BHP Billiton Ltd. (BHP.AU) said Tuesday it temporarily closed the underground Perseverance nickel mine in Western Australia after the second rockfall caused by a seismic event at the operation this month.

One worker was trapped underground after the rockfall for about 90 minutes before walking out unharmed, and all staff are now safe and accounted for, a spokeswoman for BHP said.

The mine will be closed until it is determined whether it is safe to begin operating again, she said.

The incident at the mine, sparked by seismic activity late Monday registering 2.3 on the Richter scale, follows a rockfall on June 11, which also trapped a miner underground.

The Australian Manufacturing Workers' Union said the incident was the latest in a string of safety problems at BHP mines and called for a federal parliamentary inquiry into mine safety.

"An independent inquiry is urgently needed to investigate why these tragic events happen on BHP mine sites and to recommend what needs to be done to guarantee the safety of BHP workers," the AMWU's Western Australian State Secretary, Steve McCartney, said in a statement.

-By Alex Wilson, Dow Jones Newswires; 61-3-9292-2094; alex.wilson@dowjones.com