scare off vs tremble

scare off

verb

  • To cause (something) to flee by frightening it. 

  • To deter 

tremble

verb

  • To fear; to be afraid. 

  • To shake, quiver, or vibrate. 

noun

  • A shake, quiver, or vibration. 

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