An unplanned roof fall occured in the #2 entry one break outby spad #1377. Fall occured 700 feet outby the working face. No persons or equipment involved. The fall measured 20' x 20' & a height of 7-8 feet. There is a rider seam 4' above the seam which measures 8-10"" thick. Area was supported with 6' torque tension bolts. Area will be rehabilitated. Agencies were notified by phone.