The huge, brittle tectonic plates that make up Earth's crust normally move only a few centimeters per year, not fast enough to be noticeable in a human lifetime. However, in the East African Rift Valley, this tectonic motion is happening with remarkable speed.
The East African Rift System
The East African Rift System is the most extensive continental rift zone on Earth, as well as one of the most active geologic regions. Stretching more than 6,000 km (3,700 miles), it begins in Lebanon and Syria to the north, proceeds along the Red Sea where it marks the boundary between the African and Arabian Plates, and continues through to Mozambique in the south.
The area of east Africa is defined by extremes. Volcanic activity along the Great Rift Valley has produced some of the world's highest mountains, including Mt. Kilimanjaro and Mt. Kenya, while the Danakil Depression in Ethiopia is one of the lowest points on the planet.
The Afar Triangle, which includes north-eastern Ethiopia, Djibouti and the southern Red Sea region of Eritrea, is the location of a tectonic triple junction where three tectonic plates meet. These three plates are moving away from each other due to an upwelling of magma from the mantle, which melts the crust and causes it to thin and pull apart. The phenomenon is similar to that which occurs at the mid-ocean ridges, where hot magma rises up and pushes the oceanic crust out to each side in the process of seafloor spreading, but it is rarely observed on Earth's surface.
The African Plate is Tearing Apart, Forming a New Plate and Ocean Basin
Recent tectonic activity in the East African Rift Valley has created vast fissures where the African Plate is being split into two parts. The Nubian Plate that comprises most of the African continent, and the Somalian Plate, on the eastern coast, are moving in opposite directions at what is known as a divergent plate boundary. As the plates pull apart, a new ocean will eventually form, and the Horn of Africa will separate from the rest of the continent, becoming an island.
In September 2005, there was a major tectonic event in the Afar region when a rift 60 km (35 miles) long and 8 meters (26 feet) wide was torn open over a period of days. The process began with a series of earthquakes, followed by a volcanic eruption.
Since the 2005 event, additional fissures have formed in the area, and geologists are observing the region with great interest as the rifting process continues, and more tectonic events are expected to occur.
Related article: The Theory of Plate Tectonics
Sources:
Pease, Roland. "Geologists Witness Ocean Birth." BBC News, Dec 8, 2005. Accessed February 26, 2010.
African Desert Rift Confirmed as New Ocean in the Making. Science News, November 2, 2009. Accessed February 26, 2010.
Guth, Alex and James Wood. "East Africa's Great Rift Valley: A Complex Rift System." geology.com Accessed February 26, 2010.
Afar Rift Consortium "The Afar Rift, Ethiopia." Accessed February 26,2010.
Terrie Schultz - Terrie Schultz holds a BS in Biochemistry and an MA in Cell and Molecular Biology. She worked for many years in the biomedical field in ...
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