Velocity-weakening friction induced by laboratory-controlled lithification

Spatial Patterns in Frictional Behavior of Sediments Along the Kumano Transect in the Nankai Trough

“…As inferred from seismological observations and numerical studies of the thermal structure at plate boundaries, frictional properties may be affected by diagenetic processes and hence variations in physical properties during subduction and accretion (Hyndman et al., 1997; J. C. Moore & Saffer, 2001; Oleskevich et al., 1999; Vrolijk, 1990). This inference is supported by laboratory experiments, which suggest that the transition from velocity‐strengthening to velocity‐weakening behavior may be caused by processes related to diagenesis or metamorphism, such as porosity reduction due to lithification (Ikari & Hüpers, 2021; J. C. Moore & Saffer, 2001; Trütner et al., 2015), or to the temperature‐dependent frictional behavior of illite‐rich materials (den Hartog et al., 2012; den Hartog & Spiers, 2013). To corroborate these observational and experimental inferences, the spatial pattern of frictional properties in a subduction zone should be evaluated using measurements on natural sediment samples.…”

“…Dissolution‐precipitation processes may cause volcanic glass to act as cement between grains and stiffen bulk sediment, preserving high porosity as observed in TF and USB facies at the Site C0006 and C0011 (Spinelli et al., 2007; White et al., 2011). Because the cementation of sediments increases the mechanical strength (Ikari & Hüpers, 2021; Schnaid et al., 2001), cementation sourced from volcanic glass may contribute to the observed difference in friction coefficient between TF/USB and MSB/LSB sediments in addition to the overconsolidation state. Cementation should increase the cohesion coefficient χ , and slightly larger χ ‐values were observed for prism toe sediments than input and inner prism sediments (Figure 3c).…”

Rapid fault healing after seismic slip

“…For example, over typical recurrence intervals of hundreds of years, fault cohesion will increase by processes such a pressure solution (30)(31)(32). Increased cohesion will not only contribute to the fault strength evolution, but will also influence the frictional stability of the gouge materials, with more cohesive materials often displaying rate-weakening behavior required for earthquake nucleation (63,64). It is plausible that transitions from rate-strengthening to rate-weakening behavior may occur as the gouge materials become more lithified during interseismic periods, potentially leading to earthquake recurrence once the frictional properties have evolved to state that promotes earthquake nucleation and unstable slip.…”

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).…”

“…Such processes are extremely relevant during the post-and inter-seismic period, when the faults are mainly locked or slowly creeping, and may act to develop the cohesive fault rocks that are abundant within the seismogenic layer (Sibson, 1977). Some experimental evidence shows that reactivation (RA) of cemented faults promotes unstable failure with large stress drops (Carpenter et al, 2014), the transition from stable to potentially unstable slip (Ikari & Hüpers, 2021), and a nearly instantaneous weakening phase (Smith et al, 2015). Furthermore, microphysical models based on pressure solution and fault fabric have been proven successful in reproducing a spectrum of slip behaviors (Chen & Spiers, 2016;van den Ende et al, 2018).…”