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THE EAST AFRICAN RIFT VALLEY
TECTONICS
• The East African rift system is formed at a
conservative plate margin involving three continental
sub -plates
• The pull-apart is not vigorous enough to create a
clean, single break through the thick plate material
• The thick continental plate is arched upwards from
the convection currents, pulled thin by the stretching
of the crust, and fractured into a rift-shaped structure
• Normal faults develop on both sides of the rift as the
plates move apart and the central grabens (displaced
rock between plates) slide downwards
• Earthquakes occur as a result of this fracturing and
movement.
-The Somalian plate is gradually moving away from the
Nubian, causing a series of rifts to form along east
Africa.
EARTHQUAKES
• The East African rift system is a zone of shallow earthquakes with a 20 km
average focal depth
• The Western branch is more seismically active than the Eastern branch, with
the Kenya rift almost devoid of seismic activity, although the rift floor is
seismically active.
• The seismic activity along the East African rift system is, although higher
than elsewhere in the continent, still low. Many frequent but low magnitude
earthquakes occur but pose no significant hazard
HTTP://WWW.GEO.ARIZONA.EDU/GEO5XX/GEOS5
77/PROJECTS/MOONEY/HAZARDS.HTM
This map shows that the
earthquakes occurring
along the African rift
tend tor range from 30.2 on the Richter scale,
indicating the the
quakes along this rift
are very minor and
cause little to no
damage to human
settlements or activity
VOLCANOES
•
As the plates pull apart, the crust thins, cracks, and settles—sometimes violently.
Magma rises to the surface putting tremendous pressure on the thinning, fragmented
crust
•
Fissure eruptions may occur
•
The central volcanoes of the rift are underlain by crustal magma chambers during
some stages of their active periods.
•
They erupt silicic magma, which when under lots of pressure breaks their roof –
either as large volume pyroclastic flow or smaller volumes of lava flows.
•
Central volcanic activity also includes long lasting eruptions or lava activity in the
central crater of the basaltic lava lake.
•
Some of the volcanoes formed are very large and iconic, including Mount Kilimanjaro
and Mount Kenya, which have become popular attractions for adventuring tourists.
VOLCANOES
ACROSS THE
RIFT
PRESERVATION
• The volcanic conditions in the East African rift system are favourable for
fossil preservation, with ash deposits favouring fossilisation of organic
remains.
• Lucy, a famous 3.2 million-year-old Australopithicus afarensis, was found in
Ethiopia's Afar Depression.
• The fossils have been vital in reconstructing the history of the human species
and explaining the link between us and modern apes.
AFRICAN RIFT GEOTHERMAL
DEVELOPMENT FACILITY ARGEO
•
ARGEO claims that: Geothermal energy is one of the most promising energy options for
countries in Africa’s Rift Valley. According to the US Geothermal energy Association, using
present-day technology, the region’s geothermal potential is in the 2.5 to 6.5 GW range. Not
only does geothermal energy present a sustainable, low-cost compliment to the region’s
hydropower and diesel-based thermal electricity, but it is also unaffected by drought and
petroleum price fluctuations.
•
ARGEO aims to:
•
Set-up a Regional Network providing support for the development of a geothermal
energy-old knowledge sharing database, as well as capacity building and awareness
raising.
•
Provide Technical Assistance programme focusing on surface investigation, risk
minimization, policy frameworks, and presenting bankable proposals to local or
international financing sources.
•
Officially launched in November 2010, the six countries are in the process of selecting
potential geothermal sites to be considered for support under the project. Additional co financing is provided by BGR (Germany) and ICEIDA (Iceland).
•
The organisation targets six African Rift countries: Kenya, Eritrea, Djibouti, Ethiopia,
Tanzania, and Uganda, all of which lie on the rift
MORE INFO.
•
http://education.nationalgeographic.co.uk/media/file/Africa_Great_Rift_Valley_Art.pdf
•
http://www.volcano.20m.com/catalog.html
•
http://www.unep.org/energy/Activities/ARGeo/tabid/79467/Default.aspx