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PRODID:-//Memento EPFL//
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SUMMARY:CESS seminar series: Fluid effects in frictional faulting
DTSTART:20230317T121500
DTEND:20230317T130000
DTSTAMP:20260531T063734Z
UID:08fa318ea08c9e5566280165408747c03465f9a9cd238438abc00074
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Nadia Lapusta\, Caltech University (USA)\nAbstract\nThe 
 main effect of fluids on frictional faulting is typically expressed throug
 h an effective normal stress equal to the fault-normal stress minus the po
 re fluid pressure.  The fault frictional resistance is then given by the 
 product of the effective normal stress and fault friction coefficient.  W
 ithin this framework\, several processes can spontaneously evolve the pore
  fluid pressure\, including thermal pressurization of fluids induced by ra
 pid shear heating\, inelastic dilatancy/compaction of the shearing layer\,
  and poroelastic effects that couple pore fluid pressure with bulk deforma
 tion.  We will focus on two examples illustrating the potential dominance
  of these effects in earthquake source processes.  First\, we will show t
 hat dynamic weakening due to thermal pressurization may explain the low-he
 at\, low-stress operation of mature continental plate-boundary faults\, wi
 th the corresponding models reproducing observations of radiated energy an
 d relative paucity of small earthquake events on such faults. Second\, we 
 will discuss how the combined effects of poroelasticity and dilatancy sign
 ificantly affect the response of a fault to fluid injection.  Finally\, w
 e will show some recent experimental evidence that faults with the same ef
 fective stress display different patterns of slip\, with stabilizing effec
 ts of higher pore fluid pressure.  Modeling one of these experiments indi
 cates that the stabilizing effect is not due to dilatancy\, for example\, 
 but is likely due to changes in friction properties\, raising a possibilit
 y that the effective stress concept may not be universally applicable.  T
 hese examples highlight the need to consider fluid effects in modeling fau
 lt slip as well as the importance of determining realistic thermo-hydro-me
 chanical properties of fault zones.\n\nBio\nNadia Lapusta received her und
 ergraduate degree in Mechanics and Applied Mathematics from Taras Shevchen
 ko National University of Kyiv in Ukraine.  She continued her education a
 t Harvard University\, receiving her S.M. and Ph.D. degrees in Engineering
  Sciences in 1996 and 2001\, respectively.  Since 2002\, she has been a f
 aculty at the California Institute of Technology\, most recently as Hanson
  Professor of Mechanical Engineering and Geophysics.  She is a co-Directo
 r of the NSF I-UCRC Center on Geomechanics and Mitigation of Geohazards (G
 MG) at Caltech\, a co-Leader of the Fault and Rock Mechanics at the Southe
 rn California Earthquake Center (SCEC)\, and an AGU Fellow.  Professor La
 pusta's interdisciplinary research group works in the areas of computation
 al mechanics of geomaterials\, earthquake source processes\, fundamentals 
 of friction and fracture\, and solid-fluid interactions.
LOCATION:GC B1 10 https://plan.epfl.ch/?room==GC%20B1%2010 https://epfl.zo
 om.us/j/66511961134
STATUS:CONFIRMED
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