Our research is focused on the physics of earthquakes and faulting and the mechanics of frictional sliding.  Activities include laboratory experiments, analysis of field data, and numerical studies of faulting and dynamic rupture.  Our laboratory work is focused on frictional and rheologic properties of brittle materials.  The goal of this work is to develop a set of friction constitutive laws to describe the rheology of brittle deformation.  A key part of the laboratory work has been identifying and documenting the effects of dilatancy and shear localization on second order variations in friction.  We also devote significant effort to the scaling problems inherent in applying laboratory data to seismogenic faults.  Connecting laboratory observations to field data and theoretical studies is a critical part of modern experimental studies.

Current Research

  • The mechanics of slow earthquakes and the spectrum of fault slip modes
  • Laboratory earthquake prediction and machine learning techniques for prediction
  • Precursors to laboratory earthquakes and their underlying mechanisms
  • Mechanics of the critical slip distance and application of laboratory data to seismic faulting
  • The rate of fault healing and implications for friction constitutive laws
  • Numerical studies of earthquake nucleation and dynamic rupture propagation
  • Numerical modeling of friction data and inversion for friction constitutive parameters
  • Upper stability transition on mature faults and the mechanics of earthquake afterslip
  • Frictional behavior of smectite and illite-rich clay gouges with application to the mechanics of subduction zone megathursts
  • Influence of grain characteristics on the friction of granular shear zones
  • The effect of humidity on granular friction
  • Creep and frictional behavior of laboratory fault zones subject to time-dependent fluctuations of normal and shear load
  • Friction and shear heating at high velocity
  • Effect of shear load, including true stationary contact, on frictional healing
  • Effect on frictional healing of loading rate and accumulated displacement
  • Last update: Oct 2018