bnfd - BSU program synthetic data computation, Near and Far Field Waveforms in a whole space.
bnfd [ -h | infile | xforce | vp | vs | den | alpha | fc | icomp | ifield ]
Basic Seismic Utilities (BSU) evaluates Equation 4.23 (Aki and Richards, p. 73, Vol 1). The computed displacement field is for a homogeneous, elastic, whole space (no boundaries). The computation is useful to gain insight into the transition from near to far field, as well as understand the relationship between radiation pattern and the source. The user may select what terms to include in the output, and what component of motion to display. The input file is used to generate headers with the source and receiver coordinates. It also serves the additional design function of specifying the sample interval, number of samples, and number of traces to be generated in the output data set. C-Language Version.
Options
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-h |
Online help giving details on command line arguments | ||
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infile |
Design file for setting geometry, tmax, number of channels, and sample interval of the output data. The input file is not altered. | ||
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xforce |
The source function is defined by an equivalent point source. If you want to model a source with finite dimensions and surface area, you will have to write new code and integrate the results of this code over a specified surface area. Currently, xforce is limited to 1 of 3 possible directions: |
1= force in positive x-axis direction
2= force in positive y-axis direction
3= force in positive z-axis direction (which is down).
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vp |
P-wave velocity (m/s) |
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vs |
S-wave velocity (m/s) |
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den |
Mass density of medium (kg/m^3) |
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alpha |
Wavelet decay constant (1/seconds) |
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fc |
Wavelet center frequency (Hz) |
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icomp |
Component of motion to output |
1=radial (x-axis, x1)
2=transverse (y-axis, x2)
3=vertical (z-axis, x3)
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ifield |
Fields to include in output waveforms. The key is Binary Code (SPN)= (S-wave, P-wave, Near) Field |
0=wavelet only
1=(001) Near Field only
2=(010) Far Field P-wave only
3=(011) Far Field P-wave plus Near Field
4=(100) Far Field S-wave only
5=(101) Far Field S-wave and Near Field
6=(110) Far Field S-wave and P-wave
7=(111) All (Near and Far P- and S- wave)
NOTE:
If invoked with no options, will prompt user for input
parameters.
EXAMPLE:
bnfd w001.seg 3 500. 200. 1600. 50. 50. 3 7
File w001.seg is used to design an output file. A vertical point force is excited in an elastic medium with Vp=500m/s, Vs=200m/s, Density=1600 kg/m^3. The wavelet will be an exonentially decaying sinusoid, decay constant 50/sec, center frequency 50 Hz. The vertical motion will be output in BSEGY format traces, and all fields (near and far) will be included in the displacements.
bnfdyyyy.seg
named according to convention (first 4char bnfd, the next 4char are the first 4char of the input file name, suffix .seg)
standard output
produces a progress bar
bnfdyyyy.lst
Echo check of input parameters in listing file, plus a tabulation of the computational results.
bhelp(1), lamb(1),
Aki, K. and Richards, P., 1980, "Quantitative Seismology: Theory and Methods", Volume 1, W.H. Freeman and Company, New York, 557p.
no known bugs
Copyright © 2024 by Paul Michaels
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
P. Michaels, PE. <[email protected]>