It’s still unclear if a grain elevator exploded or whether it was just structural failure that made a mess in north-central Iowa this morning. A grain storage elevator ruptured just before 8 A.M. in Clarion this morning, spilling thousands of bushels of corn and evacuating a two-block area for investigation. Tom Winkle, safety coordinator for the Max Yield Corporation, says they’re assessing the damage and won’t yet comment on what caused the bin to rupture.No injuries are reported in the incident. In February, a different grain bin in Clarion exploded, injuring one person.