topogrd

2-D binary grid file with the topography of the load (in meters); See GRID FILE FORMATS below. If -T is used, topogrd may be a filename template with a floating point format (C syntax) and a different load file name will be set and loaded for each time step. The load times thus coincide with the times given via -T (but not all times need to have a corresponding file). Alternatively, give topogrd as =flist, where flist is an ASCII table with one topogrd filename and load time per record. These load times can be different from the evaluation times given via -T. For load time format, see -T.

-Drm/rl[/ri]/rw

Sets density for mantle, load, infill (optional, otherwise it is assumed to equal the load density), and water or air. If ri differs from rl then an approximate solution will be found. If ri is not given then it defaults to rl.

-ETe

Sets the elastic plate thickness (in meter); append k for km. If the elastic thickness exceeds 1e10 it will be interpreted as a flexural rigidity D (by default D is computed from Te, Young's modulus, and Poisson's ratio; see -C to change these values).

-Goutfile

If -T is set then grdfile must be a filename template that contains a floating point format (C syntax). If the filename template also contains either %s (for unit name) or %c (for unit letter) then we use the corresponding time (in units specified in -T) to generate the individual file names, otherwise we use time in years with no unit.

-ANx/Ny/Nxy

Specify in-plane compressional or extensional forces in the x- and y-directions, as well as any shear force [no in-plane forces]. Compression is indicated by negative values, while extensional forces are specified using positive values.

-Cppoisson

Change the current value of Poisson's ratio [0.25].

-CyYoung

Change the current value of Young's modulus [7.0e10 N/m^2].

-Fnu_a[/h_a/nu_m]

Specify a firmoviscous model in conjunction with an elastic plate thickness specified via -E. Just give one viscosity (nu_a) for an elastic plate over a viscous half-space, or also append the thickness of the asthenosphere (h_a) and the lower mantle viscosity (nu_m), with the first viscosity now being that of the asthenosphere. Give viscosities in Pa*s. If used, give the thickness of the asthenosphere in meter; append k for km.

-N[a|f|m|r|s|nx/ny][+a|[+d|h|l][+e|n|m][+twidth][+v][+w[suffix]][+z[p]]

Choose or inquire about suitable grid dimensions for FFT and set optional parameters. Control the FFT dimension:

Control detrending of data: Append modifiers for removing a linear trend:

Control extension and tapering of data: Use modifiers to control how the extension and tapering are to be performed:

Control writing of temporary results: For detailed investigation you can write the intermediate grid being passed to the forward FFT; this is likely to have been detrended, extended by point-symmetry along all edges, and tapered. Append +w[suffix] from which output file name(s) will be created (i.e., ingrid_prefix.ext) [tapered], where ext is your file extension. Finally, you may save the complex grid produced by the forward FFT by appending +z. By default we write the real and imaginary components to ingrid_real.ext and ingrid_imag.ext. Append p to save instead the polar form of magnitude and phase to files ingrid_mag.ext and ingrid_phase.ext.

-Llist

Write the names and evaluation times of all grids that were created to the text file list. Requires -T.

-Mtm

Specify a viscoelastic model in conjunction with an elastic plate thickness specified via -E. Append the Maxwell time tm for the viscoelastic model (in ).

-Sbeta

Specify a starved moat fraction in the 0-1 range, where 1 means the moat is fully filled with material of density ri while 0 means it is only filled with material of density rw (i.e., just water) [1].

-Tt0[u][/t1[u]/dt[u]|file]|n][+l]

Specify t0, t1, and time increment (dt) for sequence of calculations [Default is one step, with no time dependency]. For a single specific time, just give start time t0. The unit is years; append k for kyr and M for Myr. For a logarithmic time scale, append +l and specify n steps instead of dt. Alternatively, give a file with the desired times in the first column (these times may have individual units appended, otherwise we assume year). We then write a separate model grid file for each given time step.

-Wwd

Set reference depth to the undeformed flexed surface in m [0]. Append k to indicate km.

-Zzm

Specify reference depth to flexed surface (e.g., Moho) in m; append k for km. Must be positive. [0].

-V[level] (more ...)

Select verbosity level [c].

-fg

Geographic grids (dimensions of longitude, latitude) will be converted to meters via a "Flat Earth" approximation using the current ellipsoid parameters.

-^ 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 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 all options, then exits.