fzinformer

Bash script to plot statistical information related to fracture zones

Synopsis

fzinformer [ -D ] [ -Fmax ] [ -Iprofile ] [ -Nmax ] [ -Smax ] [ -Tprefix ] [ -Wmax ] [ -V[level] ]

Note: No space is allowed between the option flag and the associated arguments.

Description

fzinformer is a script developed as part of the Global Seafloor Fabric and Magnetic Lineation Project [see GSFML for a full description of the project]. It make plots of statistical information obtained by fzanalyzer as a function of position along a fracture zone (FZ).

Optional Arguments

-D: Use the filtered output from fzblender instead of the raw analysis file in making the plot. This requires that you ran fzblender with the -D option.

-Fmax: Sets the maximum F-statistic amplitude for the plot [10000]. A logarithmic scale is used for this panel; all others are linear.

-Iprofile: By default we plot all the cross-profiles in one stack. To select a single profile only, append the running number of the profile, where 0 is the first profile.

-Nmax: Sets the maximum range of VGG amplitudes (in Eotvos) for the plot [200].

-Smax: Sets the maximum (±) half-range of FZ offsets (in km) [25].

-Tprefix: Sets the file name prefix used when running fzanalyzer and fzblender [The default is fztrack]. The files used here are prefix_analysis.txt (or prefix_filtered.txt if -D is used) and prefix_blend.txt.

-Wmax: Sets the maximum range of FZ widths (in km) [50].

-V[level]: Select verbosity level [w]. (See full description) (See cookbook information).

-Zacut/vcut/fcut/wcut: We will attempt to assign a single quality index Q that summarize how good we believe a model fit to be. This assignment relies of four threshold values that need to be determined empirically. Here, a_cut is the minimum peak-to-trough amplitude (in Eotvos) of a model for the crossing profile [25], v_cut is the minimum variance reduction offered by the model (in %) [50], f_cut is the minimum F statistic computed for the model [50], and w_cut is a typical FZ trough width (in km) [15]. Currently, the first three quantities are used to arrive at a 5-level quality index (0-1) for fitted models, as follows: (1) Very Good: Requires model parameters to exceed all three thresholds; (0.75) Good: Requires amplitude and variance reduction to exceed thresholds; (0.5) Fair: Requires the variance reduction only to exceed its threshold; (0.25) Poor: Requires the amplitude only to exceed its threshold; and (0) Bad: None of the criteria were met. We compute separate quality indices for the trough and blend models. For the empirical trough model we only have estimates or peak-to-trough amplitude, -A, and trough width, -W. Here, we form the ratio (A/a_cut) over (W/w_cut), take \(\tan^{-1}\) of this ratio and scale the result to yield the range 0-1 rounded to the nearest multiple of 0.25.

-borecord[+b|l] (more …): Select native binary format for table output.

-donodata[+ccol] (more …): Replace output columns that equal NaN with nodata.

-icols[+l][+ddivisor][+sscale|d|k][+ooffset][,…][,t[word]] (more …): Select input columns and transformations (0 is first column, t is trailing text, append word to read one word only).

-ocols[+l][+ddivisor][+sscale|d|k][+ooffset][,…][,t[word]] (more …): Select output columns and transformations (0 is first column, t is trailing text, append word to write one word only).

-q[i|o][~]rows|limits[+ccol][+a|t|s] (more …): Select input or output rows or data limit(s) [all].

-^ or just -: Print a short message about the syntax of the command, then exit (Note: on Windows just use -).
-+ or just +: Print an extensive usage (help) message, including the explanation of any module-specific option (but not the GMT common options), then exit.
-? or no arguments: Print a complete usage (help) message, including the explanation of all options, then exit.
--PAR=value: Temporarily override a GMT default setting; repeatable. See gmt.conf for parameters.

Plot Features

fzinformer packs much information into each plot by using different symbols and colors. Empirical information obtained from raw data are shown in red. Information derived from a forced trough FZ model are shown in green, while the information derived from the optimal blend model are shown in blue. We present 7 panels for each FZ. Panel 1 (top) shows how the F-statistic parameter varies with distance for the trough (green) and blend (blue) models. Panel 2 shows the reduction in variance for the same two models. Panel 3 shows the maximum amplitude for the two models and the empirical data (red). Panel 4 shows the width of the FZ signal for all three data. Panel 5 presents the offset (in km) between the digitized trace and the optimal FZ locations (one curve for each type). Panel 6 shows which side (left is -1, right = +1) is the young side assuming a Pacific edge-anomaly model (it will tend to jump back and forth where the signal is close to symmetric and should only be used when we have clearly asymmetric signals). Finally, panel 7 shows the compression parameter C for the blend and trough models, as well as the blend parameter A (black line) for the optimal blend model.

Examples

To look at the statistics for the 5th (0 is first) FZ analyzed as part of a larger group called traces, accepting default values except we override the maximum amplitude by using 100, try:

fzinformer -Ttraces -N100 -I5

The statistical plot will be named prefix_stat.pdf.

References

Wessel, P., Matthews, K. J., Müller, R. D., Mazzoni, A., Whittaker, J. M., Myhill, R., Chandler, M. T., 2015, “Semiautomatic fracture zone tracking”, Geochem. Geophys. Geosyst., 16 (7), 2462–2472. https://doi.org/10.1002/2015GC005853.