Formation Conditions for Nanoparticles in a Fault Zone and Their Role in Fault Sliding

Abstract

AbstractRecent high‐velocity rotary shear experiments results show that spherical nanoparticles can reduce fault friction dramatically during seismic slip. But questions like what are the roles of the nanoparticles in the whole slip are largely open problems. In this study, two types of nanoparticles were found in the Red River fault zone, including agglomerated nanoparticles in the ductile shear zone and spherical nanoparticles adjacent to the brittle faults. To ascertain the formation of these nanoparticles and explore the role of nanoparticles, the experiments under high temperature and pressure were conducted. The results of the experiments and of the previous studies suggest that the spherical nanoparticles can produce at the low temperature, which may lubricate the fault and significantly reduce the dynamic coefficient of friction. With the rise in temperature, the spherical nanoparticles are elongated or deformed to the agglomerated nanoparticles, which may no longer lubricate the fault, and lead the fault slip to slow down until it stops. Accordingly, this paper summarizes the role of these nanoparticles throughout the whole process of fault sliding.