AN UNINTENTIONAL ROOF FALL OCCURRED ON THE 1ST WEST SUB-MAIN OFF THE 4TH N. SUB-MAIN IN #9 ENTRY AT #18 CROSS CUT. THIS ROOF FALL WAS LOCATED IN AN INTERSECTION & WAS SUPPORTED WITH 6'POINT ANCHOR ROOF BOLTS. THE ROOF FALL MEASURED 20'LONG X 18'WIDE X 9'HIGH & THE ROOF FALL WILL NOT BE CLEANED UP.