The Grand Kenyan – A huge fissure in the East African Rift valley

A huge fissure developed in the East African Rift Valley in Kenya on March 19, 2018.

From Daily Nation/JAMES KAHONGEH on March 20, 2018:

At the intersection of the damage with the busy Maai Mahiu-Narok road, what was recently an even plain of fertile, arable land has been reduced to a rugged expanse, with a huge tear that is as much as 50 feet deep and more than 20 metres wide running through it.

This spot, however, is just one of the tens, perhaps hundreds, of other weak spots on the Great Rift Valley, which runs through the continent from the Horn of Africa to Mozambique, scientists say.

[…]
Families living near the fissure started moving out yesterday, with 72-year-old Mary Wambui saying “staying here is like courting death”.

She was having dinner with the rest of the family on Monday when the Earth suddenly cracked beneath their feet, cutting their home into two.

Activity here has been going on for several million years. It’s not a new discovery. But it is a complex system. The East African Rift Valley is splitting off the horn of Africa due to the upwelling of magma from the mantle. The area has active volcanoes as well as frequent earthquakes.

The cause of this particular crack is debated by scientists as some say it may be a surface reflection of a deep-seated structural fault while others say it was caused by rains.

From Lucia Perez Diaz at The Conversation:

Initially, the appearance of the crack was linked to tectonic activity along the East African Rift. But although geologists now think that this feature is most likely an erosional gully, questions remain as to why it has formed in the location that it did and whether its appearance is at all connected to the ongoing East African Rift. For example, the crack could be the result of the erosion of soft soils infilling an old rift-related fault.

Rifts just don’t “split a continent in two” overnight. There isn’t one big crack down the middle and everything falls apart. But that is what the headlines of many news stories suggested to casual readers. The split is expected on a time scale of millions of years. Meanwhile, people living in the Valley need to be watchful of surface fissures, especially during rains. And, authorities must take into account faults and geological hazards when building infrastructure.