A NEW APPROACH TO DETERMINE THE ACTIVE AND QUIET PERIOD OF EARTHQUAKES IN MAINLAND OF CHINA AND ITS APPLICATION

an index called cycle coefficient, which is a measurement of seismicity, is proposed with the method of wavelet transformation.Based on the method, the variation of the coefficient with 22 years cycle and 10 years cycle from 1890 to 2002 in the mainland of China is analyzed.The results show that the seismic active period and the occurrence of M≥7.5 earthquakes were mainly at the descending segment of the coefficient with 22 years cycle, whereas, the quiet period was at the ascending segment.The coefficient with 10 years cycle can separate the active period from quiet period, which presents a new approach for the judgment of seismic active period.The study shows that the mainland of China has approached to the end of the fifth active period from the 20th century.