Source mechansim inversion based on 3D Greens functions:
CMT3D/ -- linearized moment-tensor inversions using 3D Greens functions (GFs). The number of GF simulations needed is the number of source parameters (9 = 6 moment tensor elements + 3 location parameters).
GRD3D/ -- grid search over strike, dip, rake and event magnitude for the best source mechanism. This is usually used to provide a a robust starting solution if the one from the catalog is not very reliable.