AN ACCURATE GRAPHICAL METHOD FOR INTERPRETING SEISMIC REFRACTION LINES*

A method of refraction computing is described which establishes the two points of incidence at the surface of the ray‐paths from any point on the refractor when observed from opposing directions. The distance between these points is used to determine the radius and the centre of a circle to which the refractor must be tangential. The matching of forward and reverse data is intrinsic in the method so that the resulting profile is automatically positioned in depth. It is shown that if the effects of dip are neglected, errors are introduced in the derived radius and also in the position of the centre but these errors are shown to cancel each other almost exactly.