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Defmod is a small, yet fully unstructured, 2D/3D, implicit/explicit, parallel, multiphysics finite element code for modeling crustal deformation over time scales ranging from milliseconds to thousands of years.

It can be used to model deformation due to dynamic and quasi-static processes such as earthquakes, volcanic rifting, viscoelastic relaxation, post-glacial rebound, poroelastic rebound, hydrological (un)loading, injection and/or withdrawal of fluids from subsurface reservoirs etc.

Defmod is written in Fortran 95 and uses PETSc's sparse data structures and solvers. Problems can be solved using (stabilized) linear tri, quad, tet or hex elements on PCs or HPC clusters. As of now, only prescribed loading is supported.

  • To download the source code, click here (zip) or here (gzip).

  • A small presentation on its capabilities, theory, and usage is available here (pdf).

Please report bugs to


A short preprint describing Defmod is available here.

Some simple utilities/scripts that users of Defmod may find useful are available here.

Chunfang Meng at MIT has developed and validated a sophisticated hybrid solver, which can simulate dynamic rupture due to quasi-static loading in poroviscoelastic media, and is useful for studying processes such as induced seismicity. He has also combined the solver with OpenSWPC, a parallel, higher-order finite difference code developed by Takuto Maeda at ERI.