1. AVO responses as modelled with a finite- difference program Peter Manning and Gary Margrave Introduction: classic AVO cases Surface seismic records F-D / Zoeppritz amplitude comparisons Wavefront / interface movies Acknowledgements Conclusions

2. Classic AVO parameters table

3. Vertical displacement seismic record Arrow indicates reflected pressure wave

4. Horizontal displacement seismic record Arrow indicates converted shear wave

5. Model amplitudes along reflected event Blue – peak, red – trough, black - Zoeppritz

6. Model amplitudes along converted reflection Blue/red – peak/trough, black - Zoeppritz

7. AVO type 1 movie

8. Quintuple point at 1000 m. AVO type 1 movie

9. AVO type 2 movie

10. Quintuple point at 1000 m.

11. AVO type 3 movie

12. Quintuple point at 1000 m.

13. AVO type 4 movie

14. Quintuple point at 1000 m.

15. The Zoeppritz equations and finite-difference models have many common features. Finite-difference models might prove useful for some quantitative predictions. Conclusions Finite-difference models might show realistic effects beyond the critical angles.

16. The reflection amplitudes at the finite-difference ‘quintuple’ point will be checked to see if the physics might be better understood. Future work

17. We would like to thank the CREWES sponsors for their generous support. Acknowledgements