seism vs tremor

seism

noun
  • A shaking of the Earth's surface; an earthquake or tremor. 

tremor

noun
  • A shake, quiver, or vibration. 

  • An earthquake. 

  • A rhythmic, uncontrollable shaking of all or part of the body due to partial muscle contractions. 

verb
  • To shake or quiver excessively and rapidly or involuntarily; to tremble. 

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