WE HAD A ROCKFALL IN ONE OF THE 2 NEUTRALS ABOUT TWO THIRDS OF THE WAY UP BESIDES #8 BELT AT SPAD #4566 MEASURING APPROX. 20' WIDE, 40' LONG AND FROM ABOUT 4' TO 12' HIGH. IT BOLTED GOOD WHEN WE MINED THROUGH IT BUT APPEARS TO BE AN UNDETECTED FAULT AREA. REPORTED IT TO MINE INSPECTOR.