Slowness‐weighted diffraction stack for migrating wide‐angle seismic data in laterally varying media

Abstract

Wide-angle prestack depth migration is an important tool for studying the nature of reflecting boundaries in the earth's crust. The slowness-weighted diffraction stack (SWDS) method has been used to incorporate both two-way traveltime constraints and slowness information in the migration. For this purpose, traveltimes and apparent slownesses of reflected arrivals must be calculated in the image space. Earlier applications of SWDS required a 1D or gently varying seismic velocity structure to obtain these quantities by ray tracing in the image space. I show that the apparent slownesses can also be derived directly from one-way traveltime maps using Fermat's principle. The SDWS is applied to an existing onshore-offshore wide-angle data set, and the example shows that the method can be used to image detailed reflectivity structure at great depths.

SAHKE geophysical transect reveals crustal and subduction zone structure at the southern Hikurangi margin, New Zealand

“…Details of the processing scheme are included in Table S1. Reflection phases identified in Figure 3b were positioned in depth by 2-D depth-migration [Van Avendonk, 2004] using the first-arrival velocity field. Those phases identified on TS030/SHOT 9 are shown in Figure 3d and additional PcP reflection arrivals picked on shot and receiver gathers are shown in Figure 8.…”

Crust and Lithospheric Structure - Active Source Studies of Crust and Lithospheric Structure

“…Frequently, intracrustal, Moho, and sub-Moho reflections can be imaged using migration techniques applied to wide-angle data (Henstock and Levander, 2000;Henstock et al, 1997;Holbrook et al, 1992;Lafond and Levander, 1995;McMechan and Fuis, 1987;Milkereit et al, 1990;Morozov and Levander, 2002;Van Avendonk, 2004). However, the velocity model for wide-angle migration needs to be more accurate than for conventional migration, as minor lateral velocity errors are compounded for travel paths with large horizontal components.…”