A three-dimensional seismic image of the crust and upper mantle beneath the Kenya rift

Abstract

A tomographic image of the seismic structure beneath the Kenya rift shows its three-dimensional character. In the lower crust, an axial zone of high seismic velocity varies in width and magnitude along the axis, suggesting that the amount of crustal modification also varies along the length of the rift. In the upper mantle, a steep-sided low-velocity body indicates the presence of partial melt, and its shape suggests that diapirs rise from a narrow wedge of asthenosphere beneath the rift axis in response to extension by pure shear.