Hot volcanic mantle rock that lies beneath Africa is trying to
split the continent apart and could eventually create a new
ocean. ?The Ethiopian rift is one of the few places in the
world where we can see the transition from continental rifting
to something that looks more oceanic,? says Dr. Cindy
Ebinger. ?It?s a unique area worldwide.?
The crack in the Earth?s surface runs from Malawi in the
South, through Tanzania, Kenya and Ethiopia, to the Red Sea
and the Gulf of Aden. Deep inside the Earth, there?s a huge
plume of warm soft mantle rock rising diagonally and running
up beneath Southern Africa towards the Afar region of
Ethiopia. This super-plume, as it?s called, may be responsible
for the high elevation of much of Southern and Eastern
Africa. It may also be the cause of the line of volcanoes that
runs up the Great Rift Valley, including Mount Nyiragongo,
which recently sent red-hot lava into the town of Goma in
the Congo.
For most of its length the East African rift valley is just an
ordinary rift, running through a continent. But as it gets
further north, it forms a line of cracks along which volcanic
magma rises to create the floor of an ever widening sea. In
Ethiopia it is in transition between the two forms and this
gives geologists a chance to see how a new ocean forms.
Project Eagle (Ethiopian Afar Geophysical Lithospheric
Experiment) wants to use seismometers to record natural
earth tremors and the vibrations from explosive charges
detonated in boreholes. The seismic waves travel at different
speeds through rocks of different temperatures and densities.
Ebinger and her colleagues want to find reservoirs of hot,
molten magma within the crust that could feed future
volcanoes. ?There are several dormant volcanoes but there
has never been a study to monitor volcanoes in the rift,? she
says. ?These are dangerous because the lava has more silica
in it and is resistant to flow, so these are explosive eruptions
that can cause death and damage to a large region.?
So far, the test show that a mantle plume alone is not
enough to open an ocean. There needs to be a sideways pull
to divide the continent, allowing the hot magma to rise
underneath to fill the gap and form the floor of the new
ocean. Scientists aren?t sure whether that will actually
happen along the East African rift. With the Atlantic Ocean
still opening and pushing on Africa from the west and India
still colliding with Asia and the Indian Ocean opening to the
east, there may be nowhere for the rift to expand.
Professor Peter Maguire, of Leicester University in the U.K. is
one scientist who believes there will be a new ocean in the
area someday. ?We do believe that we are on the transition
from continental to oceanic rifting,? he says. ?The continent
in the northern part of Ethiopia is separating and there will be
an ocean penetrating down into East Africa.?
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