Seismic Fault Slip Behavior Predicted From Internal Microphysical Processes. Issue 11 (15th November 2022)

• Record Type: Journal Article
• Authors: Chen, Jianye; Niemeijer, Andre R.; Spiers, Christopher J.
• Is Part Of: Journal of geophysical research. Volume 127:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-15
• Subjects: high‐velocity friction -- seismic slip -- dynamic weakening -- superplastic flow -- viscous flow; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2022JB024530
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: Earthquake simulation and hazard prediction are strongly hampered by insufficient physical knowledge of the constitutive behavior of faults. Laboratory studies of carbonate fault friction suggest that seismogenic rupture on faults in carbonate terrains can be explained by a transition from high friction at low initial sliding velocities ( V ) to low friction at seismic slip velocities, that is, by rapid dynamic weakening. One proposed explanation for this weakening, invokes frictional heating resulting in deformation by grain boundary sliding accommodated by solid‐state diffusion (sometimes referred to as "viscous" or "superplastic" flow). We recently added this dynamic weakening mechanism to a microphysically based model addressing the (rate‐and‐state) frictional behavior of granular gouges undergoing low V shear characteristic of rupture nucleation and arrest. In the present study, we applied the full model to simulate seismic slip in laboratory carbonate faults. Assuming that slip localizes in a principal shear band within the fault (gouge) zone, and accounting for grain size evolution with velocity and temperature, the model reproduces the frictional, thermal and (micro‐)structural evolution observed during seismic slip experiments. In particular, it predicts spatial and temporal evolutions of grain size, porosity, and dominant deformation mechanisms, within and outside the assumed shear band, consistent with trends identified in the laboratory and natural fault zones. Plain Language Summary: Improving the basis for earthquake hazard assessment relies in part on structural observation of natural fault zones, on laboratory experiments, and on theoretical developments. While quantitative models that reproduce the laboratory data on frictional slip on faults is the minimum necessary to simulate their mechanical behavior in nature, convincing models must ultimately also account for all key fault zone observations. Taking a fault in carbonate rock as an example, and using fundamental data on the microscale processes that lead to fault friction, this study takes a first step toward simulating the dynamic evolution and self‐organization of internal fault zone (micro)structure, processes and properties during a seismic slip event. The results show that the model captures many key observations on seismic fault behavior, paving the way for still further improvements in developing a physics‐based understanding of earthquake rupture in future.