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.TH "HOTSPOTTER" "1gmt" "May 21, 2019" "5.4.5" "GMT"
.SH NAME
hotspotter \- Create CVA image from seamount locations
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.SH SYNOPSIS
.sp
\fBhotspotter\fP [\fItables\fP]  \fB\-E\fP\fIrotfile\fP  \fB\-G\fP\fICVAgrid\fP
 \fB\-I\fP\fIincrement\fP
 \fB\-R\fP\fIregion\fP
[  \fB\-N\fP\fIupper_age\fP ]
[  \fB\-S\fP ] [  \fB\-T\fP ]
[  \fB\-V\fP[\fIlevel\fP] ]
[ \fB\-bi\fPbinary ]
[ \fB\-di\fPnodata ]
[ \fB\-e\fPregexp ]
[ \fB\-h\fPheaders ]
[ \fB\-i\fPflags ]
[ \fB\-o\fPflags ]
[ \fB\-:\fP[\fBi\fP|\fBo\fP] ]
.sp
\fBNote:\fP No space is allowed between the option flag and the associated arguments.
.SH DESCRIPTION
.sp
\fBhotspotter\fP reads (longitude, latitude, amplitude, radius, age)
records from \fItables\fP [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 \fB\-:\fP on how to
read (latitude,longitude,...) files.
.SH REQUIRED ARGUMENTS
.INDENT 0.0
.TP
.B \fItable\fP
One or more ASCII (or binary, see \fB\-bi\fP[\fIncols\fP][\fItype\fP]) data
table file(s) holding a number of data columns. If no tables are given
then we read from standard input.  
.UNINDENT
.INDENT 0.0
.TP
\fB\-E\fP\fIrotfile\fP
Give file with rotation parameters. This file must contain one
record for each rotation; each record must be of the following format:
.sp
\fIlon lat tstart [tstop] angle\fP [ \fIkhat a b c d e f g df\fP ]
.sp
where \fItstart\fP and \fItstop\fP are in Myr and \fIlon lat angle\fP are in
degrees. \fItstart\fP and \fItstop\fP are the ages of the old and young ends
of a stage. If \fItstop\fP is not present in the record then a total
reconstruction rotation is expected and \fItstop\fP is implicitly set to
0 and should not be specified for any of the records in the file. If
a covariance matrix \fBC\fP for the rotation is available it must be
specified in a format using the nine optional terms listed in
brackets. Here, \fBC\fP = (\fIg\fP/\fIkhat\fP)*[ \fIa b d; b c e; d e f\fP ]
which shows \fBC\fP made up of three row vectors. If the degrees of
freedom (\fIdf\fP) 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.
.UNINDENT
.INDENT 0.0
.TP
\fB\-G\fP\fICVAgrid\fP
Specify name for output grid file.
.UNINDENT
.INDENT 0.0
.TP
\fB\-I\fP\fIxinc\fP[\fIunit\fP][\fB+e\fP|\fBn\fP][/\fIyinc\fP[\fIunit\fP][\fB+e\fP|\fBn\fP]]
\fIx_inc\fP [and optionally \fIy_inc\fP] is the grid spacing. Optionally,
append a suffix modifier. \fBGeographical (degrees) coordinates\fP: Append
\fBm\fP to indicate arc minutes or \fBs\fP to indicate arc seconds. If one
of the units \fBe\fP, \fBf\fP, \fBk\fP, \fBM\fP, \fBn\fP or \fBu\fP 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 \fIy_inc\fP is given
but set to 0 it will be reset equal to \fIx_inc\fP; otherwise it will be
converted to degrees latitude. \fBAll coordinates\fP: If \fB+e\fP is appended
then the corresponding max \fIx\fP (\fIeast\fP) or \fIy\fP (\fInorth\fP) 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 \fInumber of nodes\fP desired by
appending \fB+n\fP 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 \fB\-R\fP\fIgrdfile\fP is used then the grid spacing has
already been initialized; use \fB\-I\fP to override the values.
.UNINDENT
.INDENT 0.0
.TP
\fB\-R\fP\fIwest\fP/\fIeast\fP/\fIsouth\fP/\fInorth\fP[/\fIzmin\fP/\fIzmax\fP][\fB+r\fP][\fB+u\fP\fIunit\fP]
\fIwest\fP, \fIeast\fP, \fIsouth\fP, and \fInorth\fP specify the region of interest,
and you may specify them in decimal degrees or in
[±]dd:mm[:ss.xxx][\fBW\fP|\fBE\fP|\fBS\fP|\fBN\fP] format
Append \fB+r\fP if lower left
and upper right map coordinates are given instead of w/e/s/n. The
two shorthands \fB\-Rg\fP and \fB\-Rd\fP stand for global domain (0/360
and \-180/+180 in longitude respectively, with \-90/+90 in latitude).
Alternatively for grid creation, give \fBR\fP\fIcode\fP\fIlon\fP/\fIlat\fP/\fInx\fP/\fIny\fP, where
\fIcode\fP 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 \fIlon\fP/\fIlat\fP coordinate
refers to, and the grid dimensions \fInx\fP and \fIny\fP with grid spacings via
\fB\-I\fP is used to create the corresponding region.
Alternatively, specify the name of an existing grid file and the
\fB\-R\fP settings (and grid spacing, if applicable) are copied from
the grid. Appending \fB+u\fP\fIunit\fP expects projected (Cartesian)
coordinates compatible with chosen \fB\-J\fP and we inversely project
to determine actual rectangular geographic region.
For perspective view (\fB\-p\fP), optionally append /\fIzmin\fP/\fIzmax\fP\&.
In case of perspective view (\fB\-p\fP), a z\-range (\fIzmin\fP, \fIzmax\fP)
can be appended to indicate the third dimension. This needs to be
done only when using the \fB\-Jz\fP option, not when using only the
\fB\-p\fP option. In the latter case a perspective view of the plane is
plotted, with no third dimension.  
.UNINDENT
.SH OPTIONAL ARGUMENTS
.INDENT 0.0
.TP
\fB\-D\fP\fIfactor\fP
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.
.UNINDENT
.INDENT 0.0
.TP
\fB\-N\fP\fIupper_age\fP
Set the upper age to assign seamounts whose crustal age is unknown
(i.e., NaN) [no upper age].
.UNINDENT
.INDENT 0.0
.TP
\fB\-S\fP
Normalize the resulting CVA grid to percentages of the CVA maximum.
.UNINDENT
.INDENT 0.0
.TP
\fB\-T\fP
Truncate seamount ages exceeding the upper age set with \fB\-N\fP [no
truncation].
.UNINDENT
.INDENT 0.0
.TP
\fB\-V\fP[\fIlevel\fP] (more ...)
Select verbosity level [c].  
.UNINDENT
.INDENT 0.0
.TP
\fB\-bi\fP[\fIncols\fP][\fBt\fP] (more ...)
Select native binary input. [Default is 5 input columns].
.UNINDENT
.INDENT 0.0
.TP
\fB\-di\fP\fInodata\fP (more ...)
Replace input columns that equal \fInodata\fP with NaN.  
.UNINDENT
.INDENT 0.0
.TP
\fB\-e\fP[\fB~\fP]\fI"pattern"\fP \fB|\fP \fB\-e\fP[\fB~\fP]/\fIregexp\fP/[\fBi\fP] (more ...)
Only accept data records that match the given pattern.  
.UNINDENT
.INDENT 0.0
.TP
\fB\-V\fP[\fIlevel\fP] (more ...)
Select verbosity level [c].  
.UNINDENT
.INDENT 0.0
.TP
\fB\-i\fP\fIcols\fP[\fB+l\fP][\fB+s\fP\fIscale\fP][\fB+o\fP\fIoffset\fP][,\fI\&...\fP] (more ...)
Select input columns and transformations (0 is first column).
.UNINDENT
.INDENT 0.0
.TP
\fB\-o\fP\fIcols\fP[,...] (more ...)
Select output columns (0 is first column).
.UNINDENT
.INDENT 0.0
.TP
\fB\-r\fP (more ...)
Set pixel node registration [gridline].  
.UNINDENT
.INDENT 0.0
.TP
\fB\-:\fP[\fBi\fP|\fBo\fP] (more ...)
Swap 1st and 2nd column on input and/or output.
.UNINDENT
.INDENT 0.0
.TP
\fB\-^\fP or just \fB\-\fP
Print a short message about the syntax of the command, then exits (NOTE: on Windows just use \fB\-\fP).
.TP
\fB\-+\fP or just \fB+\fP
Print an extensive usage (help) message, including the explanation of
any module\-specific option (but not the GMT common options), then exits.
.TP
\fB\-?\fP or no arguments
Print a complete usage (help) message, including the explanation of all options, then exits.
.UNINDENT
.SH GEODETIC VERSUS GEOCENTRIC COORDIINATES
.sp
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.
.SH EXAMPLES
.sp
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
.INDENT 0.0
.INDENT 3.5
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
gmt hotspotter seamounts.d \-EDC85.d \-GCVA.nc \-R130/260/\-66/60 \-I10m \-N145 \-T \-V
.ft P
.fi
.UNINDENT
.UNINDENT
.UNINDENT
.UNINDENT
.sp
This file can then be plotted with grdimage\&.
.SH NOTES
.sp
GMT distributes the EarthByte rotation model Global_EarthByte_230\-0Ma_GK07_AREPS.rot.
To use an alternate rotation file, create an environmental parameters named
\fBGPLATES_ROTATIONS\fP that points to an alternate rotation file.
.SH SEE ALSO
.sp
gmt, grdimage,
grdrotater,
grdspotter,
project,
mapproject,
backtracker,
gmtpmodeler,
grdpmodeler,
grdrotater,
originator
.SH REFERENCES
.sp
Wessel, P., 1999, "Hotspotting" tools released, EOS Trans. AGU, 80 (29), p. 319.
.sp
Wessel, P., 2008, Hotspotting: Principles and properties of a plate
tectonic Hough transform, Geochem. Geophys. Geosyst. 9(Q08004):
doi:10.1029/2008GC002058.
.SH COPYRIGHT
2019, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
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