Rio's subsidiary Kennecott Utah Copper said it is looking to cut further positions in the coming days as it continues to take steps to reduce the impact on its workforce.
The workers can choose between using vacation time, taking unpaid leave or retiring with a one-time $20,000 resignation incentive.
"At this time, Kennecott does not have the total number of employees impacted by the slide. Kennecott is continuing to take measures to reduce the impacts to its workforce by making employee preference a priority," Kennecott said in a statement.
Rio Tinto estimated that over 165 million tonnes of earth slid into the open-pit Bingham Canyon Mine in mid-April and caused greater than expected damage to equipment.
The landslide is expected to reduce planned copper production by 50% in 2013.
Bingham Canyon Mine is an open-pit mining operation extracting a large porphyry copper deposit south-west of Salt Lake City, Utah, in the Oquirrh Mountains.
It has been in operation since 1906 and has a pit over 0.97km deep, 4km wide and covering 770ha.
In June 2012, Rio Tinto announced its plans to spend about $660m over the next seven years to extend the life of the mine to 2029 from the present 2018.
Image: Bingham Canyon Mine is an open-pit mining operation extracting a large porphyry copper deposit south-west of Salt Lake City, Utah. Photo: Andreas Feininger.