1. Inverting Resistivity and Seismic Data to Find Subsurface Faults
Sherif Hanafy
King Abdullah University of science and Technology (KAUST)
The 6th International Conference
“Inverse Problem and Simulation”
23 May 2012

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= 𝑗=1 𝑁 𝑗 𝑥 𝑗 𝑠 𝑗
𝑡= 𝑗=1 𝑁 𝑗 𝑥 𝑗 𝑠 𝑗
𝑡 𝑖 = 𝑗=1 𝑁 𝑗 𝑥 𝑖𝑗 𝑠 𝑗
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
KAUST
Qadema Fault

9. (Resistivity and Seismic)
Data Acquisition
(Resistivity and Seismic)

10. (Resistivity and Seismic)
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 Resistivity Equipment: Geometrics
(NZXP + Geode)
No of Profiles:
No. of shots:
Shot Interval: m
No. of Receivers:
Receiver Interval: 3 m
Profile Length: m
Resistivity
Equipment: Syscal R2
No. of Profiles: 2
No. of Nodes:
Node Interval: 5 m
Profile Length: 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 Results Site # 1
No. of Nodes:
Node Interval: 5 m
Profile Length: m
Array Type: Wenner
Raw Data

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

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

18. Resistivity Results Site # 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 Time (s) X (m) No. of shots: 109
0.25
324
X (m)
Time (s)
No. of shots:
Shot Interval: m
No. of Receivers:
Receiver Interval: 3 m
Profile Length: m
No of TT:
TT passes Reci. Test: 9488
No. of TT rejected:
No. of Iterations:

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