hotspotter(1gmt)
NAME
hotspotter - Create CVA image from seamount locations
SYNOPSIS
hotspotter [tables] -Erotfile -GCVAgrid
-Iincrement
-Rregion [ -Nupper_age ] [ -S ] [ -T ] [ -V[level] ] [ -bibinary ]
[ -dinodata ] [ -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 Volcano Amplitude grid (CVA). See option -: on how to read (latitude,longitude,...) 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
rotation cannot be found.
-GCVAgrid
Specify name for output grid file.
-Ixinc[unit][=|+][/yinc[unit][=|+]]
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.
-R[unit]west/east/south/north[/zmin/zmax][r]
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 dimension.
OPTIONAL ARGUMENTS
-Dfactor
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.
-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
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 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
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_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
gmt, grdimage, grdrotater, grdspotter, project, mapproject, backtracker, gmtpmodeler, grdpmodeler, grdrotater, originator
REFERENCES
Wessel, P., 1999, "Hotspotting" 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
2016, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
