What's causing Nakuru fissures? Geologists break it down
A police officer points to a three-metre-deep fissure that developed near the Eveready roundabout in Nakuru town following heavy rainfall in September 2024, which left a trail of destruction in its wake.
The Geological Society of Kenya has raised concerns over ground fissures in Nakuru County, warning that the cracks pose a growing threat to infrastructure and communities.
In a statement, the society’s president, Mr Ng’ang’a Kuria says the fissures, (long cracks caused by underground fault movements and volcanic activity), are often hidden beneath soil and only become visible after damage occurs.
He noted that when rainwater seeps into the fissures, it speeds up erosion, widens the cracks, and increases the risk of sudden ground collapse.
“These processes pose a serious threat to roads, railways, buildings, and other infrastructure,” Kuria notes.
Because Nakuru is located in the active East African Rift Valley, geologists say urgent measures are needed to reduce risks.
The society now recommends the establishment of a local geohazard observatory for real-time monitoring, integrating hazard zones into county land-use plans, enforcing geotechnical assessments before building approvals, conducting detailed geological mapping, and rolling out public education programs on geological risks and disaster response.
According to Kuria, the county lies within one of Africa’s most geologically active zones, where underground faulting, volcanic activity, and erosion combine to create unstable ground conditions.
He adds that lava (molten rock) tubes also present another hidden hazard in the Rift.
These underground tunnels were formed long ago when lava flowed beneath the surface and later drained away, leaving empty spaces that can stretch for kilometers.
One can think of this as a termite hill—on the surface, the mound looks solid, but once the outer layer is broken, hollow tunnels are found inside.
In the same way, the land above lava tubes can suddenly sink, creating sinkholes or damaging buildings, roads, and farms.
“As population growth and urban development expand in the region, the likelihood of damage and disruption also rises, particularly in areas where thorough geological assessments have not been conducted,” Kuria warns.
The society is urging proactive measures, saying that without careful monitoring and planning, rapid urban growth in the Rift Valley could amplify the dangers.