catastrophe vs ethnic cleansing

catastrophe

noun
  • A disaster beyond expectations. 

  • Any large and disastrous event of great significance. 

  • The dramatic event that initiates the resolution of the plot; the dénouement. 

  • A type of bifurcation, where a system shifts between two stable states. 

ethnic cleansing

noun
  • The mass expulsion or killing of people belonging to one ethnic group by those of another. 

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