The world witnessed dramatic enormous crack opened in the ground in southwestern Kenya back in March 2018. It appeared suddenly after heavy rains, measured several kilometers in length and swallowed a section of the Nairobi-Narok highway. This region belongs to the Kenyan Rift Valley, which is again the  part of East African Rift, one of the most tectonically active regions in the world. 

The rift, which began developing about 25 million years ago, extends over a staggering 3,500km (2,174 miles), from the Red Sea in the north all the way to Mozambique in the southeast of the African continent. Seismic & volcanic activity occurs along its entire length, and is responsible for creating mountains including Kilimanjaro and Mount Kenya.

THE SPLIT

Till the period of 1970s it was believed that Africa is rest  upon a single tectonic plate but soon the evidences   suggested that  the African plate is rupturing into two new plates – the Nubian and Somali plates

The reasons of this rift is  highly debated among the geophysicists &  geologists. Seismicity in the East African Rift System is characterized by low-magnitude. The current prevailing theory is that plumes of heat within Earth’s mantle are making the lithosphere (the crust & solid upper mantle) beneath Kenya and Ethiopia dome and stretch.

This leads to the thinning of the lithosphere which again resulted in huge volcanic eruptions called flood basalts – which pushes up the lava from emerging fissures & fractured the brittle continental crust into a series of faults.

THE SPEED OF RIFTING.

The Nubian and Somali plates are diverging at an average rate of 7mm (0.2in) per year, slowly pulling the continent apart. Today, the rift remains above sea level, but as it widens, the land within the valley will sink.  The oceanic flood waters  may separate the entire Horn of Africa from the mainland. The Red Sea & the Gulf of Aden, are examples of similar rifts at more advanced stages of evolution.

There is a consensus among the geologists that, the  rift is developing from a pre-existing crevice which remained  undetected because of a cover of  volcanic ash from eruptions.

Scientists, in 2020, predicted a new ocean would be created as Africa gradually splits into two separate parts. The division of the continent is connected to the East African Rift, a crack that stretches 56 kilometres & appeared in the desert of Ethiopia in 2005, triggering the formation of a new sea, according to a study published in the peer-reviewed journal Geophysical Research Letters. 

This geological process will inevitably divide the continent, resulting in currently landlocked countries, such as Uganda & Zambia, obtaining their own coastlines in due time, which would take 5 to 10 million years.

The necessary evacuation of people & the potential loss of lives will be an unfortunate cost of this natural phenomenon. However, on the upside, the emergence of new coastlines will unlock a myriad of opportunities for economic growth.

As the Somali and Nubian tectonic plates continue to pull apart from each other, a smaller continent will be created from the rift, which will include present-day Somalia and parts of Kenya, Ethiopia, and Tanzania.

According to Ken Macdonald, a marine geophysicist at the University of California, the Gulf of Aden and the Red Sea will eventually flood into the Afar region in Ethiopia and the East African Rift Valley, leading to the formation of a new ocean.

The three plates — the Nubian African Plate, Somalian African Plate and Arabian Plate — are separating at different speeds. The Arabian Plate is moving away from Africa at a rate of about an inch per year, while the two African plates are separating even slower, between half an inch to 0.2 inches per year, according to Macdonald.

Rifting refers to the geological process in which a single tectonic plate is split into two or more plates separated by divergent plate boundaries.

While the process of rifting may often go unnoticed, the separation of the Nubian and Somali plates can result in the formation of new faults, fissures & cracks or the reactivation of pre-existing faults, leading to seismic activity.

Over a span of ten million years, seafloor spreading will gradually advance along the entire extent of the rift. This will lead to the flooding of the ocean, resulting in the African continent becoming a smaller, significant island composed of fragments of Ethiopia and Somalia, including the Horn of Africa.

Evidence for the existence of this hotter-than-normal mantle plume has been found in geophysical data and is often referred to as the “African Superswell”. This superplume is not only a widely-accepted source of the pull-apart forces that are resulting in the formation of the rift valley but has also been used to explain the anomalously high topography of the Southern & Eastern African Plateaus.

The East African Rift is unique in that, it allows us to observe different stages of rifting along its length. To the south, where the rift is young, extension rates are low and faulting occurs over a wide area. Volcanism and seismicity are limited.

Nevertheless, recent studies suggest that, climate change may be exacerbating this process. As global temperatures rise, the ice caps in Greenland & Antarctica are melting at an alarming rate.

This melting ice is causing a significant shift in the weight distribution of the Earth’s crust, which in turn is putting pressure on the East African Rift System.

According to a study published in an environmental journal, “The melting of the Greenland & Antarctic ice sheets is contributing to sea-level rise, but it is also causing a redistribution of mass on the Earth’s surface that affects the Earth’s rotation and gravitational field.” This redistribution of mass is causing changes in the Earth’s crustal stress, which can affect the formation of rift valleys.

In addition to the weight distribution shift, climate change is also causing an increase in rainfall & flooding in the region. This increased rainfall is causing erosion, which is further weakening the Earth’s crust in the area.

As a result, the rift valley is widening, and the risk of earthquakes & volcanic activity is increasing. According to a study published in Quaternary Science Reviews, “The interplay of tectonics, erosion, sedimentation, and climate is highly dynamic, and all of these factors have to be considered to understand the evolution of the East African Rift System”.

The Earth is an ever-changing planet, even though in some respects change might be almost unnoticeable to us. Plate tectonics is a good example of this. But every now and again something dramatic happens and leads to renewed questions about the African continent splitting in two.