placation vs subsidence

placation

noun
  • A process or act of placating; appeasement or an expression of appeasement. 

subsidence

noun
  • The process of becoming less active or severe. 

  • A sinking of something to a lower level, especially of part of the surface of the Earth due to underground excavation, seismic activity or underground or ground water depletion. 

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