Geoscience Reference
In-Depth Information
Normalised pressure ield (
t
= 268 ms)
Normalised electric potential (
t
= 268 ms)
200
200
5
5
100
100
0
0
0
0
−100
−100
−5
−5
Electrode
−200
Geophone
−200
−200
−100
0
100
200
−200
−100
0
100
200
Offset (m)
Offset (m)
Recorded pressure at geophone
Recorded potential at electrode
4
4
2
2
0
0
−2
−2
−4
−4
0
100
200
300
0
100
200
300
Time (ms)
Time (ms)
Figure 1.23
Same as Figure 1.18 for time 268.0 ms. The traveling (P-wave) seismic disturbance has reached ith an electrode (reference
electrode to infinity). The geophone and the electrode record a pressure and an associated electrical disturbance. The electrical field
corresponding to the electrical disturbance is called the coseismic field. (
See insert for color representation of the figure
.)
0
4
Source
50
3.5
100
3
150
Shale
2.5
200
2
250
1.5
Figure 1.24
Snaphot of the
seismoelectrical disturbance
(seismoelectric conversion) generated
at an interface between two media of
different electrical conductivities (here a
conductive shale and a less conductive
sandstone) during the passage of a seismic
P-wave. The star represents the seismic
source. The radiation occurs in the first
Fresnel zone of the seismic wave.
(
See insert for color representation of
the figure
.)
300
1
350
Sandstone
0.5
400
0
450
Receivers
500
−0.5
0
100
200
300
400
500
Offset (m)
