gmtflexure - Compute flexural deformation of 2-D loads, forces, bending and
] ] [
] [ -CyYoung
] [ -Qargs
] [ -S
] [ -V
] ] [ -Wwd
] [ -bi
binary ] [ -d
nodata ] [
regexp ] [ -h
headers ] [ -i
flags ] [ -o
No space is allowed between the option flag and the associated
computes the flexural response to 2-D loads using a range of
user-selectable options, such as boundary conditions, pre-existing
deformations, variable rigidity and restoring force, and more. The solutions
are obtained using finite difference approximations to the differential
- Sets density for mantle, load, infill (optionally,
otherwise it is assumed to equal the load density), and water. If
ri is not given then it defaults to rl.
- 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 instead (by default D
is computed from Te, Young's modulus, and Poisson's ratio; see
-C to change these values). Alternatively, supply a file
with variable plate thicknesses or rigidities. The file must be
co-registered with any file given via -Q.
- Sets the boundary conditions at the left and
right boundary. The bc can be one of four codes: 0 selects
the infinity condition, were both the deflection and its slope are set to
zero. 1 selects the periodic condition where both the first and third
derivatives of the deflection are set to zero. 2 selects the clamped
condition where args (if given) sets the deflection value  (and
its first derivative is set to zero), while 3 selects the free condition
where args is given as moment/force which specify the
end bending moment and vertical shear force [0/0]. Use SI units for any
- Change the current value of Poisson's ratio [0.25].
- Change the current value of Young's modulus [7.0e10
- Set a constant horizontal in-plane force, in Pa m 
- Sets the vertical load specification. Choose among these
three options: -Qn means there is no input load file and that any
deformation is simply driven by the boundary conditions set via -A.
If no rigidity or elastic thickness file is given via -E then you
must also append min/max/inc to initiate the
locations used for the calculations. Append + to inc to
indicate the number of points instead. -Qq[loadfile] is a
file (or stdin if not given) with (x,load in Pa) for all equidistant data
locations. Finally, -Qt[topofile] is a file (or stdin if not
given) with (x,load in m or km, positive up); see -M for topography
unit used [m].
- Compute the curvature along with the deflections and report
them via the third output column [none].
- Supply a file with pre-existing deformations [undeformed
- Specify water depth in m; append k for km. Must be positive
. Any subaerial topography will be scaled via the densities set in
-D to compensate for the larger density contrast with air.
- Specify reference depth to flexed surface in m; append k
for km. Must be positive . We add this value to the flexed surface
- -V[level] (more ...)
- Select verbosity level [c].
- -bi[ncols][t] (more ...)
- Select native binary input.
- -d[i|o]nodata (more ...)
- Replace input columns that equal nodata with NaN and
do the reverse on output.
- -e[~]"pattern" |
-e[ ~]/regexp/[i] (more ...)
- Only accept data records that match the given pattern.
- Skip or produce header record(s).
- Select input columns and transformations (0 is first
- -ocols[,...] (more ...)
- Select output columns (0 is first column).
- -^ 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.
option controls the units used in all input and output files.
However, this option does not
control values given on the command line
to the -E
, and -Z
options. These are assumed to be in
meters unless an optional k
for km is appended.
We solve for plate flexure using a finite difference approach. This method can
accommodate situations such as variable rigidity, restoring force that depends
on the deflection being positive or negative, pre-existing deformation, and
different boundary conditions.
To compute elastic plate flexure from the topography load in topo.txt
for a 10 km thick plate with typical densities, try
gmt flexure -Qttopo.txt -E10k -D2700/3300/1035 > flex.txt
gmt, gravfft, grdflexure, grdmath
2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe