CENTURION - Sinkholes are posing a major safety threat around parts of Gauteng.
They have swallowed homes in Khutsong, Ekurhuleni and roads have been collapsing in Centurion in east of Tshwane.
A significant part of Gauteng contains dolomite, which can dissolve in water and lead to surface collapse. It is a known hazard.
This rock according, to Tebogo Makhubela, a National Geographic Explorer, is billion years and covers almost a two third of the province on both surface and sub-surface.
This dolomite does not just dissolve on its own another contributing factor is excessive water that affects the rock.
This can be from rain but also water from sewage systems, leaking taps.
"This water ends up on the sub-surface and continuing to dissolve the rock which will then form cracks. These cracks will then get wider as they get exposed to water," Makhubela said.
Geologically speaking there are a lot of areas globally that are not ideal for building infrastructure and residential buildings but this is where civil engineering comes in.
"The purpose of that engineering is to devise ways of how one can build in such an area," Makhubela said.