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SUMMARY:Numerical modeling of heterogeneous asperity distributions control
 ling the growth of shear rupture on a frictional fault  
DTSTART:20160713T150000
DTEND:20160713T154500
DTSTAMP:20260919T215402Z
UID:5a0307fc7dcf4248fc8ae063a6d0e13b18749a1996fd5cab2355ac06
CATEGORIES:Conferences - Seminars
DESCRIPTION:Paul Selvadurai\, Civil and Environmental Engineering (Univers
 ity of California\, Berkeley)\nA better understanding of the strength dist
 ributions and the seismic response of asperities failing within a cohesive
  (or breakdown) region of the growing shear rupture is important in many e
 ngineering disciplines\, such as\, hydraulic fracture and induced seismici
 ty.  In the laboratory\, a fault is experimentally modeled by a 400 mm x 
 80 mm x 12 mm PMMA slider sheared across a large PMMA base plate.  \nA p
 ressure-sensitive film was employed to localize and size\, and measure nor
 mal stress upon contact junctions.  Moments prior to rapid sliding\, mult
 iple discrete and localized dynamic events (or foreshocks) were observed a
 t a section of the fault that exhibited a sparse to dense transition in as
 perity distribution.   Experiments showed that foreshocks occurred as th
 e crack (rupture front) moved into the resistive patch of densely distribu
 ted asperities. \nWe use the results of pressure sensitive film asperity 
 measurements to develop a heterogeneous finite element (FE) model that stu
 dies the effect of asperities within the cohesive region have on the expan
 ding shear crack.  Slip accumulated heterogeneously during the loading cy
 cle due to the non-uniform distribution of asperities.  We study the cons
 titutive behavior of a frictional interface where local slip is determined
  by the asperities and their ability to communicate elastically.  A fores
 hock (Mw ~ -7.4) was simulated in a quasi-static manner by instantaneously
  removing an asperity contact during the loading cycle.  The foreshock in
 creased shear stress perturbations to neighboring regions up to distances 
 of ~ 10 to 15 source radii.
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STATUS:CONFIRMED
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