Unfortunatelly many companies in NIgeria are trying to make much money quickly and they cut down expenses on buying cheaper materials and violate the technology of constraction. That is one of the major reasons why these buildings are collapsing. Some companies hire unprofessional builders. And that is another reason.
Building collapse in Nigeria can blamed on lots of factors. It include use of quacks, poor quality of building material, wrong specification of material, poor soil/land load bearing capacity inefficiency of standard Organization of Nigeria (SON), lack of regard for Planning Laws, corruption of official in the building industry, apathy of government/justice system in punishing offenders of building law/code, Obsolete/Aging building for occupation, Congestion/Pressure on building beyond specification, faulty design/shoddy work, poverty and inflation.
According to survey ranking
A report from cement factory in Nigeria as say that the price at which the chemical are bought are at high rate so the factory decided to use more lime rock for small chemical and that will make them get their money back and the cement will remain less power and it wouldn't hold houses for long time
Other research are powerless foundation for story buildings. Hope that answer your question