EGU22-9997
https://doi.org/10.5194/egusphere-egu22-9997
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Effects of asperities and roughness on frictional slip of laboratory faults

simon Guerin-Marthe, Georg Dresen, Gzegorz Kwiatek, Lei Wang, Audrey Bonnelye, and Patricia Martinez-Garzon
simon Guerin-Marthe et al.
  • Helmholtz-Zentrum Potsdam, GFZ German Research Centre for Geosciences, section 4.2, Germany (simongm@gfz-potsdam.de)

Natural faults are heterogeneous features, with complex geometries and material properties. Understanding how the geometrical complexities of a fault affects the dynamics and preparatory phase of earthquakes is of crucial importance for seismic hazard assessment. In laboratory samples, frictional sliding along prefabricated faults may produce so called stick-slips comparable to dynamic ruptures observed during earthquakes. While the effect of roughness has been shown to influence significantly the frictional behavior of laboratory faults, there are only a few studies investigating more complex types of fault heterogeneities. In this study, we conduct friction experiments on granite with inclined sawcut faults, under a constant confining pressure of 35MPa. Samples are loaded using an axial displacement rate of 0.5 µm/s.  At  similar boundary conditions we compare the slip behavior of (1) a smooth fault, (2) a smooth fault with a single asperity, a 7 mm diameter vertical pin traversing the contact interface, and (3) a rough fault prepared by sandblasting the surface with silicon carbide. A key result of this study is that slip behavior depends on fault roughness and is influenced in a non-trivial way by asperities. The smooth fault displays unstable stick-slip as opposed to the rough fault showing predominantly creep. The smooth fault with the pin exhibits a slip behavior in-between, with very regular stress oscillations that seem to be attenuated by the presence of the pin (asperity). Only after failure of the pin, we observe the stress drop during instabilities to increase regularly with cumulative slip. We also show that in the case of a fault with a single asperity, the slip velocity is less than an order of magnitude lower compared to a similar smooth fault without this asperity.

How to cite: Guerin-Marthe, S., Dresen, G., Kwiatek, G., Wang, L., Bonnelye, A., and Martinez-Garzon, P.: Effects of asperities and roughness on frictional slip of laboratory faults, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9997, https://doi.org/10.5194/egusphere-egu22-9997, 2022.