41. Bird, P. (1999) Thin-plate and thin-shell finite element programs for forward dynamic modeling of plate deformation and faulting, Computers & Geosciences, 25, no. 4, 383-394.

Abstract. Experiments on deformation of the lithosphere can be performed only in computers. Finite element codes are best because they can represent lateral strength variations, including faults. Although variations of temperature, strength, and density in the lithosphere must be represented in three dimensions, it is usually sufficient to parameterize the velocity field in two dimensions, giving "thin-plate" or "thin-shell" codes. Four such freeware codes (LARAMY, FAULTS, PLATES, and SHELLS) are offered through my tree of downloadable files. Their capabilities include local neotectonic problems with many faults, global neotectonic problems with many plates, and finite strain problems with crust/mantle detachment; the only capability not yet available is finite strain with discrete faults of large offset. Model predictions include velocities, fault slip rates, anelastic strain rates, and vertically integrated stresses, which can be tested by comparison with data from geologic mapping, seismology, and geodesy.

P.S. Copyright restrictions do not permit placing the whole article on-line here. Read it in your library, e-mail me (pbird@ess.ucla.edu) to request a reprint, or subscribe on-line at Computers & Geosciences. P. Bird 2000.09.21

Table 1. Comparison of the Freeware Programs Offered Here
Program	Application	Reference(s)	New features	Limitations
LARAMY	western United States	Bird (1988); Bird (1989); Bird (1992)	method for convergence; two-layer grid (crust, mantle lithosphere); finite strain	flat-Earth; no faults in interior
FAULTS	California	Bird and Kong (1994)	fault elements	one-layer (crust); flat-Earth; neotectonic
PLATES	Alaska	Bird (1996)	strength of crust and mantle lithosphere combined (one-layer)	neotectonic; flat-Earth; no detachment of crust from mantle lithosphere
SHELLS	Asia	Kong (1995); Kong and Bird (1995); Kong and Bird (1996)	spherical-shell	neotectonic; no detachment of crust from mantle lithosphere
SHELLS	Earth	Bird (1998); Bird and Liu (1999)	whole-Earth	neotectonic; no detachment of crust from mantle lithosphere

See a global finite-element grid for SHELLS in animated 3-D (2.2 MB animated .GIF)