PSGRN/PSCMP - a new code for calculating co- and post-seismic deformation, geoid and gravity changes based on the viscoelastic-gravitational dislocation theory
We present a new numerical code for modeling co- and post-seismic response of the Earth's crust to earthquakes. The code consists of two FORTRAN programs: the first program, PSGRN, calculates the time-dependent Green functions of a given layered viscoelastic-gravitational half-space for four fundamental dislocation sources [the strike-slip double-couple, the dip-slip double-couple, the compensated linear vertical dipole (CLVD) and the point inflation] at different depths. The results provide a data base for the second program, PSCMP, which automatically discretizes the earthquake's extended rupture area into a number of discrete point dislocations and calculates the co- and post-seismic deformation by linear superposition. According to the correspondence principle, the same propagator algorithm used in our previously published elastic modeling software, EDGRN/EDCMP, is adopted to compute the spectral Green functions. The temporal Green functions are then obtained by the fast Fourier transform extended with an anti-aliasing technique, that ensures numerical stability when calculating the post-seismic transients. Moreover, the new software considers the coupling between the deformation and the Earth's gravity field, so that its output includes not only the complete deformation field consisting of 3 displacement components, 6 stress (strain) components and 2 tilt components, but also the geoid and gravity changes. In particular, the gravity effect is treated using a new consistent approach that remedies an incorrect formulation used in many earlier publications. The performance of the software is shown by an example. (c) 2005 Elsevier Ltd. All rights reserved.
dislocation theory green functions laplace-hankel transform inelastic deformation the 1960 valdivia (chile) earthquake