Article,
LABORATORY-DERIVED FRICTION LAWS AND THEIR APPLICATION TO SEISMIC FAULTING
Annu. Rev. Earth Planet. Sci., (1998)
Abstract
This paper reviews rock friction and the frictional properties of earthquake faults.
The basis for rate- and state-dependent friction laws is reviewed. The friction
state variable is discussed, including its interpretation as a measure of average
asperity contact time and porosity within granular fault gouge. Data are summa-
rized showing that friction evolves even during truly stationary contact, and the
connection between modern friction laws and the concept of “static” friction is
discussed. Measurements of frictional healing, as evidenced by increasing static
friction during quasistationary contact, are reviewed, as are their implications for
fault healing. Shear localization in fault gouge is discussed, and the relationship
between microstructures and friction is reviewed. These data indicate differences
in the behavior of bare rock surfaces as compared to shear within granular fault
gouge that can be attributed to dilation within fault gouge. Physical models for the
characteristic friction distance are discussed and related to the problem of scaling
this parameter to seismic faults. Earthquake afterslip, its relation to laboratory
friction data, and the inverse correlation between afterslip and shallow coseismic
slip are discussed in the context of a model for afterslip. Recent observations of
the absence of afterslip are predicted by the model.
