ATLANTA (AP) -- Photos and mementos that were snatched up and blown hundreds of miles by a cluster of Southern tornadoes are giving researchers new insight on how debris is carried by the storms and how it could threaten the public.

A new study has documented one picture's flight of almost 220 miles over Alabama and Tennessee in 2011. That is among the longest-documented trajectories of tornado debris, the researchers found.

The photo was among 934 objects in a database built by University of Georgia associate professor John Knox and his students. They say the research could aid public safety by predicting where tornado-borne toxic or radioactive debris might fall.

The research relied heavily on a Facebook page created by an Alabama woman, who posted pictures of the debris.