landslip vs mudflow

landslip

noun
  • The sliding of a mass of land down a slope or cliff; a landslide 

mudflow

noun
  • A type of landslide characterized by large flows of mud and water. 

  • The dried-out product of such a flow. 

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