Dynamic rupture experiments elucidate tensile crack development during propagating earthquake ruptures

We used optical experiments and high-speed photography to interpret the origins of tensile fractures that form during dynamic shear rupture in laboratory experiments. Sub-Rayleigh (slower than the Rayleigh wave speed, cR) shear ruptures in Homalite-100 produce damage zones consisting of an array of...

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Bibliographic Details
Published in:Geology (Boulder) 2009-09, Vol.37 (9), p.795-798
Main Authors: Griffith, W. Ashley, Rosakis, Ares, Pollard, David D, Ko, Chi Wan
Format: Article
Language:English
Subjects:
cracks
dynamics
earthquake prediction
Earthquakes
Engineering geology
experimental studies
focus
fractures
Geology
laboratory studies
propagation
rock mechanics
rupture
Seismology
shear
Shear strength
Tensile strength
tension
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Summary:We used optical experiments and high-speed photography to interpret the origins of tensile fractures that form during dynamic shear rupture in laboratory experiments. Sub-Rayleigh (slower than the Rayleigh wave speed, cR) shear ruptures in Homalite-100 produce damage zones consisting of an array of tensile cracks. These cracks nucleate and grow within cohesive zones behind the tips of shear ruptures that propagate dynamically along interfaces with frictional and cohesive strength, simulating a "strong" fault. The tensile cracks are produced only along one side of the interface where transient, fault-parallel, tensile stress perturbations are associated with the growing shear rupture tip. Results of this study represent an important potential bridge between geological observations of structures preserved along exhumed faults and theoretical models of earthquake propagation, potentially leading to diagnostic criteria for interpreting velocity, directivity, and static prestress states associated with past earthquakes on exhumed faults.
ISSN:0091-7613
1943-2682
DOI:10.1130/G30064A.1