Could Global Warming be a Blessing for Mankind?

Seismologists customarily use coda waves to study the inhomogeneouscharacteristics of the earth.However,P coda waves have seldom been studieddue to their weak signals and short duration time when the epicenterdistance is less than 100 km.In order to manifest the characteristics of theP coda,a measurement of 2-D physical modeling was made by systematicallychanging the scattering attenuation and the intrinsic attenuation ofthe medium.Based on the experimental results,the decay rate of the P coda withelapse time is independent of the scattering attenuation;in contrast,theexcitation level of the P coda is proportional to the scattering attenuation.Moreover,the amplitude decay with the elapse time of P coda waves can besatisfactorily interpreted by the model of energy transfer(Shang and Gao,1988).

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