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Stick‐slip and creep behavior in lubricated granular material: Insights into the brittle‐ductile transition
Author(s) -
Reber Jacqueline E.,
Hayman Nicholas W.,
Lavier Luc L.
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl059832
Subject(s) - creep , rheology , materials science , slip (aerodynamics) , brittleness , mechanics , viscous liquid , shear (geology) , composite material , strain rate , thermodynamics , physics
Crustal deformation can occur via stick‐slip events, viscous creep, or strain transients at variable rates. Here we explore such strain transients with physical experiments comprising a quasi‐two‐dimensional shear zone with elastic, acrylic discs and interstitial viscous silicone. Experiments of solely elastic discs produce stick‐slip events and an overall (constant volume) strengthening. The addition of the viscous silicone enhances localization but does not greatly change the overall pattern of strengthening. It does, however, damp the stick‐slip events, leading to transient, creep‐like behavior that approaches the behavior of a Maxwell body. There is no gradual transition from frictional to viscous deformation with increasing amounts of silicone, suggesting that the mixed rheology is in effect as soon as an interstitial fluid is present. Our experiments support the hypothesis that a possible cause for strain transients in nature is an interstitial viscous phase in shear zones.