Review of Geothermal Resources as Manifestations of Volcanism in Eastern Africa

Abstract

Igneous rocks are naturally occurring materials which continue to evolve from a molten state (magma) through cooling processes. The solid materials that evolve are often crystalline compounds known as minerals. Magmatic chambers that are located at shallow depths often form high temperature geothermal systems. The systems derive their heat from magmatic processes that culminate into volcanic activities in localities at which the magma gets extruded onto the ground surface. The magma gets extruded, in form of lava or volcanic ash, as a result of violent volcanic activities. Often volcanic activities are related to geothermal processes in favourable hydrogeological conditions. Geothermal reservoirs develop as a result and can be encountered on exploration. Such reservoirs are distributed all over the globe. They are prevalent along plate boundaries and continental rift systems as witnessed in Eastern Africa. Volcanic activities are usually related to plate tectonics and continental drifting. For instance, the Great Rift Valley, which traverses African Continent from the North to East and Central Africa, hosts numerous volcanoes. The volcanoes are both active and dormant and are located on the floor of the valley as well as on its flanks. This paper examines geothermal activities that are manifested at the ground surface in different forms with emphasis on geothermal features of Eastern Africa, particularly on the features that are conspicuous in the Kenya Rift System. The features include hot springs, warm springs or geysers, steam jets, fumaroles, hot grounds and surface deposits of sulphur. Major global distribution of volcanic centers are also captured and related to plate tectonic setting. Subsequently, main operational geothermal investments in those volcanic centers are mentioned accordingly. For instance, Kenya government continues to invest heavily in exploration of geothermal resources as preferred form of green energy to spur development in all sectors of the economy. Indeed, major reserves are being exploited to add the generated energy to the national grid. Keywords - Rocks, magma upwelling, Geothermal activities, high temperature geothermal systems, geothermal manifestations, Geysers, Great Rift Valley, continental rifting and drifting, plate tectonics and volcanism.