A RAPID METHOD OF DETERMINING THE FORM OF A SEISMIC*

A set of refraction line arrival times can be readily converted into a set of delay‐times providing the refractor velocity is known. If we then subtract the delay‐time at the shot‐point end, we arrive at a set of delay‐times representing the refractor depths at the receiving end. This paper is concerned with the conversion of such a set of delay‐times into a profile of the refractor.

The method is semi‐graphical and very easy to apply. For each geophone station an arc of a circle is constructed, such that the envelope of the series of arcs represents the surface of the refractor. While the method is not quite exact, especially when the dips are large, it is of particular value in allowing for the effects of varying dips upon the offset distance. The method treats the overburden above the refractor as if it were of uniform velocity.