cave in vs fracture

cave in

noun
  • The act of something collapsing or caving in. 

  • The act of relenting. 

  • The location where something has caved in. 

verb
  • To collapse inward or downward. 

  • To relent; to grant approval against one's initial will. 

fracture

noun
  • An instance of breaking, a place where something has broken. 

  • A break in bone or cartilage. 

  • A fault or crack in a rock. 

verb
  • To amuse (a person) greatly; to split someone's sides. 

  • To break, or cause something to break. 

How often have the words cave in and fracture occurred in a corpus of books? (source: Google Ngram Viewer )