natural disaster vs upheaval

natural disaster

noun
  • The emergency situation that is the consequence of such an event. 

  • Any natural phenomenon that causes great damage and loss of life. 

upheaval

noun
  • A sudden violent upset, disruption or convulsion. 

  • Disruptive change, from one state to another. 

  • The process of being heaved upward, especially the raising of part of the earth's crust. 

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