Johannesburg was born from a gold rush in 1886 and grew into the richest city in Africa on the strength of what lay beneath it. Nearly a century and a half later, that same underground geology has become the city's most dangerous liability. Across Gauteng and the wider gold reef, illegal miners known as zama zamas, Zulu for " those who try" are descending into abandoned shafts by the thousand, and the infrastructure above them is starting to give way.

Johannesburg was born from a gold rush in 1886 and grew into the richest city in Africa on the strength of what lay beneath it. Nearly a century and a half later, that same…

Whole chunks of a once-busy road in Johannesburg have collapsed because of damage caused by the illegal mining rampant across South Africa's economic hub.