1. COLLUVIAL WEDGE IMAGING USING X-WELL AND CDP TRAVELTIME TOMOGRAPHY MAIKE-L. BUDDENSIEK GERARD T. SCHUSTER RONALD L. BRUHN

2. Introduction Seismic Survey ResultsConclusion INTRODUCTIONINTRODUCTION SEISMIC SURVEY SUMMARYSEISMIC SURVEY SUMMARY RESULTS AND INTERPRETATIONRESULTS AND INTERPRETATION CONCLUSIONCONCLUSION OUTLINE

3. (a) Pre - Earthquake (b) (c) Earthquake 1000 years later Colluvial Wedge Introduction Seismic Survey ResultsConclusion COLLUVIAL WEDGES

4. COLLUVIAL WEDGE Seismic Survey Introduction ResultsConclusion

5. COLLUVIAL WEDGE Seismic Survey ResultsConclusion Introduction

6. Introduction SLCSLC SLCSLC LOCATION: Mapleton LOCATION: Mapleton WFZ, Provo Segment PROVOPROVO PROVOPROVO Wasatch Fault Zone, Utah ResultsConclusion

7. GEOLOGY Seismic Survey Introduction Footwall Side Hanging Wall Side af 1 ResultsConclusion

8. Seismic Survey Footwall Side Hanging Wall Side Line 3 HiRes af 1 SEISMIC SURVEY I IntroductionResultsConclusionTrench Line 2

9. SURVEY SITE Seismic Survey IntroductionResultsConclusion

10. SURVEY SITE Seismic Survey IntroductionResultsConclusion Low-ResLow-Res Hi-ResHi-Res

11. IntroductionResultsConclusion GIGA TRENCH done by Sue Olig, URS Corp. !!! GROUNDTRUTH !!!

12. SEISMIC SURVEY II Seismic Survey ResultsConclusionIntroduction SHOT POSITIONS GEOPHONE LINES 2 geophone lines 2 geophone lines shot line on surface shot line on surface

13. SEISMIC SURVEY II Seismic Survey ResultsConclusionIntroduction 2 geophone lines 2 geophone lines 2 shot lines 2 shot lines 1 vertical profile 1 vertical profile shot line on bench shot line on bench SHOT POSITIONS GEOPHONE LINES

14. REFRACTION VS. CROSSWELL Seismic Survey ResultsConclusionIntroduction

15. SURVEY SUMMARY Line 1: 83.5 m high-res line (E-W)Line 1: 83.5 m high-res line (E-W) Line 2: 595 m low-res line (N-S)Line 2: 595 m low-res line (N-S) Line 3: 595 m low-res line (E-W)Line 3: 595 m low-res line (E-W) Trench results, preliminary borehole resultsTrench results, preliminary borehole results X-well 1: Geophones @ Suface, shots @ 1st benchX-well 1: Geophones @ Suface, shots @ 1st bench X-well 2: Geophones @ 1st bench, shots @ surfaceX-well 2: Geophones @ 1st bench, shots @ surface 1 vertical profile (12 geophones, 4 shots)1 vertical profile (12 geophones, 4 shots) Seismic Survey ResultsConclusionIntroduction

16. HIGH-RES LINE Introduction Seismic Survey Results Conclusion 6 faults 6 faults 4 colluvial wedges 4 colluvial wedges

17. WEDGE 1 Introduction Seismic Survey Results Conclusion

18. Introduction Results Conclusion WEDGE 2

19. WEDGE 3 Introduction Seismic Survey Results Conclusion

20. WEDGE 4 Introduction Seismic Survey Results Conclusion

21. HI-RES & TRENCH RESULTS Introduction Seismic Survey Results Conclusion Groundtruth agrees approx. with seismic Groundtruth agrees approx. with seismic Tomogram can do greater depth than Tomogram can do greater depth than trenching, but wedges are subtle and trenching, but wedges are subtle and faults shifted faults shifted

22. HI-RES & X-WELL Introduction Seismic Survey Results Conclusion Faults are imaged well in both tomograms Faults are imaged well in both tomograms Overall structure is the same Overall structure is the same No indication of biggest wedge in X-Well No indication of biggest wedge in X-Well Velocities in X-Well smaller than in CDP Velocities in X-Well smaller than in CDP tomography. Opening the trench loosened tomography. Opening the trench loosened material. (half data set, no QC yet) material. (half data set, no QC yet)

23. Introduction Seismic Survey Results Conclusion MIGRATION

24. Small structures are very sensitive to schedules of the inversion.Small structures are very sensitive to schedules of the inversion. Colluvial wedges may be very subtle or not resolved.Colluvial wedges may be very subtle or not resolved. Faults are resolved well with X-Well and refraction tomography.Faults are resolved well with X-Well and refraction tomography. Seismic tomography does not give as much resolution as trenching, but it reaches greater depth.Seismic tomography does not give as much resolution as trenching, but it reaches greater depth. Introduction Seismic Survey Results Conclusion CONCLUSION

25. CONCLUSION Introduction Results Conclusion Why is this interesting? This comparison with groundtruth shows, that high resolution tomography can achieve such a good resolution, that ambiguities like in the INCO data set could actually be determined.

26. FUTURE WORK Introduction Seismic Survey Results Conclusion Process all trench data to find velocity of colluvial wedgeProcess all trench data to find velocity of colluvial wedge Compare X-Well results with Line 1Compare X-Well results with Line 1 Synthetic test: What size and velocity contrast does a coll. wedge need to be resolved?Synthetic test: What size and velocity contrast does a coll. wedge need to be resolved? Is there a schedule that does resolve small scale features reliably?Is there a schedule that does resolve small scale features reliably?

27. REFERENCES Introduction Seismic Survey Results Conclusion Morey, D., and Schuster, G. T., 1999, Paleoseismicity of the Oquirrh fault, Utah from shallow seismic tomography: Geophys. J. Int., 138,25-35Morey, D., and Schuster, G. T., 1999, Paleoseismicity of the Oquirrh fault, Utah from shallow seismic tomography: Geophys. J. Int., 138,25-35 Nemeth, T., Normark, E., and Qin, F., 1997, Dynamic smoothing in cross-well traveltime tomography: Geophysics, 62, 168-176Nemeth, T., Normark, E., and Qin, F., 1997, Dynamic smoothing in cross-well traveltime tomography: Geophysics, 62, 168-176 Lund, W.R., Schwartz, D. P., Mulvey, W. E., Budding, K. E., Black, B. D., 1991, Fault behavior and earthquake recurrence on the Provo segment of the Wasatch fault zone at Mapleton, Utah County, Utah, UGMS Special studies 75.Lund, W.R., Schwartz, D. P., Mulvey, W. E., Budding, K. E., Black, B. D., 1991, Fault behavior and earthquake recurrence on the Provo segment of the Wasatch fault zone at Mapleton, Utah County, Utah, UGMS Special studies 75.

28. THANKS TO Susan Olig and URS Corp for their trench resultsSusan Olig and URS Corp for their trench results Travis Crosby for his experience in the field and his cheerful attitudeTravis Crosby for his experience in the field and his cheerful attitude Min Zhou for his experience with PC_GUI and LINUX_GUIMin Zhou for his experience with PC_GUI and LINUX_GUI The UTAM students for their help in the field and their programming experienceThe UTAM students for their help in the field and their programming experience Ann Mattson for her help in interpreting tomograms for colluvial wedgesAnn Mattson for her help in interpreting tomograms for colluvial wedges Last spring’s GG5220 class for their help in the fieldLast spring’s GG5220 class for their help in the field Introduction Seismic Survey Results Conclusion