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Reflection Methods and Results Geophysics 492/692

Reflection Methods and Results Geophysics 492/692. L. Josh Michaels, Zach Reynolds, Nick Prina, Molly Hunsaker Survey run by Dr. Lee Liberty of Boise State University . Line 4 Location Map. Lakeside Drive and Manzanita Lane to the north corner of Jasper Lane and Manzanita Lane. Methods.

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Reflection Methods and Results Geophysics 492/692

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  1. Reflection Methods and ResultsGeophysics 492/692 L Josh Michaels, Zach Reynolds, Nick Prina, Molly Hunsaker Survey run by Dr. Lee Liberty of Boise State University

  2. Line 4 Location Map Lakeside Drive and Manzanita Lane to the north corner of Jasper Lane and Manzanita Lane.

  3. Methods • 1 meter geophones and source intervals • Usually 3 shotsat each source location • Seismographs record each shot individually • Not stacked in the field • Used rollbox to keep the source centered • Excluding the ends of the line

  4. Processing Data • Line 4 = 887 total shot records of 120 traces each • Processed using JRG and Viewmat (v. 3.6.3) • Selected records examined with a range of bandpass filters • Designed to maximize reflections and minimize other seismic waves and noise • 20-100 Hz (10% dip) optimal for reflections in Line 4 • Individually examined every record; removed any traces that failed our criteria • Non-functioning or incorrectly functioning geophone traces • Bad records caused by a misfired trigger on the source, indicated by no coherent seismic wave pattern • Strong hyperbola patterns caused by movement along the reflection line during recording

  5. Record 8064

  6. Processing Data • Line 4 = 887 total shot records of 120 traces each • Processed using JRG and Viewmat (v. 3.6.3) • Selected records examined with a range of bandpass filters • Designed to maximize reflections and minimize other seismic waves and noise • 20-100 Hz (10% dip) optimal for reflections in Line 4 • Individually examined every record; removed any traces that failed our criteria • Non-functioning or incorrectly functioning geophone traces • Bad records caused by a misfired trigger on the source, indicated by no coherent seismic wave pattern. • Strong hyperbola patterns caused by movement along the reflection line during recording. • Constant velocity stacking • Ranged from 500 to 3500 m/s (100 m/s intervals) • Stacking reduces random-sourced signals

  7. Dix Velocity Intervals

  8. NMO Interpolated velocity

  9. Dip-filtered CMP stack • Dashed black lines = interpreted faults • Green shapes = artifact errors

  10. Frequency Analysis • From the unfiltered CMP stack • Dominant frequencies at ~30Hz

  11. Improvement? • More controlled acquisition environment • Geophone functionality • Removal of 60 Hz electrical noise • Known to exist, but not dominating signal • More thorough velocity model • Our results are only preliminary • Pre-stacked depth migration

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