Mantle Convection Modeling with Viscoelastic/Brittle Lithosphere: Numerical and Computational Methodology

The Earth’s tectonic plates are strong, viscoelastic shells which make up the outermost part of a thermally convecting, predominantly viscous layer; at the boundaries between plates the rheology is thought to be dominated by brittle processes. Brittle failure of the lithosphere occurs when stresses are high. In order to build a realistic simulation of the planet’s evolution, the complete viscoelastic / brittle convection system needs to be considered. A Lagrangian Integration point finite element method is discussed which can simulate very large deformation viscoelasticity with a strain-dependent yield stress. We also describe the general, parallel implementation of this method (SNARK) and compare the performance to a highly optimized, serial prototype code (ELLIPSIS). The specialized code shows better scaling for a single processor. The parallel scaling of the general code is very flat for “realistic” problem sizes indicating efficient use of multiple processors.