1. Subsurface Fault and Colluvial Wedge Detection Using Resistivity, Refraction Tomography and Seismic Reflection Sherif Hanafy King Abdullah University of science and Technology (KAUST)

2. Outline Motivations Methodology Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work

3. Outline Motivations Methodology Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work

4. Motivations 1.Demonstrate the capability of geophysics to detect shallow subsurface faults 2.Is Qademah fault exists? 3.Track the Qademah fault (if exist) 4.trenching and dating ancient earthquakes at Qademah fault to assess size and recurrence intervals

5. Outline Motivations Methodology Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work

6. Methodology Ground surface Depth t’s are known, x’s are know, and s’s are unknown

7. Outline Motivations Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work

8. KAUST Qadema Fault Study Area

9. Data Acquisition (Resistivity and Seismic)

10. Data Acquisition (Resistivity and Seismic)

11. Topography

12. Outline Motivations Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work

13. Data Acquisation Resistivity Equipment: Syscal R2 No. of Profiles: 2 No. of Nodes: 64 Node Interval: 5 m Profile Length: 315 m Array Type: Wenner Seismic Equipment: Geometrics (NZXP + Geode) No of Profiles: 1 No. of shots: 109 Shot Interval: 3 m No. of Receivers: 109 Receiver Interval: 3 m Profile Length: 324 m

14. Outline Motivations Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work

15. Resistivity Results Site # 1 Raw Data No. of Nodes: 64 Node Interval: 5 m Profile Length: 315 m Array Type: Wenner

16. Resistivity Results Site # 1 Inverted Data S SabkhaCW Colluvial Wedge F FanSG Sand-silt-gravel LS Limestone

17. Resistivity Results Site # 2 Raw Data No. of Nodes: 64 Node Interval: 5 m Profile Length: 315 m Array Type: Wenner

18. Resistivity Results Site # 2 Inverted Data S SabkhaCW Colluvial Wedge F FanSG Sand-silt-gravel LS Limestone

19. Outline Motivations Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work

20. No. of shots: 109 Shot Interval: 3 m No. of Receivers: 109 Receiver Interval: 3 m Profile Length: 324 m CSG # 60 0 0.25 0 324 X (m) Time (s) Common Shot Gather No of TT: 11881 TT passes Reci. Test: 9488 No. of TT rejected: 2393 No. of Iterations: 40

21. Refraction Tomogram

22. Reflection Stacked Section

24. Result Summary

25. Outline Motivations Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work

26. Resistivity and seismic methods used to detect the Qademah fault One colluvial wedge is shown on both ERT and refraction tomogram Reflection stacked section shows the Qademah fault and the associated antithetic fault(s)

27. Summary and Future Work The Qademah Fault will be tracked to the south with Seismic Resistivity EM and possibly GPR A trench will be made at Qademah fault to date the colluvial wedge If more than one colluvial wedge is found, then we will be able to find the fault recurrence.

28. Thank You