@PommyMommy , what about Tomnod? Anyone familiar with them?
Tomnod - Wikipedia
Tomnod
As I understand it, they take aerial photos of an area of concern and then post them online so the public can help scan areas looking for any relevant detail. Online searchers mark which areas show something of interest, which can then be investigated more closely.
ETA: Apparently Tomnod is in the process of switching to some new but similar searching methods. Posting this anyway in case it gives anyone better ideas.