escalate vs richen

escalate

verb
  • To increase (something) in extent or intensity; to intensify or step up. 

  • To climb. 

  • In technical support, to transfer a customer, a problem, etc. to the next higher level of authority 

richen

verb
  • To gain richness; become heightened or intensified in brilliancy. 

  • To make or render rich or richer. 

  • To become rich or richer; become superior in quality, condition or effectiveness. 

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