East African Rift System - an Overview

The main characteristics of the East African Rift System are outlined from selected references. The difference between the Eastern Rift with high volcanicity on two domal uplifts as against the Western Rift of restricted volcanism, but sediment and lake filled grabens is pointed out. This is also evident from the earthquake activity: Large earthquakes occur in the Western Rift, whereas earthquake swarms of mosty microseismic activity characterize the Eastern Rift. The difference is significant for the geothermal potential of the region. The high temperature geothermal systems are closely related to volcanic centres. High volcanoes are not easily accessible for developing geothermal reservoirs in their roots. But hot outflows at lower ground near to them may prove significant, however, of lower temperature. By mapping a volcanic system as a whole and defining a related fissure swarm of faults and eruptive fissures, local concentration of high activity may show up as possible geothermal targets.