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Acquisiton of Passive Acquisiton of Passive Seismic Data at Tooele Seismic Data at Tooele
Army Depot, UtahArmy Depot, Utah
David Sheley, Travis Crosby, David Sheley, Travis Crosby, Jianming ShengJianming Sheng
Survey LocationSurvey Location
Nor
thN
orth
1 Mile1 Mile
Survey LocationSurvey Location
GeophonesGeophones
48 40-Hz 48 40-Hz 2 m intervals2 m intervals
48 8-Hz groups48 8-Hz groups2 m intervals2 m intervals6 geophones/group6 geophones/group2 m array length2 m array length
Source: Hammer DrillSource: Hammer Drill
Source PeriodSource Period = 0.7 sec= 0.7 sec
Source DepthSource Depth = 60 m= 60 m
Target DepthTarget Depth (Bedrock)(Bedrock) = 140 m= 140 m
SeismographsSeismographs
Recording ParametersRecording Parameters
40-Hz Geopones40-Hz Geopones 8-Hz Geophone Groups8-Hz Geophone Groups
dt = 2 msdt = 2 ms dt = 2 msdt = 2 ms
5000 samples5000 samples 31,000 samples31,000 samples
10 sec record10 sec record 64 sec record64 sec record
4 Hz low cut4 Hz low cut 4 Hz low cut4 Hz low cut
250 Hz high cut250 Hz high cut 250 Hz high cut250 Hz high cut
130 m source horiz. offset130 m source horiz. offset 130 m source horiz. offset130 m source horiz. offset
60 m source depth60 m source depth 60 m source depth60 m source depth
Source GathersSource Gathers40-Hz Geopones40-Hz Geopones 8-Hz Geophone Groups8-Hz Geophone Groups
00
11
22
33
Tra
velt
ime
(s)
Tra
velt
ime
(s)
00
00 9696Offset (m)Offset (m)
11
22
33
Tra
velt
ime
(s)
Tra
velt
ime
(s)
00 9696Offset (m)Offset (m)
Source GathersSource Gathers40-Hz Geopones40-Hz Geopones 8-Hz (20 – 250 Hz BP Filt)8-Hz (20 – 250 Hz BP Filt)
00
11
22
33
Tra
velt
ime
(s)
Tra
velt
ime
(s)
00
00 9696Offset (m)Offset (m)
11
22
33
Tra
velt
ime
(s)
Tra
velt
ime
(s)
00 9696Offset (m)Offset (m)
Conclusions & Future WorkConclusions & Future Work• Hammer drill provides adequate energy Hammer drill provides adequate energy
at shallow depths to generate reflections.at shallow depths to generate reflections.
• 40-Hz geophones attenuate surface 40-Hz geophones attenuate surface wave energy.wave energy.
• Next: Crosscorrelate the data to Next: Crosscorrelate the data to image bedrock.image bedrock.
• 8-Hz geophone arrays need to be 8-Hz geophone arrays need to be lengthened, but this will damage the lengthened, but this will damage the signal.signal.
