Nakuru’s shaky ground a threat to tall buildings

By Alex Kiprotich

A large part of Nakuru town has cracks and fissures that pose danger to tall buildings.

However, this scare has not deterred developers. Although the town’s planners have always insisted on construction of low-storey buildings –– less than four floors –– this is not the case.

According to geologists, the proximity of the Menengai crater to the town makes the region’s surface weak and therefore unable to sustain heavy weight.

But the desire to maximise on space and make a quick buck have overshadowed fears that should a tremor occur, these buildings would tumble like a pack of cards.

Buildings with more than four storeys include CK Patel, Ndumo House, and Kwanza House.

The recently built Highway Plaza, Ereto Plaza, and Biashara centre are also fighting for space in Nakuru’s skies.

Rift Valley Provincial Geologist Thomas Ndola says the area, particularly the west and southwest, often experiences ground failure –– shaking that affects the stability of the ground –– during earthquakes.

Ndola says Ngata, Rhonda estate, and Barut shopping centre have the weakest surface points.

Other areas include west of Rhonda Hill, Bangladesh, North of Nakuru GK Prison, and Githima, where Eveready Company is located.

"These areas have very poor surface runoff because of fissures running across them from Menengai crater that erupted thousands of years ago," he says.

The geologist says the fissures cutting underneath the town open up during heavy rainfall.

"The fissures, due to unconsolidated deposits accompanied by slumping and flushing of material deep down, produce holes and funnel shaped depressions, which cannot hold heavy weights," he says.

He says his department does not directly deal with buildings.

"It is the work of the municipal council and the structural engineers to determine how many floors a building should have after analysing the strength of the soil," he says.

Ndola says during heavy rains and earth tremors, buildings located on the weak spots are likely to collapse.

A municipal council engineer who spoke on condition of anonymity said the council approves all buildings so long as the plan is accompanied by a report from the structural engineer.

He said the council is aware of some spots, west of town, which have very weak surface that cannot even sustain a single storey building.

When asked why tall buildings have sprung up in Central Business District, the engineer said at times ‘investors use outside influence to exert pressure on engineers’.

"I cannot point out which buildings have exceeded the limit but definitely engineers at times turn a blind eye on some cases," he said.

He said previously investors took seriously reports on the nature of soil to determine the height of a building but they now use corrupt means to erect tall buildings in the CBD.

He said residents have expressed concern over buildings that shake.

The council has put a limit on the height of buildings now being constructed.

"We do not allow the construction of buildings that have more than five storeys. Those that have more than three must have a report from a geologist," he said.

Engineers are also expected to sign an indemnity form to take responsibility should the building collapse.

A copy of the council by-laws touching on buildings was unavailable. Officials said the council was waiting for deliveries from the Government Printer.

Ndola expresses concern that a major earthquake is likely to have devastating consequences.

"The origin of previous tremors has been outside the country. The case would be different if it originated from here," he says.

Residents in multi-storey buildings complain of ‘shaking’, especially along Kenyatta Avenue.

"It is scary. Every time heavy vehicles pass on the road 50 metres away, tall buildings shake," says Ms Martha Mwangi.