Seismologists customarily use coda waves to study the inhomogeneous characteristics of the earth. However, P coda waves have seldom been studied due to their weak signals and short duration time when the epicenter distance is less than 100 km. In order to manifest the characteristics of the P coda, a measurement of 2-d physical modeling was made by systematically changing the scattering attenuation the the intrinsic attenuation of the medium.

Based on the experimental results, the decay rate of the P coda with elapse time is independent of the scattering attenuation; in contrast, the excitation level of the P coda is proportio11al to the scattering attenuation. Moreo\7er, the amplitude decay with the elapse time of P coda waves can he satisfactorily interpreted by the n1odel (.>f energy transfer (Shang and Gao, 1988).