Skip to content

Programs for Supporting Parameter Settings

fdmcond.x

The grid width in space and time in the finite difference method is controlled by the stability condition. The wavelength condition will affect the allowed maximum frequency radiated from the source.

The tool fdmcond.x can help determine these parameters to satisfy the conditions. After the user specifies several parameters, such as the grid width, maximum frequency (fmax), rise time (Tr), and minimum and maximum velocities in the medium (vmin, vmax), the program can suggest the other parameters.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
$  ./fdmcond.x 

----------------------------------------------------------------------
                           FDM CONDITION                           
----------------------------------------------------------------------


  Model Dimension ? --> 3
   1) 2D
   2) 3D


 Source Type ? --> 3
   1) Triangle
   2) Herrmann
   3) Kupper


 Parameter Combination ? --> 5
   1) dh   (space grid),  fmax (max freq.),  vmax (max vel.)
   2) dh   (space grid),  Tr   (rise time),  vmax (max vel.)
   3) dh   (space grid),  fmax (max freq.),  dt (time grid)
   4) dh   (space grid),  Tr   (rise time),  dt (time grid)
   5) dh   (space grid),  vmin (min vel.),   vmax (max vel.)
   6) dh   (space grid),  vmin (min vel.),   dt (time grid) 
   7) fmax (max freq.) ,  vmax (max vel.),   dt (time grid)
   8) Tr   (rise time) ,  vmax (max vel.),   dt (time grid)
   9) vmin (min vel.)  ,  vmax (max vel.),   dt (time grid)


 Assumed Parameters: 
   dx     =   0.25
   dy     =   0.25
   dz     =   0.25
   vmin   =   0.3
   vmax   =   8.0

 Derivaed Parameters: 
   dt    <=   0.01546
   fmax  <=   0.17143
   Tr    >=  13.41667

mapregion.x

The geographical region of the simulation will be automatically determined by the parameters clon, clat, phi, xbeg, ybeg, nx, ny, dx, and dy. The mapregion.x program reads the parameter file and exports the outer edge of the region in longitude and latitude.

1
$ mapregion.x -i input.inf -o region.dat
If the option -o is omitted, the result will be printed to the standard output on the screen. This program will also estimate the total memory usage in the standard error output.

mapregion.gmt

These scripts use mapregion.x to visualize the region by using GMT. GMT version 5 or later is necessary. By default, these scripts plot only the region around the Japanese Islands.