burn up vs set afire

burn up

verb
  • To catch fire and burn until destroyed. 

  • To feel overly hot or inflamed. 

  • To anger; to annoy. 

  • To destroy by burning. 

  • To experience a high fever. 

set afire

verb
  • Synonym of set on fire 

How often have the words burn up and set afire occurred in a corpus of books? (source: Google Ngram Viewer )