BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Memento EPFL//
BEGIN:VEVENT
SUMMARY:CESS Seminar - Fracture Mechanics of Faults with Rate-and-State Fr
 iction: from slow to fast slip
DTSTART:20221111T121500
DTEND:20221111T130000
DTSTAMP:20260916T203827Z
UID:1956c41de0e6996a4f2552f0daa80f5e421275646783d1e197bf1b71
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Dmitry I. Garagash\, Dalhousie University (Halifax\, Can
 ada)\nAbstract\nNumerical simulations show that propagation of slip transi
 ents on a fault governed by rate-and-state-dependent friction resembles a 
 fracture whose near tip region is characterized by a large stress departur
 e from the steady-state sliding strength. This observation holds for both 
 slow-aseismic and fast-earthquake-like slip fronts. In this work\, we deve
 lop a near fracture tip solution that describes the unsteady dynamics and 
 allows to obtain a closed-form expression for the fracture energy $G_c$\, 
 associated with overcoming strength-excursion away from the frictional ste
 ady-state\, as a function of the fracture front speed $v_r$. This allows u
 s to apply the ‘small scale yielding’ concept of fracture mechanics to
  model rate-state slip transients as singular cracks characterized by the 
 simplified\, steady-state frictional resistance in the bulk of the fractur
 e\, and by a stress singularity at the fracture tip defined in terms of $G
 _c(v_r)$ [Garagash\, PTRS 2021]. As a result\, we develop an analytical eq
 uation of motion to study slip driven by a combination of uniform backgrou
 nd stress and of a localized disturbance of the fault strength characteriz
 ed by the net Coulomb force $\\Delta T$. The framework can be used to stud
 y and forecast run-out of aseismic and seismic slip on faults under either
  natural (e.g. plate tectonics) or/and anthropogenic (e.g. fluid injection
 ) forcing. For the case of a fluid injection into the subsurface in a faul
 t's proximity\, $\\Delta T$ becomes a proxy for the injected fluid volume.
  We show in the case of ongoing fluid injection\, that the propagation spe
 ed of an aseismic fault slip transient scales with the fluid injection rat
 e. And\, once the injection is stopped\, the long-term\, maximum slip run-
 out distance on the fault scales with the square of the injected fluid vol
 ume. We show that under typical injection scenarios\, aseismic slip fronts
  far outrun the pore pressure diffusion fronts\, thus\, potentially explai
 ning the triggering of distant seismicity on hydraulically stimulated fau
 lts.\n\nBio\nDr. Dmitry I. Garagash is Professor of Civil and Resource Eng
 ineering at Dalhousie University in Halifax\, Canada.  He received his BS
  and MSc in Applied Mathematics and Mechanics from Moscow State University
  and PhD in Geological Engineering from the University of Minnesota.  In 
 his research\, Dr. Garagash applies mechanics and physics principles to pr
 oblems in  Earth and environmental sciences and geo-energy engineering. 
 He studies hydraulic fracture propagation as pertains to the stimulation o
 f hydrocarbon reservoirs\, geological sequestration of liquid waste\, and 
 associated fault slip transients and induced seismicity. His other researc
 h interests are in the broader physics of the earthquake source\, from nuc
 leation to fully developed dynamic rupture\, and the underlying constituti
 ve behavior of fault gouge at slow and fast slip.
LOCATION:GC B3 30 https://plan.epfl.ch/?room==GC%20B3%2030
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR