Test examples of the computation of R/T coefficients
Four test examples on running the program
'rtcoef.for'
to control the computation of R/T coefficients using the subroutine
'coef52.for'
are included. The data files for these examples
are 'test1',
'test2',
'test3',
and 'test4'.
These files contain both the input data and the results of
computations, but both are separated by an empty line. Thus, these
files can be directly used as input data files.
First test example.
Data file 'test1'.
The model corresponds to a single interface between two
non-dissipative media. Consequently, RMOD must be the same as
RMOD0, and RPHASE the same as RPH0. The model is the same as
that used in Cerveny (2001) to demonstrate the behaviour of R/T
coefficients. The angle loop is considered. Only NC=1 is used,
so that the P1P1 reflection coefficient is computed in TEST1.
Using various NC and NH, we can compare all computed R/T
coefficients with those displayed in Figs. 5.1, 5.2, 5.6. 5.7
and 5.11 of Cerveny (2001).
Second test example.
Data file 'test2'.
The model corresponds to a single interface between two
dissipative media. The model is the same as the model used for
extensive computations by Brokesova and Cerveny(1998), see Figs.
8 - 23. Only NC=1 is used, so that the P1P1 reflection coefficient
is computed in TEST2. The angle loop is considered. A strongly
inhomogeneous incident plane wave is considered in this example,
with GAMMA=75 degrees. For comparison, see Fig.9 of Brokesova
and Cerveny (1998), which displays the same P1P1 reflection
coefficient for nine different GAMMA's.
Third test example.
Data file 'test3'.
The model is the same as in the second test example, but the
frequency loop is considered (with NF=20, FMIN=1., DF=4.). The
homogeneous incident plane wave is assumed (GAMMA=0.). The S1S1
reflection coefficient (NC=6) for the normal angle of incidence
(0 degrees) is computed. The obtained frequency-dependent effects
(related to dissipation and dispersion) in the S1S1 reflection
coefficients are not great for the normal incidence.
Fourth test example.
Data file 'test4'.
The model is the same as in the second example, only a
thin stack of two layers is inserted between the two halfspaces
(NZ=4). The thickness of each thin layer is 20 m. The stack has
a laminated character: The parameters in the upper thin layer
correspond to the bottom halfspace and the parameters in the
lower thin layer correspond to the top halfspace. The homogeneous
incident plane wave is considered (GAMMA=0.). The P1P1 reflection
coefficient (NC=1) for the normal incidence (angle of incidence
0 degrees) is computed. The frequency loop is considered (with
NF=20, FMIN=1, DF=4.).
The test examples may be executed by command
perl go.pl rtcoef.h
running the demonstration history file
'rtcoef.h'.
References
- Brokesova,J. (2001):
Reflection/transmission coefficients at a
plane interface in dissipative and non-dissipative media:
A comparison.
J.Comput.Acoustics, 9,623 -641.
- Brokesova,J., and Cerveny,V. (1998):
Inhomogeneous plane waves
in dissipative, isotropic and anisotropic media. Reflection/
transmission coefficients.
In Seismic waves in complex 3-D
structures, Report No. 7, pp. 57 - 146. Department of
Geophysics, Charles University, Prague.
- Cerveny,V. (1989):
Synthetic body wave seismograms for laterally
varying media containing thin transition layers.
Geophys. J. Int., 99, 331-349,
- Cerveny,V. (2001):
Seismic ray theory.
Cambridge Univ. Press, Cambridge.
- Muller,G. (1985):
The reflectivity method. A tutorial.
J.Geophys., 58, 153-174.