This is the command hotspottergmt that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator
hotspotter - Create CVA image from seamount locations
hotspotter [tables] rotfile CVAgrid increment region [ upper_age ] [ ] [ ] [ [level] ] [
-bi<binary> ] [ -di<nodata> ] [ -h<headers> ] [ -i<flags> ] [ -o<flags> ] [ -:[i|o] ]
Note: No space is allowed between the option flag and the associated arguments.
hotspotter reads (longitude, latitude, amplitude, radius, age) records from tables [or
standard input] and calculates flowlines using the specified stage or total reconstruction
rotations. These flowlines are convolved with the shape of the seamount (using a Gaussian
shape given amplitude and radius = 6 sigma) and added up to give a Cumulative Volcano
Amplitude grid (CVA). See option -: on how to read (latitude,longitude,...) files.
table One or more ASCII (or binary, see -bi[ncols][type]) data table file(s) holding a
number of data columns. If no tables are given then we read from standard input.
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.
Specify name for output grid file.
x_inc [and optionally y_inc] is the grid spacing. Optionally, append a suffix
modifier. Geographical (degrees) coordinates: Append m to indicate arc minutes or s
to indicate arc seconds. If one of the units e, f, k, M, n or u is appended
instead, the increment is assumed to be given in meter, foot, km, Mile, nautical
mile or US survey foot, respectively, and will be converted to the equivalent
degrees longitude at the middle latitude of the region (the conversion depends on
PROJ_ELLIPSOID). If /y_inc is given but set to 0 it will be reset equal to x_inc;
otherwise it will be converted to degrees latitude. All coordinates: If = is
appended then the corresponding max x (east) or y (north) may be slightly adjusted
to fit exactly the given increment [by default the increment may be adjusted
slightly to fit the given domain]. Finally, instead of giving an increment you may
specify the number of nodes desired by appending + to the supplied integer
argument; the increment is then recalculated from the number of nodes and the
domain. The resulting increment value depends on whether you have selected a
gridline-registered or pixel-registered grid; see App-file-formats for details.
Note: if -Rgrdfile is used then the grid spacing has already been initialized; use
-I to override the values.
west, east, south, and north specify the region of interest, and you may specify
them in decimal degrees or in [+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower
left and upper right map coordinates are given instead of w/e/s/n. The two
shorthands -Rg and -Rd stand for global domain (0/360 and -180/+180 in longitude
respectively, with -90/+90 in latitude). Alternatively for grid creation, give
Rcodelon/lat/nx/ny, where code is a 2-character combination of L, C, R (for left,
center, or right) and T, M, B for top, middle, or bottom. e.g., BL for lower left.
This indicates which point on a rectangular region the lon/lat coordinate refers
to, and the grid dimensions nx and ny with grid spacings via -I is used to create
the corresponding region. Alternatively, specify the name of an existing grid file
and the -R settings (and grid spacing, if applicable) are copied from the grid.
Using -Runit expects projected (Cartesian) coordinates compatible with chosen -J
and we inversely project to determine actual rectangular geographic region. For
perspective view (-p), optionally append /zmin/zmax. In case of perspective view
(-p), a z-range (zmin, zmax) can be appended to indicate the third dimension. This
needs to be done only when using the -Jz option, not when using only the -p option.
In the latter case a perspective view of the plane is plotted, with no third
Modify the sampling interval along flowlines. Default [0.5] gives approximately 2
points within each grid box. Smaller factors gives higher resolutions at the
expense of longer processing time.
Set the upper age to assign seamounts whose crustal age is unknown (i.e., NaN) [no
-S Normalize the resulting CVA grid to percentages of the CVA maximum.
-T Truncate seamount ages exceeding the upper age set with -N [no truncation].
-V[level] (more ...)
Select verbosity level [c].
-bi[ncols][t] (more ...)
Select native binary input. [Default is 5 input columns].
-dinodata (more ...)
Replace input columns that equal nodata with NaN.
-V[level] (more ...)
Select verbosity level [c].
-icols[l][sscale][ooffset][,...] (more ...)
Select input columns (0 is first column).
-ocols[,...] (more ...)
Select output columns (0 is first column).
-r (more ...)
Set pixel node registration [gridline].
-:[i|o] (more ...)
Swap 1st and 2nd column on input and/or output.
-^ or just -
Print a short message about the syntax of the command, then exits (NOTE: on Windows
use just -).
-+ 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 options, then
Print GMT version and exit.
Print full path to GMT share directory and exit.
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.
To create a CVA image from the Pacific (x,y,z,r,t) data in the file seamounts.d, using the
DC85.d Euler poles, run
gmt hotspotter seamounts.d -EDC85.d -GCVA.nc -R130/260/-66/60 -I10m -N145 -T -V
This file can then be plotted with grdimage.
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.
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