Inverting Resistivity and Seismic Data to Find Subsurface Faults Sherif Hanafy King Abdullah University of science and Technology KAUST The 6 th International Conference Inverse Problem and Simulation ID: 774076
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Inverting Resistivity and Seismic Data to Find Subsurface Faults Sherif HanafyKing Abdullah University of science and Technology (KAUST) The 6 th International Conference “Inverse Problem and Simulation” 23 May 2012
Outline Motivations Methodology Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work
Outline Motivations Methodology Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work
Motivations Demonstrate the capability of geophysics to detect shallow subsurface faultsIs Qademah fault exists? Track the Qademah fault (if exist) trenching and dating ancient earthquakes at Qademah fault to assess size and recurrence intervals
Outline Motivations Methodology Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work
Methodology Ground surface Depth t ’s are known, x ’s are know, and s ’s are unknown
Outline Motivations Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work
KAUST Qadema Fault Study Area
Data Acquisition (Resistivity and Seismic)
Data Acquisition (Resistivity and Seismic)
Topography
Outline Motivations Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work
Data Acquisation ResistivityEquipment: 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: 1No. of shots: 109Shot Interval: 3 mNo. of Receivers: 109Receiver Interval: 3 mProfile Length: 324 m
Outline Motivations Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work
Resistivity Results Site # 1Raw Data No. of Nodes: 64 Node Interval: 5 m Profile Length: 315 m Array Type: Wenner
Resistivity Results Site # 1Inverted Data S Sabkha CW Colluvial Wedge F Fan SG Sand-silt-gravel LS Limestone
Resistivity Results Site # 2Raw Data No. of Nodes: 64 Node Interval: 5 m Profile Length: 315 m Array Type: Wenner
Resistivity Results Site # 2Inverted Data S Sabkha CW Colluvial Wedge F Fan SG Sand-silt-gravel LS Limestone
Outline Motivations Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work
No. of shots: 109 Shot Interval: 3 mNo. of Receivers: 109Receiver Interval: 3 mProfile 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
Refraction Tomogram
Reflection Stacked Section
Reflection Stacked Section
Result Summary
Outline Motivations Study Area Data Acquisition (Resistivity and Seismic) Data Processing and Interpretation Resistivity Seismic Summary and Future Work
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)
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.
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