40 



V. P. GORBATOVA 



discuss all possible two -layered media in this paper but only those which 

 have parameters with the values shown in Tables 1 and 2. We are taking it 

 that in the case of media where Vq <Cv^ the angles at which the wave 



strikes the reflecting boundary satisfy the ratio sin ocqK 0.75 -AE , and for 



'hP 



media where Vq^ > z;j the ratio sin ocq < 0.6. 



Given these limitations we see by comparing the curves in Figs. 10 and 11 

 as well as the intensity values for waves reflected above the shot point, that 



^ 0-5 



F iG. 11. Curves for the damping of doubly reflected waves in two-layered media. 



double echoes are always less intense than single ones. The ratio of their 

 intensities is found within the following limits: 



^0 ^0, p Qi ^1, p 



^ 7double ^ 

 y single 



go, ^o,p-gi^i,p 



Qo ^0, p + Qi Vi, p 



(17) 



where < h^^ < Aq. 



The ratio yjjQu]3ie//gjjjgig for media where z;^^ > t;j p will be slightly greater 

 than for media where ^o p '^ ^i p' provided A is the same. This ratio 

 increases as A increases and as y decreases but A does not alter. 



Multi-layered Media 



Of the many problems connected with the intensity of reflected waves 

 excited in multi -layered media, we shall here consider only the following: 



(a) the influence of the values of transverse velocity on the intensity of 

 reflected waves: 



