MALAIKA MAHLATSI | Gauteng is a geological disaster waiting to happen

This past Sunday, an earthquake measuring 4.4 on the local magnitude scale was felt across parts of Gauteng. With its epicentre in Boksburg, in the City of Ekurhuleni, the tremors lasted for just under half a minute and travelled through several municipalities in the province.

While it did not cause major damage or claim casualties, it was a significant event. As a geographer, I am deeply troubled by it. Investigations are still underway to determine the cause of the earthquake, but given the region in which it occurred and its proximity to an active mine, preliminary indications are that it was caused by mining activities. In fact, mining activities, as opposed to the nature of the geology of the East Rand region, which could naturally release seismic waves, is the cause of most earthquakes in Gauteng. The reasons for this are largely historical.

The evolution of the topographic and bathymetric features of Gauteng is linked to the Mineral Revolution that started in 1867 with the discovery of diamonds in Kimberley. Within two decades, in 1886, gold was discovered in the Witwatersrand, which encompasses the west, east, central and southern regions of the province.

The Witwatersrand basin holds the world’s largest known gold reserves and accounts for almost a quarter of the gold accounted for in the world. Thus, the discovery of gold led to extensive mining within the region by multinational and local companies. In recent years, there’s been a rise in the informal mining of gold in mines long abandoned by these companies who have made fortunes out of South Africa’s minerals.

But while discussions about the Mineral Revolution often centre on how it shaped the economy and the politics of colonial and later apartheid SA, the period made an even bigger impact on the environment.

The geomorphology of Gauteng has been greatly affected by this history of mining. The province is littered with open pits, several of which have claimed the lives of children who fall into them while playing. Furthermore, mining has severely polluted water resources in Gauteng. Acid from the mined minerals is carried off mines by rainwater or surface drainage and deposited into lakes, rivers, streams and groundwater.

This process, known as acid mine drainage, severely degrades water quality and leads to faster erosion of bulk infrastructure underground. Worryingly, this process whereby acid leaches from minerals and excavated rocks can last hundreds, even thousands of years, after mining has occurred. The biodiversity in the province has also been affected by the pollution emanating from mining activities.

Another impact of mining in Gauteng is the formation of sinkholes that now line streets across the province. Chemical exposure from mining also causes soil erosion, which has an effect on what arable land is available in the province that can be used to mitigate against the devastating impacts of food insecurity.

The increasing scale of earthquakes is also another concern, especially because the infrastructure in Gauteng was not built to be resilient to earthquakes and related natural (and man-made) disasters. The implication of all these factors, compounded by the lack of meaningful investment in the rehabilitation of the province’s underground water resources, the closure of open-pits, the appropriate development of infrastructure on dolomite and the regularisation of informal artisanal mining, makes Gauteng a disaster waiting to happen.

The provincial government and municipalities must not dismiss Sunday’s earthquake as insignificant. They must recognise that it signals the geological and environmental dangers that the province is confronted with, and which, if unresolved, set parameters for catastrophe.