Somali plate rotates at a velocity of 0.076°/m in the Nubian fixed reference frame the velocity increasing from south to north. We also found that the seismotectonic parameters of both sets of plate boundaries are embodied by lithospheric thinning and oceanic accretion, including a scissor-shaped opening. Normal faults are active along a series of fissure boundaries. This NubianSomalian divergence across the East African rift system implies a redistribution of deformation and stress regulation along rift segments connecting rigid blocks that allows for the heterogeneity of the East African basement. We also note the presence of very high-risk seismic zones.