SPECFEM3D

SPECFEM3D is a high-performance, open-source software package for simulating seismic wave propagation in three-dimensional heterogeneous media using the spectral-element method (SEM). It solves the time-domain elastodynamic equations for isotropic or anisotropic solids, enabling the modeling of P- and S-waves, mode conversions, and surface waves in realistic Earth-like models.

The program uses a high-order spectral-element discretization on hexahedral meshes, combining accuracy with geometric flexibility. It employs explicit time stepping and is designed to run on large-scale parallel systems. Boundary conditions include absorbing layers and free surfaces to minimize artificial reflections. SPECFEM3D supports regional to global-scale simulations and can incorporate complex Earth structures, variable material properties, and diverse source types.

Input to SPECFEM3D typically includes geometry and mesh information, material properties (density and elastic moduli, with optional anisotropy), a specified seismic source time function, and receiver locations. Output consists of time-domain seismograms at receivers, as well as volumetric snapshots and other data products for visualization and analysis. The software is commonly used to investigate earthquake physics, perform synthetic seismogram calculations for tomographic inversions, study wave propagation in heterogeneous media, and support exploration geophysics.

Development and distribution reflect a collaboration within the seismology community, with connections to researchers who introduced SEM for seismic applications. The project is maintained through public repositories and documentation, and is widely cited in scientific literature for enabling realistic 3D wave-field modeling. Licensing is open-source, with terms available in the official repository; users should consult the current terms for specifics.