Reflection Methods and ResultsGeophysics 492/692
Josh Michaels, Zach Reynolds, Nick Prina, Molly HunsakerSurvey run by Dr. Lee Liberty of Boise State University
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Line 4 Location MapLakeside Drive and Manzanita Lane to the north corner of Jasper Lane and Manzanita Lane.
Methods 1 meter geophones and source intervals Usually 3 shots at 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
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
Record 8064
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
Dix Velocity Intervals
NMO Interpolated velocity
Dip-filtered CMP stack
Dashed black lines = interpreted faults
Green shapes = artifact errors
Frequency Analysis
From the unfiltered CMP stack Dominant frequencies at ~30Hz
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