A roof fall occurred on the 1st right panel off ""r"" section mains at S.S. #4487 in the No.4 neutral entry. the fall measured 40'L x 10'h x 18'w. the fall occurred in an area of known bad top and supplemental supports (10' cable bolts and cribs) had been installed in the area prior to the fall. the fall is located approx. 3200' outby the active 002-0 section.