Analysis And Research Of The Infrasound Signals Before The Earthquake

As one of important methods to forecast earthquake, we found that the infrasound observation make a good effect on the earthquake prediction by observing and researching for more than twenty years. Usually the earthquake will occur in 9 days after the abnormal infrasound signals received, we can predict the magnitude and time of the earthquake according to the time and range of signals received. The error of the earthquake magnitude is less than 0.8 and the error of the time is less than 4 days. There are abnormal infrasound signals which can be received when there is wind, thunder storm or nucleus exploded and volcano erupted. It's very valuable for a the earthquake prediction to find the characteristic of the earthquake abnormal infrasound signals and non-earthquake abnormal infrasound signal and the correlation between the earthquake abnormal infrasound signal and earthquake by analyzing and proposing the data. What mentioned hereinbefore is the contents and significance of the paper.This paper investigated the correlations between infrasound signal before the earthquake received by the Institute of Earthquake Prediction Research in Beijing University of Technology and earthquake more than magnitude 7 occurred in the world wide from Jan. 1, 2001 to Dec. 31, 2005 by using the knowledge of random theory and correlation theory, the correlation between sunspot and infrasound from Jan.1, 2001 to Mar. 31, 2005, the correlation between sunspot and earthquake from Dec. 7, 1996 to Mar. 31, 2005.As examples, 5 earthquakes occurred in Japan, 5 earthquakes occurred in other areas and 5 non-earthquake abnormal infrasound signals received while there was wind or thunder storm were analyzed for the frequency characteristic of the signals by using Fourier transform theory. Wavelet decomposing and continuous wavelet transform of the signals were also carried out. The similarities and differences between the earthquake abnormal infrasound signals of different areas, and the similarities and differences between the earthquake abnormal infrasound signals and the non-earthquake abnormal infrasound signals were found.