Decomposition of the wave field into optimized Gaussian packets

History file 'mgp-an.h' performs the decomposition of the common-shot seismograms into optimized Gaussian packets (for theory see Zacek, 2006). The wave field to be decomposed is represented by seismograms (common-shot gathers) of the "Marmousi model and dataset". The seismograms for shots 1 to 240 are in binary files 'seis-001.h@' to 'seis-240.h@' and can be found at http://sw3d.cz/software/marmousi/marmousi.htm. Run history file 'mgp-an.h' to decompose and compose the seismograms.

Notes on history file 'mgp-an.h'

The distributed version of the history file 'mgp-an.h' is set to compute decomposition for the shot 77 (at a horizontal coordinate of 4.9 km). To perform decomposition for other shots, enable the respective lines in the history file by removing the hashes.

It is necessary at first to compute optimum initial parameters of Gaussian beams (see Optimization of the Shape of Gaussian Beams) and then run history file mgp-an.h. To run decompositions for other common-shot gathers you need to compute optimum initial parameters for each gather.

History file 'mgp-an.h' launches another history file 'mgp-an1.h' for each shot, and generates PostScript plots of seismograms. History file 'mgp-an1.h' transforms the original Marmousi seismograms from binary to ASCII files, and calculates the amplitudes of optimized Gaussian packets using the program 'gpanal.for'. The program 'gpanal.for' is located in the directory 'data/mar'. Use command 'perl f.pl gpanal' to compile the program.

There is also possibility to use uniform initial parameters of Gaussian beams. In this case run history file 'mgb-uni.h' to create uniform (constant) initial parameters and than run history file 'mgp-an.h'.

Output files 'ssdxxx.ps' contain the PostScript plots of seismograms to be decomposed, 'sscxxx.ps' contain the plots of seismograms after composition and 'difxxx.ps' contain the plots of differences between seismograms. Output files 'amprxxx.out' and 'ampixxx.out', containing the real part and the imaginary part of amplitudes of Gaussian packets, are used as input in Gaussian packet migration in the Marmousi model.

Memory requirements

To run the history file 'mgp-an.h' it is necessary to compile program 'gpanal.for' with parameter MRAM=12000000. Include file 'ram.inc' is distributed with MRAM=4000000.

References

Zacek, K. (2006): Decomposition of the wave field into optimized Gaussian packets. Stud. Geophys. Geod., 50, 367-380.