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gmtpmodeler(1)                        GMT                       gmtpmodeler(1)




NAME

       gmtpmodeler - Evaluate a plate motion model at given locations


SYNOPSIS

       gmtpmodeler  table   -Erot_file -Sflags [  -Fpolygonfile ] [  -Tage ] [
       -V[level] ] [ -bbinary ] [ -dnodata ] [ -eregexp  ]  [  -hheaders  ]  [
       -iflags ] [ -oflags ] [ -:[i|o] ]

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


DESCRIPTION

       gmtpmodeler reads a table with lon, lat and optionally age triplets and
       a  plate  motion  model and evaluates one of several model predictions.
       Optionally, the user may supply a clipping polygon in  multiple-segment
       format;  then,  only the part of the points inside the polygon are used
       to determine the model prediction.  The results are written to standard
       output.


REQUIRED ARGUMENTS

       table  Name  of one or more tables with geographical (lon, lat) coordi-
              nates and optionally a third column with ages  in  Myr.   If  no
              file is given then we read from standard input.

       -Erotfile
              Give  file  with rotation parameters. This file must contain one
              record for each rotation; each record must be of  the  following
              format:

              lon lat tstart [tstop] angle [ khat a b c d e f g df ]

              where  tstart  and  tstop  are  in  Myr and lon lat angle are in
              degrees. tstart and tstop are the ages of the old and young ends
              of  a  stage. If tstop is not present in the record then a total
              reconstruction rotation is expected and tstop is implicitly  set
              to  0  and should not be specified for any of the records in the
              file. If a covariance matrix C for the rotation is available  it
              must  be  specified  in  a  format using the nine optional terms
              listed in brackets. Here, C = (g/khat)*[ a b d; b c e; d e  f  ]
              which  shows  C  made up of three row vectors. If the degrees of
              freedom (df) in fitting the rotation is 0 or not given it is set
              to  10000. Blank lines and records whose first column contains #
              will be ignored. You may prepend a leading + to the filename  to
              indicate  you wish to invert the rotations.  Alternatively, give
              the filename composed of two plate IDs  separated  by  a  hyphen
              (e.g.,  PAC-MBL)  and we will instead extract that rotation from
              the GPlates rotation database. We return an error if  the  rota-
              tion cannot be found.

       -Sflags
              Type  of  model  prediction(s). Append one or more items: choose
              from a for plate motion azimuth,  d  for  great-circle  distance
              between  current location and its origin at the ridge (in km), s
              for plate motion model stage ID (1 is  youngest),  v  for  plate
              motion  rate (in mm/yr), w for plate rotation rate (degree/Myr),
              x for change in longitude relative to location of  crust  forma-
              tion,  y  for  change  in latitude relative to location of crust
              formation, X for longitude of crust formation, and Y  for  lati-
              tude  of  crust formation.  If no arguments are given we default
              to all [adsvwxyXY].


OPTIONAL ARGUMENTS

       -Fpolygonfile
              Specify a multisegment closed polygon file  that  describes  the
              area where the model should be evaluated; points outside will be
              skipped [use all data points].

       -Tage  Use a fixed age for model evaluation (i.e.,  override  the  ages
              given in the input table). This lets you evaluate the model at a
              snapshot in time, and is a required option if  the  input  table
              does not contain ages.

       -V[level] (more a|)
              Select verbosity level [c].

       -bi[ncols][t] (more a|)
              Select native binary input. [Default is 2 input columns].

       -d[i|o]nodata (more a|)
              Replace  input  columns  that  equal  nodata with NaN and do the
              reverse on output.

       -e[~]^<i>apattern^<i>a | -e[~]/regexp/[i] (more a|)
              Only accept data records that match the given pattern.

       -h[i|o][n][+c][+d][+rremark][+rtitle] (more a|)
              Skip or produce header record(s).

       -icols[+l][+sscale][+ooffset][,^<i>a|] (more a|)
              Select input columns and transformations (0 is first column).

       -ocols[,a|] (more a|)
              Select output columns (0 is first column).

       -^ or just -
              Print a short message about the  syntax  of  the  command,  then
              exits (NOTE: on Windows just use -).

       -+ or just +
              Print  an extensive usage (help) message, including the explana-
              tion of any module-specific  option  (but  not  the  GMT  common
              options), then exits.

       -? or no arguments
              Print a complete usage (help) message, including the explanation
              of all options, then exits.


GEODETIC VERSUS GEOCENTRIC COORDIINATES

       All spherical rotations are applied to  geocentric  coordinates.   This
       means  that  incoming data points and grids are considered to represent
       geodetic coordinates and must first be converted to geocentric  coordi-
       nates.  Rotations  are then applied, and the final reconstructed points
       are converted back to geodetic coordinates.  This default behavior  can
       be  bypassed  if  the  ellipsoid  setting  PROJ_ELLIPSOID is changed to
       Sphere.


                                        ----




EXAMPLES

       We  will  use  a  table  with  locations  and  ages  of  Pacific  crust
       (pac_age.txt),  a  plate motion model (Pac_APM.txt), and a polygon that
       contains the outline of the present Pacific plate  (pac_clip_path.txt).
       To  evaluate  the  plate  motion  azimuths  at the present time for the
       Pacific, try

              gmt gmtpmodeler pac_age.txt -EPac_APM.txt -V -Fpac_clip_path.txt \
                               -Sa -T0 > pac_dir_0.txt

       To determine the changes in latitude  since  crust  formation  for  the
       entire Pacific, try

              gmt gmtpmodeler pac_age.txt -EPac_APM.txt -V -Fpac_clip_path.txt \
                              -Sy > pac_dlat.txt

       To  determine  the  plate  motion velocities in effect when the Pacific
       crust was formed, try

              gmt gmtpmodeler pac_age.txt -EPac_APM.txt -V -Fpac_clip_path.txt \
                              -Sv > pac_vel.txt

       To determine how far the crust has moved since formation, try

              gmt gmtpmodeler pac_age.txt -EPac_APM.txt -V -Fpac_clip_path.txt \
                              -Sd > pac_dist.txt

       To save the coordinates of the crustas formation, try

              gmt gmtpmodeler pac_age.txt -EPac_APM.txt -V -Fpac_clip_path.txt \
                              -SXY > ac_origin_xy.txt


NOTES

       GMT   distributes   the   EarthByte   rotation   model    Global_Earth-
       Byte_230-0Ma_GK07_AREPS.rot.  To use an alternate rotation file, create
       an environmental parameters named GPLATES_ROTATIONS that points  to  an
       alternate rotation file.


SEE ALSO

       backtracker(1),  grdpmodeler(1), grdrotater(1), grdspotter(1),
       hotspotter(1), originator(1), rotconverter(1)


COPYRIGHT

       2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe



5.4.2                            Jun 24, 2017                   gmtpmodeler(1)

gmt5 5.4.2 - Generated Wed Jun 28 16:31:40 CDT 2017
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