f Lateral Effects Problem in Shallow Refraction Seismic Interpretation

The first and probably the most important step in shallow refraction seismic measurements is to decide in the field whether there are lateral changes along refracting interfaces or along the overburden layer(s), while the second step is how to detect these lateral variatians with a minimum number of profiles. The problem associated with lateral variations along the overburelen layer(s) is considered to be a very difficult problem for the shallow refraction seismic technique. This is because the head wave traveltime elements recorded from the lower refractor have pseudo apparent refractor velocities, pseudo inflection points and usually an increase or decrease in their number. Surprisingly, this problem is rarely discussed in literature, and if ever, it is often without suggestions for identification or solution, so the name lateral effects is used to define it.