Complex sentence: In 1996, it became the only active mining community in the country after the closure of the saltpeter works at Pedro de Valdivia, following which many workers and their families were relocated to Maria Elena.
Split into simpler sentences: In 1996, it became the only active mining community in the country after the closure of the saltpeter office at Pedro de Valdivia. After the closure of the latter office, many workers and their families were relocated to Maria Elena.