PRIMARY DISCUSSION ON CODA AMPLITUDE RATIO,TIME-ENTROPY AND ITS APPLICATION

Based on the simulated and digital earthquake records of 75 earthquakes recorded by telemetered seismic network of Shandong province from 1994 to 2000, the Coda amplitude ratio and energy ratio is determined, and the Coda Q-value as well as mean freedom distance in Shandong area is assessed.The absorption quality factor Q_i and scattering quality factor Qs are also calculated.From those values we concluded that the attenuation of Coda wave in Shandong area was caused largely by scattering.Through examination to the parameter used to describe the attenuation of Coda amplitude with time(Coda time-entropy ST), we found that the attenuation of Coda time-entropy before medium and strong earthquakes is very clear, which may be useful in the prediction of medium and strong earthquakes.