An unplanned roof fall occurred at spad #143+50 to spad #144+90 in the #8 entry of the 3rd North Mains. An unseen slip was in the area. The fall measured 140' long by 19' wide by app. 6'-7' high. There were no injuries and ventilation and travel was not affected. This area is approximately 1000' outby #2 unit, MMU 002-0