you can use FAULTKIN or WINTENSOR, but i think that wintensor is better for many raison, with this softawre you can calculate de R ratio and you can deduce the stress regime.
My suggestion is to use open source code in Fortran or Matlab, you can find some ones in the web. I can send you a code in Fortran to calculate the coseismic deformation from a big earthquake. My email: [email protected]