Gold Fields’ Driefontein mine, the biggest gold mine in South Africa, has closed after a tremor on 20 June caused the deaths of two people working in an underground shaft.

Eleven workers were trapped inside the mine, which has several shafts, when an underground tunnel caved in after an earth tremor measuring 3.5 on the Richter scale.

On 13 June the mine was partially closed after the death of two workers, due to another tremor.

Twelve workers died at the mine last year.

In total, about 80 workers have died in South African mines so far this year.