Authorities are looking for the cause of the weekend collapse of a corn storage silo in northern Iowa’s Winnebago County. The concrete silo at the Farmer’s Co-op in the town or Rake collapsed Saturday. No one was hurt. The silo had stood 120-feet tall and contained 110-thousand bushels of corn — which is now strewn on the ground. It was built in the 1970s and was insured. A train was being loaded at the time the silo fell.