1. d(r) = m(x) G(s|x) G(x|r) G(x|r) [] * * ,r,s Trial image pt x Direct wave Backpropagated traces T=0 Reverse Time Migration Generalized Kirch. Migration Most Kirchhoff Tricks for Kirchhoff Migration can be Implemented for RTM Calc. Green’s Func. By FD solves xsr = dot product data with hyperbola Generalized Kirchhoff kernel Convolution of G(s|x) with G(x|r) Expensive to store Calc. Green’s Func. By FD solves QED: RTM can now enjoy: Anti-aliasing filter Obliquity factor Angle Gathers UD Separation Decomplexify back&forward felds according 2 taste Etc. etc.

2. [G(s|x)G(x|g)]* d(s|g) s,g 1. RTM:  [{ } { } ]* d(s|g) G(s|x) G(x|g) ++ s,g  = d  (x) = d  (x) = G(s|x) G(x|g) { } s,g  ~ * d(s|g) Super-wide Angle Phase Shift Migration First Arrival Filter Single Arrival Kirchhoff w/o high-freq. appox Early Arrival Filter Multiple Arrival Kirchhoff w/o high-freq. appox (or Super beam migration) Frechet Derivative True RTM Phase Shift, Beam, Kirchhoff Migrations are Special Cases of True RTM ds First Arrival Filter & U p+Down filter

3. Example (Min Zhou, 2003) Standard FD Wavefront G(s|x) Early Arrival FD Wavefront G(s|x) Standard RTM vs Early Arrival RTM

4. Is Superresolution by RTM Achievable? Tucson, Arizona Test 60 m Poststack Migration ~Kirchhoff Mig. ~Scattered RTM This is highest fruit on the tree..who dares pick it? (Hanafy et al., 2008)

5. Can Scatterers Beat the Resolution Limit? Recorded Green’s functions G(s|x) divided into: - Shot gathers with direct arrivals only - Shot gathers with scattered arrivals only