Research progress on seismic radio sounding technology

Electromagnetic monitoring methods are in good graces of the experts on short-term and immediate earthquake prediction. Radio sounding technology is one of the methods which has been studied for more than 10 years in Russia and Japan. The research has showed the functions in revealing the seism-ionospheric coupling mechanism and earthquake prediction. Various ways of radio sounding technology to monitor the seism-ionospheric perturbations at home and abroad are summarized in the paper. The typical experiments methods in radio sounding technology are summarized in this paper. The research progress on mechanism of seism-ionospheric disturbances is concluded. The analysis methods of earthquake precursor information and the results in the study at two different frequencies are introduced contrastively. According to the deficiency of the research on radio sounding technology in China, the suggestions on future development are given.