MINER WAS OPERATING ROCKBOLT JUMBO IN 254 STOPE. A LARGE ROCK STRUCK THE JUMBO ROPS CANOPY. HE GOT OFF JUMBO TO INVESTIGATE AND ROOF BEGAN FALLING IN AROUND JUMBO. HE RAN FROM STOPE & WAS NOT INJURED. APPROXIMATELY 80'L X 18'W X 8'H. FELL FROM ROOF BURYING JUMBO - ESTIMATE 800 TO 1000 TON FAILURE.