NAME
dspec8 - set up data file for the programs hspec9 and
hspecp (hspecX)
SYNOPSIS
dspec8 [ -C ] [ -Mnames ] [ -Hname2 ] [ -dsdepth ] [
-drdepthr ] [ -flfl ] [ -fufu ] [ -dtdt ] [ -ltlt ] [ -aal-
pha ] [ -xlxleng ] [ -xfxfac ] [ -Eieqex ]
DESCRIPTION
This program is designed to reduce some of the i/o load on
the hspecX programs. Data entry is either from an earth
model file containing all the parameters including comment
lines giving field definitions or from command line entry.
Either way, the actual model itself (velocities, etc) is
brought in from a named file. dspec8 serves several pur-
poses.
First it is the lead program in a sequence of programs for
computing offset synthetic seismograms. The sequence is as
follows:
dspec8
- model specification and diagnostics
hspec[9,p]
- evaluate (f,k) response (f,p for plane waves)
rhfoc
- compute (x,t) or (p-tau) from (f,k) or (f,p)
Note: an example of complete model run scripts will be given
at the back of these manual pages.
Second, since the hspecX programs are large (really only
hspec9), this program does some simple computations to
reformat the input data for hspecX. In addition, the program
establishes the length of the unformatted spectra file gen-
erated by hspecX. This information is essential since the
file so generated are large and one must from the beginning
whether the file can fit in the available disk storage. To
compute the exact number of bytes, the program uses a modi-
fied version of the excit subroutine in hspecX, to compute
how many wavenumbers are required per frequency.
Besides setting up the data file for hspecX, this program is
also useful for recovering from unexpected external determi-
nation of an execution of hspecX, such as might happen dur-
ing a system crash or a scheduled system shutdown. This is
useful because the program hspecX performs a huge number of
computations. Hence a recovery operation is useful.
If the output file generated by hspecX exists, dspec8 will
read it to determine the last complete frequency entry to
that file. A new input file for hspecX is created which
instructs hspecX to skip over logically complete entries,
and to resume computations at the next logical frequency.
This recovery operation works because the UNIX (TM Bell
Laboratories) system does permit a program to create a file
and not remove the file if the program is abnormally ter-
minated. An operating system such as IBM's VM/CMS does not
do this, and no recovery is possible.
Command line arguments (NOTE: first 2 nonoptional
-C Enter the command line argument '-C' to bring global
parameters from the command line (default is card file
for everything).
-M names
Enter name of file containing earth model (velocities,
depths, etc). Default is to use the stdin re-direction
in arrow from a disk model file. See Earth Model For-
mat below.
-H name2
Enter name of spectrum file to be created by hspexX to
be input to rhfoc
-ds depth
Enter initial depth of source (default=0)
-dr depthr
Enter initial depth of receiver (default=0)
-fl,-fu fl, fu
Enter low cut and high cut frequencies (defaults:
fl=1.0, fu=Nyquist/2)
-dt dt
Enter sample interval in secs (default=.004)
-lt lt
Enter length of traces in samples (should be power of
2). No default.
-a alpha
Enter damping parameter (see below). Default = 0.5
-xl xleng
Enter spatial length parameter (see below). Default =
35000.
-xf xfac
Enter wave number sampling parameter (see below).
Default = 4.0
-jb jbdry
Enter topmost boundary flag (default=0: elastic
halfspace)
-jh jbhaf
Enter halfspace boundary flag (default=0: elastic
halfspace)
These establish top surface & halfspace boundary conditions
respectively:
jbdry = -1 RIGID HALFSPACE
0 ELASTIC HALFSPACE
1 FREE SURFACE
jbhaf = -1 RIGID HALFSPACE
0 ELASTIC HALFSPACE
1 HALFSPACE IS A FREE SURFACE
In the case of a rigid or free halfspace, the halfspace
velocities must be entered, even though they are not used.
To avoid problems with the wavenumber sampling, a set of
reasonable values would just be to repeat the layer veloci-
ties or the normal elastic halfspace values.
-E ieqex
Enter source type flag described below. There are 16
possible Green's functions that the various source
functions can generate but not all are necessarily
active.
GREEN'S FUNCTIONS and their ORDERING
ieqex = 0: EARTHQUAKE + EXPLOSION
Traces will ultimately be output in the order:
1-ZDD 2-RDD 3-ZDS 4-RDS 5-TDS 6-ZSS 7-RSS 8-TSS
9-ZEP 10-REP
where Z = vertical; D = displacement; S = slip or shear; E =
explosion (e.g. TSS = tangential motion due to strike slip
source; ZEP = vertical motion due to an explosion)
ieqex = 1: POINT FORCES + EXPLOSION (some vibroseis + some
explosion)
Traces will ultimately be output in the order:
11-ZVF 12-RVF 13-ZHF 14-RHF 15-THF 16-PEP 9-ZEP 10-
REP
where Z = vertical; V = vertical; R = radial; H = horizon-
tal; E = explosion; P = pressure (e.g. ZVF = vertical motion
due to vertical force)
ieqex = 2: ALL GREEN FUNCTIONS (completely general source)
Traces will ultimately be output in the order:
1-ZDD 2-RDD 3-ZDS 4-RDS 5-TDS 6-ZSS 7-RSS 8-TSS
9-ZEP 10-REP 11-ZVF 12-RVF 13-ZHF 14-RHF 15-THF 16-
PEP
where Z = vertical; D = displacement; S = slip or shear; E =
explosion; V = vertical; R = radial; H = horizontal; T =
tangential; E = explosion; P = pressure; F = force (e.g. RHF
= radial motion due to horizontal force)
ieqex = 3: EXPLOSION ONLY
Traces will ultimately be output in the order:
9-ZEP 10-REP
where Z = vertical; R = radial; E = explosion; P = pressure
(e.g. ZEP = vertical motion due to explosive dispacement
only field)
ieqex = 4: EARTHQUAKE ONLY (e.g. double couples)
Traces will ultimately be output in the order:
1-ZDD 2-RDD 3-ZDS 4-RDS 5-TDS 6-ZSS 7-RSS 8-TSS
where Z = vertical; R = radial; H = horizontal; T = tangen-
tial; D = displacement; S = slip or shear (e.g. RSS = radial
motion due to strike slip source)
ieqex = 5: POINT FORCES ONLY (vibroseis)
Traces will ultimately be output in the order:
11-ZVF 12-RVF 13-ZHF 14-RHF 15-THF
where Z = vertical; R = radial; H = horizontal; D = dis-
placement; F = force (e.g. ZVF = vertical displacement due
to horizontal point force)
EARTH MODEL FORMAT
The format consists of the lines
500. 4850. 1000. 1.00 10000. 10000.
2500. 7000. 2500. 2.30 10000. 10000.
0.0 9500. 3500. 2.30 10000. 10000.
where the first column is layer thickness, the second is P
velocity, the third is S velocity, the fourth is density,
the fifth and sixth columns are respectively P and S Q's and
where a zero thickness refers to the halfspace. Each numer-
ical entry is a field of 10 (i.e. thickness: cols1-10; Vp:
cols11-20; etc).
A water layer is denoted by a zero S velocity.
OUTPUT
The diagnostic output of dspec8 is written on standard prin-
tout files. The data for hspecX is written on stdout using
the re-direction out arrow to a disk file.
SEE ALSO
hspecp, hspec9, rhfoc
AUTHOR
R. B. Herrmann, Saint Louis University, 1983
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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