calamity vs natural disaster

calamity

noun
  • The distress that results from some disaster. 

  • An event resulting in great loss. 

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. 

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