It is deeply troubling how routinely geological expertise is sidelined in Kenya's built environment.
Every safe structure begins not when the mixer meets the concrete, but when the ground beneath is fully understood. What lies beneath our feet is not just earth, it’s a living, dynamic system that silently governs the stability of any structure above.
Soil and rock characteristics vary dramatically and dynamically over short distances. A site may appear suitable on the surface, but a few centimetres deeper, you may encounter highly weathered zones, weak seams, voids, karstic cavities, or permeable and porous carbonates and/or tuffs. Without rigorous investigation, these hidden hazards remain undetected until it’s too late.
Before foundations are cast, a proper geological and geotechnical investigation should be standard practice, employing: Trial pits and borings (auger, wash, rotary, percussion) to access and classify the soil layer.
Probing and subsurface soundings to assess consistency and depth of weak materials—geophysical methods (seismic refraction, electrical resistivity) to reveal subsurface anomalies such as voids, fractures, moisture pockets, or unstable zones.
These approaches are not technical luxuries—they are critical risk management tools. A proper ground investigation is the only way to establish safe design parameters before the pick meets the ground.
Let’s not forget the role of water, arguably the most destructive force if misjudged. Infiltration through porous soils or weak strata can lead to structural heave, collapse, or liquefaction, particularly in areas with poor drainage or concealed weathered zones.
The presence of clay-rich soils, carbonates, and volcanic tuffs, common in Kenya, only amplifies this risk when their properties are not fully understood or tested. Worse still, many new buildings are squeezed between older developments where stormwater runoff and wastewater have no planned exit, leading to gradual underground erosion.
This is a call to all geologists. We have a responsibility to take the lead. We must champion this knowledge to the public, the industry, and professionals, including architects, civil engineers, quantity surveyors and contractors on the irreplaceable value of proper geological and geotechnical assessments before any project begins.
Let us not continue to respond only after a tragedy. Construction safety does not begin at the concrete mixer—it begins beneath our feet, with informed geological assessment.
Let us explain how our disciplines contribute not only to hazard detection but also to design parameters and safety assurance.
Highlighting: How geology predicts material behavior under load and vibration; How it identifies depth to competent strata; How it detects voids, saturation zones, and seismic vulnerabilities; And how it informs material selection and design standards.
Meanwhile, our trust in construction materials continues to be misplaced.
Common failures include: sand with excessive clay content, weakening mortar and concrete mixes; Highly porous and permeable blocks, which absorb water during curing and increase structural loads significantly; Untested cement, whose setting times and compressive strength are simply assumed; And now, steel reinforcement bars whose tensile strength is rarely verified, and which often fail to meet Eurocode standards.
Structural steel is fundamental to safety, yet many sites accept deliveries based solely on appearance and supplier reputation, without any laboratory tensile or bend tests. We must acknowledge that material quality is not constant. What passed last month may fail this week. The assumption that a supplier’s past record guarantees current quality is misleading and dangerous.
The issue is systemic and thus Institutions like Nema must understand that by the time a hazard manifests on the surface, the subsurface has already been severely compromised, often through human negligence, untested materials, or overlooked geological indicators.
It is now urgent that the National Construction Authority (NCA) makes it mandatory for all developments, regardless of size to undergo geological and geotechnical site investigations before any construction or excavation begins, before the pick hits the ground. This should be as routine as submitting structural drawings or architectural plans.
The writer is a geologist from Geological Society of Kenya. Email: [email protected]
