Complex sentence: Its population has dwindled from more than 1,000 residents in 1980 to only 10 in 2010--a result of the coal mine fire, which has been burning beneath the borough since 1962.
Split into simpler sentences: Its population has dwindled from more than 1,000 residents in 1980 to only 10 in 2010. This is the result of the coal mine fire, which has been burning beneath the borough since 1962.