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Acoustic emission and microslip precursors to stick‐slip failure in sheared granular material
Author(s) -
Johnson P. A.,
Ferdowsi B.,
Kaproth B. M.,
Scuderi M.,
Griffa M.,
Carmeliet J.,
Guyer R. A.,
Le Bas PY.,
Trugman D. T.,
Marone C.
Publication year - 2013
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 - 10.1002/2013gl057848
Subject(s) - shearing (physics) , materials science , acoustic emission , shear (geology) , slip (aerodynamics) , composite material , dilatant , thermodynamics , physics
We investigate the physics of laboratory earthquake precursors in a biaxial shear configuration. We conduct laboratory experiments at room temperature and humidity in which we shear layers of glass beads under applied normal loads of 2–8 MPa and with shearing rates of 5–10 µm/s. We show that above ~ 3 MPa load, acoustic emission (AE), and shear microfailure (microslip) precursors exhibit an exponential increase in rate of occurrence, culminating in stick‐slip failure. Precursors take place where the material is in a critical state—still modestly dilating, yet while the macroscopic frictional strength is no longer increasing.