# Presentation information

[JJ] Oral

S (Solid Earth Sciences) » S-SS Seismology

# [S-SS17] [JJ] Fault Rheology and Earthquake Physics

Sun. May 21, 2017 10:45 AM - 12:15 PM A09 (Tokyo Bay Makuhari Hall)

convener:Takanori Matsuzawa(National Research Institute for Earth Science and Disaster Resilience), Takeshi Iinuma(National Research and Development Agency Japan Agency for Marine-Earth Science and Technology), Wataru Tanikawa(Japan Agency for Marine-Earth Science and Technology, Kochi Instutute for Core Sample Research), Hideki Mukoyoshi(Department of Geoscience Interdisciplinary Graduate School of Science and Engineering, Shimane University), Chairperson:Takanori Matsuzawa(National Research Institute for Earth Science and Disaster Resilience), Chairperson:Wataru Tanikawa(Japan Agency for Marine-Earth Science and Technology, Kochi Instutute for Core Sample Research), Chairperson:Hideki Mukoyoshi(Department of Geoscience Interdisciplinary Graduate School of Science and Engineering, Shimane University)

11:18 AM - 11:36 AM

# [SSS17-21] Microscopic derivation of rate- and state-dependent friction and its scaling properties

## ★Invited papers

Keywords:friction law, critical slip distance

In this talk, a scaling argument is given for the the length constant in the rate- and state-dependent friction law.
In general, the dynamic friction coefficient is not the single-variable function of the sliding velocity, as friction involves some aging processes such as frictional healing. Therefore, one needs additional variables to describe the behavior of friction coefficient. In the simpleset case, a single “state variable” is introduced to describe an aging process and the friction coefficient is described with the two variables: the sliding velocity and the state variable. This formulation is referred to as the rate- and state-dependent friction (RSF) law. It includes three important parameters and they determine the frictional stability/instability. Thus, it is widely used to understand earthquakes as the frictional instability.
Unfortunately, to this date, the RSF is purely empirical and therefore one cannot judge its applicable limit. In addition, it is not clear at all how these important parameters are determined from (or related to) the physical entity of the fault surface.
Because the macroscopic friction force is supported by microscopic junctions of protrusions, any macroscopic friction law should be derived from constitutive laws of such microscopic junctions. With this procedure one can overview the micro-macro correspondence in friction and understand the physical meaning of phenomenological parameters in an macroscopic friction law. Here we carry out this program for the RSF law; i.e., we derive the RSF from constitutive laws of the microscopic junctions. Consequently, the microscopic expressions are given of the RSF parameters such as the relaxation length Dc. The system-size dependence of the relaxation length is discussed.