Off-fault tensile cracks: A link between geological fault observations, lab experiments, and dynamic rupture models

D. Ngo*, Y. Huang, A. Rosakis, W. A. Griffith, D. Pollard

*Corresponding author for this work

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

We examine the local nature of the dynamic stress field in the vicinity of the tip of a semi-infinite sub-Rayleigh (slower than the Rayleigh wave speed, cR) mode II crack with a velocity-weakening cohesive zone. We constrain the model using results from dynamic photoelastic experiments, in which shear ruptures were nucleated spontaneously in Homalite-100 plates along a bonded, precut, and inclined interface subject to a far-field uniaxial prestress. During the experiments, tensile cracks grew periodically along one side of the shear rupture interface at a roughly constant angle relative to the shear rupture interface. The occurrence and inclination of the tensile cracks are explained by our analytical model. With slight modifications, the model can be scaled to natural faults, providing diagnostic criteria for interpreting velocity, directivity, and static prestress state associated with past earthquakes on exhumed faults. Indirectly, this method also allows one to constrain the velocity-weakening nature of natural ruptures, providing an important link between field geology, laboratory experiments, and seismology.

Original languageEnglish (US)
Article numberB01307
JournalJournal of Geophysical Research: Solid Earth
Volume117
Issue number1
DOIs
StatePublished - Jan 1 2012

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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