High-velocity frictional properties of clay-rich fault gouge in a megasplay fault zone, Nankai subduction zone

We conducted high‐velocity friction experiments on clay‐rich fault gouge taken from the megasplay fault zone in the Nankai subduction zone under dry and wet conditions. In the dry tests, dehydration of clay minerals occurred by frictional heating, and slip weakening is related to thermal pressurizat...

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Bibliographic Details
Published in:Geophysical research letters 2010-12, Vol.37 (24), p.np-n/a
Main Authors: Ujiie, Kohtaro, Tsutsumi, Akito
Format: Article
Language:English
Subjects:
Clay minerals
clay-rich fault gouge
Continental dynamics
Dehydration
Drying
dynamic weakening
Earth sciences
Earth, ocean, space
Earthquakes
Exact sciences and technology
Fault lines
Faults
Geology
grain size segregation
Heating
high-velocity friction
Microstructure
Nankai subduction zone
Plate tectonics
Pressurization
Pressurizing
Rheology
Seismic activity
Seismic phenomena
Shear stress
Slip
splay fault
Vaporization
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Summary:We conducted high‐velocity friction experiments on clay‐rich fault gouge taken from the megasplay fault zone in the Nankai subduction zone under dry and wet conditions. In the dry tests, dehydration of clay minerals occurred by frictional heating, and slip weakening is related to thermal pressurization associated with water vaporization, resulting in a random distribution of clay‐clast aggregates in the gouge matrix. In the wet tests, slip weakening is caused by pore‐fluid pressurization via shear‐enhanced compaction and frictional heating, and there is a very weak dependence of the steady‐state shear stress on the normal stress. The resulting microstructure reflects the grain size segregation in a granular‐fluid shear flow at high shear rates. These results suggest that earthquake rupture propagates easily through clay‐rich fault gouge by high‐velocity weakening, potentially leaving the microstructures resulting from the frictional heating or the flow sorting at high slip rates.
ISSN:0094-8276
1944-8007
DOI:10.1029/2010GL046002