bionic (1) gmtpmodeler.1gmt.gz
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) coordinates 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 rotation 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 formation, y
for change in latitude relative to location of crust formation, X for longitude of crust
formation, and Y for latitude 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 …)
Select verbosity level [c].
-bi[ncols][t] (more …)
Select native binary input. [Default is 2 input columns].
-d[i|o]nodata (more …)
Replace input columns that equal nodata with NaN and do the reverse on output.
-e[~]”pattern” | -e[~]/regexp/[i] (more …)
Only accept data records that match the given pattern.
-h[i|o][n][+c][+d][+rremark][+rtitle] (more …)
Skip or produce header record(s).
-icols[+l][+sscale][+ooffset][,…] (more …)
Select input columns and transformations (0 is first column).
-ocols[,…] (more …)
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 explanation 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
coordinates. 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 crust’s 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_EarthByte_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, grdpmodeler, grdrotater, grdspotter, hotspotter, originator, rotconverter
COPYRIGHT
2018, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe