Nakuru sinkholes: Inside the geologically unstable grounds of Rift Valley

Geologists say the phenomenon is often triggered by heavy rains, which expose fault lines buried deep beneath the surface. And as our reporter Maryanne Nyambura now reports, experts note that tectonic plates in the rift valley drift by one to two centimetres each year, with the formation of a new lake a process that could take hundreds of years.

The rains that pound this neighbourhood no longer bring relief but fear. 

For residents like Mercy Nyaboke and Sheila Bukachi, every drop revives memories of May 9th, 2024, when a massive sinkhole opened up, displacing more than 500 families and destroying homes. One year on, some houses remain unsalvageable, while others have been patched up and repaired.

And with every heavy downpour, residents are reminded that the ground beneath their feet could give way again.

“Mvua ikinyesha nyinyi huwa tunatoka nje tuone kama tutabebwa au hatutabebwa,” Mercy Nyaboke a resident of Kaptembwa. 

“Inaweza poromoka na hatuna habari…tuko na uwoga kwa sababu shimo bado iko ukienda hiyo upande,” says Sheila Bukachi. 

Across Nakuru County, fissures cut through farms, roads, and residential estates. Invisible to the naked eye, they are often exposed during the rainy season. The recurring fissures and sinkholes have left residents on edge.

On September 4, 2025, a sinkhole opened up along the Nakuru–Eldoret highway at the Eveready area. Earlier, a similar sinkhole had formed at the same spot on the same date, September 4th, just a year earlier, in 2024.

“Tunakaa na uwoga kama vile iliteremsha manyumba huko chini inahitaji suluhisho,” Martin Obongi, a resident of Kapkures. 

Geologists have now mapped out the most vulnerable areas. Citizen TV has learnt that a fault line, dubbed the ‘Makalia fault,’ running from the Menengai crater, a massive dormant volcano, through to Lake Nakuru, is active.

Along this faultline are the areas of Kaptembwa in the western part of Nakuru, Gioto, Northeast of Nakuru, Eveready north west of Nakuru and Kiamunyi north west of Nakuru, where sinkholes have appeared repeatedly in the past three years. 

Geologists are still conducting studies after sinkholes formed in areas such as Ngata, southwest of Nakuru city and Gilgil, northeast of Nakuru.

“That is only one but some of them are not visible because of the layer…we have done some mapping and we shall be able to identify them…we are still continuing with the studies to map all of them…so that we can warn the public not to construct along the area,” says John Lagat, a geologist at GDC. 

“All the estates, Kaptembwa through the Shabaab area that separates rift valley institute. We have a bigger one in the area of the Bagaria River. The Bagaria river and Njoro River are potential sinking areas,” Kamau Kuria, a CEC for housing and urban development. 

The phenomenon has fuelled speculation that the rift valley could be splitting, even giving rise to a new lake. But experts caution that while tectonic plates do drift, the process is slow and any major transformation could take hundreds of years.

“People are associating it with the rifting, and there are reports that there will be a lake soon. The rate it is opening up is one cm or 2 cm per year. It will take hundreds of years for that to happen,” adds Lagat. 

Nakuru is one of Kenya’s fastest-growing cities, with new estates and multi-storey buildings rising rapidly. But as the city expands, a critical question emerges: how does a fast-growing urban centre plan safely and sustainably in the face of these unique geological challenges?

“A number of building have cracks, we do not have a rock basement …Menengai, Longonot, Eburru is dormant how sure are we of dormancy that may not trigger a vent that will make them erupt,” says Clement Lenashuru, a natural resource scientist.

County officials say resilience planning is already underway. By February next year, Nakuru, Naivasha, and Gilgil are set to have a comprehensive resilience plan designed to guide urban growth and keep residents safe.

“There are areas we are limiting the approvals and that is the western side along the fault line, river Njoro, Bagaria faultline and this other area in consultation with NEM, and we will will peg these areas to ensure there is no actual development,” Kuria adds. 

As geologists move swiftly to conduct studies that could deepen understanding of this phenomenon, urban planners caution that approvals for the construction of multistorey buildings can only be done after comprehensive geotechnical surveys have been conducted.