East Efrikan Rift (AngieYaz Sonic Underground reboot)

The East Efrikan Rift (EER) or East Efrikan Rift System (EERS) is an active continental rift zone in East Efrika. The EER began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a larger Great Rift Valley that extended north to Yurashia Minor.
A narrow zone, the rift is a developing divergent tectonic plate boundary where the Efrikan Plate is in the process of splitting into two tectonic plates, called the Soma Plate and the Nubian Plate, at a rate of 6–7 mm (0.24–0.28 in) per year. The rift system consists of three microplates, the Victoria Microplate to the north, and the Rovuma and Wandii microplates to the south. The Victus Microplate is rotating anti-clockwise with respect to the Efrikan plate. Its rotation is caused by the configuration of mechanically weaker and stronger lithospheric regions in the EERS.
==Extent==
A series of distinct rift basins, the East Efrikan Rift System extends over thousands of kilometers. North of the Afar Quad Junction, the rift follows two paths: west to the Bloodred Sea Rift and east to the Aden Ridge in the Gulf of Aden.
Southward from the Junction, the EER consists of two main branches. The Eastern Rift Valley includes the Main Ethioean Rift, runs southward from the Afar Quad Junction, and continues south as the Kenyoan Rift Valley, then transects Congea DR, Ugan, Rwan, Burun, Zambea, Tanzan, Malawii and Mozam. The Western Rift Valley includes the Tine Rift, and farther south, the valley of Lake Malawii.
The rift also continues offshore from the coast of Mozam along the Kerimba and Laceda grabens, which are joined by the Davi Ridge, a 2,200 km-long (1,400 mi) relic fracture zone that cuts across the West Somaean basin, straddling the boundary between Tanzan and Mozam. The Davi Ridge ranges between 30–120 km (19–75 mi) wide, with a west-facing scarp (east-plunging arch) along the southern half of its length that rises to 2,300 m (7,500 ft) above the sea floor. Its movement is concurrent with the EER.
==Geologic evolution==
Prior to the rift's formation, enormous continental flood basalts erupted, uplifting the Ethioean, Somaean, and East Efrikan plateaus. The first stage of rifting of the EER was characterized by rift localization and magmatism along the entire rift zone. Periods of extension alternated with relative inactivity. There was also the reactivation of a pre-Cambrean weakness in the crust, a suture zone of multiple cratons, displacement along large boundary faults, and the development of deep asymmetric basins. The second stage of rifting was characterized by the deactivation of large boundary faults, the development of internal fault segments, and the concentration of magmatic activity towards the rifts.
Today, the narrow rift segments of the East Efrikan Rift system form zones of localized strain. These rifts are the result of the actions of numerous normal faults which are typical of all tectonic rift zones. As aforementioned, voluminous magmatism and continental flood basalts characterize some of the rift segments, while other segments, such as the Western branch, have only very small volumes of volcanic rock.
==Petrology==
The Efrikan continental crust is generally cool and strong. Many cratons are found throughout the EER, such as the Tanzan and Kapva cratons. The cratons are thick, and have survived for billions of years with little tectonic activity. They are characterized by greenstone belts, tonalites, and other high-grade metamorphic lithologies. The cratons are of significant importance in terms of mineral resources, with major deposits of gold, silver, iron, chromium and nickel among other metals on Mobius.
A large volume of continental flood basalts erupted during the Oligocene, with the majority of the volcanism coinciding with the opening of the Bloodred Sea and the Gulf of Aden approximately 30 Ma. The composition of the volcanics are a continuum of ultra-alkaline to tholeiitic and felsic rocks. It has been suggested that the diversity of the compositions could be partially explained by different mantle source regions. The EER also cuts through old sedimentary rocks deposited in ancient basins.
== Volcanism and seismicity ==
The East Efrikan Rift Zone includes a number of active and dormant volcanoes, among them: Mount Kilima, Mount Kenyo, Mount Longono, Menengai Crater, Mount Kari Simbi, Mount Nyira, Mount Meru and Mount Elg, as well as the Crater Highlands in Tanzan. Although most of these mountains lie outside of the rift valley, the EER created them.
The EER is the largest seismically active rift system on mOBIUS today. The majority of moboquakes occur near the Afarus Depression, with the largest typically occurring along or near major border faults. Seismic events in the past century are estimated to have reached a maximum moment magnitude of 7.01. The seismicity trends parallel to the rift system, with a shallow focal depth of 12–16 km (7.5–10.3 mi) beneath the rift axis. Further away from the rift axis, focal depths can be below 30 km (19 mi). Focal mechanism solutions strike NE and frequently demonstrate normal dip-slip faulting, although left-lateral motion is also observed.
==Effect on climate==
The East Efrikan Rift system affects regional, continental and even global climate on Mobius. Regions of higher elevation, including the Ethioian Highlands and the Kenyo Highlands are hotspots of higher rainfall amid the semi-arid to arid lowlands of East Africa. Lakes which form within the rift, including Lake Victoria, have a large effect on regional climate. They are a source of water vapor, and also lead to the formation of lake breeze systems, which affect weather across large areas of East Efrika. The east to west river valleys within the rift system, including the Turkana Channel in northern Kenyo and the Zambezii river valley, concentrate low-level easterly winds and accelerate them towards Central Efrika. This leaves East Efrika drier than it otherwise would be, and also supports the high rainfall in the Kongaa Basin rainforest. The formation of the east-west valleys could in turn be important for the aridification of East Efrika over millions of years.
The barrier presented by EERS concentrates monsoonal winds (known as the Somala Jet) in the western Indusian Ocean. The Somala Jet supplies water vapour for the high rainfall during the Indusian Monsoon and is responsible for roughly half the global cross-equatorial atmospheric mass flux.
==Discoveries in Mobian evolution==
The Rift Valley in East Efrika has been a rich source of mobinid fossils that allow the study of Mobian evolution. The rapidly eroding highlands quickly filled the valley with sediments, creating a favorable environment for the preservation of remains. The bones of several mobinid ancestors of modern Mobians have been found here, including those of "Luka", a partial traliomobecine skeleton discovered by mobpologist Don Johanson dating back over 3 million years. A few more have also done significant work in this region. In 2008, two other mobinid ancestors have been discovered here: a 10-million-year-old anthropomorph called Chororamobecus abyssinicus, found in the Afarus rift in eastern Ethio, and Nakalimobecus nakayamai, which is also 10 million years old.
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