upthrow vs upthrust

upthrow

verb
  • To be thrown up from below, causing a fault. 

  • To throw up (a mass of material) from below, causing a fault. 

noun
  • A fault in which a mass of material has been thrown up from below. 

upthrust

verb
  • To thrust something upwards. 

  • To be thrust upwards. 

noun
  • Buoyancy. 

  • An upward movement of part of the Earth's crust. 

  • An upward thrust. 

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