Abandon is a good word, because the return you describe seems to be passive. Many of the abandoned sites have lots of belongings left behind, with no sign of ac

Abandon is a good word, because the return you describe seems to be passive. Many of the abandoned sites have lots of belongings left behind, with no sign of active clean-up effort. Since the intention that can be read from the signs is "leaving", the act is best described as "abandoning".