A rift valley is gradually splitting Africa, the second largest continent on Earth, into two, Live Science reported, citing a report from the Geological Society of London. This rift valley is also known as the East African Rift.
The East African Rift is a network of valleys that stretches some 3,500 km from the Red Sea to Mozambique.
The question that geologists are now interested in is whether Africa was completely broken up and when did this happen?
The East African Rift is a network of rift valleys that stretches from the Red Sea to Mozambique. Pictured is the Ethiopian Rift Valley, part of the rift. (Photo: LuCaAr/Getty Images)
According to NASA's Earth Observatory, the East African Rift Zone runs along the Somali tectonic plate pulling eastward the Nubian tectonic plate.
The Somali and Nubian plates are also breaking away from the Arabian Plate to the north. The Geological Society of London says these tectonic plates meet in Ethiopia's Afar region, creating a Y-shaped rift system.
The East African Rift began forming about 35 million years ago between Arabia and the Horn of Africa on the eastern side of the continent, according to geologist Cynthia Ebinger, chair of the geology department at Tulane University in New Orleans and science adviser to the U.S. State Department's Bureau of Africa.
The East African rift zone has been stretching south over time and slowed in northern Kenya around 25 million years ago, Ebinger said.
This rift zone consists of two parallel broad rift zones located beneath the Earth's crust.
The eastern rift passes through Ethiopia and Kenya, while the western rift runs in an arc from Uganda to Malawi, according to the Geological Society of London. The eastern branch is arid, while the western branch borders the Congo rainforest.
The existence of eastern and western rift zones and the discovery of offshore earthquake and volcanic zones suggest that Africa is slowly opening up along several lines. Estimates suggest that it is opening up at rates of more than 6.35 mm per year.
“The rifting is happening very slowly, about the same rate as an adult's toenails grow,” Ken Macdonald, professor emeritus of earth sciences at the University of California, Santa Barbara, told Live Science.
According to the Geological Society of London, the East African Rift was most likely formed by heat released from the asthenosphere—the hotter, weaker upper part of the Earth’s crust—between Kenya and Ethiopia. This heat caused the upper crust to expand and rise, leading to the stretching and fracturing of brittle continental rock. This led to significant volcanic activity, including the formation of Mount Kilimanjaro, the tallest mountain in Africa.
A map showing tectonic plate boundaries (gray lines) as well as the East African Rift (dotted lines).
There are different opinions about how Africa actually broke up and how it happened. One scenario is that most of the Somali tectonic plate broke away from the rest of the African continent, with a sea forming between them.
This new land would include Somalia, Eritrea, Djibouti and the eastern parts of Ethiopia, Kenya, Tanzania and Mozambique. Another scenario would see only eastern Tanzania and Mozambique split off.
If the African continent were to rupture, “the rift in Ethiopia and Kenya could separate from the Somali plate within the next 1 million to 5 million years,” Ebinger said.
However, many geologists still believe that the African continent cannot split in two, as geological forces are too slow to pull apart the Somali and Nubian tectonic plates. A notable example of failed rifting elsewhere in the world is the 3,000-km-long Midcontinental Rift that runs through the Upper Midwest of North America.
According to the Geological Society of London, the eastern branch of the East African Rift is a failed rift. However, the western branch remains active.
Tra Khanh (Source: Live Science)
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