On the role of fluids in stick‐slip dynamics of saturated granular fault gouge using a coupled computational fluid dynamics‐discrete element approach. Issue 5 (3rd May 2017)

• Record Type: Journal Article
• Authors: Dorostkar, Omid; Guyer, Robert A.; Johnson, Paul A.; Marone, Chris; Carmeliet, Jan
• Is Part Of: Journal of geophysical research. Volume 122:Issue 5(2017)
• Page Start: 3689
• Page End: 3700
• Publication Date: 2017-05-03
• Subjects: CFD‐DEM -- stick slip -- granular matter -- granular fault gouge -- shear stress -- earthquake; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1002/2017JB014099
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: The presence of fault gouge has considerable influence on slip properties of tectonic faults and the physics of earthquake rupture. The presence of fluids within faults also plays a significant role in faulting and earthquake processes. In this paper, we present 3‐D discrete element simulations of dry and fluid‐saturated granular fault gouge and analyze the effect of fluids on stick‐slip behavior. Fluid flow is modeled using computational fluid dynamics based on the Navier‐Stokes equations for an incompressible fluid and modified to take into account the presence of particles. Analysis of a long time train of slip events shows that the (1) drop in shear stress, (2) compaction of granular layer, and (3) the kinetic energy release during slip all increase in magnitude in the presence of an incompressible fluid, compared to dry conditions. We also observe that on average, the recurrence interval between slip events is longer for fluid‐saturated granular fault gouge compared to the dry case. This observation is consistent with the occurrence of larger events in the presence of fluid. It is found that the increase in kinetic energy during slip events for saturated conditions can be attributed to the increased fluid flow during slip. Our observations emphasize the important role that fluid flow and fluid‐particle interactions play in tectonic fault zones and show in particular how discrete element method (DEM) models can help understand the hydromechanical processes that dictate fault slip. Key Points: The 3‐D CFD‐DEM study of slip instabilities in saturated granular fault gouge Hydromechanical effect of fluid flow on characteristics of slip events Increased mean stress drop of slip events due to fluid hydromechanical effects