At the present time, a functioning version of simul2000 
is available via FTP at the following link:
SIMUL2000 Download
There are two versions of the code with slightly differenti input formats, one
for Suns (UNIX), the other for Macs/LINUX (MAC).
The users guide for simulps12 is included. 

IMPORTANT - send email to if you download
the code so that you can be informed of future revisions or bug fixes!

One major change is the ability to link nodes, as described in Thurber 
and Eberhart-Phillips (Computers & Geosciences, v. 25, 809-818, 1999). 

The input velocity model file can include node-linking information 
in the following form immediately after any fixed nodes are indicated:

0 0 0   [indicates end of fixed node list]
6 3 2   [master node]
2       [indicates link type - linear or constant]
5 3 2   [slave node]
0 0 0   [indicates end of slave node list]
14 3 21 [master node]
1       [indicates link type - linear or constant] 
13 3 21 [slave node]
15 3 21 [slave node]
0 0 0   [indicates end of slave node list]
0 0 0   [indicates end of linked nodes list]

This is followed by the usual velocity grid.

The other significant change is the ability to model attenuation structure. 
A "switch" controlling this option has been added - iusep 
and iuses are now followed by parameter iuseq. 

To invert for velocity, iuseq must be 0 and iusep and iuses can be 1 or 0 according to the user's needs. To invert for Q, iuseq must be 1 and iusep and iuses must be 0.
Please send comments or concerns to