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Welcome to GEMINI

GEMINI is a program package to calculate Green's functions and surface wave modes of the elastic wave equation for one-dimensional depth dependent media. Applications of the code range from high-frequency, small-scale wave propagation problems like ultrasonic waves, seam waves and shallow seismics to continental-scale seismic waves from earthquakes.

A description of the underlying mathematical approach can also be found in the paper by Friederich and Dalkolmo, Geophysical Journal International, 122, 537-550, 1995. Please cite this paper if you publish results obtained using GEMINI.

Requirements

  • gfortran (at least 4.2) and gcc for compilation
  • GNU make
  • m4 macro processor

Compilation

Set the variable F95 in your shell environment to the path to your Fortran compiler. Use Makefile and Make.f90 for compiling the Green function codes:

  • touch *.m4
  • make gfdsvrkf
  • make gfdsvrkf_mpi
  • make -f Make.f90 gfdsvrkfseis
  • make -f Make.f90 plotGreenFKSpectra

The m4 macro processor is used to automatically generate code needed for gfdsvrkf from a common template. If anything goes wrong do a "make clean" and repeat the compilation procedure.

Usage

The code is self-explaining. Just enter the name of the executable and you get a description of arguments and options. For theoretical background look into the documentation or into the paper by Friederich and Dalkolmo (GJI, 1995).

Info file:
   All information about source and receiver is provided by an info file (see examples folder).
   For more information consult the module include/sourceReceiver.f90.

gfdsvrkf:
   calculate frequency-wavenumber spectra for the displacement stress vector (DSV)
   with components U, R, V, S, W, T and optionally spatial derivatives either for
   for one source and many receiver depths or for one receiver and many source depths.

gfdsvrkf_mpi:
   an embarassingly parallel version of gfdsvrkf which distributes calculations for
   different frequencies to available processors.

gfdsvrkfseis:
   calculate synthetic seismograms (takes stations and components from an info file),
   current ourput formats: SFF and SSA (a special file with allows direct access).

Look into the examples folder where you find Makefiles for different applications of gfdsvrkf.

Seismogram format SFF

SFF (Stuttgart File Format) is a slight modification of GSE2.0 with CMPR6 compression. In the folder libstuff you find some Fortran modules which provide routines for reading and wirting SFF files. As far as I know SFF files can be read in using Seismic Handler. Look into stuff.f for a detailed description of the format.

Format SSA

SSA is very helpful when a big amount of seismograms are written because it permits direct access to any seismogram upon reading. There is a Fortran module "include/ssaDataset.f90" which provides routines for reading SSA-files.