Friday 30 March 2018

Dramatic rifting splits roads and homes in Narok County, Kenya.

A dramatic rift has opened up in Narok County, Kenya (to the west of Nairobi), splitting the main Mai Mahiu-Narok road in two. The rift, which is described as being about 15 m wide and 15 m deep, opened up on Monday 26 March 2018, and runs largely through farmland, though as well as splitting the Mai Mahiu-Narok road it is reported to have destroyed a number of homes, although no injuries have been reported following the event.

Aerial photograph showing newly formed geological rift splitting the Mai Mahui-Narok road in Narok County, Kenya. Emergency repairs are currently allowing the passage of traffic. Face2Face Africa.

Western Kenya lies within the the of the Great Rift Valley, which is slowly splitting the African Plate in two along a line from the Red Sea through Ethiopia, and which includes the great lakes and volcanoes of east-central Africa. This has the potential to open into a new ocean over the next few tens of millions of years, splitting Africa into two new, smaller, continents; Nubia to the west and Somalia to the east.

 Movement on the African Rift Valley, with associated volcanoes. Rob Gamesby/Cool Geography.

However, this rifting does not usually result in the opening up of dramatic openings at the surface, even in areas like Western Kenya, where the two plates are drawing apart at a rate of about 2.5 cm per year. Geologist David Ahede of Rock Link Geological Consultants has suggested that the immediate cause of the rifting is likely to be movement beneath Mount Suswa, a small shield volcano (dome-shaped volcano made up of successive layers of lava) within the Rift Valley. A number of small Earth tremors were recorded near the volcano earlier in the week, which may indicate the movement of magma between chambers beneath the mountain, a possible precursor of future volcanic eruptions. Such movements can place stress on the geology of the surrounding area, causing events like the rift opening observed in Narok County this week.

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