Geoscience Reference
In-Depth Information
0.04
−100
−150
−200
−250
−300
−350
−400
−450
−500
−550
0.02
0
−0.02
−0.04
−0.06
−0.08
122
244
366
488
610
732
854
977
Time (ms)
0.06
0.04
t
0
0.02
0
−0.02
−0.04
−0.06
−0.08
t
2
−0.1
122
244
366
488
610
732
854
977
Time (ms)
(a)
0.1
−100
−150
−200
−250
−300
−350
−400
−450
−500
−550
0.08
0.06
0.04
0.02
0
−0.02
−0.04
−0.06
122
244
366
488
610
732
854
977
Time (ms)
0.1
0.08
Seismoelectric
conversion
t
0
0.06
Coseismic signal
0.04
0.02
0
−0.02
t
1
t
2
−0.04
−0.06
0
122
244
366
488
610
732
854
977
Time (ms)
(b)
Figure 4.18
Example of seismograms and electrograms corresponding to shot #5 (deeper source).
a)
Seismograms recorded in the
offset borehole with a typical parabolic shape. An example of seismogram is given for geophone #25.
b)
Electrograms recorded
in the offset borehole showing the seismoelectric conversion at the vertical interface and the coseismic signal. An example
of electrogram is given for electrode #25 (position
x
=500 m,
z
=300 m). The source occurs at
t
= 110 s.
number domain. It is important to point out that the
wave number is related to the model geometry and the
separation distances between source and receivers.
Equation 4.65 is solved repeatedly for several wave
numbers, and then the solution is transformed from
the wave number domain to the spatial domain following
the approach taken by Dey andMorrison (1979) using an
inverse cosine transform.
