THREE miners were killed early on Wednesday and four others injured when an earth tremor caused a ground fall in a gold mine west of Johannesburg, mine owners Goldfields said. The accident at the Driefontein Consolidated Gold Mine near Carletonville occurred at almost 3000 metres underground and followed a seismic tremor which measured three on the Richter Scale, a statement from Goldfields said. Concern about safety on mines is high after 20 people were killed last month at the Mponeng gold mine, also near Carletonville. A memorial service for the 19 miners was held Wednesday and attended by about 2000 people, including friends and relatives from neighbouring Mozambique and Lesotho.