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Slowness-wavenumber analysis on array traces

command: FK <trclist> <starttime> <endtime> [<minfreq>] [<maxfreq>] [<maxslowness>] [<sloresult>] [<azresult>]

Perform FK analysis on array traces, determine slowness and azimuth of incoming plane wave. Based on obspy routine "array_processing".

parameters

  • <trclist> parameter type: trace list
    List of input traces for FK algorithm.
  • <starttime> parameter type: float
    Start time of time window in seconds read from time axis.
  • <endtime> parameter type: float
    End time of time window in seconds read from time axis.
  • <minfreq> parameter type: float
    Lower bound of frequency window for FK in Hz.
  • <maxfreq> parameter type: float
    Upper bound of frequency window for FK in Hz.
  • <maxslowness> parameter type: float
    Upper bound of slowness in s/deg in x and y direction.
  • <sloresult> parameter type: output variable
    Name of output variable for slowness result in s/deg.
  • <azresult> parameter type: output variable
    Name of output variable for azimuth result.

qualifiers

  • /winlen=<winlen>
    Window length in s for segments put into FK algorithm. Default: <endtime> - <starttime>, i.e. only one time step is computed.
  • /winfrac=<winfrac>
    Fraction of window used as step size (see description of obspy array_processing routine). Default 0.05.
  • /slostep=<slostep>
    Slowness step size, determines resolution of output matrix, default <maxslowness>/100.
  • /scatter=<outfile>
    Output filename for scatter plot. The scatter plot contains the results of each time step.
  • /polar=<outfile>
    Output filename for polar plot. The polar plot contains a histogram of the results of all time steps.
  • /slownessmap=<outfile>
    Output filename for slowness map. The slowness map contains the slowness matrix of a single time step.
  • /kmunits
    Input numbers and plot scalings are given in s/km instead of s/deg.

example

fk 17-51 53. 69. 0.4 3.0 15.0 &slo &az /slownessmap=slmap.png
Compute slowness and azimuth for signals between seconds 53. and 69. for traces 17 to 51 in a frequency range between 0.4 and 3 Hz and a maximum slowness of 15 s/deg. The results are copied into variables "slo" and "az". The slownessmap of this single time step is produced in file "slmap.png".