Ravell Call, Deseret News
Haul trucks carry loads on the new mine access ramp at Kennecott's Bingham Canyon Mine, Wednesday, Nov. 6, 2013.

BINGHAM CANYON — Workers at the bottom of Kennecott Utah Copper's Bingham Canyon Mine were evacuated Friday after about 150 feet of material shifted unexpectedly.

An employee first noticed the movement about 12:30 p.m. Friday, confirmed by ground monitoring, which triggered a precautionary evacuation of employees and contractors in the bottom of the pit, said Kennecott spokesman Justin Jones.

"It isn't uncommon in mining activity to see movement like this, but of course our No. 1 concern is keeping our mine employees safe, so we went ahead and made this precautionary move to prevent any injuries, Jones said.

Workers above the small slide and in other areas of the mine were allowed to continue work.

A section about 150 feet wide in the northeastern area of the mine shifted downward Friday, Jones said. Crews hadn't approached the area to measure how far down it moved.

No additional movement was seen or expected. All employees were told to continue reporting for work, and the closed areas of the mine could be reopened by Saturday morning, Jones said.

The slide was in the same area as a record-breaking slide in April that sent 165 million tons of earth into the bottom of the world's largest pit mine. New data about the slide revealed the massive movement triggered 16 earthquakes.

A small slide also prompted a brief evacuation at the mine in September.

— McKenzie Romero