interact uses dc3d.f as provided by Y. Okada as in Okada (BSSA,
1992), has .f90 code converted from Nikkhoo and Walter (GJI,2015),
linear algebra routines from SLATEC, LAPACK, and EISPACK. Might
contain other copyrighted material by others (e.g. Numerical
Recipes). Petsc implementation based on Dave May's examples and
assistance, and .m to .f90 conversion for slip inspired by code by
P. Bird.
See files INSTALLATION, README.md, and help.txt for
documentation and COPYRIGHT and COPYING for the license and
warranty disclaimers.
If you use interact please cite the following
@Article{becker02c,
author = {Becker, T. W. and Schott, B.}, title = {On boundary-element models of elastic fault interaction (abstract)}, journal = {EOS Trans. AGU}, year = 2002, volume = 83, number = 47, pages = {NG62A-0925} }
Copyright (C) Thorsten W. Becker 2000 - 2023
This directory contains source codes needed to compile the elastic 2-D
and half-space dislocation program interact as well as several tools
that go with it.
To compile, edit the makefile as described in the INSTALLATION
document and type make. The default might have some extra packages
included, and sources a number of other files. For the simplest
compile, try make -f makefile.simple, which should work out of the
box, without any extra packages besides EISPACK (that should get
compiled automatically, as provided).
General settings as to the operation of interact are set in
makefile, material properties such as the shear modulus are set in
properties.h, and all system-dependent settings should be changed in
makefile.gcc or similar. The reasoning behind this setup is that
you are not likely to change the, say, shear modulus very often
because it simply affects the scaling. Likewise, you will also not
want to change the way interact works that frequently, so we hardwire
several options to avoid calls to IF statements for efficiency. After
compilation, the operation of interact is affected by command line
arguments and input files.
For documentation, use program -h after compilation, and refer to
the numerous comments in the source code as well as in the
makefiles. The output of interact -h is supplied as the file
help.txt.
The example.?.txt files describe some simple example calculations to, hopefully, elucidate the usage of interact and affiliated programs. (See our Fall 2002 AGU poster at http:///www-udc.ig.utexas.edu/external/becker/agu02_disp.pdf).
Typing make will compile most programs, see the makefile. If you
want all tools, type make really_all.
A list of the programs that will be compiled and several batch scripts
that are provided in addition follows with short descriptions what
they do. For each program, more information can be obtained by typing
program -h.
IN PARTICULAR, THE INPUT FORMATS ETC. ARE DESCRIBED WHEN TYPING
interact -h
interact: reads in fault geometry and boundary conditions. Can do a one-step calculation where a system of equations is solved based on boundary conditions in stress and/or displacement on the rectangular fault patches. BCs can have non-negativity constraints, e.g. motion only in one direction. Program can also simulate a loading experiment where patches behave according to a friction criterion (so far, only Coulomb with static and kinetic friction is implemented).
makefault:
produces regular fault segments based on input
parameters such as strike that can be selected on the command
line with arguments like -strike 32. output is in the
geom.in format.
points2patch: convert four points defining a rectangle in 3-D to a best fitting, Okada type fault patch
patch2xyz: converts a patch file (with fault segments) into a file that holds the geometry in a xyz file to be read with GMT (<5)
patch2vtk: converts a patch file (with fault segments) into a VTK file
create_random_stress_file: create fsi.in input file for interact which holds randomly distributed initial values for the strike, dip and normal stress components for each patch of the fault system.
create_random_mu_file: create fp.in input file for interact which holds randomly distributed initial values for static and dynamic friction coefficients each patch of the fault system.
randomflt: produces randomly oriented and sized fault patches in patch format
randomize_strike: reads in locations for future faults and randomizes the strike, optionally the dip and depth alignment to. output in patch format.
pgeom: (GMT batch script) plots the GMT xyz file produced by patch2xyz in 3D using a GMT batch command file
pgeom2d: (GMT batch script) plots 2D projection of the GMT xyz file produced by patch2xyz
project_stress: projects a stress tensor (six components) into a fault local system where the traction vector is resolved onto the local strike, dip, and normal vector
calc_eigen_from_cart_stress: calculates the eigensystem of a given cartesian stress matrix
calc_cart_from_eigen_stress: convert a given stress state in principal axis to a cartesian stress matrix
i) plotting or data analysis
pdisp: (batch script) plots displacement fields as produced by one-step calculations with interact
peventfile: (batch/gnuplot script) plots the cevents.dat file that holds individual rupture events produced by a loading simulation with interact
pfstress: plots the stress and slip on a fault as a function of time, read flkt.*.dat files
plotevents: (only if PGPLOT support included) reads a binary event file produced by interact and plots the activations using PGPLOT
plotgr: (batch script) reads the cevents.dat file that holds individual rupture events produced by a loading simulation with interact and plots a Gutenberg Richter statistic
pslip: (GMT script) plots slip on the patches that belong to a certain fault group. useful for one-step calculation when solving for slip subject to stress boundary conditions.
ii) input/output conversion
patch2bc: converts a patch file (with fault segments) into a file that hold boundary condition input based on the orientation of faults.
patch2corners: converts a patch file (with fault segments) into a file that holds the four corners of the fault patch as (x,y,z) triples
patch2group: converts a patch file (with fault segments) into a file that holds the group geometry (can be made up of several patches) in patch format
patch2xyzvec: converts a patch file (with fault segments) into a file that holds the corner coordinates and basis (strike, normal, dip) vectors
read_bin_events: reads in binary events from an interact loading simulation and writes the ASCII equivalent to stdout.
sort_events: reads in cevents.dat file and sorts for fore- and aftershocks
patchquad2patchtri: converts rectangular patches into triangles
tri2patch: convert three points defining a triangle in 3-D to internal format.
iii) interaction matrix related
calc_interaction_matrix:
calculates the interaction matrix which holds the Green's
functions coefficients for stress change of type l on fault i
due to slip of fault j of type k. input is a file in the
patch format. writes the result to file, and prints to the
screen if matrix is small (nrflts<100)
check_feedback:
calculates the interaction matrix for a fault system as
described by a file in the patch format and checks for
interactions between patches that would lead to a positive
feedback loop. this can arise when the coulomb stress changes
on another patch are larger than the reduction of coulomb
stress on the patch itself. this is an effect of the
discretization, on average stresses of groups of patches will
always be OK.
Output from interact -h follows (run code for updated versions!)
main: binary: interact
main: compiled for double precision on Apr 9 2023 at 19:29:33, initializing
init: version:
Interact: calculate fault stresses and displacements in a half space or in 2-D using a boundary element approach.
Program reads in fault patch geometries (usually rectangular) and either solves
for stresses and/or displacements in a one-step problem for various boundary
conditions (sign-constrained or unconstrained), or for a simulated loading
cycle where each patch follows a frictional constitutive law (e.g. Navier-Coulomb)
and repetitive rupture is allowed during continuous plate-tectonic loading.
WHEN STRESSES (STRESS TENSOR COMPONENTS) OR PRESSURE ARE REFERRED TO, POSITIVE VALUES MEAN EXTENSIONAL AND COMPRESSIONAL REGIMES, RESPECTIVELY (PHYSICS CONVENTION).
Output is written to files and in real-time to X11 if PGPLOT support was compiled in. (PGPlot support was compiled in.)
PetSc support was compiled in, providing limited access to parallel solves for one-step problems. For LU solve, use "-pc_factor_mat_solver_type scalapack -mat_type scalapack" or "-pc_factor_mat_solver_type elemental -mat_type elemental". For iterative solve "-ksp_type fgmres -pc_type none -ksp_max_it 10000 -ksp_rtol 1.0e-8" or "-ksp_type fgmres -pc_type jacobi -ksp_max_it 10000 -ksp_rtol 1.0e-8". Check the makefile for other solver options and MPI settings. When running a one-step computation, will also compute stress fields in parallel.
(1) The fault geometry is input via the file geom.in,
a list of fault patches.
This file has the following (patch) format for rectangular faults or point sources
(free format ASCII list of parameters):
x_0 y_0 z_0 strike_0 dip_0 hlength_0 hwidth_0 group_0 ...
x_1 y_1 z_1 strike_1 dip_1 hlength_1 hwidth_1 group_1 ...
...
x_N-1 y_N-1 z_N-1 strike_N-1 dip_N-1 hlength_N-1 hwidth_N-1 group_N-1 ...
Here, N is the total number of patches and
- x,y,z are the coordinates of the center of the rectangular fault patch or
in the case of a point source, the point source location.
- strike and dip are fault plane orientation angles in degree
strike is defined in degrees clockwise from North
dip is defined in degrees downward from the horizontal, 90 degrees means vertical fault
note that right now, the geometrical rake has to be 90 or 0 degrees, i.e. no tilted rectangles
slip can, however, have a rake as given by different along-strike and along-dip values, see below
- hlength (L) and hwidth (W) are the patch's -->HALF<-- length and half width in
strike and dip direction, respectively. The patch area is thus 4LW.
- group is the patch's fault group, a number that is used to define faults that consist of
several patches (discretizing fault planes by rectangular elements) (0 <= group <= N-1))
- ... at the end mean possible additional input, see below.
If you would like to use the 2-D mode, point sources or triangles, recompile with ALLOW_NON_3DQUAD_GEOM flag set.
Examples:
0 0 -1 30 90 4 2 0
for a rectangular, vertical fault patch centered at depth -1, striking 30 degrees from North
with length 8 and width 4, patch group number is 0.
Please note that there are various programs to convert to and from the above patch format,
e.g. patch2xyz to go to GMT style xyz coordinates for the edges of each patch,
patch2vtk to go from patch format to (paraview) VTK format, or
points2patch to convert a set of four points in FE ordering to the above patch format.
(2) Boundary conditions and the operational mode are input via the bc.in file
which has the following format (free format ASCII list of parameters):
operational_mode:
1: one step calculation
2: loading simulation, and
3: loading simulation and x window plotting.
IF ONE STEP CALCULATION IS CHOSEN, the following input fields should be
print_bulk_fields
If print_bulk_fields is set to 0, no stress or displacement fields will be output.
If print_bulk_fields is set to 1, the program will read in the boundaries from the next line
xmin xmax n ymin ymax m zmin zmax o
where n, m, and o are the number of samples between the given limits.
If o is set to -1, the output will be in a plane with the
average strike and dip direction of fault group 0. x/y min/max are then the
limits in strike and dip direction.
If o is set to -2, the output will be in a plane with the
average strike and normal direction of fault group 0. x/y min/max are then the
limits in strike and normal direction.
In these cases, the coordinates in the output files will correspond to the local,
rotated systems, e.g. for -2, x will go along strike, and y along the normal direction
with respect to the average fault patch geometry, with origin in the center of the fault
group. HOWEVER, the displacements and stresses will still be given in the old system!
If the -pc switch is set, the global coordinates will be printed to `plane.xyz`
If print_bulk_fields is set to 2, the program will read the output locations from file `oloc.dat`
This file has the x, y, and z coordinates in ASCII as an unformatted list.
patch_number boundary_code boundary_value
patch_number runs from 0 to N-1, where N is determined from the number of patches
(fully read lines, unformatted) in the geometry file.
If patch_number < 0, then the line should instead read
-increment start_fault stop_fault boundary_code boundary_value ... ...
and boundary code boundary_code will be assigned with value
boundary_value from start_fault to stop_fault with increments increment.
If start_fault < 0 and stop_fault < 0, will select all patches.
The patch_number ... boundary_value line can be repeated as often as necessary (say, twice for each fault
if the strike and dip movement modes are to be activated the same time).
Possible boundary conditions (as indicated by their integer codes) are:
(A) 0, 1, 2: slip on fault specified (if called several times, will add up) 0 means strike, 1 dip, and 2 normal direction
For strike: positive values of slip mean left-lateral fault, negative right-lateral;
this corresponds to a resulting drop resp. increase in the strike component of stress.
(We use stress values with signs, that is a negative stress drop corresponds to a
reduction of positive shear stress, a positive stress drop to reduction of shear
stress with negative sign. Both times, the absolute value of the shear stress is
reduced).
For dip: positive values of slip mean thrust fault, negative normal fault;
this corresponds to a resulting drop resp. increase in the dip component of stress.
For normal: positive values of slip mean explosive source, negative implosive;
this corresponds to a resulting drop resp. increase in the normal component of stress.
(B) 10, 11, 12 or 20, 21, 22 or 30, 31, 32: stresses are specified
where the following codes indicate the degree of freedom for the faults to
achieve that stress starting from 0
10 strike slip, either way
11 strike slip, left lateral (stress drop bc usually < 0 for activation)
12 strike slip, right lateral (stress drop bc usually > 0 for activation)
20 dip direction, either way
21 dip direction, thrust (stress drop bc usually < 0 for activation)
22 dip direction, normal (stress drop bc usually > 0 for activation)
30 normal direction, either way
31 normal direction, explosive (stress drop bc usually < 0 for activation)
32 normal direction, implosive (stress drop bc usually > 0 for activation)
If any of the strike or dip modes (10, 11, 12 or 20, 21, or 22) are given as
(110, 111, 112 or 120, 121, or 122) instead (add 100) this means
that the target stress should be corrected by the change in normal
stress times the dynamic coefficient of friction (makes sense for Coulomb type rupture).
(C) 50, 51, 52: read in background loading (see -l, NOT -s), reduce resolved stresses on faults
50 such that faults are shear-stress free after slip in strike and dip directions
51 or such that the shear stress is given by the static friction coefficient
times the normal stress, after slip in strike and dip direction
52 or such that faults are shear stress free after slip in strike direction only
For the above two cases, the BC value (the last number) is meaningless.
NOTE: The final stresses, e.g. in flt.dat, after slip will correspond to the stress drops
needed to reduce the background load as specified above. The stresses will NOT include
the resolved background stresses since those are only used to initialize the problem
as boundary conditions. I.e. add the resolved background shear stress to the shear stress
specified in flt.dat stress to get shear stress free conditions for the 50 case, for example.
For debugging, the resolved shear, dip, and normal stresses for each patch will be written to `rstress.dat`.
Mixed boundary conditions: If you want to mix specified slip boundary conditions with stress
boundary conditions, slip has to be completely specified first such that subsequent stress conditions
can take the stress changes induced by the slip into account.
Example:
1 1
-5 5 51 -5 5 51 -1 -1 1
-1 -1 -1 10 1
IF LOADING SIMULATION IS CHOSEN (with or without X output)
the first three numbers are:
time_step print_interval stop_time
where time runs from 0 to stop_time in base time steps of time_step and the program will print to fault files every print_interval intervals.
The time_step will normally be adjusted (but see -ct) based on the program's prediction of the next rupture time or change in shear stress sign. The max step is given by print_interval to ensure frequent enough output to the flt.*.dat files. The minimum time step was set to 1e-15. Time has to monotonously increase from zero.
If X windows output is chosen, the next line (two numbers) should read
x_plot_interval x_scroll_interval
where x_plot_interval and x_scroll_intervals give the timing for the map view and time vs. x plots, respectively.
All following lines assign active modes to faults and are of format:
patch_number activation_mode_code
where fault numbers should be given from 0 to N-1, N being the number of patches. If patch_number < 0 then give
-increment start_fault stop_fault activation_mode_code
instead. If start_fault<0 and stop_fault<0 will select all patches, as above.
Activation_mode_codes are: 0 inactive(default) 10 strike slip, either way 110 strike slip, Coulomb correction, either way 11 strike slip, left lateral 111 strike slip, Coulomb correction, left lateral 12 strike slip, right lateral 112 strike slip, Coulomb correction, right lateral 20 dip direction, either way 120 dip direction, Coulomb correction, either way 21 dip direction, thrust 121 dip direction, Coulomb correction, thrust 22 dip direction, normal 122 dip direction, Coulomb correction, normal 30 normal direction, either way (not implemented yet) 31 normal direction, explosive (not implemented yet) 32 normal direction, implosive (not implemented yet) 40 maximum stress direction in strike/dip plane 140 maximum stress direction in strike/dip plane, Coulomb correction
If Coulomb correction is set, the modes that involve slip in strike and dip direction will result in a correction for normal stress changes, assuming that the target stress drop is modified by the product of normal stress change during slip and the dynamic friction coefficient.
NOTICE: Program maintains normal (opening) modes. If this is not needed, recompile with the NO_OPENING_MODES switch set to save memory.
PARAMETERS:
Elastic and frictional law properties are hard-coded and should be set in the properties.h file.
Whenever you want to change those, you will have to recompile the program. This was done to improve
the execution speed, assuming that material properties will not change between different model runs.
In the following, we will refer to two different matrices, A and I. The interaction, or I, matrix is assembled once for the loading simulations and holds all possible stress influence coefficients for all combinations of patch slips for a given geometry. I is typically held in memory and can be quite big, depending on the problem. Hence, there is the option to store a reduced, sparse version of I. If patches are activated (slipping) during a loading simulation (according to their frictional law), a system of equations A x = b is set up to solve for the slip vector x that corresponds to the target stress drop. This A matrix is also the only matrix that is assembled for a one-step calculation as we specifically know the patch/boundary conditions we have to consider in this case. There are several possible modes for solving completely unconstrained A x = b systems; constrained systems (where some entries in x have to be >=0 for unidirectionally constrained slip) are always solved with a direct implementation of Lawson and Hanson's solver.
The following parameters can be set to non-default values on the command line:
-
-c value sets the cohesion term of the friction law to value, by default: 5 If the cohesion=0 at all times, recompile with NO_COHESION set to improve speed. (Stress drop is set to 1, which is 0.0001 times mu).
-
-pr value set the background pressure to value
value. The background pressure amplitude is 10 by default, both for one-step and loading simulations. The pressure is constant with depth (see properties.h). -
-ms value set minimum stress drop to value
value. (Characteristic stress drops are set to 1.) The minimum stress drop is zero by default, ie. allowing stress drops of all sizes (loading simulation). -
-ei value set matrix cutoff value for sparse storage of I or A in absolute values (5.000000e-05 by default.) (only used if I matrix is stored as sparse, see -nd option, or for sparse Ax=b solver.)
-
-wc value will use value as the maximum fraction of singular value for an SVD solution (default: 7.00e-15)
OPTIONS:
The following operational modes (switches) can be switched on or off by using the toggle options listed below (type, eg, interact -s) Please read carefully which switches are ON by default. If those active switches are selected, they will be switched OFF instead.
-
-s read in initial stress values for each fault from file
fsi.in, format:s_strike^0 s_dip^0 s_normal^0 s_strike^1 s_dip^1 s_normal^1 ...
(repeated for each patch). Here, the s_i are the initial values of the stress tensor resolved on the fault slip directions. All values are ADDED to the homogeneous background stress as set in the program, ie. use all zeros for normal initial stress state. (loading simulation) --> WARNING: This option will only work for the loading simulation mode, for one-step calculations specify fault stresses as individual boundary conditions, or use -l to get a resolved background stress.
ON by default, if switch is set will be OFF.
-
-f read in fault properties from file
fp.in, so far only parameters for the friction law are supported. Format:mu_static^0 mu_dynamic^0 mu_static^1 mu_dynamic^1 ...
(repeated for each fault). Static and dynamic coefficients of friction for Coulomb. ON by default, if switch is set will be OFF.
-
-i suppress all interactions between fault patches except the self-effect of slip on any patches within the group that the patch belongs to and the effect of slip on the number 0 master group (this should be the main fault). (Meant as a experimental feature for LOADING SIMULATIONS ONLY!) OFF by default, if switch is set will be ON. See -ni for suppressed interactions in one step.
-
-ni suppress all interactions between faults except the interactions of fault patches
-
-ct use constant time steps for the loading simulation OFF by default, if switch is set will be ON.
-
-b suppress output of all fault stress and slip data. Normally, individual output files for each group of faults are generated when the number of groups is smaller than 50. If -b is set, this maximum number will be set to zero.
-
-p prints information about the cumulative slip of every patch in a group to the slipline.*.dat files if the fault files are used (see -b). (loading simulation) OFF by default, if switch is set will be ON.
-
-w whole fault activation mode (loading simulation) If set, one patch will activate all patches in the group for sliding. Also, if one patch is switched off because of low normal stress, all patches in the group will be switched off as well (unless -v is set). OFF by default, if switch is set will be ON.
-
-k keep slipping mode (loading simulation) If set, the first critical patches can trigger slip on other patches. If so, the initial patches will keep slipping, and the solution is obtained at each iteration until no more triggering takes place. If not set, slip on triggering patches is exhaustive, and iteration checks for triggering step by step (faster, since old solution doesn't have to be removed from stress field). The exhaustive method is affected by tiny differences in critical stress! If keep slipping, critical stress is -7.000000e-15, else -7.000000e-15. ON by default, if switch is set will be OFF.
-
-v whole fault deactivation mode (loading simulation) If set (and -w is not set), the deactivation (low compressive normal stress) of a patch will lead to a deactivation of the whole fault group. If -w is on (whole fault activation mode), this is the default. If you use -v in this case, the whole fault de-activations will be suppressed. OFF by default, if switch is set will be ON.
-
-l reads a/b factors for the linear background loading stress relationship. If set, the file
smlin.inis read, it should hold 6 pairs of a_i b_i factors where the non-hydrostatic background stress at time t is given by s_i=a_i+b_i*t s_i = {s_xx, s_xy, s_xz, s_yy, s_yz, s_zz}, so that the format isa_xx b_xx a_xy b_xy ... a_zz b_zz
To these factors, a depth independent hydrostatic pressure of 10 will be added. You can change the amplitude of the pressure (e.g. to zero) with -pr.
If no factors are read in (if
smlin.inis not found), the code will use simple shear loading with b_xy=1 plus the depth independent hydrostatic pressure of 10.(Modify pressure amp. with -pr). If you want to specify resolved background stresses in a one-step calculation, simply use the a_i factors to specify the stress at time t=0 but mind the hydrostatic part.
ON by default, if switch is set will be OFF.
-
-nd switches to sparse matrix I storage, no matter what the I matrix size is. By default, the program goes from dense to sparse only if the matrix is bigger than 8000 MB. The sparse matrix storage implies that matrix elements whose absolute value is less than 5.000e-05 are discarded. This behavior can be changed by specifying a different cutoff value using the -ei parameter option. (Make sure to use -si if you want to keep the matrix.) OFF by default, if switch is set will be ON. note that sparse here refers to only the storage mode of the I matrix, not the solution method of A.x=b. (see -ss).
-
-ci checks the interaction matrix for positive Coulomb stress feedback loops, once calculated This may be useful for loading simulations. OFF by default, if switch is set will be ON.
-
-si saves the interaction (I) matrix during a loading simulation, if I is written to a file during runtime and not held in memory. Else,
/tmp/iand/tmp/i.hdrwill be deleted. OFF by default, if switch is set will be ON. -
-oi reads old interaction (I) matrix from files
/tmp/i.datand/tmp/i.hdr. Saves time when the geometry does not change between subsequent model runs (this is not automatically checked!) (Make sure to use -si if you want to keep the matrix.) OFF by default, if switch is set will be ON. -
-sa saves the A x = b A matrix to
a.datanda.dat.hdrduring a one-step calculation. Binary format, with dimensions (n x m) and precision (p, in bytes) in the header file as n p m OFF by default, if switch is set will be ON. -
-oa reads A matrix from files
a.datanda.dat.hdrduring a one-step calculation. Saves time when A does not change between subsequent model runs (this is not automatically checked!) (Make sure to use -sa if you want to keep the matrix.) NOTE that A is only constant for a constant geometry and the boundary conditions are either pure slip or pure stress components. If you are specifying a Coulomb stress change, elements of A will be modified by the boundary conditions, and not only b as one might think! OFF by default, if switch is set will be ON. -
-r attempts to restart a loading simulation model run based on previous results WARNING: all result files will be overwritten NOT appended, so save before. For this to work,
geom.inandbc.in(and possiblyfsi.inandfp.inshould not be substantially changed.Slip events from the previous run in the format as in the output file
events.binwill be read in from the restart event filerestart.events.bin -
-sn will print NaN values in displacement and stress outputs of the one-step calculation. Normally, those locations (end patch/segments) yielding one or more inf values in the stress matrix or the displacement vector will be omitted during output. OFF by default, if switch is set will be ON.
-
-pc will print the global coordinates if fault-local planes are chosen for bulk stress and displacement output (-1 or -2 for o in zmin zmax o), writes xyz to
plane.xyzON by default, if switch is set will be OFF. -
-sv uses SVD solver for the unconstrained A x = b system. This approach should reliably find the least-squares minimum norm solution if the A matrix is singular. Note that LU can be orders of magnitude faster than SVD but use caution. If non-negative solutions are sought (as for specified slip directions), the program will automatically default back to the NNLS solver.
-
-sl uses LU solver for the unconstrained A x = b system (default). LU can be orders of magnitude faster than SVD, but use caution. If non-negative solutions are sought (as for specified slip directions), the program will automatically default back to the NNLS solver.
-
-d run in debug mode OFF by default, if switch is set will be ON.
-
-h prints out this help message and exits to the operating system
(C) Thorsten Becker, [email protected], 1999 - 2023) interact - boundary element code for elastic half-spaces 3-D quad dislocationS based on Okada (BSSA, 1992). 3-D triangular dislocations based on Nikkhoo and Walter (GJI, 2015). 2-D segment slip solution from Crouch and Starfield (1973). May include routines based on copyrighted software of others. Distributed under the GNU public license, see "COPYING".