The collapse took place on October 1. Although no fatalities or equipment damage were reported, mining activities have been suspended and an assessment of the impact is underway. Mining is continuing at the company's Marvoe and Kinjor-South pits at New Liberty.
The company's gold production and cost guidance was already under review, and this event is likely to impact that process, although it does also have operations in neighbouring Burkina Faso.
"It didn't kill anyone or damage any equipment which was lucky, but they can't go back into the pit till the pit wall is stabilised and new benches are cut to ensure stability," said SP Angel research analyst John Meyer.
"[The] question is, how bad is the main access ramp? This could be a more major and longer-term issue if it is damaged. There are some other pits, but mining will operate at a reduced level till things are sorted out."