Acquisiton of Passive Seismic Data at Tooele Army Depot, Utah

1
Acquisiton of Passive Seismic Data at Tooele Army
Depot, Utah

• David Sheley, Travis Crosby, Jianming Sheng

2
Survey Location
1 Mile
North
3
Survey Location
4
Geophones
48 40-Hz 2 m intervals
48 8-Hz groups 2 m intervals 6
geophones/group 2 m array length
5
Source Hammer Drill
Source Period 0.7 sec
Source Depth 60 m
Target Depth (Bedrock) 140 m
6
Seismographs
7
Recording Parameters
40-Hz Geopones 8-Hz Geophone Groups
dt 2 ms dt 2 ms
5000 samples 31,000 samples
10 sec record 64 sec record
4 Hz low cut 4 Hz low cut
250 Hz high cut 250 Hz high cut
130 m source horiz. offset 130 m source horiz. offset
60 m source depth 60 m source depth
8
Source Gathers
8-Hz Geophone Groups
40-Hz Geopones
0
0
1
1
Traveltime (s)
Traveltime (s)
2
2
3
3
0
96
0
96
Offset (m)
Offset (m)
9
Source Gathers
8-Hz (20 250 Hz BP Filt)
40-Hz Geopones
0
0
1
1
Traveltime (s)
Traveltime (s)
2
2
3
3
0
96
0
96
Offset (m)
Offset (m)
10
Conclusions Future Work

• Hammer drill provides adequate energy at shallow
  depths to generate reflections.

• 40-Hz geophones attenuate surface wave energy.

• 8-Hz geophone arrays need to be lengthened,
  but this will damage the signal.

• Next Crosscorrelate the data to image bedrock.