The seismicity of Kenya

Abstract

The Kenya Rift Valley, part of the East African Rift System, which extends from Lake Turkana in the north to Lake Magadi in the south, is seismically active. It is surprisingly free of teleseismic events compared to the Western Rift, but experiences considerable microseismic activity releasing the elastic strain energy. This is consistent with the crust having a low tensile strength, probably due to raised geotherms beneath the rift valley arising from lithospheric aattenuation. The microseismicity suggests presently active rifting occurs as far north as 2.5°N. This is consistent with recent seismic reflection results in this region which show deep half-grabens beneath Lake Turkana. There is also a broad zone of seismicity subparalleling the rift and displaced about 150 km to the east. This may be associated with a second culmination of the lithosphere-asthenosphere boundary. In order to obtain a better understanding of the rifting process in Kenya it is suggested that a microseismic study be carried out in the Turkana region, whose near surface 3-dimensional morphology has already been examined via the seismic reflection method.