Experts: what could make a rock to shift base
Rock formations are common features of Abeokuta, the Ogun state capital, and its neighbouring villages even as Abeokuta – people who live under the rocks – derived its name from there.
While some of the rocks which were formed centuries ago, according to geologists, are tourist sites such as the Olumo Rock. Others situating in remote areas, remained veritable sources of granites and stones in commercial quantities to people within and outside the state, for construction works.
And some of the residents, acting on the eroneous belief that rocks neither die nor decay, and perhaps because of the cool ambience they are said to engender at night, elected to erect their homes near or below those rocks, while others build atop of them, including altars of prayer, especially those who attached spiritual conotation to rocks.
So far, since 1830 AD when the Egba people arrived and settled in Abeokuta, both the rocks and the residents had co-habited with each other and safely, too, not even the earth tremor that occured in the city in 1986 could rupture that hundreds of years of living safely near rocks.
But penultimate Friday, that changed. A ‘treacherous’ rock in Iberekodo, Abeokuta, crushed four persons, including mother, two children and a grandchild, to death when it tipped off its base and rammed lethally on them after knocking down the wall of their bedroom.
The rocky Iberekodo community in Abeokuta North Local Government Council of Ogun state were left in shock and grief.
However, the man of the house, Ismail Lawal, Sukurat and Rofiat, survived the assault on the modest home by the deadly rock because they happened to be relaxing at the sitting room when it struck but they incurred serious injuries.
The victims – Mrs Silifat Lawal, her two children: Rasheedat (15), Semia (4) and a grandchild Mariam – had barely fallen into a deep sleep on their bed after a Friday dinner when the rock killed them.
The Nation gathered that the rock has been in existence in Iberekodo community before the Egba people settled in Abeokuta, the Ogun state capital, around 1830 AD.
Some of the villagers said the heavy downpour that fateful day, which they claimed softened the base of the rock situating on a location overlooking Ismail Lawal’s home, caused the ground to give way. According to them, the rock, having lost its balance, tumbled and rolled lethally on Lawal’s home beneath.
Mrs Khadijat Adegoke, a neigbour of the victims, said she was jolted from sleep by the deafening sound of the impact of the rock as it rolled down the hilly neighbourhood before smashing itself into Lawal’s home.
According to her, neigbours got to know that the rock had dealt a lethal blow when Mr Lawal rushed out and began shouting for help but could not do anything as the victims had already been crushed.
“The incident happened around 9pm. The rain was very heavy since 5pm. When the rock shifted and crushed them, we didn’t hear because of the sound of the rain. The father came out shouting. We rushed there only to find out that all the four of them had been crushed to death.
“The father was sleeping in the sitting room. That was why he escaped with another daughter,” Mrs Adegoke said.
The Nation visited neighbourhood on Wednesday and observed that the residents were unwilling to make any further comment about the tragedy, while the home of Ismail Lawal appeared deserted with nobody in sight.
But experts are unwilling to accept the explanations by the villagers that the ground where the rock hitherto sat, shifted following a heavy downpour some hours earlier and primed it to tumble after the said rain had weakened the base of the rock.
An expert, Akintola Akintunde Isaac, gave some conditions that could cause a rock to lose balance and roll off its base or shift position.
Akintola, a geologist and lecturer at the Olabisi Onabanjo University(OOU), Ago – Iwoye, said structural factors such as earth tremor and vibration from stone blasting by people digging well or making quarry could jolt a rock off its base.
He recalled that in 1986 or there about, there was an occurrence of earth tremor in Abeokuta, the Ogun State capital, with its vibrating impact felt by residents but, according to him, there was no incident of rocks falling.
The don noted that even if a heavy rain had preceded the Iberekodo tragedy, it could only have been a secondary factor and may not neccessarily be the trigger.
According to him, unless there is a visit to the site for on-the-spot expert assessment of the situation, one may not be able to tell exactly what tipped the Iberekodo rock off its base it had sat for hundreds of years until a week ago when it lost its base, traversed into the home of Ismail Lawal and killed his wife, two children and a grandchild.
“Blasting of stones with electrode and dynamite around the area could shake the rock off its suport base and if there is earth tremor due to structural defect, it could cause the movement of rocks.
“In 1986 or there about, a tremor was observed in Abeokuta and the vibration was felt but no cases of rocks falling off or being uprooted was recorded. But you see, blasting can cause that. One is suspecting stone blasting.
“During blasting, rocks can fall. When people are digging wells (bore-holes) and they meet a rock, they blast the rock to make way for the digging to proceed. And when you blast, it is like where bomb is being thrown and it affects anything within its range of impact,” he said.
Another geologist, Dr Ajibade Michael, who advised that it is not safe to live near rocks or below them, said the Iberekodo incident could be caused by the long-term impact of physical and biological weathering (cracks and breaking down of rocks) through agents such as heat, cold, burrowing animals, pressure, plant roots, among others.
According to Ajibade, a don, attachment of plants and weeds to rock surface as could be observed in Iberekodo neighbourhood and other rocky parts of Abeokuta, increases the physical and chemical breakdown of layers of rocks while the growth of living organisms also widen the crevices and make a rock vulnerable to water and chemical infiltration and then subsequent disintegration.
Governor Ibikunle Amosun, reacting through his media aide, Adejuwon Soyinka, described the insident as unfortunate and sad.
In a release signed by his Senior Special Assistant Soyinka, the governor said: “The incident you referred to was indeed very unfortunate and whatever caused it is still being investigated by the relevant agencies of government.
“As sad as it is, the incident further reinforces the state government’s position that it is illegal and dangerous for anyone to build under rocks. This is also why the state government regularly conducts public awareness and enlightenment programmes to sensitise the people on the dangers inherent in building under rocks.”
