Linking grain-scale and fault-scale earthquake simulations

Ryan Payne, Benchun Duan, & David Sparks

Submitted August 15, 2016, SCEC Contribution #6932, 2016 SCEC Annual Meeting Poster #049

Geologically active faults are complex structures, marked by an interaction of many different physical processes at varying time and length scales. Much progress has been made utilizing advanced computer models as an effective way of studying the different components of these systems, however, little has been done to link various models together into a more complete and realistic simulation of the natural world. This study utilizes a dynamic rupture model along with granular dynamics simulations to examine interactions between the two scales, particularly those leading to slip and weakening.

Experiments modeling rupture along an entire fault were performed for a variety of earthquake sizes and rupture speeds. Each simulation produced normal stress perturbations on the fault – in this case induced by rupture along a bimaterial interface (a Weertman pulse) – which were then input into a granular system. The granular system models the fault gouge found in the fault core and was held under the same normal and shear stress conditions as the ruptured fault. Normal stress perturbations on the granular material were aimed at inducing slip in the grains, and capturing the weakening mechanisms at play, such as pore pressurization and acoustic fluidization.

The exact mechanisms leading to slip, or the changes that cause slip, are still poorly understood. Developing an understanding of this process relies on accurately modeling the fault-scale input and the granular reaction. By linking together the granular behavior with the larger scale fault dynamics we have the opportunity to examine relationships that previously have not been studied. Linking together two vastly different scales may be the key to understanding the physics controlling earthquake behavior.

Citation
Payne, R., Duan, B., & Sparks, D. (2016, 08). Linking grain-scale and fault-scale earthquake simulations. Poster Presentation at 2016 SCEC Annual Meeting.


Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)