Structural evolution of Lake Malaŵi, Africa

Over 2,000 km of seismic reflection profiles have been collected in Lake Malaŵi (Nyasa), the southernmost of the East African Rift Lakes. These studies, reported here, reveal a severely faulted lake floor bounded by rift structures of Pliocene or greater age. Faults that penetrate the uppermost sedimentary units and numerous earthquakes1 attest to continuing activity in the rift. Inter-basinal differences in fault spacing, orientation and sedimentary thicknesses have led to a subdivision of Lake Malaŵi into four discrete structural provinces. These provinces only now are linked by faults attributed to the most recent episodes of extension. An evolutionary sequence of: (1) initial block faulting and subsidence, (2) fragmentation of fault blocks, (3) uplift and (4) renewed subsidence and rotation of fault blocks is proposed for the central part of the Malaŵi Rift. © 1984 Nature Publishing Group.