REFRACTED AND REFLECTED LONGITUDINAL WAVES 



17 



3. To determine the value of the coefficient of refraction (P^- Pi^i) {Pi+i Pi) 



at the point x = sin a- (where a.- is the lesser of the angles a, and a,+i) 



from the curve in Fig. 3 corresponding to the parameter which is the same 



as at the boundary of the ith and ilth layers, we take the value of the ordi- 



^Qi'^i p Qi + lt^i+l p 

 nate [(PjP,4i) (P,+i i'.)] rel and multiply by. ' ' .3 , which 



\(Ji ^i, p^ vi+i'^i+i, p) 



is the product of coefficients of refraction (P,Pj_j.j) (Pj^^ P-), of the plane 



waves when incidence is vertical. 



10 



09 



^ 0-. 



0-7 



0-6 



02 



Sin a, 



0-4 



06 



08 



P'iG. 3. Curves for determining the coefficient of refraction [(^j ^j + i) (^/-|-i^0]- 



The product obtained thus gives the value for the coefficient of refraction 

 (PiPi^x) iPi^iP.)- 



Vn-l, p 



4. The coefficient F^^ (p) is taken at the point x = sin a^ 



"j p 



from the curve corresponding to the parameters y, A and a which charac- 

 terize the boundary of the relth and nth layers (Fig. 4). Fig. 4 (a and b) 

 shows the P^^ (p) curves for two values of the parameter a (dotted hnes — 

 cr = 0.7; thick lines -a = 1.0). 



Applied geophysics 



