An unplanned roof fall above the anchorage zone occurred on the MMU 006/007 (#2 section) belt line between spad number 1689 and 1717 in the belt #4 entry. the fall was approximately 75 feet wide X 18 feet wide X 8 feet thick. No injuries or entrapment were involved. No escapeway or ventilation involved. Conveyor belt line was under the fall.