Gpsh

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Synopsis

gpsh [OPTIONS] [FILE]

Description

Computes the SH transfer function for layered models given through stdin or FILE.

The input is the soil column defined as listed below. The output is the Fourier transfer function for VERTICALLY INCIDENT plane S waves

The computation is based on the reflectivity method ([1]), as implemented in ([2], [3])

Format for layered models:

 Line 1  : <number of layers n including half-space for first model>
 Line 2  : <thickness (m)> <Vp (m/s)> <Vs (m/s)> <Density (kg/m3)>[ <Qp> <Qs>]
 ....
 Line n+1 : 0 <Vp (m/s)> <Vs (m/s)> <Density (kg/m3)>[ <Qp> <Qs>]
 Line n+2 : <number of layers m including half-space for a second model - if wished>
 Line n+3 : <thickness (m)> <Vp (m/s)> <Vs (m/s)> <Density (kg/m3)>[ <Qp> <Qs>]
 ....
 Line n+m+2 : 0 <Vp (m/s)> <Vs (m/s)> <Density (kg/m3)>[ <Qp> <Qs>]
 Line n+m+3 : <number of layers l including half-space for a third model - if wished>
 ....

Quality factors are mandatory. Any number of models can be given as input.

Output

The output is the modulus of the transfer function, over the specified frequency range and with the specified frequency sampling. It is corrected for the free surface effect (i.e., divided by 2)


Gpsh options

  • -n <count> Number of frequency samples (default=100)
  • -max <max> Maximum frequency up to which the transfer function s to be computed (default=20 Hz)
  • -angle <angle> Incidence angle (default=90, vertical incidence)

Generic options:

  • -help <SECTION> Show help about options. SECTION may be empty or:
                           all, examples, generic, gpsh
  • -version Show version information
  • -app-version Show short version information
  • -reportbug Start bug report dialog, information about bug is
                           passed through stdin. This option is used
                           internally to report bugs if option -nobugreport is
                           not specified.
  • -reportint Start bug report dialog, information about
                           interruption is passed through stdin. This option
                           is used internally to report interruptions if
                           option -nobugreport is not specified.
  • -nobugreport Do not generate bug report in case of error

Examples

        gpsh < test.model
 Calculates SH transfer function from 0.2 Hz to 20 Hz for model 'test.model'.
        gpsh < test.model | figue -c
 Calculates the same function and plot it.
        gpsh < test.model | figue -c -m sh.mkup
 Shows the same function on a log-log plot. 'sh.mkup' is a tar.gz file
 containing an xml description of the graphic format, it can be generated from
 figue's interface.


Copyright

Copyright (c) 2002-2008 Marc Wathelet. All rights reserved.

See http://www.geopsy.org for more information.
  1. Kennett, B. L. and N. J. Kerry (1979). Seismic waves in stratified half space, Geophys. J. R. Astron. Soc. 57, 557-583.
  2. Bard, P.-Y., & J.-C. Gariel, 1986. The seismic response of two-dimensional sedimentary deposits with large vertical velocity gradients. Bull. seism. Soc. Am., 76, 343-366
  3. Theodulidis, N., P.-Y. Bard, R.J Archuleta and M. Bouchon, 1996. Horizontal to vertical spectral ratio and geological conditions: the case of Garner Valley downhole array in Southern California, Bull. seism. Soc. Am., 86, 306-319.