hotspotter — GMT 5.1.1 documentation

### Navigation

- index
- next
- previous
- Project Home »
- GMT 5.1.1 documentation »
- SPOTTER »
- Search:

# hotspotter

hotspotter - Create CVA image from seamount locations

## Synopsis

hotspotter [table] -Erotfile -GCVAgrid -Ixinc[unit][=|+][/yinc[unit][=|+]] -R[unit]xmin/xmax/ymin/ymax[r] [ -Nupper_age ] [ -S ] [ -T ] [ -V[level] ] [ -bi[ncols][type][w][+L|+B] ] [ -h[i|o][n][+c][+d][+rremark][+rtitle] ] [ -icols[l][sscale][ooffset][,...] ] [ -ocols[,...] ] [ -:[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 infiles [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 B. GMT 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]
  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, 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][type] (more ...)
  Select binary input. [Default is 5 input columns].

-V[level] (more ...)
  Select verbosity level [c].

-icols[l][sscale][ooffset][,...] (more ...)
  Select input columns.

-ocols[,...] (more ...)
  Select output columns.

-r (more ...)
  Set pixel node registration [gridline].

-:[i|o] (more ...)
  Swap 1st and 2nd column on input and/or output.

-^
  Print a short message about the syntax of the command, then exits (NOTE: on Windows use just -).
+
  Print an extensive usage (help) message, including the explanation of any module-specific option (but not the GMT common options), then exits.
-?
  Print a complete usage (help) message, including the explanation of options, then exits.
--version
  Print GMT version and exit.
--show-datadir
  Print full path to GMT share directory and exit.

## 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.

## See Also

gmt, grdimage, grdrotater, grdspotter, project, mapproject, backtracker, 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.

### Navigation

- index
- next
- previous
- Project Home »
- GMT 5.1.1 documentation »
- SPOTTER »
- Search: