BAMP

SH-wave enhanced down-hole data in BSEGY format (*.seg files) are processed for amplitude decay with frequency. Beam spreading is corrected for assuming spherical divergence. The frequency increment, delf, should be no smaller than the reciprocal of the record length. For a 0.5 second recording, 2 Hz is the finest resolution.

 bamp infile emin emax fmin fmax delf bw tmax
  
 infile  =input file name 
 emin    =scan gate: (min_elev) 
 emax    =scan gate: (max_elev) 
 fmin    =min band pass center frequency (Hz) 
 fmax    =max band pass center frequency (Hz) 
 delf    =frequency step (Hz) 
 bw      =bandwidth of filter (Hz) 
 tmax    =time gate: max_time

Output includes a file, bamp.his which can be used in procedure cainv3 (see section 8.2.7). Also output are Postscript files, bamp.ps and bampqc.ps. The bamp.his file is 3 columns (frequency, decay 1/meters, standard deviation). For example:

    5.00      0.0000      0.0186
    7.00      0.0104      0.0121
    9.00      0.0287      0.0109
   11.00      0.0576      0.0105
   13.00      0.1077      0.0099
   15.00      0.1251      0.0070
   17.00      0.0771      0.0055
   19.00      0.0574      0.0059
   21.00      0.0703      0.0059
   23.00      0.0840      0.0062

Figure 30: BAMP: SH body-wave amplitude decay for down-hole data same as seen in Figure 28 velocity dispersion. Corrected for beam spreading, a viscous, Kelvin-Voigt material, the decay should increase with frequency (Michaels, 1998).