Geology Reference
In-Depth Information
Fig. 6.9.
Time migrated seismic profile from central Wyoming.
TWT:
Two-way travel time;
T
i
: interval
thickness.
a
Original profile having a vertical scale of 7.5 in per second and a horizontal scale of 12 traces
per in. Vertical exaggeration (
ve
) is 1.87 : 1.
b
The vertical scale is the same as in
a
, the horizontal scale
is reduced by two-thirds. Vertical exaggeration is 5.6 : 1.
c
Unexaggerated version produced by expand-
ing the horizontal scale. Thickness
T
1
is now constant across the profile. (After Stone 1991)
occurs. Because seismic velocity varies with depth, the profile might remain exagger-
ated at other depths. Normally seismic velocity increases with depth and so the ver-
tical exaggeration decreases with depth. This method does not take into account
horizontal velocity variations. A further caution is that the thickness variations seen
in Fig. 6.9a are just like those that are caused by deformation. The inferred vertical
exaggeration should always be cross checked by other methods whenever possible. If
the profile is also horizontally exaggerated, then this method will give the correct
exaggeration ratio of 1 : 1, but both the horizontal and vertical scales could be exag-
gerated. Eliminate the horizontal exaggeration while maintaining the ratio constant
to produce a depth section.
