Abstract

High-resolution computer simulations of earthquake sequences in three or even two dimensions pose great demands on time and energy, making lower-cost simplifications a competitive alternative. We systematically study the advantages and limitations of simplifications that eliminate spatial dimensions, from 3D down to 1D in quasi-dynamic earthquake sequence models. We demonstrate that models in any number of spatial dimensions simulate qualitatively similar quasi-periodic sequences of quasi-characteristic earthquakes. Certain coseismic characteristics like stress drop and fracture energy are largely controlled by frictional parameters and thus their overall values are observed to be comparable across models of different dimensions. However, other observations are more strongly affected by dimension reduction. We find corresponding increases in recurrence interval, coseismic slip, peak slip velocity, and rupture speed. We find that these changes are largely explained by the elimination of velocity-strengthening patches that transmit loading conditions onto the velocity-weakening fault patch, thereby reducing the interseismic loading rate and enhancing the slip deficit. This is supported by a concise theoretical framework that explains some of these findings quantitatively. Given the computational efficiency of lower-dimensional models, this contribution aims to provide qualitative and quantitative guidance on economical model design and interpretation of modeling studies.