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Program package ANRAY, version 4.30
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Ivan Psencik,

Geophysical Institute, Acad.Sci. of the Czech Rep.,
Bocni II, 141 31 Praha 4, Czech Republic

Main differences from the version 4.01
--------------------------------------
There are several new options offerred in this version. The most
important are the following:

(a) The first test version of program WEAKAN based on the zero-order
quasi-isotropic (QI) approximation for calculation of coupled qS waves
in weakly anisotropic media or in singular regions of qS waves was
developed.

(b) The input data are read in by list-directed input (free format).

(c) Graphical output using the software developed for the CRT package
can be used

(d) Many errors and problems have been removed and other small scale
modifications have been made. Substantial changes were made in
program VELPL for plotting various velocity surfaces, smaller changes
were also made in the program ANRAYPL. Tests were indroduced, which
guarantee that polarization vectors vary smoothly along a ray and
do not jump by 180 degrees. The x- and y-components of displacement,
which were incorrectly called "radial" and "transverse" in previous
versions are called x- and y-components. Possibility to rotate
horizontal axis, to which displacement is projected, was introduced
to SYNTAN. I shall be grateful for indication of problems since with
the new options, new bugs were surely introduced.


Description of the package
--------------------------
     Program package ANRAY can be used for computation of rays,
travel times, ray amplitudes and ray synthetic seismograms (for qS
waves also the QI approximation may be used) in 3-D laterally varying
structures containing isotropic and/or anisotropic layers.
Synthetic seismograms can be constructed at receivers distributed
regularly or irregularly along surface, interfaces or vertical
profiles.

    Program package consists of ten programs, basic program ANRAY
and programs WEAKAN, ANRAYPL, SYNTAN, SEISPLOT, POLARPLOT, FRESAN,
SYNFAN, BPLOT, VELPL and most recently ANRAYVRM.

    Program ANRAY is an updated version of program with the same
name which has been used in packages ANRAY86 and ANRAY89 written by
Gajewski & Psencik [1], [2]. It is
designed for ray, travel time and ray amplitude computations. Two ways
of approximation of distribution of elastic parameters are available.
In the first, "B-spline approximation", elastic parameters in an
arbitrary point of a layer are determined by B-spline approximation
from values of parameters specified at grid points of a 3-D rectangular
network. B-splines with tension by A.K.Cline [3] with
additions by L.Klimes [4], are used. In the second
way, "isosurface interpolation", elastic parameters are determined
by vertical linear interpolation of values specified at interfaces,
which represent surfaces of constant values of elastic parameters.
Rays can be computed in two modes. In the first one, rays are specified
by the point source location and the initial orientation of the
slowness vector at the source: initial-value ray tracing. In
the second mode, rays are specified by the point source location and
a system of regularly or irregularly distributed receivers situated on
surface or on an interface or on a vertical profile: two-point ray
tracing. The point source can be situated at any point of the model.
Polarization vectors, geometrical spreading and reflection,
transmission and conversion coefficients may be evaluated along the rays.

    Program ANRAY can produce seven files, one for plotting ray diagrams,
travel times and ray amplitudes in program ANRAYPL, second for computation
of synthetic seismograms in programs SYNTAN or SYNFAN, third for plotting
plane sections of slowness, phase velocity or group velocity surfaces.
The remaining four files can be produced for the generation of 3-D
images of the model and rays in it. Program ANRAY consists of 6 blocks
of routines, ANRAY.FOR, A2.FOR, A3.FOR, A4.FOR, A5.FOR, and
MODBS.FOR or MODIS.FOR, which must be linked together. If B-spline
approximation is to be used, MODBS.FOR must be used, if isosurface
interpolation is to be used, MODIS.FOR must be used. The selection
can be made at the end of the file anray.for.
Default is the B-spline interpolation.
Refer to the description of program ANRAY.

    The program WEAKAN is a first version of the program for the
calculation of qS waves in weakly anisotropic media and in qS wave
singular regions, based on the quasi-isotropic (QI) approximation,
[5]. The two coupled linear differential equations
for the calculation of frequency-dependent amplitudes in the zero-order
QI approximation are solved here along rays, which were calculated in
the program ANRAY in a background isotropic medium. The results are
stored in the file LU1. The frequency-dependent amplitudes are further
used for the calculation of synthetic seismograms. At present, the
program works only in the B-spline mode, i.e., it requires MODBS.FOR
routines. The program WEAKAN generates a file to be further processed
in program FRESAN and subsequent programs.
Refer to the description of program WEAKAN.

    The program ANRAYPL can be used for plotting of horizontal and
vertical ray diagrams, time-distance and amplitude-distance curves
of individual elementary waves computed in the program ANRAY and
stored in the file LU1. Several types of point sources, namely explosive
source, single force, double couple source can be considered. Program
ANRAYPL is a modification of the program RAYPLOT from the package SEIS83
[6]. Program ANRAYPL consists of routines:
ANRAYPL.FOR, BORDER.FOR, SOURCE.FOR and CALCOPS.FOR.
Refer to the description of program ANRAYPL.

    The program SYNTAN can be used for time domain computation of
ray synthetic seismograms from the results computed in the program
ANRAY and stored in the file LU2. Gabor wavelet is used as a source-time
function. Hilbert transform of this wavelet is evaluated by approximate
formula, see [7]. Several types of point sources, namely
explosive source, single force, double couple source, can be considered.
Program SYNTAN is a modification of the program SYNTPL from the
program package SEIS83 [6]. Program SYNTAN consists
of routines: SYNTAN.FOR, SOURCE.FOR and CALCOPS.FOR.
Refer to the description of program SYNTAN.

    Programs FRESAN and SYNFAN can be used for frequency domain
computation of ray synthetic seismograms. Frequency response is
computed in the program FRESAN from the data generated by the
program ANRAY and WEAKAN (if the QI approximation is used) and stored
in the files LU2 (ANRAY) and LU6 (WEAKAN). In the program SYNFAN it
is multiplied by the spectrum of the considered source-time function.
Inverse Fourier transform is then used to evaluate synthetic seismograms.
Programs FRESAN and SYNTAN are modifications of the programs GB and
SYNTGB from the package BEAM87 by V.Cerveny. Program FRESAN consists
of routines FRESAN.FOR, BORDER.FOR, SOURCE.FOR and CALCOPS.FOR. Program
SYNFAN consists of routines SYNFAN.FOR and CALCOPS.FOR.
Refer to the description of program FRESAN.
Refer to the description of program SYNFAN.

    Programs SEISPLOT, BPLOT and POLARPLOT can be used for plotting
results computed in progams SYNTAN and SYNFAN. Program SEISPLOT can
be used for plotting synthetic seismograms generated by the program
SYNTAN and stored in the file LU4, program BPLOT can be used for
plotting synthetic seismograms generated by the program SYNFAN and
stored in the file LU8. The program POLARPLOT serves for plotting
particle motion diagrams and can be used with two (each file for one
component of the displacement vector) files LU4 generated by the
program SYNTAN or BPLOT. Programs SEISPLOT and POLARPLOT are
modifications of the programs with the same name from the package
SEIS83, program BPLOT is a modification of the program with the same
name from the package BEAM87. Program SEISPLOT consists of routines
SEISPLOT.FOR, BORDER.FOR and CALCOPS.FOR. Program BPLOT consists of
routines BPLOT.FOR, BORDER.FOR and CALCOPS.FOR. Program POLARPLOT
consists of routines POLARPLOT.FOR, BORDER.FOR and CALCOPS.FOR.
Refer to the description of program SEISPLOT.
Refer to the description of program BPLOT.
Refer to the description of program POLARPLOT.

    Program VELPLOT can be used for plotting plane sections of
slowness, phase velocity and group velocity surfaces from the file
generated in the program ANRAY and stored in the file LU3. Plots in polar
or Cartesian coordinates can be optionally generated. Program VELPLOT
consists of routines VELPL.FOR and CALCOPS.FOR.
Refer to the description of program VELPLOT.

    Program ANRAYVRM can be used for producing 3-D images of the
model and rays in it from the files LUBRD, LUGRD, LUIND, LURAY
optionally generated by the program ANRAY. The program was compiled
by Xuyao Zheng using the graphic software developed for the CRT
package. For its proper operation the program ANRAYVRM requires the
routines COLORS.FOR, ERROR.FOR, FORMS.FOR, LENGTH.FOR, SEP.FOR
WRL.FOR, SEP.INC and RAM.INC from the package FORMS.
Refer to the description of program ANRAYVRM.

    All files with the main programs (anray.for, weakan.for, anraypl.for,
syntan.for, fresan.for, synfan.for, seispl.for, bplot.for, polar.for,
velpl.for and anrayvrm.for) contain, at their ends, Fortran 90 INCLUDE
commands to include all subroutine files required. It is thus no need to
compile subroutine files separately and to submit them to a linker.

    FORTRAN77 is used throughout the program package ANRAY. Modified
CALCOMP routines, namely PLOTS, PLOTN, PLOT, SYMBOL and NUMBER are used
in plotting programs (2-D graphics). Calcomp-PostScript interface containing
the above listed routines and developed by L.Klimes, is a part of the
package. This makes possible to generate the graphical output in the form
of ASCII files coded in the PostScript level 2 language - encapsulated
postscript file format version 3.0. The Calcomp-PostScript interface is
a part of the block of routines CALCOPS.FOR. This block must be linked with
each program of the package.

    The package is supplemented by a set of test input data.

    The data with extension ani are data for a VSP experiment in
a vertically inhomogeneous model of HTI medium with axis of symmetry
45 degrees out of the plane containing the source and the borehole.
The data anray.ani are specified for B-spline approximation,
i.e. for the program ANRAY linked with MODBS. Program ANRAY
with these data generates "anisotropic" ray results for two qS waves.
The data anraypl.ani are input data for the program ANRAYPL.
They generate postscript files anrpl1.ps and anrpl2.ps with ray diagrams, travel-
time and amplitude curves of the two qS waves. The data fresan.ani,
synfan.ani and bplot.ani are input data for programs FRESAN, SYNFAN
and BPLOT. They generate the postscript file seisanv.ps with section
of ray synthetic seismograms of a vertical component. The data
polar.dat generate the postscript file polatv.ps with projections
of particle motion diagrams into the transverse-vertical plane if files
with ray synthetic seismograms generated by BPLOT for vertical and
transverse components are available.

   The data with extension 'qi' are data for the same experiment as
the data above ('ani') but the computations are based on the QI
approximation. The data anray.qi are specified for an isotropic model
forming a background of the model 'ani'. Again, B-spline approximation
is used. Program ANRAY with these data generates "isotropic" ray
results for an S wave. The data anraypl.qi are input data for the
program ANRAYPL. They generate postscript file anrplis.ps with ray
diagram, travel-time and amplitude curves of the S wave. The data
weak.qi are the input data for the program WEAKAN, in which the two
coupled differential equations of the QI approximation are solved.
The data fresan.qi, synfan.qi and bplot.qi are input data for
programs FRESAN, SYNFAN and BPLOT. They generate the postscript
file seisqiv.ps with section of synthetic seismograms of a vertical
component in the QI approximation. The data polar.dat may generate
the postscript file polqtv.ps with projections of particle motion
diagrams into the transverse-vertical plane if files with QI
synthetic seismograms generated by BPLOT for vertical and transverse
components are available and if the name "polqtv.ps" is specified
in the input data.

   The data with extension 'chs' are data for another VSP experiment
based on the ray computations in a model, in which isosurface
approximation is used. It means that the program ANRAY must be
linked with MODIS in this case. Program ANRAY with the data
anray.chs generates "anisotropic" ray results for a qP wave and
two qS waves. The data syntan.chs and seispl.chs
are input data for programs SYNTAN and SEISPL. They generate the postscript file
seischs.ps with section of ray synthetic seismograms of a vertical
component of displacement vector.

   The data with extension 'rfr' are data for a refraction/reflection
experiment based on the ray computations in a model, in which isosurface
approximation is used. It means that the program ANRAY must be
linked with MODIS. Program ANRAY with the data anray.rfr
generates a file for 3-D image of model and rays of qP refracted and
reflected waves. The program ANRAYVRM uses these data to generate graphic
file anvrml01.wrl.

    The data anray.vel are the input data for the ANRAY program,
generating a file for plotting a section of the phase velocity
surface in the program VELPL. The section is calculated in the
above model 'ani', close to the model surface. The data velpl.vel
are the input data for the program VELPL. They generate a postscript
file phvel.ps.

    In case of publication of results obtained with the program
package ANRAY, the users are asked kindly to refer to this report.

Good luck!

Praha, June 2001


REFERENCES
                                                        
[1] Gajewski,D., Psencik,I., 1986. Numerical modelling of seismic
    wave fields in 3-D laterally varying layered anisotropic
    structures - Program ANRAY86, Internal Report Inst.of Earth and
    Planet.Phys., University of Alberta, Edmonton.
                                                        
[2] Gajewski,D.,  Psencik,I.,1989. Ray  synthetic seismograms  in 3-D
    laterally inhomogeneous anisotropic structures - Program ANRAY89,
    Internal  Report   Centre  for  Computational   Seismology,  LBL,
    Berkeley.
                                                        
[3] Cline,A.K.,1981. FITPACK, Dept. of Computer Sciences, Univ. of
    Texas at Austin.
                                                        
[4] Cerveny,V., Klimes,L., Psencik,I.,1988. Complete seismic ray
    tracing in three-dimensional structures. In: Seismological
    Algorithms, D.J.Doornbos edit., Academic Press, New York, pp.89-168.
                                                        
[5] Psencik,I.,1998. 1998.  Green's functions for inhomogeneous weakly
    anisotropic media. Geophys.J. Int., 135, 279-288.
                                                        
[6] Cerveny,V., Psencik,I.,1984. Documentation of earthquake
    algorithms. SEIS83 - Numerical modeling of seismic wave fields
    in 2-D laterally varying layered structures by the ray method.
    E.R.Engdahl, edit., Report SE-35, Boulder, 36-40.
                                                        
[7] Cerveny,V., Molotkov,I.A., Psencik,I.,1977. Ray method in seismology,
    Univerzita Karlova, Praha.