In this paper,the theoretical model for the developing earthquake media has been proposed and the mechanics relations and motion equation intwo-phase media have been established.The properties of two-kind p-waves in the developing earthquake media have been demonstrated.The authors have studied also the reflective and refractive coefficients for propagation of seismic waves in the layered multi-phase media.The methods for selecting parameteres have been discussed and The displacement field in the developing earthquake media calculated.Specifically,for instance,the authors have analysed the temporal and spatial characteristics of the amplitude ratio,including those of the imminent shock anomaly before and after the Haicheng earthquake of February 4.1975 Finally,the amplitude ratio anomaly is interpreted preliminarily from the point of view of physical implication.
Theoretical and practical results show that (1) The seismic velocities,amplitudes and waveforms may variate when they travel through the developing earthquake media,especially,the variations of the p-amplitude are bigger.The variations of amplitude ratio depend mainly on the variations of p-amplitude.In the two-phase media with gas saturation,the p-amplitude is bigger than in the solid-phase,oppositely,in the two-phase media with liquid-saturation the p-amplitude is less than in the solid-phase.(2) The forms of the temporal variation before and after the Haicheng earthquake appeared as follows:lower value and then revalue-higher and stable value-occurence of shock-falling.The spatial variation was that the amplitude ratio in the periphery was lower,in the middle higher,the fringe on the high-value region was a dangerous region of major shcok.(3) The amplitude retio increased sharply before imminent shock and earthquak occured when the amplitude peak was falling.The time for appearing peak depended on the epicentral distance and azimuth Generally,it appeared in periphery and in some position at first and then in epicentral area.Based on the preceding coclusions the possibility that the amplitude ratio as a pre cursor may be applied to earthpuakes prediction has increased.