Rupture nucleation and fault slip: Fracture versus friction

The Role of Fault Rock Fabric in the Dynamics of Laboratory Faults

“…Furthermore, faults within the seismogenic layer also bear widespread evidence of fluid‐rock interactions (e.g., Collettini et al., 2019; Cox, 2016; Sibson, 1992; Tarling et al., 2019). These chemical processes are known to promote strength recovery and healing in granular materials (Angevine et al., 1982; Karner & Marone, 1998; Tenthorey et al., 2003), suggesting that the processes of shear failure in lithified faults are also relevant to earthquake nucleation (Cox, 2017; Ikari & Hüpers, 2021; Ikari, Niemeijer, & Marone, 2011; Muhuri et al., 2003).…”

“…Most of these rocks are cohesive, which means that the cataclastic material is chemically bound and presents resistance to deformation comparable to that of an intact rock. This is the result of both frictional and chemical healing promoted by pressure‐solution, crack‐sealing, plastic deformation at grain contacts, porosity reduction, and the precipitation of new mineral phases (Bos et al., 2000; Chester et al., 1993; Cox, 2017; Renard et al., 2000; Sibson, 1992; Tarling et al., 2018). Laboratory experiments show that fault healing and associated strength recovery can be achieved through both fluid‐assisted cementation of fault gouge (e.g., Bos et al., 2000; Muhuri et al., 2003; Tenthorey et al., 2003; Yasuhara et al., 2005), via frictional healing following plastic deformation at grain contacts (e.g., Dieterich & Kilgore, 1994; Karner & Marone, 1998; Renard et al., 2012) and welding by frictional melt immediately after the propagation of an earthquake (Hayward & Cox, 2017; Mitchell et al., 2016).…”