Diffraction traveltime in multilayer media

In this section, we turn our attention to the case of diffraction traveltime and apply the proposed framework to compute the effective time-migration velocity that honors the effects from lateral heterogeneity (equation 7). The synthetic data are generated from Kirchhoff modeling using an accurate two-point ray bending scheme (Sripanich and Fomel, 2014).

Following similar procedure as before, we first evaluate the new expressions of traveltime derivatives in each sublayer above a point diffractor (equation 15) and evaluate the proposed recursive relationship (equations 11 and 12). We finally compute equation 7 using the result from the recursion. We consider the same structural model shown in Figure 4 but replace the bottommost reflector by a point diffractor at 4.3 $km$.