Sherif Hanafy King Abdullah University of science and Technology (KAUST)

1. Subsurface Fault and Colluvial Wedge Detection Using Resistivity, Refraction Tomography and Seismic Reflection SherifHanafy 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 Demonstrate the capability of geophysics to detect shallow subsurface faults Is Qademah fault exists? Track the Qademah fault (if exist) 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. Study Area Qadema Fault KAUST

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 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 • Resistivity • Equipment: Syscal R2 • No. of Profiles: 2 • No. of Nodes: 64 • Node Interval: 5 m • Profile Length: 315 m • Array Type: Wenner

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

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

16. Resistivity ResultsSite # 1 S Sabkha CW Colluvial Wedge F Fan SG Sand-silt-gravel LS Limestone Inverted Data

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

18. Resistivity ResultsSite # 2 S Sabkha CW Colluvial Wedge F Fan SG Sand-silt-gravel LS Limestone Inverted Data

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

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

21. Refraction Tomogram

22. Reflection Stacked Section

23. 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. Summary and Future Work • 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