The form of the shot continuation operator varies dramatically depending on the distance the shot is shifted. For illustration, Figure 5 depicts a shot gather s1, which is shifted various distances. The original shot gather contains a single event at (t1 = 1.0, h1 = 0.25) and it is shifted to s2 at the center of the geophone spread. The distance shifted varies from frame to frame as the shot location of s1 advances from the right to the left of the geophone spread.
Each thin line in Figure 5 represents the kinematic solution as it is derived and rendered by Mathematica. The background raster plot is computed by the Ratfor routine shct.rst incorporating amplitude variations along the operator.
The operator is a symmetric DMO-like smile when s2 coincides with the midpoint associated with the input impulse at (t1, h1). However, the operator skews sideways and finally collapses to a point as the shot location s1 or the geophone g1 approaches s2. Beyond the identical and reciprocal shot position, the operator turns into a frown. In addition to the variations induced by varying shift distances, the operator also varies with different impulse event times t1.