A review on the theory of coda wave interferometry and its research progress

This review first presents the basic theory of coda wave interferometry (CWI), and then introduces the application and research progress of CWI in source location variation and scatter moving status. Finally the advantages and the disadvantages as well as development direction of the CWI in monitoring velocity variation of underground media are discussed by using repeating earthquakes, active sources and ambient noise cross-correlation function. Due to the characteristics of multiple scattering waves， CWI can be used to extract source locations and monitor subtle variations of media. The temporal change of media may provide us ideas and guidances of preparation and development of earthquakes or volcanoes.