hotspotter(1) GMT hotspotter(1)
NAME
hotspotter - Create CVA image from seamount locations
SYNOPSIS
hotspotter [tables] -Erotfile -GCVAgrid
-Iincrement
-Rregion [ -Nupper_age ] [ -S ] [ -T ] [ -V[level] ] [ -bibinary ]
[ -dinodata ] [ -eregexp ] [ -hheaders ] [ -iflags ] [ -oflags ] [
-:[i|o] ]
Note: No space is allowed between the option flag and the associated
arguments.
DESCRIPTION
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 Vol-
cano Amplitude grid (CVA). See option -: on how to read (latitude,lon-
gitude,a|) files.
REQUIRED ARGUMENTS
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.
-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.
-GCVAgrid
Specify name for output grid file.
-Ixinc[unit][+e|n][/yinc[unit][+e|n]]
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, nau-
tical mile or US survey foot, respectively, and will be con-
verted to the equivalent degrees longitude at the middle lati-
tude 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 coordi-
nates: If +e 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 +n to
the supplied integer argument; the increment is then recalcu-
lated from the number of nodes and the domain. The resulting
increment value depends on whether you have selected a grid-
line-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.
-Rwest/east/south/north[/zmin/zmax][+r][+uunit]
west, east, south, and north specify the region of interest, and
you may specify them in decimal degrees or in
[A+-]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. Appending +uunit expects projected (Carte-
sian) 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 dimension.
OPTIONAL ARGUMENTS
-Dfactor
Modify the sampling interval along flowlines. Default [0.5]
gives approximately 2 points within each grid box. Smaller fac-
tors gives higher resolutions at the expense of longer process-
ing time.
-Nupper_age
Set the upper age to assign seamounts whose crustal age is
unknown (i.e., NaN) [no upper age].
-S Normalize the resulting CVA grid to percentages of the CVA maxi-
mum.
-T Truncate seamount ages exceeding the upper age set with -N [no
truncation].
-V[level] (more a|)
Select verbosity level [c].
-bi[ncols][t] (more a|)
Select native binary input. [Default is 5 input columns].
-dinodata (more a|)
Replace input columns that equal nodata with NaN.
-e[~]^<i>apattern^<i>a | -e[~]/regexp/[i] (more a|)
Only accept data records that match the given pattern.
-V[level] (more a|)
Select verbosity level [c].
-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).
-r (more a|)
Set pixel node registration [gridline].
-:[i|o] (more a|)
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 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
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.
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
gmt(1), grdimage(1), grdrotater(1), grdspotter(1), project(1),
mapproject(1), backtracker(1), gmtpmodeler(1), grdpmodeler(1),
grdrotater(1), originator(1)
REFERENCES
Wessel, P., 1999, aHotspottinga tools released, EOS Trans. AGU, 80
(29), p. 319.
Wessel, P., 2008, Hotspotting: Principles and properties of a plate
tectonic Hough transform, Geochem. Geophys. Geosyst. 9(Q08004):
doi:10.1029/2008GC002058.
COPYRIGHT
2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
5.4.2 Jun 24, 2017 hotspotter(1)
gmt5 5.4.2 - Generated Thu Jun 29 13:42:59 CDT 2017