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Emergent Wave Conversion as a Precursor to Shear Crack Initiation
Author(s) -
Modiriasari Anahita,
PyrakNolte Laura J.,
Bobet Antonio
Publication year - 2018
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 - 10.1029/2018gl078622
Subject(s) - shear (geology) , coalescence (physics) , geology , amplitude , wave propagation , instability , shear waves , fracture mechanics , wave speed , surface wave , seismology , mechanics , geophysics , materials science , composite material , physics , optics , petrology , astrobiology
Geophysical assessments of subsurface instability rely on a link between physical failure mechanisms and a geophysical measurement. Here a laboratory study demonstrates the emergence of a converted phase at the damage onset in limestone prior to failure from shear crack formation. Shear ( S ) to compressional ( P ) wave conversions arise from the presence of an array of disconnected microcracks and occur prior to the crack initiation detection from surface displacement measurements. The converted waves increase in amplitude with shear crack propagation until crack coalescence. The inception of the S to P wave converted phase supports the use of elastic wave conversions as an active diagnostic tool to detect the initiation and propagation of shear cracks.